Feature Proposal: Make zones less intrusive, especially for non-HTML output

Motivation

1. It's impossible to emit custom HTML without contamination from unwanted plugin output. So simply let the skin authors use %RENDERZONE{"head"}% and %RENDERZONE{"script"}% explicitly
2. Foswiki.pm isn't the place for zones code. If anything, it might go in Render.pm
3. The if $contentType ne 'text/plain' is just a bit mad, we can do better than that
4. Wasting CPU cycles on requests that don't do anything with zones, let alone output HTML

Description and Documentation

Two main changes, the first removes the assumption that we always want zones rendered with output which happens to contain a "</head>" string:

diff --git a/core/lib/Foswiki.pm b/core/lib/Foswiki.pm
index 562a64c..478b738 100644
--- a/core/lib/Foswiki.pm
+++ b/core/lib/Foswiki.pm
@@ -755,11 +755,6 @@ JS
               $cgis, $context, $usingStrikeOne )/gei;
     }
 
-    if ( $contentType ne 'text/plain' ) {
-
-        $text = $this->_renderZones($text);
-    }
-
     # SMELL: can't compute; faking content-type for backwards compatibility;
     # any other information might become bogus later anyway
     my $hdr = "Content-type: " . $contentType . "\r\n";
diff --git a/core/templates/foswiki.tmpl b/core/templates/foswiki.tmpl
index 5a4674b..fbd6a29 100644
--- a/core/templates/foswiki.tmpl
+++ b/core/templates/foswiki.tmpl
@@ -74,8 +74,10 @@ Item2476: Put IE8 into compatibility mode to work around slow, erratic textarea
        <link rel="alternate" href="%SCRIPTURL{edit}%/%BASEWEB%/%BASETOPIC%?t=%GMTIME{"$epoch"}%" type="application/x-wiki" title="edit %BASETOPIC%" />
        <meta name="description" content="%TOPIC%" />
     <base href="%SCRIPTURL{%SCRIPTNAME%}%/%WEB%/%TOPIC%" /><!--[if IE]></base><![endif]-->
-       %TMPL:P{"script"}%
        %TMPL:P{"defaultstyle"}%
+       %RENDERZONE{"head"}%
+       %RENDERZONE{"script"}%
+       %TMPL:P{"script"}%
 </head>%TMPL:END%%{
 ---------------------------------------------------
 }%%TMPL:DEF{"titleaction"}%%TMPL:END%%{

Secondly, refactor the code out of Foswiki.pm.

Examples

Impact

WhatDoesItAffect:

%WHATDOESITAFFECT%

edit

Implementation

-- Contributors: PaulHarvey - 12 Nov 2010

Discussion

I guess we could make a Foswiki.spec to preserve compatibility with 1.1 skins which rely on the existing s/</head>/STUFF/ behaviour.

OTOH any skin that inherits foswiki.tmpl version of head DEF should be fine

-- PaulHarvey - 12 Nov 2010

The patch is absolutely the right thing to do next now that skins and plugins have been infiltrated by zones to a sufficient level.

I agree that we should add an {AutoRenderStandardZones} kind of setting to the foswiki specs, which defaults to off. Sol old skins can be made working switching it on again.

-- MichaelDaum - 17 Nov 2010

Looks like this should be accepted. Since it looks simple enough, slotting it into 2.1, But let's discuss.

-- Main.GeorgeClark - 27 Jul 2015 - 01:21