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From: Christian Gollwitzer <auriocus@gmx.de>
Newsgroups: comp.lang.tcl
Subject: Re: support for built-in -opt style options for proc
Date: Tue, 25 Jun 2024 08:14:55 +0200
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Am 24.06.24 um 10:11 schrieb Mark Summerfield:
> I want to create a couple of procs with these usages:
> 
> dialog::prepare ?-parent .? ?-modal true? window
> 
Here is another very simple argument parser: Use "dict merge".

proc someprocwithargs {args} {
	set defaults {-parent . -modal false}
	set options [dict merge $defaults $args]
	if {[dict size $options] != [dict size $defaults]} {
		return -code error "Unknown option"
	}
	# now use the stuff in options
}

To extend by a mandatory argument is left as an exercise to the reader, 
you basically take off the last element from "args". It is advisable to 
do it this way, i.e. to make the mandatory argument positional, either 
in the beginning - then you can simple stuff it before "args" - or at 
the end. This way, an option can not be confused with a positional 
argument, and no "--" stuff is needed.

There have also been LOTS of advanced implementations in pure Tcl around 
the discussion of TIP 457 
https://core.tcl-lang.org/tips/doc/trunk/tip/457.md

	Christian