bionic (3) Tcl_ParseArgsObjv.3tcl.gz
NAME
Tcl_ParseArgsObjv - parse arguments according to a tabular description
SYNOPSIS
#include <tcl.h>
int
Tcl_ParseArgsObjv(interp, argTable, objcPtr, objv, remObjv)
ARGUMENTS
Tcl_Interp *interp (out) Where to store error messages.
const Tcl_ArgvInfo *argTable (in) Pointer to array of option descriptors.
int *objcPtr (in/out) A pointer to variable holding number of arguments in objv.
Will be modified to hold number of arguments left in the
unprocessed argument list stored in remObjv.
Tcl_Obj *const *objv (in) The array of arguments to be parsed.
Tcl_Obj ***remObjv (out) Pointer to a variable that will hold the array of unprocessed
arguments. Should be NULL if no return of unprocessed
arguments is required. If objcPtr is updated to a non-zero
value, the array returned through this must be deallocated
using ckfree.
________________________________________________________________________________________________________________
DESCRIPTION
The Tcl_ParseArgsObjv function provides a system for parsing argument lists of the form “-someName
someValue ...”. Such argument lists are commonly found both in the arguments to a program and in the
arguments to an individual Tcl command. This parser assumes that the order of the arguments does not
matter, other than in so far as later copies of a duplicated option overriding earlier ones.
The argument array is described by the objcPtr and objv parameters, and an array of unprocessed arguments
is returned through the objcPtr and remObjv parameters; if no return of unprocessed arguments is desired,
the remObjv parameter should be NULL. If any problems happen, including if the “generate help” option is
selected, an error message is left in the interpreter result and TCL_ERROR is returned. Otherwise, the
interpreter result is left unchanged and TCL_OK is returned.
The collection of arguments to be parsed is described by the argTable parameter. This points to a table
of descriptor structures that is terminated by an entry with the type field set to TCL_ARGV_END. As
convenience, the following prototypical entries are provided:
TCL_ARGV_AUTO_HELP
Enables the argument processor to provide help when passed the argument “-help”.
TCL_ARGV_AUTO_REST
Instructs the argument processor that arguments after “--” are to be unprocessed.
TCL_ARGV_TABLE_END
Marks the end of the table of argument descriptors.
ARGUMENT DESCRIPTOR ENTRIES
Each entry of the argument descriptor table must be a structure of type Tcl_ArgvInfo. The structure is
defined as this:
typedef struct {
int type;
const char *keyStr;
void *srcPtr;
void *dstPtr;
const char *helpStr;
ClientData clientData;
} Tcl_ArgvInfo;
The keyStr field contains the name of the option; by convention, this will normally begin with a “-”
character. The type, srcPtr, dstPtr and clientData fields describe the interpretation of the value of the
argument, as described below. The helpStr field gives some text that is used to provide help to users
when they request it.
As noted above, the type field is used to describe the interpretation of the argument's value. The
following values are acceptable values for type:
TCL_ARGV_CONSTANT
The argument does not take any following value argument. If this argument is present, the int
pointed to by the srcPtr field is copied to the dstPtr field. The clientData field is ignored.
TCL_ARGV_END
This value marks the end of all option descriptors in the table. All other fields are ignored.
TCL_ARGV_FLOAT
This argument takes a following floating point value argument. The value (once parsed by
Tcl_GetDoubleFromObj) will be stored as a double-precision value in the variable pointed to by the
dstPtr field. The srcPtr and clientData fields are ignored.
TCL_ARGV_FUNC
This argument optionally takes a following value argument; it is up to the handler callback
function passed in srcPtr to decide. That function will have the following signature:
typedef int (Tcl_ArgvFuncProc)(
ClientData clientData,
Tcl_Obj *objPtr,
void *dstPtr);
The result is a boolean value indicating whether to consume the following argument. The clientData
is the value from the table entry, the objPtr is the value that represents the following argument
or NULL if there are no following arguments at all, and the dstPtr argument to the
Tcl_ArgvFuncProc is the location to write the parsed value to.
TCL_ARGV_GENFUNC
This argument takes zero or more following arguments; the handler callback function passed in
srcPtr returns how many (or a negative number to signal an error, in which case it should also set
the interpreter result). The function will have the following signature:
typedef int (Tcl_ArgvGenFuncProc)(
ClientData clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *const *objv,
void *dstPtr);
The clientData is the value from the table entry, the interp is where to store any error messages,
the keyStr is the name of the argument, objc and objv describe an array of all the remaining
arguments, and dstPtr argument to the Tcl_ArgvGenFuncProc is the location to write the parsed
value (or values) to.
TCL_ARGV_HELP
This special argument does not take any following value argument, but instead causes
Tcl_ParseArgsObjv to generate an error message describing the arguments supported. All other
fields except the helpStr field are ignored.
TCL_ARGV_INT
This argument takes a following integer value argument. The value (once parsed by
Tcl_GetIntFromObj) will be stored as an int in the variable pointed to by the dstPtr field. The
srcPtr field is ignored.
TCL_ARGV_REST
This special argument does not take any following value argument, but instead marks all following
arguments to be left unprocessed. The srcPtr, dstPtr and clientData fields are ignored.
TCL_ARGV_STRING
This argument takes a following string value argument. A pointer to the string will be stored at
dstPtr; the string inside will have a lifetime linked to the lifetime of the string representation
of the argument value that it came from, and so should be copied if it needs to be retained. The
srcPtr and clientData fields are ignored.
SEE ALSO
Tcl_GetIndexFromObj(3tcl), Tcl_Main(3tcl), Tcl_CreateObjCommand(3tcl)
KEYWORDS
argument, parse