Tk_ParseArgv(3) Tk Library Procedures Tk_ParseArgv(3)______________________________________________________________________________NAMETk_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 spec‐
ify 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, ter‐
minated 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_LEFT‐
OVERS, and TK_ARGV_NO_DEFAULTS.
_________________________________________________________________DESCRIPTIONTk_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 argu‐
ment 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 par‐
tially 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 val‐
ues 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 place‐
holders: 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 spec‐
ifier whose key matches the argument exactly, if such a specifier
exists. Otherwise Tk_ParseArgv selects a specifier for which the argu‐
ment is a unique abbreviation. If the argument is a unique abbrevia‐
tion 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 fol‐
lowing 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 argu‐
ment 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 match‐
ing 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 speci‐
fiers 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 speci‐
fier 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 argu‐
ment in the normal fashion. In either event the matching argu‐
ment 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 fol‐
lowing 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 hap‐
pens 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 spe‐
cial treatment.
TK_ARGV_NO_ABBREV
Normally, Tk_ParseArgv accepts unique abbreviations for key val‐
ues 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; argu‐
ments 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
TkTk_ParseArgv(3)
