Difference: TWikiPlugins (24 vs. 25)

Revision 252003-12-12 - PeterThoeny

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TWiki Plugins

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Preinstalled Plugins

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TWiki comes with three Plugins as part of the standard installation.
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TWiki comes with a set of Plugins as part of the standard installation.
 
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  • DefaultPlugin optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)

  • EmptyPlugin is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.

  • InterwikiPlugin is preinstalled but can be disabled or removed. Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
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  • DefaultPlugin: Optionally handles some legacy variables from older versions of TWiki. You can control this option from TWikiPreferences. (Perl programmers can also add rules for simple custom processing.)
  • EmptyPlugin: Is a fully functional module, minus active code; it does nothing and serves as a template for new Plugin development.
  • InterwikiPlugin: Use it for shorthand linking to remote sites, ex: TWiki:Plugins expands to TWiki:Plugins on TWiki.org. You can edit the predefined set of of Wiki-related sites, and add your own.
  • EditTablePlugin: Edit TWiki tables using edit fields, date pickers and drop down boxes
  • RenderListPlugin: %RENDERLISTPLUGIN_SHORTDESCRIPTION%
  • SlideShowPlugin: Create web based presentations based on topics with headings.
  • SmiliesPlugin: Render smilies as icons, like  :-)  as smile or  :eek:  as eek!
  • SpreadSheetPlugin: Add spreadsheet calculation like "$SUM( $ABOVE() )" to TWiki tables or anywhere in topic text
  • TablePlugin: Control attributes of tables and sorting of table columns
 

Installing Plugins

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  • Method 2: List the Plugin being tested in the DISABLEDPLUGINS variable in TWikiPreferences. Redefine the DISABLEDPLUGINS variable in the Sandbox web and do the testing there.
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A Note on Performance

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A Note on Plugin Performance

 
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The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that needs to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null http://twiki.npl.illinois.edu/bin/view/TWiki/AbcPlugin
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The performance of the system depends on the number of Plugins installed and on the Plugin implementation. Some Plugins impose no measurable performance decrease, some do. For example, outsidePREHandler is an expensive callback function, or a Plugin might use many Perl libraries that need to be initialized with each page view (unless you run mod_perl). It is recommended to measure the performance with and without a new Plugin. Example for Unix:
time wget -qO /dev/null http://twiki.npl.illinois.edu/bin/view/TWiki/AbcPlugin
  In case you need to install an "expensive" Plugin and you need its functionality only in one web you can place the Plugin topic into that web. TWiki will initialize the Plugin only if the Plugin topic is found (which won't be the case for other webs.)
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  • All but the initPlugin are disabled. To enable a call back, remove DISABLE_ from the function name.
  • For best performance, enable only the functions you really need. NOTE: outsidePREHandler and insidePREHandler are particularly expensive.
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Most Plugins use either the commonTagsHandler or startRenderingHandler for rendering tasks:
  • commonTagsHandler: Use it to expand %XYZPLUGIN% and %XYZPLUGIN{...}% variables
  • startRenderingHandler: Use it for your own rendering rules or to overload TWiki's internal rendering like [[links]]

TWiki:Codev/StepByStepRenderingOrder helps you decide which rendering handler to use.

Hints on Writing Fast Plugins

  • Delay the Plugin initialization to the actual function which is handling the tag. This way all the expensive initialization is done only when needed.
  • For example, use an eval block like:
    eval { require IPC::Run }
    return "<font color=\"red\">SamplePlugin: Can't load required modules ($@)</font>" if $@;
  • You could return errors as strings to show what happened
  • You can use a flag to avoid running the initialization twice
 

Plugin Version Detection

To eliminate the incompatibility problems bound to arise from active open Plugin development, a Plugin versioning system and an API GetVersion detection routine are provided for automatic compatibility checking.

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  1. Link from the doc page to a new, blank page named after the Plugin, and ending in Dev, ex: MyFirstPluginDev. This is the discussion page for future development. (User support for Plugins is handled in TWiki:Support.)

-- AndreaSterbini - 29 May 2001

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-- PeterThoeny - 29 Jan 2003
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-- PeterThoeny - 11 Dec 2003
 -- MikeMannix - 03 Dec 2001
 
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