Provided by: shapetools_1.4pl6-14_amd64 
NAME
shape - identify and build program configurations from versions of source objects
SYNOPSIS
shape
[ -f <description file> ]
[ -R <version selection rule> ] [ -V <variant name> ]
[ -echo <macro name> ] [ -force <target> ] [ -rebuild <target> ]
[ - dDehiknprs ]
[ -bct ] [ -help ] [ -nomsg ] [ -novclass ] [ -version ] [ -xpoff ] [ -xpon ]
[ target1 target2 ... ] [ macro=value ... ] [ macro+=value ... ]
DESCRIPTION
Shape allows to transparently compile source objects that are either regular files, or source object
versions in the ShapeTools version object base. More generally, shape produces a set of derived objects
(``targets'') from appropriately selected versions of corresponding source objects according to a
description of the dependencies between the objects. Shape keeps track of the relevant parameters for
compilations (source versions, compiler versions, compiler switches etc.) and thus provides a safe and
efficient build machinery.
When shape compiles source objects, it stores the resulting derived objects together with the effective
compile parameters in its derived object cache. Before the derivation process for a requested object is
actually started, shape attempts to find an existing derived object that matches the requirements for the
target, in the derived object cache. Caching and restoring of objects that are derived from immutable
versions allows developers to profit from previous builds by other team members. Overall compile costs in
projects are substantially reduced.
When serving a build request, shape considers a possibly large number of versions that are stored for an
object. Which particular version is bound to an object's name in the description file, is determined by
version selection rules.
Shape can manage builds of different variants of a system in parallel. Shape uses the combined potential
of dynamic version selection, dynamic macro redefinition, and derived object management to handle variant
builds. As most - if not all - of the objects and parameters involved in a build are defined as macros,
shape provides a great deal of flexibility by allowing to alter some or all of the macros dynamically,
depending on which variant shall be built. The concept of variant definition in shape's description file
offers a clear focal point for all definitions that are relevant for a certain variant.
OPTIONS
-f <description file>
shape uses the supplied argument as name of the description file to be used for the build. If no
-f option is specified, shape tries to find a description file under one of the names
``Shapefile'', ``shapefile'', ``Makefile'', and ``makefile'' (from left to right). If no regular
file with one of these names can be found, but versions of respective files are available in the
version object base, shape will use the most recent version. When more than one -f <description
file> argument pair appears, shape reads each description file in turn. If the name of the
description file is specified as ``-'', shape will read the system description from standard
input. It is possible to specify the description file in bound version notation, e.g.
Shapefile[2.8] or Shapefile[Release4] (see vbind(1) for details about bound version notation).
-R <selection rule name>
activates the specified selection rule as initial version binding for source objects. If the -R
option is present, and a selection rule is defined as the first dependency of the first target,
shape will use the selection rule passed via the command line, and ignore the first (and only the
first) selection rule activation within the description file. The option is useful to override
initial default selection rules, specified within the description file, from the command line.
-V <variant name>
activates the variant specified by <variant name>. Several variants can be activated
simultaneously from the command line by specifying the -V option multiple times. All variant
specific definitions will be in effect as soon as shape reads the corresponding variant definition
in the description file.
-force <target>
forces shape to build the specified target unconditionally, i.e. even if a suitable, previously
build object exists.
-echo <macro name>
the value of the macro <macro name> is written to standard output. This option is useful to
extract information from the system description file (e.g. shape -echo SOURCES, or shape -echo
SUBSYSTEMS), or to control the effect of variant activations.
-rebuild <target>
attempt a precise rebuild of target according to a bound configuration thread, supplied in a file
named <target>.bct (see description of -bct switch).
-d run shape in debug mode. Print out detailed information about object dependencies and attributes.
-D print detailed information about the version binding process, and shape's reasoning regarding
(re)builds of targets, or retrievals from the derived object cache. This switch is useful to find
out about the exact reasons, why shape rederives a target (or not).
-e macro definitions that are imported from the environment (see description of special macro IMPORT,
below) override macro definitions in the description file (by default, macro definitions in the
description file have precedence over imports from the environment).
-h print usage information on standard output (this is an abbreviation for the -help switch, see
below).
-i ignore error codes returned by commands.
-k when a nonzero error status is returned by an invoked command, the work on the current target is
abandoned but shape continues with other branches that do not depend on the failed target.
-n no execution mode. Shape prints out commands, but does not execute them. Even command lines
beginning with @ are printed. If a command contains the $(MAKE) macro reference, however, that
line is always executed in order to allow tracing of recursive build processes.
-p print out the complete set of macro definitions, target descriptions, and rule definitions,
respectively.
-r do not use shape's built-in implicit rules. Implicit rules defined in the description file remain
in effect.
-s run in silent mode. Shape does not print out the commands before executing them.
-bct record the build in a bound configuration thread file. A shape configuration thread contains
precise definitions of all source versions, their dependencies, the involved tools, and related
options that were in effect for a build. The configuration thread for a produced toplevel target
(the first target in the description file, or a target requested from the command line) is stored
in a file named <target>.bct. Bound configuration threads can be used as input for rebuilds (see
option -rebuild, above). If the source version context of a bct-build is unsafe, shape will record
that fact in the bct, and issue a warning message.
-help print usage information on standard output.
-nomsg turn off the trace facility msg in version selection rules.
-novclass
disable checking for incompatibility of activated variants.
-version
print the version identification of the shape program.
-xpoff turn off attribute expansion in source versions retrieved from the object base. By default,
attribute expansion is turned on for all source objects that are directly retrieved from the
object base, and turned off for source objects that are regular files (see retrv(1) for details
about attribute expansion).
-xpon turn on attribute expansion for all source objects, even in regular files. By default, attribute
expansion is turned off for source objects that are regular files, and turned on for all source
objects that are directly retrieved from the object base.
target ...
A list of target names can be passed to shape via the command line. If no target is given on the
command line, and the special target .DEFAULT is not defined within the description file, shape
tries to produce the first target defined in the description file.
<macro definition>
It is possible to define or modify macros in the description file from the command line. Macros
that are defined this way take precedence over all other definitions. Command line macro
definitions have either of two forms:
NAME=VALUE
and
NAME+=VALUE
with NAME being a word and VALUE an arbitrary string. If VALUE contains white space, make sure to quote
it. The first form of command line macro definitions sets NAME to the substitution VALUE. If VALUE is
empty, the macro is reset. The second form appends VALUE with a leading space character to the current
substitution of NAME. The current substitution may be defined in the description file, or by a previous
setting on the command line. For details about the semantics of macro definitions and substitutions, see
the respective sections below.
DESCRIPTION FILES
The operation of shape is controlled by a system description file (usually a Makefile) that provides
structural information about the system to be managed. Other than make(1), shape works on top of AtFS
(Attributed File System), a repository of versioned objects, rather than plain files. Thus, genuine shape
description files (usually called Shapefile) feature version selection rules, and variant definitions in
addition to standard Makefile dependency rules. Shape's description file is an upward compatible
extension of make(1)'s description file, the Makefile. A useful structuring convention for shape
description files is to maintain a Makefile, and a Shapefile in parallel. Only genuine shape constructs
(such as version selection rules, or variant definitions) are kept in Shapefile, while the bulk of target
rule- and macro definitions is kept in Makefile. The Makefile shall be included in Shapefile (see
description of include directive, below). This structuring convention has the advantage that programs
that were developed with the support of the ShapeTools system can be shipped as source distribution to
sites that don't use ShapeTools.
Although shape is largely downward compatible with the original make program, it should be noted that
several popular extensions of the original make program, such as GNU Make or Sun Make, provide features
not present in shape. See the section on known incompatibilities below.
The description file provides an ideal central information base for all sorts of product related
definitions. Shape encourages the development of a set of (project- or organization-specific)
conventions for system description, and provides a simple way to extract this information for use by
other tools (see -echo option, above). The description file syntax not only serves to specify component
dependencies that are relevant for build processes, but allows a general, hierarchical definition of
product oriented tasks. The concept of recursive dependencies maps directly to a stepwise refinement of
task definitions. Such tasks can be fully, partly, or not at all automated as appropriate. Thus, certain
activities may be automated and standardized, while other activities are just informally described in
order to document them or to reason about them (see shape_rms(1) for examples).
Syntactical Structure
The basic syntactical structure of shape's description file is made up of:
Comments
Comments begin with a ``#'' character and extend to the end of the line. In Shapefiles, the end of
a line is defined as an unescaped newline (``\<newline>''), or the end of the file. The comment
character can't be escaped, but can be quoted in single- or double quotes. Comment characters in
command lines of target rules are ignored by shape.
Directives
Directives are special keywords, known to shape. Directives begin at column 0 of a line and extend
to the line end. Currently, the only directive recognized by shape is
include <list of file names>
Macro Definitions
Macro definitions have the general form:
NAME <macro definition symbol> VALUE
NAME must be a single word consisting of a sequence of name characters. Name characters are all printable
characters except the following:
$ # : = ; <space> \t \n
The macro definition symbol is either of ``='', ``+='', or ``:=''. VALUE is an arbitrary string
terminated by the end of the line, or a comment. Macro definitions usually begin in the first column of a
line, but may be preceded by leading <space> characters. Macro definitions must not contain leading <tab>
characters (see section on Macro Definitions, below, for more details).
Macro References
Macro references have one of the following forms:
$(<macro name>)
${<macro name>}
$<single character name>
The macro substitution operator (``$'') can't be escaped, but can be represented by the substitution
``$$''. Macro substitution occurs anywhere in the description file, except in comments, macro names, left
hand sides of version selection rule- and variant definition headers (see next section), and variant
class definitions (see section on Macro Substitutions, below, for more details).
Rules Rules are made up from a rule header, and an optional rule body. The rule header consists of a
left hand side, a rule definition symbol, and an optional right hand side. The left hand side
usually begins in column 0 of a line, and may be preceded by leading <space> characters. Left hand
sides of rule headers must not contain leading <tab> characters. The optional right hand side of a
rule header extends to the end of the line, or the beginning of the rule body. A rule body
consists of consecutive lines beginning with a <tab> character. The body of a rule is terminated
by the next line not beginning with a <tab> character, or the end of the file.
Shape recognizes three different kinds of rules, distinguished by their respective rule definition
symbols:
•
target rules. Target rules have a single colon character (``:'') as rule definition symbol. The
left hand side of target rule headers is a space-separated list of names. The optional right
hand side consists of a space-separated list of names, followed by an optional list of
production ingredients (see section on Target Rules, below).
•
version selection rules. Version selection rules have the rule definition symbol ``:-''. The
rule header of version selection rules has a single word on its left hand side, and no right
hand side (see section on Version Selection Rules, below).
•
variant definitions. Although variant definitions are - as the name suggests - definitions, not
rules (from a semantical view point), their syntactical representation is that of a rule.
Variant definitions have the rule definition symbol ``:+''. The rule header of a variant
definition has a single word on its left hand side, and no right hand side (see section on
Variant Definitions, below).
Variant Class Definitions
Variant class definitions have the form
vclass <name> ::= (variant1, variant2, ...)
(see section on Variants, below).
Line Continuations
If the end of an input line is escaped by a backslash (``\'') the next line is considered as a
continuation line. The backslash newline character sequence is replaced by a space.
Macro Definitions
Macro definitions associate names with strings that will be substituted wherever the name of the macro is
referenced (see next section). Macros are useful for writing maintainable, and somewhat generic
description files. Even moderately large projects will find it extremely rewarding to define conventions
for naming and usage of certain macros throughout the product description file.
There are three different kinds of macro definitions:
Simple Macro Definitions
A simple macro definition looks like
NAME = <any string>
The string that is associated with the macro name can contain macro references. If a macro is defined
multiple times within a description file, the last definition will be effective. Macros defined on the
command line take precedence over definitions of the same macro in the description file.
Additive Macro Definitions
This type of macro definition looks like
NAME += <any string>
The string on the right hand side of the definition is appended to any existing value associated with
NAME, separated by a space character. Multiple additive macro definitions are concatenated in the order
in which they appear in the description file. If an additive macro definition occurs on the command line,
the last string value defined in the description file is prepended to the string value defined on the
command line. Additive macro definitions in the description file are appended to string values defined on
the command line.
Evaluative Macro Definitions
Evaluative macros are defined in the following way:
NAME := <any string>
First, the string value is associated to NAME in the same way as for simple macro definitions. When NAME
is substituted for the first time, the right hand side of the definition is evaluated, and the result of
this evaluation replaces the original string value associated with NAME. Thus, evaluation of the right
hand side occurs exactly once. This is particularly useful if the defining string is a command
substitution (see next section).
Macro Substitutions
Macro substitution is the process of substituting a macro reference by the string value associated with a
macro name. References to undefined macros are substituted by an empty string. Macro references have
either of the forms:
$(NAME)
${NAME}
$<any single character>
The following are valid macro references:
$(CFLAGS)
$7
${SOURCE-FILES}
$(X)
$X
The last two references have identical substitutions. The macro reference
$$
will substitute a single dollar sign.
Before a macro reference is substituted, the associated string will be evaluated. Evaluation of a string
value includes
-
substitution of all macro references in the string value
-
command substitution. Any substring of the string value enclosed in backquotes (```'') will be passed
as command to the shell, and be replaced by the command's standard output.
-
string substitution. If a macro reference has the form
$(NAME:<old>=<new>)
the reference will be substituted by the evaluated value of NAME, with all occurrences of the string
<old> replaced by the string <new>. This is particularly useful to maintain related lists, such as
CSOURCES and OBJECTS for example, automatically:
CSOURCES := `echo *.c`
OBJECTS := $(CSOURCES:.c=.o)
Shape substitutes macro references as late as possible. Macro references occurring in a macro definition
are only substituted when the defined macro itself is substituted. Macro references on the dependencies
side of target rules are substituted when the rule is evaluated. Macro references on the target side of
target rules are substituted immediately after shape has read the description file, i.e. before any
production is started. Macro references in include directives are substituted when the directive is
executed while shape reads the description file.
Built-in and Special Purpose Macros
In order to provide parametrization of shape's built-in implicit rules, a number of predefined macros is
supplied by convention. These macros have meaningful initial values that can be altered by the user.
There are also several macros that have special meaning for shape.
Macro Purpose Initial value Remark
@ full name of the current <dynamic>special
target
? list of target dependencies <dynamic>special
< name of the first target <dynamic>special
dependency
* prefix shared by target <dynamic>special
and the dependent filenames
# bound version id of the current <dynamic>special
dependency
$ the character ``$'' $<special>
+ name of object to be bound <dynamic>special
to a version (selection rules
only!)
AS Program for doing assembly asconventional
ASFLAGS Flags for the assembler <none>conventional
CC Program for compiling C ccconventional
programs
CFLAGS Flags for the C compiler <none>conventional
FC Program for compiling Fortran f77conventional
programs
FFLAGS Flags for the Fortran compiler <none>conventional
HOSTTYPE Host architecture of the <none>special
computer that runs shape.
The value of this macro is
used by shape to construct
the derivation key attribute
for derived objects
IMPORT List of environment variables <none>special
that shall be imported as
macro definitions
LD Program to link programs ldconventional
LDFLAGS Flags for the linker <none>conventional
LEX Program to turn Lex grammars lexconventional
into C or Ratfor programs
LFLAGS Flags for the lexical analyzer <none>conventional
lex
LOGNAME The name or network-id under <dynamic>special
which the user who owns the
shape process is logged on
M2C Program for compiling Modula2 m2cconventional
programs
M2FLAGS Flags for the Modula2 compiler <none>conventional
MAKE The command line with which shape $(MAKEFLAGS)special
shape has been invoked.
This macro is used for
recursive calls to shape
MAKEFLAGS Command line flags relevant <defined fromspecial
for recursive calls to shape command line>
PC Program for compiling Pascal pcconventional
programs
PFLAGS Flags for the Pascal compiler <none>conventional
RFLAGS Flags for the Fortran compiler <none>conventional
for Ratfor programs
SHAPEPID The process id of the <dynamic>special
running shape program
SHAPEVERSION The version id of theshape_CM-4.4special
shape program (or above)
SHELL The command processor for /bin/shspecial
the target rule command
lines. The referenced command
processor must be able to
take its commands from
standard input (see section
on Command execution,
below)
VPATH Search path extension for <none>special
localizing source components
YACC Program to turn Yacc grammars yaccconventional
into C programs
YFLAGS Flags for yacc <none> conventional
vpath Dynamic search path extension <none>special
for variants of source components
The function of the special purpose macros HOSTTYPE, IMPORT, MAKE, VPATH, and vpath are described in the
sections on OPERATION, and Variants below.
Target Rules
A target rule defines how, and under what conditions a target is derived from a set of source objects
and/or other targets. A target is a name that can refer to a file but need not to do so. Target rules
have the following format:
<target>... : [<version binding>] [+<variant>...] [<dependency>...] \
[: <ingredient>...] [; <command>]
\t[<command>]
...
The header of a target rule (see Syntactical Structure, above) consists of a list of targets, terminated
by a colon, followed by an optional list of dependencies, and an optional list of production ingredients,
beginning after a second colon character. The rule header is terminated by a newline or a semicolon, and
followed by the optional rule body. The rule body consists of command lines that are executed when a
target needs to be rederived. The first command line may immediately follow the semicolon that
terminates the rule header. Subsequent command lines must begin with a <tab> character. The target rule
body is terminated by the first line that doesn't begin with a <tab>, or by the end of the file.
Targets
When multiple targets appear on the left hand side of a rule header, and the derivation process needs to
be started, shape will derive all of the targets in a single run.
Dependencies
Shape checks a target's dependencies from left to right. The first dependency is examined whether it is
the name of a version selection rule. If it is, shape sets the selection rule active (eclipsing all
previous selection rule activations), and proceeds to the next dependency. Next, shape checks whether the
dependency is a variant activation. If the dependency starts with a ``+'' character followed by the name
of a variant, the variant is activated (see the section on Variants, below). Shape proceeds to check for
variant activations until the first dependency that isn't a variant activation is found. Next, shape
proceeds through the list of remaining dependencies, and binds (or derives) each of them as necessary,
performing a depth first traversal of the dependency graph (see the section on OPERATION, below).
Production Ingredients
After all dependencies have been bound, shape constructs the derivation key for the target. The
derivation key is an attribute that defines the complete set of parameters that determine whether a
target needs to be rebuild. Besides all bound dependencies, the derivation key contains the production
ingredients that were specified in the target rule header. Production ingredients are typically complete
definitions of the macros that are referenced in the command lines of the rule's body. Thus, tool
versions and switches affecting the operation of a tool can be made part of the derivation parameters of
a target. In order to include macro definitions into the derivation key of a target, the special
reference
+(NAME1) +(NAME2) ...
must occur in place of the production ingredients.
Command Lines
When shape concludes that a target needs to be (re-)derived, the commands in the target rule body are
executed. The rule body consists of consecutive lines that are treated as separate commands. Each command
line is evaluated as described in the section on Macro Substitution, above, and passed to the command
interpreter defined by the macro SHELL. Each command line is executed as a separate process. If complex
commands are needed that don't fit on a single line, or if the overhead of repeated process invocations
shall be avoided, a logical command line can be extended by escaping the newline with a backslash
character (\<newline>), and continuing it on the next physical line.
Command lines may be preceded by one or two special characters:
- shape ignores any nonzero error code returned by a command line for which the first character is a
minus sign. The minus sign is not passed to the shell. When a command returns a nonzero return
status, shape usually considers the derivation process for the target as failure and terminates,
unless the -i or -k switches, or the .IGNORE special target is in effect.
@ If the first character of a command is a ``@'', shape does not print the command before executing
it. The ``@'' is not passed to the shell.
@- If the first two non-<tab> characters are ``@-'', shape ignores nonzero return codes, and
suppresses the printing of the command line.
If shape is invoked in no execution mode (-n), the evaluated command lines are printed on standard
output, showing what shape would do if invoked without -n. Command lines that contain the macro reference
$(MAKE) are always executed, even if -n is set. This is done to allow simulation of recursive builds that
may span over subdirectories. The reference $(MAKE) is substituted by a shape command invocation with all
relevant command line switches set.
Within command lines of the rule body, some parts of the target rule header can be dynamically
referenced. When a command line is evaluated, the following substitutions are possible
Reference Substitution
$@ full name of the current target
$? list of dependencies
$< name of the first dependency
$* prefix shared by current and the dependent filenames
$# bound version id of the current dependency
(implicit rules only)
Implicit Rules
Shape's target rules come in two different flavors: explicit, and implicit. Implicit rules can be seen as
templates that define dependency patterns which apply to most targets of a given kind. For this reason,
implicit rules are sometimes called pattern rules. Shape converts make's old-style implicit rules (e.g.
.c.o:) to pattern rules while it reads the description file. A typical dependency pattern is, for
example, the dependency of files containing linkable object code, e.g. module.o to corresponding files
containing source code, e.g. module.c. The derivation process for most of these source/derived pairs is
identical. Rather than writing separate rules for all source/derived dependencies of a system, it is
possible to write a single, generic rule, called implicit rule. An implicit rule has the following
format:
%[.<suff1>] %[.<suff2>] ... : %[.<suff3>] %[.<suff4>]... \
[: <ingredient>...] [; <command>]
\t[<command>]
\t[<command>]
...
While the structure of implicit rules is the same as described above, the names of targets and
dependencies are replaced by target patterns, and dependency templates respectively. The percent
character in a target pattern acts as wildcard that is matched against all of a target's name up to the
optional trailing suffix. For shape, an object name suffix is the sequence of characters enclosed by the
last period character (``.'') within the name, and the <space> character terminating the name. The
following example illustrates shape's concept of suffixes:
Name Suffix
sample.cde cde
sample.x.y.cc
sample_c
.sample.c c
The following is an example for an implicit rule that derives linkable object code from corresponding C
source files:
%.o : %.c : +(CC) +(CFLAGS)
\t@echo shape - executing: $(CC) -c $(CFLAGS) $#;
\t@$(CC) $(CFLAGS) -E %.c |
sed 's;^\(# [0-9][0-9]* \"\)%.c\(\".*\)$$;e1$#\2;' > %.i;
\t@$(CC) -c $(CFLAGS) %.i;
\t@rm %.i;
NOTE: This rule is shape's built-in implicit rule to compile C source files. The cryptic command
sequence has the purpose to encode the complete file version id into the object code (e.g. sample.c[3.4]
rather than sample.c). This is extremely useful in conjunction with with the -g switch of most C
compilers, and version sensitive debuggers, such as vgdb.
If a target is derived using implicit rules, the name of the target is matched against the target
patterns of the implicit rules. If a rule matches, the matching portion of the target name (the stem,
referred to by the ``%'') is consistently substituted for all other occurrences of the wildcard character
throughout the rule. Once this is done, the implicit rule is treated like an explicit target rule.
Explicit Rules
Explicit rules associate explicit target names with explicit dependencies. Explicit rules are most
typically used to specify dependencies that cannot be covered by implicit rules, such as deriving an
executable program by linking many object code modules. In many cases, explicit rules are used to
specify only those target dependencies that are not implied by an implicit rule (such as include
dependencies for object files), while the ``natural'' dependencies are assumed as being present. If a
description file contains only this sort of explicit dependencies, the omitted implicit dependencies (and
an applicable rule body) are automatically added by shape to the total list of target dependencies.
Built-in Implicit Rules
Shape provides a number of predefined implicit target rules that cover many common source/target
derivations. The following table lists target patterns, and dependency templates for shape's built-in
implicit rules.
Target Dependency Derivation
%.a %.c Compile archive library from C source
%.c %.l Generate C programs from Lex grammar
%.c %.y Generate C programs from Yacc grammar
%.o %.l Compile object code from Lex grammar
%.o %.y Compile object code from Yacc grammar
%.o %.s Translate assembler program to object code
%.o %.r Compile Ratfor source
%.o %.F Compile Fortran source
%.o %.f Compile Fortran source
%.sym %.def Compile Modula definition modules
%.o %.mod Compile Modula implementation modules
%.o %.p Compile Pascal source
%.o %.c Compile C source
% %.sh Make executable program from shell-script
% %.r Build executable program from Ratfor source
% %.F Build executable program from Fortran source
% %.f Build executable program from Fortran source
% %.p Build executable program from Pascal source
% %.mod Build executable program from Modula source
% %.c Build executable program from C source
For a complete definition of shape's built-in implicit rules, run shape -p.
Special Purpose Targets
Several aspects of shape's operation are controlled by special purpose targets that can be put into the
description file. Special purpose targets by convention begin with a period character, and have no
associated commands.
Target Purpose
.DEFAULT: commands in the rule body of the .DEFAULT target rule are executed for all targets that
cannot be derived by explicit or implicit target rules. If no commands at all shall be
executed for a rule but .DEFAULT is needed for other targets, that rule can be given an empty
command (either a ``;'' at the end of the rule header, or an empty line beginning with
<tab>). If .DEFAULT has dependencies, and no targets are requested from the command line,
these dependencies are treated as if they were targets requested from the command line.
.IGNORE: causes shape to ignore non zero return codes of invoked commands. Equivalent to the -i
switch
.SILENT: silent command execution. The command lines are not printed before execution. Equivalent to
the -s switch
.BPOOL: only the dependencies associated with this target are stored in the derived object cache
.NOBPOOL: dependencies associated with this target are not stored in the derived object cache.
If both, .BPOOL, and .NOBPOOL are defined, only the difference set of both dependency lists will be
stored in the derived object cache.
Version Selection Rules
When shape builds a target, it uses version selection rules to bind a unique version to each name of the
prerequisite source objects. Version selection rules consist of a name, and an associated set of
predicate lists in the rule body. The format of version selection rules is:
<name> [( <arg1>, <arg2>,...)] :-
\t[<pattern1>,] <pred1> (...), <pred2> (...);
\t[<pattern2>,] <pred1> (...), <pred2> (...);
...
\t.
The body of a version selection rule consists of a sequence of alternatives, separated by semicolons.
Each of the alternatives is an optional pattern, followed by a comma-separated list of predicates. The
selection rule is terminated by a period character. The semicolon-separated sequence of alternatives in a
version selection rule constitutes a logical OR expression. The comma-separated list of predicates in an
alternative constitutes a logical AND expression.
Version Binding
Version binding is the process of determining exactly one version of a given source object from the set
of all available versions. Version binding is said to succeed if one of the rule alternatives succeeds.
An alternative succeeds, if it leads to the identification of exactly one version. It is said to fail
otherwise. When shape binds a version to the name of a source object, it tries each alternative with a
matching pattern, until the name is unambiguously bound to a version. If the pattern is omitted, the
alternative will be tried unconditionally.
The functioning of version selection rules is one of shape's most important, yet most subtile aspects. In
order to provide a basis for an intuitive understanding of the selection rule mechanism, an example is
described. The rule most_recent, below, binds:
- files that were checked out for modification by the shape-invoking user
- versions of files that were recently modified (→ status saved) by the same user
- the most recently proposed version (→ status proposed) of files modified by other users,
- or the file version from the last release.
LASTRELEASE := `lastrelease`# "lastrelease" returns the name
# of the last release
most_recent :-
eq (status, busy), exists ($+[locked_by($(LOGNAME)):]);
ge (status, saved), max (mtime),
max (version), eq (author, $(LOGNAME));
ge (status, proposed), max (mtime),
max (version);
eq (__SymbolicName__, $(LASTRELEASE));
cut ($_rule$: couldn't bind $+ as requested!).
locked_by (user_id) :-
max (version), eq (locker, $_user_id$).
For a more detailed description of version selection rule syntax, semantics, and the list of built-in
predicates, see BindRules(7).
Activation of Version Selection Rules
A version selection for a certain target is invoked by specifying the name of the selection rule as first
dependency of a target, or by supplying a selection rule name as argument to the -R option. If no
selection rule is specified explicitly, shape uses its built-in version selection rule that tries to bind
a regular file, or the most recent version to the name of an object.
Variants
The term variant refers to the intention to manage a product that must comply with different sets of
varying external constraints as a unit. Independently from particular semantics that might be associated
with the variant notion, there exists a small number of techniques to implement software variation on a
technical level. These techniques are:
physical separation of variant components. This is achieved by maintaining separate copies of components
in different directories, or by maintaining variant specific branches in version control systems;
source preprocessing of variant components. With this technique, multiple logical variants of a source
component are maintained in a single file that contains preprocessor instructions. Before a particular
variant can be accessed, a preprocessor must extract it from the common source. A popular example of this
technique is conditional compilation, controlled by the #if, and #ifdef instructions within the domain of
C/C++ programming;
composition variation of complex product variants. This technique addresses the case when different
variants of a complex product (such as a program) are composed from different sets of components;
derivation variation (or variation of the process) that produces different variants of derived objects
from the same set of sources by modifying parameters of the derivation process. A typical example for
this case is cross compilation of the same sources for different target platforms, or code
instrumentation for various purposes, such as debugging, testing, profiling, or optimization.
Depending on the particular needs of a project, all of these techniques may be in simultaneous use, and
can occur intermixed as appropriate. Shape allows to associate logical variant names with a set of
definitions that control all of the above mentioned techniques, making it possible to request builds of
particular system variants (and combinations of compatible variants) without the need to worry about how
these variants are realized technically.
Variant Definitions
Shape derives its flexibility from using macro substitution in the description file wherever possible.
Shape variant definitions are basically groups of macro definitions that take effect when the variant is
activated for a build. A variant definition has the following format:
<variant-name> :+
\t<Macro name1>=<Value>
...
When a variant is activated, the macro definitions associated with the variant become effective. Any
previous definition of a macro made in the description file, or on the command line is replaced by the
variant macro substitution. If a macro is defined in several variants that are activated together, the
respective values are concatenated.
Locating physically separate Variant Source Objects
Shape provides a special macro, vpath, that is intended to be used in variant definitions. The vpath
macro defines shape's search precedence when source version archives are located. If vpath is non-empty,
shape tries to find any referenced source object in the vpath directories first. If several activated
variants define vpath, the variant search path is concatenated and searched from right to left, i.e. the
last variant that has been activated has precedence. Only if a referenced source component cannot be
found in any of the vpath directories, the current directory is searched. If a source object has been
found, it will be bound by the current version selection rule, and be temporarily installed in the build
directory. This means that components which are maintained in a vpath subdirectory are temporarily moved
up to the main directory. Thus, it is not necessary to make any reference to a vpath subdirectory path in
the target rules.
Variant Activation
When a product is configured and built, variants are typically activated by supplying a variant name as
argument to the -V options.
Variants can also be activated for a given target by specifying respective, ``+''-prefixed variant names
as dependencies (see section on Target Rules, above). Variant activations for a target must occur before
any real object dependency on the dependency line, and after the optional version selection rule
activation.
Variant Class Definitions
With Variant class definitions, shape offers a construct that allows to define incompatible variants,
i.e. variants that cannot be activated simultaneously. Shape variant class definitions have the following
format:
vclass <variant-class-name> ::= ( <var1>, <var2> ...)
The same variant name can occur in multiple variant class definitions. If a combination of variants is
requested with any two variant names that are member of the same variant class, shape will issue an error
message, and terminate. Checking of variant classes can be disabled by specifying the -novclass switch on
the command line.
NOTE: variant class definitions must occur in the description file before any variant definition
referenced in a variant class. Variant classes that are defined after referenced variants cannot enforce
mutual exclusion of incompatible variants.
An Example
The following example shall illustrate the use of variant definitions, and variant classes:
vclass compiler ::= (gnu, prop)
gnu:+
CC = gcc -Wall
OPTIMIZE = -O2 -inline-functions
DEBUG = -g -g3
PROFILE = -pg -a
STDC = -ansi
prop:+
CC = cc
OPTIMIZE = +O3
DEBUG = -g -z +Y
PROFILE = -G
STDC = -Aa
vclass quality ::= (debug, profile, optimize)
debug:+
VARCFLAGS = $(DEBUG)
profile:+
VARCFLAGS = $(PROFILE)
optimize:+
VARCFLAGS = $(OPTIMIZE)
CFLAGS += $(VARCFLAGS)
If a variant requires the modification of macros with predefined meaning, it is sometimes a good idea not
to redefine the macro itself in the variant section. In such a case it is possible to augment an existing
macro value by using shape's additive macro definition facility, and a macro from the variant definition
defined for this purpose (e.g. VARCFLAGS in the example above).
OPERATION
When invoked, shape first parses the command line. Shape records the names of the variants to be
activated from the command line via the -V option. Next, shape initializes the built-in, and special
macros. Also, shape's built-in derivation rules are initialized.
Reading the Description File
After that, all macro definitions made on the command line are made effective. Shape then locates and
opens its description file. If no description file is specified as argument to the -f option, shape tries
to find one of the files Shapefile, shapefile, Makefile, or makefile. For each of these names, shape
tries to find a regular file first, and, if no such file exists, to find the most recent version of that
file in a version control archive. If no such version can be found, shape tries the next name.
When shape reads the description file, it collects all macro definitions, and makes them immediately
effective, unless a macro of the same name has been defined on the command line. If the special macro
IMPORT is encountered, the listed environment variables are defined as macros. If macros with the same
name as an imported environment variable occurs in the description file, it has precedence over the
definition from the environment, unless the -e switch is in effect.
When shape reads an include directive, it evaluates the rest of the line (i.e. the characters that
immediately follow the directive), and interprets each word as the name of a file to be read. Each of the
file names is bound to either a regular file, or the most recent version of the file. Shape opens each of
the included files, suspends reading the current description file, and continues to read the contents of
the included file(s), before it resumes reading of the original control file. If multiple file names are
specified in an include directive, shape reads each of the files in turn, starting with the leftmost, and
ending with the rightmost file name. If an included file could not be opened, shape issues a warning.
While shape reads its description files, version selection rules, and target rules are collected. They
are defined only after shape has finished reading the description file. Macro-, variant-, and variant
class definitions are made effective as soon as they have been recognized.
The Build Process
After the description file has been read, shape determines which targets have been requested. If targets
have been requested from the command line, shape will attempt to build each of them, starting with the
leftmost target and proceeding towards the rightmost. If no target has been requested from the command
line, shape searches the description file for a target named .DEFAULT. If such a target exists, and there
are any dependencies associated with it, shape will attempt to build each of these dependencies, from
left to right. If no .DEFAULT target rule has been defined in the description file, shape will attempt to
build the first target defined in the description file.
When shape builds a target, it proceeds as follows:
1)
determine the names of the source objects for a given target by traversing the dependency graph, using
built-in and user supplied target rules. The dependency graph is traversed depth first. The ids of all
applied rules are recorded.
2)
for each required source object, locate the source version archive in the repository. Locating of
source version archives takes the current vpath into account.
3)
bind each of the source object's names to an appropriate version as implied by the currently active
version selection rule. Record the id of each bound dependency. If a dependency is itself a derived
object, use its cache key as id.
4)
construct the derivation key for the current target from the target name and the records resulting
from steps 1) and 3).
5)
search the derived object cache for an object that has a derivation key identical to the key
constructed in step 4).
6a)
if an appropriate derived object was found, a copy of it is installed in the build directory, rather
than deriving it from its sources.
6b)
if no appropriate derived object was found, it is created by deriving it from its parts. The resulting
derived object is put into the derived object cache, and associated with the derivation key resulting
from step 4).
Targets with an empty list of dependencies - and thus an empty derivation key - are always (re-) derived.
When shape determines the dependencies of a requested target, it does so by evaluating either explicit
target rules, or by applying - possibly built-in - implicit rules. If explicit target rules specify
object dependencies but no derivation script in the rule body, shape will attempt to supply an
appropriate default derivation script. When searching for such a default derivation script, shape tries
to find an applicable implicit rule for the current target. An implicit rule is considered applicable, if
it has the current target in its list of targets (after pattern substitution), and all - explicit, and
implied - dependencies exist. If no implicit rule is found to be applicable, shape looks for the .DEFAULT
target rule. If such a rule exists, and if it has an associated derivation script in its rule body, this
script will be supplied as default derivation script. If neither of the two possibilities leads to a
default derivation script, shape gives up.
Derived Object Caching
Before the derivation process for a requested target is started, it is attempted to find a suitable
derived object in the derived object cache that matches the required properties. Shape is based on the
derivation key concept for target objects. The derivation key is constructed according to the algorithm
described above. Relevant parameters that go into the derivation key are the list of dependency ids, the
target rule id, the list of production ingredients, the build platform (usually defined by the macro
HOSTTYPE; if this macro is not defined, shape takes the host id as build platform), and the attribute
expansion status of each source object. When an object has been derived, shape stores it in the derived
object cache, and marks it with the derivation key attribute. For a detailed trace of shape's derived
object cache handling, and the use of derivation keys, run shape with the -D switch.
Command Execution
When a target needs to be (re-) derived, shape executes the commands associated with the target. Before
the commands are executed, shape sets up the command execution context. The version objects of the
target's dependencies are installed as regular files in the file system. If necessary, shape retrieves
source objects from the version control archive. If a file with the object's name already exists in the
place where a version is to be installed, shape will temporarily move it to the AtFS subdirectory. After
the command script has completed, shape will restore the original state of all affected directories.
Shape executes a command line by starting the program referenced in the $(SHELL) macro, and opening a
pipe to the resulting process. The command line is written to the pipe, and thus sent to the $(SHELL)
process' standard input.
Each of the command lines in a rule body are executed by a separate process. Thus, the execution status
of separate commands is not preserved. If multiple commands are needed that rely on the execution status
of previous commands, all these commands must occur in a single command line. This is possible with line
continuations (see section on Syntactical Structure, above).
NOTE: many command interpreters use the ``$'' character as special symbol (typically as variable
reference). Make sure to pass ``$'' characters in commands to the $(SHELL) process by using the ``$$''
special macro (see section on Macro References, above).
INCOMPATIBILITIES
In order to facilitate migration from make(1), shape was designed to be upward compatible with Makefiles.
Although most of make's description file features are present in shape, there is a number of
incompatibilities that may need to be taken care of. There exists also a number of popular extensions of
the original make program (e.g. Sun's Make, HP's Make, GNU Make, nmake etc.) that offer various special
features that aren't supported by other make extensions, or by shape. When a migration from make to shape
is planned, it should be checked whether special extensions or incompatible features are used.
Features not supported by shape
Double colon rules
Double colon rules associate the same target with different derivation scripts. This type of rule
is useful to support different derivations for a target depending on which dependencies are out of
date. Because shape bases its decision whether to derive on the derivation key, rather than mere
modification time stamps of files, this sort of rule makes no sense in shape.
Archive member targets
Archive member targets are objects that live in an archive file (see ar(1)) rather than the file
system. Within these archives, make bases its decisions on the modification time stamps of source
files, and archive entry dates. There is no way for shape to simulate the concept of derivation
keys for archive members. Maintenance of archives, however, is easy with shape, because all data
for compiled object files is maintained in the derived object cache. If the source for an object
that is stored in an archive is modified, shape can rederive this object, and selectively replace
the entry in the archive.
SCCS stuff
In order to provide basic support for team oriented development processes, make allows to retrieve
the most recent version of source files from SCCS archives. Because of the awkward naming
convention for SCCS version archive files, special support for dealing with these archives had to
be built into make. Because shape is tightly integrated with the AtFS version object repository,
there is no need for any special SCCS support.
Special targets
Shape does not recognize the special targets .PRECIOUS:, and .SUFFIXES:. The .PRECIOUS target in
Makefiles has the purpose to prevent deletion of expensively derived intermediate targets (by
default, make deletes intermediate targets). Because shape stores intermediate targets in the
derived object cache, there is no need for the .PRECIOUS feature. To prevent caching of possibly
large, useless intermediate targets, use the .NOBPOOL: special target (see section on Special
Targets, above). The .SUFFIXES target in Makefiles has the purpose to introduce new suffix types
into make's derivation engine, and to determine the order in which implicit rules (suffix rules in
make terminology) are applied. In shape, new suffix types can be added dynamically, simply by
introducing new implicit rules. Moreover, shape has an intelligent algorithm the determines the
applicable implicit rule.
Features with different semantics
Environment Variables
Many make programs import the entire set of environment variables as macro definitions into the
build process. This can sometimes produce surprising results. In shape, environment variables are
explicitly imported with the IMPORT special macro.
? Macro
In make's target rules, the special macro reference $? is substituted by the names of those
dependency file names that have been updated since the current target has been derived. Because
shape bases its decision whether to derive on the concept of derivation key, rather than mere file
modification time stamps, the ? macro cannot be correctly defined. Instead, shape substitutes the
entire list of dependency names - updated or not.
FILES
Shapefile, shapefile, Makefile, makefile, /tmp/shapeXXXXXX, <target name>.bct
SEE ALSO
make(1), save(1), retrv(1), vadm(1), vl(1), vgdb(1), vbind(1), afintro(3), atfstkintro(3), sttkintro(3),
bindrules(7)
CAVEATS AND BUGS
Macro references containing string substitutions cause a syntax error if used in place of target
dependencies. Workaround: use indirect macro substitution.
There are probably more bugs in shape. Please report any bug findings to shape-cr@cs.tu-berlin.de.
FURTHER READING
Axel Mahler:
``Using the Shape Toolkit for Cooperative Software Development - A Tutorial'', in the toolkit
distribution.
Axel Mahler and Andreas Lampen:
``An Integrated Toolset for Engineering Software Configurations'', Sigplan Notices, Vol. 24,
No. 2, or Software Engineering Notes, Vol. 13, No. 5, November 1988.
Andreas Lampen and Axel Mahler:
``An Object Base for Attributed Software Objects'', Proceedings of the Fall 1988 EUUG
Conference.
These and other papers are available via anonymous ftp from coma.cs.tu-berlin.de (pub/shapeTools/papers).
AUTHOR
Shape was designed by the shape project team at Technical University Berlin. The program was originally
implemented by Wolfgang Obst (1988). Extensive fixes and modifications were introduced by Axel Mahler
(1992). Valuable contributions came from Steve Emmerson. In 1993 most parts of shape were re-implemented
by Axel Mahler. The version binding was re-implemented by Andreas Lampen. A complete re-implementation of
the Shapefile parser was done by Juergen Nickelsen.
Contact:
SHAPE
Technical University Berlin
Sekr. FR 5-6
Franklinstr. 28/29
10587 Berlin
General correspondence: shape@cs.tu-berlin.de
Bug reports and modification requests: shape-cr@cs.tu-berlin.de