Tk_ParseArgv(3Tk)Tk_ParseArgv(3Tk)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.
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
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doesn't 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 interp->result 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 {
char*key;
int type;
char*src;
char*dst;
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:
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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 an
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
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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 interp->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 doesn't 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 aren't 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
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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 interp->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 hadn't 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 doesn't 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 isn't
specified.
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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", interp->result);
exit(1);
}
/*
* Remainder of the program.
*/
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}
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
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