<--

   PLEASE DO NOT EDIT THIS TOPIC

   It is automatically generated from the subversion repository, and any changes
   you make will simply be overwritten the next time a release is generated.

   Instead, you could check your fix in, raise a bug in the Bugs web, or mail the author(s).
-->

IfDefinedPlugin

Description

Powered by WikiRing Consultants

The other way is to use blocks of content surrounded by expressions like this:

%IFDEFINEDTHEN{"test"}%
...
%ELSIFDEFINED{"test"}%
...
%ELSEDEFINED%
...
%FIDEFINED%

Related work

The advantage of this plugin is that you get a simpler mechanism for checking the condition which is however more flexible as the string can be generated arbitrarily using TWikiML. Furthermore, and possibly more important, this plugin is backwards compatible and may be used on a TWiki/Beijing, TWiki/Cairo and TWiki/Dakar engine.

This plugin has been externalized from the TWiki:Plugins/NatSkinPlugin.

Syntax Rules

IFDEFINED

%IFDEFINED{"test" 
  [action="view,edit,preview,..."]? 
  [as="..."]
  then="..." 
  else="..." 
  glue="on,off"}%

returns the "then or "else" content depending on the "test" expression expanding to the emtpy string or matching the string given in "as". Optionally the current topic action is checked to match the one given in "action". Normally, all surrounding whitespaces are removed, that is the resulting content is glued together in a way. You may switch that off by setting "glue" to "off" thus preventing all whitespace as it is.

The "then" and "else" strings may contain the following pseudo-variables:

• $n: substituted with a newline character (\n)
• $percnt: substituted with a percent character (%)
• $dollar: substituted with a dollar character ($)
• $test or $variable: substituted with the "test" string
• $value: substituted with the "as" string

IFDEFINEDTHEN, ELSIFDEFINED, ELSEDEFINED, FIDEFINED

%IFDEFINEDTHEN{"test" [action="view,edit,preview,..."]?}% 
  <then content> 
[%ELSIFDEFINED{...}% 
  <elsif content>]* 
[%ELSEDEFINED%
  <else content>]?
%FIDEFINED%

This is the multi-line version of IFSDEFINED. IFDEFINEDTHEN expressions can be nested safely. Within a single IFDEFINEDTHEN the ELSIFDEFINED parts can be repeated arbitrarily. Before rendering the <then|elsif|else condition> any $nop string will be removed first. Thereby nested TWikiML expressions can be prevented from being expanded in advance.

IFACCESS

%IFACCESS%

%IFACCESS{"<webtopic>" 
  [type="view|change"] 
  [user="<WikiName>"] 
  [then="<then-clause>"] 
  [else="<else-clause>"] 
  [glue="on|off"]}%

This checks the access permissions a user has on a given topic and then renders the <then-clause> if access is granted and lt;else-clause> otherwise. By default, the current user's view access will be checked on the current topic (%IFACCESS%). The other parameters are:

• <webtopic>: the name of the topic to be checked, defaults to current
• user="<WikiName>": the name of the user to be checked, defaults to the current user
• type="view|change": the type of access to be checked, either view access or change/edit access, defaults to "view"
• then="<then-clause>": the string to be returned on granted access, defaults to "1"
• else="<else-clause>": the string to be returned if no access is granted, defaults to "0"
• glue="on|off": apply glue around the IFACCESS tag or not, defaults to "on"

IFEXISTS

%IFEXISTS{"<webtopic>"
  [then="<then-clause>"] 
  [else="<else-clause>"] 
  [glue="on|off"]}%

This tag checks if webtopic exists and expands then-clause or else-clause as needed. A similar functionality is available using %CALC{"$IF($EXIST(<webtopic>,<then-clause>),<else-clause>)"}% of the SpreadSheetPlugin. This is still preferable if you need more computation based on CALC in the then/else branches. The IFEXISTS version however is more lightweigted, comes with a much simpler syntax and allows more complex TWikiMarkup in the then/else branches.

Demo

• Set FOO = foo
• FOO is defined.
• FOO is not defined as "bar".
• BAR is not defined.
• TWikiGuest has no write access to IfDefinedPlugin
• TWikiGuest has no write access to IfDefinedPlugin

Plugin Installation Instructions

• Download the ZIP file
• Unzip it in your twiki installation directory. Content:

  File:	Description:
  data/TWiki/IfDefinedPlugin.txt	Plugin topic
  lib/TWiki/Plugins/IfDefinedPlugin.pm	Plugin Perl module

• (Dakar) Visit configure in your TWiki installation, and enable the plugin in the {Plugins} section.

Plugin Info

<-- provided for compatibility only 

 Set SHORTDESCRIPTION = Render content conditionally
 
-->

<-- specify latest version first -->

-- TWiki:Main.MichaelDaum - 03 Jul 2008

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