Difference: TWikiVariables (86 vs. 87)

Revision 872011-03-27 - TWikiContributor

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TWiki Variables

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  You can also set preferences variables on a topic by clicking the link Edit topic preference settings under More topic actions. Use the same * Set VARIABLENAME = value syntax. Preferences set in this manner are not visible in the topic text, but take effect nevertheless.

Parameterized Variables (Macros)

It is possible to pass parameters to TWiki variables. This is called a macro in a programming language.

To define a parameterized variable, set a variable that contains other variables, such as:

   * Set EXAMPLE = Example variable using %DEFAULT%, %PARAM1% and %PARAM2%
   * Set DEMO = Demo using %DEFAULT%,
                %PARAM1% and %PARAM2%

A special %DEFAULT% variable denotes the default (nameless) parameter of the calling variable. Variables optionally may list a default="..." parameter that gets used in case the calling variable does not specify that parameter.

To use a parameterized variable (or call a macro), add parameters within the curly brackets, such as:

   * %EXAMPLE{ "foo" PARAM1="bar" PARAM2="baz" }%
   * %DEMO{ "demo" PARAM2="parameter 2" }% -- note that PARAM1 is missing
which resolves to:
  • Example variable using foo, bar and baz
  • Demo using demo, (undefined) and parameter 2 -- note that PARAM1 is missing

Parameters in the variable definition are expanded using the following sequence:

  1. Parameter from variable call. In above example, %PARAM1% gets expanded to bar.
  2. Session variable and preferences settings


Define variables:

   * Set DRINK = red wine
   * Set FAVORITE = My %DEFAULT% dish is %DISH%,
                    my %DEFAULT% drink is %DRINK%.
TIP The default can be defined with a default parameter (%DISH{default="steak"}%), or as a preferences setting (Set DRINK = ...).

Use Variables:

%FAVORITE{ DISH="Sushi" DRINK="Sake" }%
My favorite dish is Sushi, my favorite drink is Sake.

My favorite dish is steak, my favorite drink is red wine.

%FAVORITE{ "preferred" }%
My preferred dish is steak, my preferred drink is red wine.

Defined in INCLUDE: 
  • Set EXAMPLE = Example variable using %DEFAULT%, %PARAM1% and %PARAM2%
  • Set DEMO = Demo using %DEFAULT{ default="(undefined)" }%, %PARAM1{ default="(undefined)" }% and %PARAM2{ default="(undefined)" }%
  • Set DRINK = red wine
  • Set FAVORITE = My %DEFAULT{default="favorite"}% dish is %DISH{default="steak"}%, my %DEFAULT{default="favorite"}% drink is red wine.

Access Control Variables

These are special types of preferences variables to control access to content. TWikiAccessControl explains these security settings in detail.

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Related Topics: UserDocumentationCategory, TWikiVariablesSearch, TWikiVariablesQuickStart
Related Topics: UserDocumentationCategory, TWikiVariablesSearch, TWikiVariablesQuickStart, ParameterizedVariables
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