Tcl_ParseArgsObjv(3tcl) Tcl Library Procedures Tcl_ParseArgsObjv(3tcl)
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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 mes-
sages.
const Tcl_ArgvInfo *argTable (in) Pointer to array of option
descriptors.
int *objcPtr (in/out) A pointer to variable hold-
ing number of arguments in
objv. Will be modified to
hold number of arguments
left in the unprocessed ar-
gument list stored in re-
mObjv.
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 un-
processed arguments.
Should be NULL if no return
of unprocessed arguments is
required. If objcPtr is up-
dated to a non-zero value,
the array returned through
this must be deallocated
using ckfree.
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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 inter-
preter 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 ter-
minated by an entry with the type field set to TCL_ARGV_END. As conve-
nience, 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 argu-
ment, 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 (integer) value of the srcPtr field is
copied to the variable pointed to by 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 ar-
gument 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 han-
dler 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 follow-
ing 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 argu-
ment, but instead causes Tcl_ParseArgsObjv to generate an error
message describing the arguments supported. All other fields ex-
cept 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 argu-
ment, but instead marks all following arguments to be left un-
processed. 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 representa-
tion 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
Tcl 8.6 Tcl_ParseArgsObjv(3tcl)
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