[ ddd-Patches-806716 ] perl: bug-fix graph display of blessed references (objects)

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Patches item #806716, was opened at 2003-09-15 20:43
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Christian Hattemer (krille)
Assigned to: Nobody/Anonymous (nobody)
Summary: perl: bug-fix graph display of blessed references (objects)

Initial Comment:
This patch has been posted to the DDD mailing list by Peter Ernst on Wed, 5 Jun 
2002 17:36:12 +0200 (MET DST)

-----------------------------------------------------------

   DDD 3.3.1 with Perl: when using the graphical display on reference
                        variables, de-referencing works nicely through
                        e.g. a double-mouse click (by means of code in
                        ddd/deref.C). However, if the references is
                        blessed (i.e. it is a object reference),
                        de-referencing does NOT work.

   Example: graph display $SeqInfoObj

            p $SeqInfoObj
     W3H::Parser::Seqinfo=HASH(0x4d3738)

            i.e. $SeqInfoObj is a blessed reference

     double-click on the graph does NOT dereference, because
     the code in ddd/deref.C tries to get the "type" of the
     reference (in this case HASH) by parsing the output of
     " p $SeqInfoObj ", and considers the first identifier as
     "type". In this case the type is "W3H" which is wrong.

     Interestingly, the regular expression to parse the output
     of " p $SeqInfoObj " (rxperlref line 359 in ddd/rxscan.L)
     already knows about the "more complicated" syntax. I.e. it
     is not necessary to fix something here.

Fix description:

     Correct is is to take the first identifier after a
     "=". This works for blessed and un-blessed references
     (un-blessed references don't have a "=" character in the
     output of " p $simple_ref "). I.e. the bug is fixed by
     changing line 72 in ddd/deref.C
  from:
     ref = val.through(rxidentifier);
  to:
     ref = val.at(rxidentifier, val.index("=") + 1);

on a blessed reference, val.index("=") + 1 points to the first
character after the "=" sign,
on a un-blessed reference, val.index("=") + 1 points to character 0.

The fix is working as you can see from the history file below:
$SeqInfoObj              is a blessed hash-reference

$SeqInfoObj->{'entries'} is an un-blessed array-reference

$SeqInfoObj->{'entries'}->[0]   aka
${$SeqInfoObj->{'entries'}}[0]
                         is an un-blessed hash-reference


from ~/.ddd/history :

------------- begin snip -------------------

exec "perl -d w3h.debugtask dnasweep -infile=ensembl_cdna:enst00000000442"
cont
c 218
graph display $SeqInfoObj
graph display %$SeqInfoObj dependent on 1
graph display @{$SeqInfoObj->{'entries'}} dependent on 2
graph display %{${$SeqInfoObj->{'entries'}}[0]} dependent on 3

------------- end snip -------------------


in case you're interested ~/.ddd/log :

------------- begin snip -------------------

GNU DDD 3.3.1 (sparc-sun-solaris2.7)
Copyright (C) 1995-1999 Technische Universität Braunschweig, Germany.
Copyright (C) 1999-2001 Universität Passau, Germany.

Compiled with GCC 2.95.2 19991024 (release), libstdc++ 2.8.0
Requires X11R6, Xt11R6, Motif 2.1 (Motif Version 2.1.0)
Includes Athena Panner, DDD core
Built 2002-06-05 by Peter Ernst <unknown>.
$  /home/dok427/fox/ddd-3.3.1/ddd/ddd --perl w3h.debugtask

------------- end snip -------------------


Kind regards,

     Peter Ernst

P.S: DDD is really a very nice program. Congratulations for it!

-- 
=======================================================================
 Peter Ernst
 Department of Molecular Biophysics - H0200
 Deutsches Krebsforschungszentrum (German Cancer Research Center) DKFZ
 Im Neuenheimer Feld 280
 69120 Heidelberg, Germany                     phone: +49-6221-42-2330
 http://genome.dkfz-heidelberg.de/               fax: +49-6221-42-2333
=======================================================================    


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