Provided by: tk8.6-doc_8.6.8-4_all 
NAME
Tk_ParseArgv - process command-line options
SYNOPSIS
#include <tk.h>
int
Tk_ParseArgv(interp, tkwin, argcPtr, argv, argTable, flags)
ARGUMENTS
Tcl_Interp *interp (in) Interpreter to use for returning error messages.
Tk_Window tkwin (in) Window to use when arguments specify Tk options. If NULL, then no Tk
options will be processed.
int argcPtr (in/out) Pointer to number of arguments in argv; gets modified to hold number
of unprocessed arguments that remain after the call.
const char **argv (in/out) Command line arguments passed to main program. Modified to hold
unprocessed arguments that remain after the call.
Tk_ArgvInfo *argTable (in) Array of argument descriptors, terminated by element with type
TK_ARGV_END.
int flags (in) If non-zero, then it specifies one or more flags that control the
parsing of arguments. Different flags may be OR'ed together. The
flags currently defined are TK_ARGV_DONT_SKIP_FIRST_ARG,
TK_ARGV_NO_ABBREV, TK_ARGV_NO_LEFTOVERS, and TK_ARGV_NO_DEFAULTS.
________________________________________________________________________________________________________________
DESCRIPTION
Tk_ParseArgv processes an array of command-line arguments according to a table describing the kinds of
arguments that are expected. Each of the arguments in argv is processed in turn: if it matches one of
the entries in argTable, the argument is processed according to that entry and discarded. The arguments
that do not match anything in argTable are copied down to the beginning of argv (retaining their original
order) and returned to the caller. At the end of the call Tk_ParseArgv sets *argcPtr to hold the number
of arguments that are left in argv, and argv[*argcPtr] will hold the value NULL. Normally, Tk_ParseArgv
assumes that argv[0] is a command name, so it is treated like an argument that does not match argTable
and returned to the caller; however, if the TK_ARGV_DONT_SKIP_FIRST_ARG bit is set in flags then argv[0]
will be processed just like the other elements of argv.
Tk_ParseArgv normally returns the value TCL_OK. If an error occurs while parsing the arguments, then
TCL_ERROR is returned and Tk_ParseArgv will leave an error message in the result of interpreter interp in
the standard Tcl fashion. In the event of an error return, *argvPtr will not have been modified, but
argv could have been partially modified. The possible causes of errors are explained below.
The argTable array specifies the kinds of arguments that are expected; each of its entries has the
following structure:
typedef struct {
const char *key;
int type;
char *src;
char *dst;
const char *help;
} Tk_ArgvInfo;
The key field is a string such as “-display” or “-bg” that is compared with the values in argv. Type
indicates how to process an argument that matches key (more on this below). Src and dst are additional
values used in processing the argument. Their exact usage depends on type, but typically src indicates a
value and dst indicates where to store the value. The char * declarations for src and dst are
placeholders: the actual types may be different. Lastly, help is a string giving a brief description of
this option; this string is printed when users ask for help about command-line options.
When processing an argument in argv, Tk_ParseArgv compares the argument to each of the key's in argTable.
Tk_ParseArgv selects the first specifier whose key matches the argument exactly, if such a specifier
exists. Otherwise Tk_ParseArgv selects a specifier for which the argument is a unique abbreviation. If
the argument is a unique abbreviation for more than one specifier, then an error is returned. If there
is no matching entry in argTable, then the argument is skipped and returned to the caller.
Once a matching argument specifier is found, Tk_ParseArgv processes the argument according to the type
field of the specifier. The argument that matched key is called “the matching argument” in the
descriptions below. As part of the processing, Tk_ParseArgv may also use the next argument in argv after
the matching argument, which is called “the following argument”. The legal values for type, and the
processing that they cause, are as follows:
TK_ARGV_END
Marks the end of the table. The last entry in argTable must have this type; all of its other
fields are ignored and it will never match any arguments.
TK_ARGV_CONSTANT
Src is treated as an integer and dst is treated as a pointer to an integer. Src is stored at
*dst. The matching argument is discarded.
TK_ARGV_INT
The following argument must contain an integer string in the format accepted by strtol (e.g. “0”
and “0x” prefixes may be used to specify octal or hexadecimal numbers, respectively). Dst is
treated as a pointer to an integer; the following argument is converted to an integer value and
stored at *dst. Src is ignored. The matching and following arguments are discarded from argv.
TK_ARGV_FLOAT
The following argument must contain a floating-point number in the format accepted by strtol. Dst
is treated as the address of a double-precision floating point value; the following argument is
converted to a double-precision value and stored at *dst. The matching and following arguments
are discarded from argv.
TK_ARGV_STRING
In this form, dst is treated as a pointer to a (char *); Tk_ParseArgv stores at *dst a pointer to
the following argument, and discards the matching and following arguments from argv. Src is
ignored.
TK_ARGV_UID
This form is similar to TK_ARGV_STRING, except that the argument is turned into a Tk_Uid by
calling Tk_GetUid. Dst is treated as a pointer to a Tk_Uid; Tk_ParseArgv stores at *dst the
Tk_Uid corresponding to the following argument, and discards the matching and following arguments
from argv. Src is ignored.
TK_ARGV_CONST_OPTION
This form causes a Tk option to be set (as if the option command had been invoked). The src field
is treated as a pointer to a string giving the value of an option, and dst is treated as a pointer
to the name of the option. The matching argument is discarded. If tkwin is NULL, then argument
specifiers of this type are ignored (as if they did not exist).
TK_ARGV_OPTION_VALUE
This form is similar to TK_ARGV_CONST_OPTION, except that the value of the option is taken from
the following argument instead of from src. Dst is used as the name of the option. Src is
ignored. The matching and following arguments are discarded. If tkwin is NULL, then argument
specifiers of this type are ignored (as if they did not exist).
TK_ARGV_OPTION_NAME_VALUE
In this case the following argument is taken as the name of a Tk option and the argument after
that is taken as the value for that option. Both src and dst are ignored. All three arguments
are discarded from argv. If tkwin is NULL, then argument specifiers of this type are ignored (as
if they did not exist).
TK_ARGV_HELP
When this kind of option is encountered, Tk_ParseArgv uses the help fields of argTable to format a
message describing all the valid arguments. The message is placed in interpreter interp's result
and Tk_ParseArgv returns TCL_ERROR. When this happens, the caller normally prints the help
message and aborts. If the key field of a TK_ARGV_HELP specifier is NULL, then the specifier will
never match any arguments; in this case the specifier simply provides extra documentation, which
will be included when some other TK_ARGV_HELP entry causes help information to be returned.
TK_ARGV_REST
This option is used by programs or commands that allow the last several of their options to be the
name and/or options for some other program. If a TK_ARGV_REST argument is found, then
Tk_ParseArgv does not process any of the remaining arguments; it returns them all at the
beginning of argv (along with any other unprocessed arguments). In addition, Tk_ParseArgv treats
dst as the address of an integer value, and stores at *dst the index of the first of the
TK_ARGV_REST options in the returned argv. This allows the program to distinguish the
TK_ARGV_REST options from other unprocessed options that preceded the TK_ARGV_REST.
TK_ARGV_FUNC
For this kind of argument, src is treated as the address of a procedure, which is invoked to
process the following argument. The procedure should have the following structure:
int
func(dst, key, nextArg)
char *dst;
char *key;
char *nextArg;
{
}
The dst and key parameters will contain the corresponding fields from the argTable entry, and
nextArg will point to the following argument from argv (or NULL if there are not any more
arguments left in argv). If func uses nextArg (so that Tk_ParseArgv should discard it), then it
should return 1. Otherwise it should return 0 and TkParseArgv will process the following argument
in the normal fashion. In either event the matching argument is discarded.
TK_ARGV_GENFUNC
This form provides a more general procedural escape. It treats src as the address of a procedure,
and passes that procedure all of the remaining arguments. The procedure should have the following
form:
int
genfunc(dst, interp, key, argc, argv)
char *dst;
Tcl_Interp *interp;
char *key;
int argc;
char **argv;
{
}
The dst and key parameters will contain the corresponding fields from the argTable entry. Interp
will be the same as the interp argument to Tcl_ParseArgv. Argc and argv refer to all of the
options after the matching one. Genfunc should behave in a fashion similar to Tk_ParseArgv:
parse as many of the remaining arguments as it can, then return any that are left by compacting
them to the beginning of argv (starting at argv[0]). Genfunc should return a count of how many
arguments are left in argv; Tk_ParseArgv will process them. If genfunc encounters an error then
it should leave an error message in interpreter interp's result, in the usual Tcl fashion, and
return -1; when this happens Tk_ParseArgv will abort its processing and return TCL_ERROR.
FLAGS
TK_ARGV_DONT_SKIP_FIRST_ARG
Tk_ParseArgv normally treats argv[0] as a program or command name, and returns it to the caller
just as if it had not matched argTable. If this flag is given, then argv[0] is not given special
treatment.
TK_ARGV_NO_ABBREV
Normally, Tk_ParseArgv accepts unique abbreviations for key values in argTable. If this flag is
given then only exact matches will be acceptable.
TK_ARGV_NO_LEFTOVERS
Normally, Tk_ParseArgv returns unrecognized arguments to the caller. If this bit is set in flags
then Tk_ParseArgv will return an error if it encounters any argument that does not match argTable.
The only exception to this rule is argv[0], which will be returned to the caller with no errors as
long as TK_ARGV_DONT_SKIP_FIRST_ARG is not specified.
TK_ARGV_NO_DEFAULTS
Normally, Tk_ParseArgv searches an internal table of standard argument specifiers in addition to
argTable. If this bit is set in flags, then Tk_ParseArgv will use only argTable and not its
default table.
EXAMPLE
Here is an example definition of an argTable and some sample command lines that use the options. Note
the effect on argc and argv; arguments processed by Tk_ParseArgv are eliminated from argv, and argc is
updated to reflect reduced number of arguments.
/*
* Define and set default values for globals.
*/
int debugFlag = 0;
int numReps = 100;
char defaultFileName[] = "out";
char *fileName = defaultFileName;
Boolean exec = FALSE;
/*
* Define option descriptions.
*/
Tk_ArgvInfo argTable[] = {
{"-X", TK_ARGV_CONSTANT, (char *) 1, (char *) &debugFlag,
"Turn on debugging printfs"},
{"-N", TK_ARGV_INT, (char *) NULL, (char *) &numReps,
"Number of repetitions"},
{"-of", TK_ARGV_STRING, (char *) NULL, (char *) &fileName,
"Name of file for output"},
{"x", TK_ARGV_REST, (char *) NULL, (char *) &exec,
"File to exec, followed by any arguments (must be last argument)."},
{(char *) NULL, TK_ARGV_END, (char *) NULL, (char *) NULL,
(char *) NULL}
};
main(argc, argv)
int argc;
char *argv[];
{
...
if (Tk_ParseArgv(interp, tkwin, &argc, argv, argTable, 0) != TCL_OK) {
fprintf(stderr, "%s\n", Tcl_GetString(Tcl_GetObjResult(interp)));
exit(1);
}
/*
* Remainder of the program.
*/
}
Note that default values can be assigned to variables named in argTable: the variables will only be
overwritten if the particular arguments are present in argv. Here are some example command lines and
their effects.
prog -N 200 infile # just sets the numReps variable to 200
prog -of out200 infile # sets fileName to reference "out200"
prog -XN 10 infile # sets the debug flag, also sets numReps
In all of the above examples, argc will be set by Tk_ParseArgv to 2, argv[0] will be “prog”, argv[1] will
be “infile”, and argv[2] will be NULL.
KEYWORDS
arguments, command line, options