Setting break point for particular condition in the subroutine

srlbharu has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Setting break point for particular condition in the subroutine by LanX (Saint) on Mar 07, 2013 at 08:22 UTC
> I tried to set as `b Engine::_Execute /INITIAL/i` but my script runs without wait. you're setting a breakpoint on the routine with a condition which checks $_ which doesn't make much sense. If I where you I would set the breakpoint at first line of body of `if($cmd =~ /INITIAL/i)` condition, that is `unless (fork)` There is more than one way to do it. Find the line number by investigating the routine with `l Engine::_Execute` and set `b line_number`. Or manipulate your source and include `$DB::single=1` before the line you want to break. Cheers Rolf	[reply] [d/l] [select]
Re^2: Setting break point for particular condition in the subroutine by srlbharu (Acolyte) on Mar 07, 2013 at 13:08 UTC
Sorry for not mentioned. I tried `$DB::single=1` and I am able to set the break point at the required place. Thanks..	[reply] [d/l]
Re^2: Setting break point for particular condition in the subroutine by srlbharu (Acolyte) on Mar 07, 2013 at 13:48 UTC
I am getting the below error only when I try to create child process using fork in the code mentioned in this Thread. `Engine::_Execute(..\..\perl\modules/Engine.pm:122): 122: unless (fork) { DB<1> s Bizarre SvTYPE [37] at ..\..\perl\modules/Engine.pm line 122. Engine::_Execute(C:/Perl/lib/Carp.pm:97): 97: { local $@; require Carp::Heavy; } # XXX fix require to not clea +r $@?` [download] It means there are some localized scalar variables are trying to restore in a child process hence throwing error "Attempt to free unreferenced scalar" There is some modules where carp.pm is used. I replaced all the places of carp with warn and tried but no luck still it is showing the same. Please let me know how to debug this issue.	[reply] [d/l]
Re^3: Setting break point for particular condition in the subroutine by LanX (Saint) on Mar 07, 2013 at 14:54 UTC
No idea, better start a new thread: "Forking Problem: Attempt to free unreferenced scalar" to attract the experts. One tip: Following the local markup conventions using `<p>` instead of `<pre>` will help in gaining acceptance and finding support. =) Cheers Rolf	[reply] [d/l] [select]
Re^3: Setting break point for particular condition in the subroutine by choroba (Cardinal) on Mar 07, 2013 at 15:13 UTC
Please, do not use `<pre>` tags for text. Read <pre> Versus <code> Tags for more information as already advised in a /msg. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re: Setting break point for particular condition in the subroutine by rjt (Curate) on Mar 07, 2013 at 08:15 UTC
It sounds like you want to insert the breakpoint at the `if ($cmd =~ /INITIAL/i)` line. Let's say that's line 123. Then, type: `b 123 $cmd =~ /INITIAL/i` Setting it to the subroutine entry is problematic because `$cmd` isn't set yet (or at least isn't set to a member of `@commands`. In addition to that, simply using `/INITIAL/i` as your condition would be running that regexp on `$_`, not `$cmd`. See perldebug for more info.	[reply] [d/l] [select]
Re^2: Setting break point for particular condition in the subroutine by srlbharu (Acolyte) on Mar 07, 2013 at 09:04 UTC
This subroutine is called from other subroutine which is intern called from my perl script. So setting break point `b 123 $cmd =~ /INITIAL/i` throws error Line 118 not breakable. because my script does not have those many lines. From the google docs I found the below statement b subname [condition] Can we use this in anyway?	[reply] [d/l]
Re^3: Setting break point for particular condition in the subroutine by rjt (Curate) on Mar 07, 2013 at 10:43 UTC
Yes, that's why you need to figure out the actual line number. "123" was just an example. You can determine the line number with `l Engine::_Execute` ... lines that are breakable will show with a colon (:) after the line number in the debugger. Hence, if you see this: `100 sub Engine::Execute 101 { 102 103: foreach (@commands) 104 { 105: $cmd = $_; 106: if($cmd =~ /INITIAL/i) 107 {` [download] ... then you would type `b 106 $cmd =~ /INITIAL/i` Again, these numbers are just examples. You need to determine the actual line number for yourself with `l Engine::_Execute`!	[reply] [d/l] [select]
Re^3: Setting break point for particular condition in the subroutine by LanX (Saint) on Mar 07, 2013 at 10:57 UTC
> From the google docs I found the below statement `b subname [condition]` Can we use this in anyway? No and I already showed you two ways to solve this. Why didn't you try? Cheers Rolf	[reply] [d/l]
Re: Setting break point for particular condition in the subroutine by choroba (Cardinal) on Mar 07, 2013 at 15:13 UTC
Please, do not use `<pre>` tags for text. Read <pre> Versus <code> Tags for more information as already advised in a /msg. لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re: Setting break point for particular condition in the subroutine by clueless newbie (Curate) on Mar 07, 2013 at 12:22 UTC
Sometimes it's easier to use "$DB::single=1;" directly in your code. For example: `my @caller=caller(0); $DB::single=1 if ($caller[0] eq 'package::of::interest' and $caller[3] + eq 'thatsub');` [download]	[reply] [d/l]