[Tcl-bugs] [ tcl-Feature Requests-1446696 ] Tcl_ParseArgv as a useful non-Tk version of Tk_ParseArgv

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Feature Requests item #1446696, was opened at 2006-03-09 11:29
Message generated for change (Comment added) made by nobody
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Category: 44. Parsing and Eval
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Sam Bromley (sbromle)
Assigned to: Donal K. Fellows (dkf)
Summary: Tcl_ParseArgv as a useful non-Tk version of Tk_ParseArgv

Initial Comment:
In porting an existing package based on C to one
that uses Tcl as the glue, I've had the desire to
have the Tk_ParseArgv functionality without Tk.
This lead me to find the following old conversation
regarding this:

http://www.google.com/url?sa=D&q=http://groups.google.ca/group/comp.lang.tcl/browse_thread/thread/c4fea8f0346cf8ae/036961bf476a3b99%3Flnk%3Dst%26q%3DTcl_ParseArgv%26rnum%3D1%23036961bf476a3b99

The arguments against Tcl_ParseArgv is that if you are
using tcl, then just use it as the main loop, and call
out to special function C codes as necessary. By doing
so, you can use one of the many Tcl Command line
parsing tools listed at http://wiki.tcl.tk/1730.

Now while the arguments against this functionality are
valid within the context of the process' main loop, it
breaks down when you want to parse options in
stand-alone commands. At least this is how I see
it.

To be more precise, I have a C library to which I want
to provide a Tcl interface.
So for each of the functions in the library, I need to
write a wrapper in C, to provide that command to Tcl.
If I want these commands to have libpopt or Tk-like
command options I either have to
  1) Parse the command arguments myself (on the C side); or
  2) Write additional wrappers to the commands in Tcl,
to pre-parse the options.
So in the case of (2), I'm making work for myself, when
all I really want to be able to do is call
Tcl_ParseArgv and be done with it in the original C
command wrapper.

NEWays, to get things working quickly, I wrote a
Tcl_ParseArgv routine, based (of course)
heavily on the tkArgv.c source (which implements
Tk_ParseArgv), but with all the Tk specific bits taken
out.  So now my wrappers can be ported very quickly
from their current libpopt handled options, to the
Tcl_ParseArgv.

Summary:
 1) Provide a Tcl_ParseArgv routine that can parse
    a standard argc,argv[] pair.
 2) Useful when functions other than main() wish
    to parse arguments in argc, argv[] format.
 3) Useful when one wishes to have libpopt style
    command line arguments to functions.
   3a) Build argc,argv from objc,objv.
   3b) Parse using Tcl_ParseArgv.
   3c) Parse remaining arguments in familiar C fashion.
 4) Makes re-writing of C-based wrappers written using
    libpopt trivial.

Code (which can be used as a shared library),
is attached.


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Comment By: Nobody/Anonymous (nobody)
Date: 2006-06-14 13:59

Message:
Logged In: NO 

Please take a look at this version, which does use
GetIndexFromObject, parses args as well options, and uses
callbacks for type checking:

http://naviserver.cvs.sourceforge.net/naviserver/naviserver/nsd/tclobjv.c?view=markup


There's lots of examples of it being used, e.g. here:

http://naviserver.cvs.sourceforge.net/naviserver/naviserver/nsd/tclrequest.c?revision=1.14&view=markup


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Comment By: Sam Bromley (sbromle)
Date: 2006-06-13 19:21

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The version I wrote using Tcl_GetIndexFromObj was causing a
crash. I've reverted to my original version in the latest
version (20060613), and it is this version that I am
currently using in production. I've included an example code
that compiles a Tcl extension that you can load using
"load", and it provides the "parseme" example command. In
addition to the coded options, you also have automatic help
via "-help".

I will be happy to assist in any way you see fit.

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Comment By: Don Porter (dgp)
Date: 2006-06-12 13:34

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I want to make a real patch
file for this.  Which of the
attached files are the right
one(s) to use?


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Comment By: Sam Bromley (sbromle)
Date: 2006-04-03 12:04

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W.r.t. the use of Tcl_GetIndexFromObj(), I did consider
it, and originally decided that it was not the way to go.
If I wished to implement a single command, I would surely
have used it, however, the benifit of the tclArgv approach,
is that the writer of the C implemented command can quite
cleanly package everything up into a single array of
Tcl_ArgInfo structures, and specify
type checking and conversion all in one neat place.

So,I originally opted for the simplicity of the current
code. I have however now rewritten it to use
Tcl_GetIndexFromObjStruct, to remove the parsing bit,
as per your suggestion. I hope this is less bizarre. :)

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Comment By: Don Porter (dgp)
Date: 2006-04-03 10:02

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Took a quick glance at the
submitted code and I see no
use of Tcl_GetIndexFromObj().
Seems very bizarre to me,
as I'd expect any command line
parsing to be a thin wrapper
around it.

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Comment By: Donal K. Fellows (dkf)
Date: 2006-04-03 02:29

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Requires a TIP. Email me for details on the process.

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Comment By: Sam Bromley (sbromle)
Date: 2006-03-10 14:47

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I've added a routine "Tcl_ParseArgsObj" that
provides libpopt or Tk_ParseArgv type parsing,
but for Tcl_Obj *objv[] array passed to
C implemented Tcl commands.

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