Item4931: CompareRevisionsAddOn no longer works with 4.2 and PatternSkin

Easy to see.

Install it.

Do a diff (which now points to the compare bin instead of diff).

You end up with a blank page.

This plugin seems to work in classic skin.

The fix is to change templates/compare.pattern.tmpl and templates/interweave.pattern.tmpl

I have not tested with the undocumented _cra templates. They are not really needed.

This plugin works in 4.1.2.

Example. Look at http://www.lavrsen.dk/twiki/bin/compare/Motion/FrequentlyAskedQuestions?rev1=52;rev2=51 to see how it looks like when it works

Note that CompareRevisionsAddOn distribution contains a small plugin called CompareRevisionsAddonPlugin. You will not find this on t.o. or SVN. This plugin is simply included with CompareRevisionsAddOn which is on SVN.

-- TWiki:Main/KennethLavrsen - 05 Nov 2007

There are also code errors I think. I get this in error log.

[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in pattern match (m//) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 143., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in pattern match (m//) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 144., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in pattern match (m//) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 145., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in pattern match (m//) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 146., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 224., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in print at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 225., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 224., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in print at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 225., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 224., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in print at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 225., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 224., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in print at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 225., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 224., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in print at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 225., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 224., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in print at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 225., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 257., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 258., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 259., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 260., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 261., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 262., referer: http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome
[Tue Nov 06 01:28:22 2007] [error] [client 192.168.1.9] [Tue Nov  6 01:28:22 2007] compare: Use of uninitialized value in substitution (s///) at /usr/local/apache2/twiki42/lib/TWiki/UI/Compare.pm line 263., referer: [[http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome][http://merlin.lavrsen.dk/twiki42/bin/view/Myweb/WebHome]]

HOWEVER same errors are not when you use classic skin so it is related to skin changes.

KJL

Strange.

Line 127 in compare

    my $tmpl = TWiki::Func::readTemplate
          ($interweave ? 'interweave' : 'compare');

returns nothing but a few empty lines when skin is pattern.

If I put another template name than interweave like rdiff then the TWiki::Func::readTemplate returns something. There seems to be a core bug that fails to read certain templates.

I will continue debugging.

-- TWiki:Main.KennethLavrsen - 06 Nov 2007

I have debugged. It is not a core bug.

When I analyse what happens in lib/Templates.pm is that the interweave.pattern.tmpl is correctly parsed and all the %TMPL:DEF are correctly parsed.

But in sub readTemplate the variable $result is empty before it reaches $result =~ s/(%TMPL\:P{.*?}%)/_expandTrivialTemplate( $this, $1)/geo;

The templates read are simply nothing but TMPL:DEFs and nothing is actually surfacing to the top.

Something changed in the 4.2 pattern skin so the sequence

%TMPL:P{"htmldoctype"}%
%TMPL:P{"head"}%
%TMPL:P{"bodystart"}%
%TMPL:P{"main"}%
%TMPL:P{"bodyend"}% 

produces no output anymore.

-- TWiki:Main.KennethLavrsen - 07 Nov 2007

Adding %TMPL:INCLUDE{"twiki"}% to interweave.pattern.tmpl brings the plugin back to life. But the layout is not correct. For example the title is double.

I cannot overview what is wrong. There are so many template files that includes each other.

-- TWiki:Main.KennethLavrsen - 07 Nov 2007

Some rigorous refactoring was needed to remove pattern skin dependent code from the lib code. The good news is that a specific pattern template is no longer needed.

I have also renamed CompareRevisionsAddonPlugin to CompareRevisionsAddOnPlugin.

-- TWiki:Main.ArthurClemens - 07 Nov 2007

I have reverted the name change.

-- TWiki:Main.ArthurClemens - 08 Nov 2007