Conditional Markup {PmWiki}

authors, admins (advanced)

Using the (:if:) Directive

The (:if:) directive allows portions of a page to be included or excluded from rendering. The generic forms of the (:if:) directive are

where "cond" names a condition to be tested (described below), and "param" is a parameter or other argument to the condition. Conditions do not nest.

The built-in conditions include:

Negated forms of conditions also work:

Any (:if:) automatically terminates the previous one, thus markup can be easily cased (and are not nested):

(:if enabled AuthPw:)* You're logged in
(:if auth read:)* You can read
(:if auth read Group.Page:)* You can read Group.Page
(:if auth edit:)* You can edit
(:if auth upload:)* You can upload
(:ifend:)

Using wildcard placeholders

The character * can be used as a wildcard to represent any character, zero, one or multiple times.
The character ? can be used as a wildcard to represent any character exactly one time.
Wildcard characters (* and ?) can be used with the name and group conditional markups, thus:

Use with page list templates

Conditional markup is used extensively with page list templates.

Use with page variables:

   =   current item
   <   previous item
   >   next item

Conditionals used to structure pagelist output:

   (:if equal {<$Group}:)               At beginning of list
   (:if equal {>$Group}:)               At end of list
   (:if ! equal {=$Group} {<$Group}:)   First item in group
   (:if ! equal {=$Group} {>$Group}:)   Last item in group

Combining conditions

Conditions (as previously defined) may be combined into more complex conditional expressions using one of these three equivalent forms:

(:if expr EXPRESSION :)
(:if [ EXPRESSION ] :)
(:if ( EXPRESSION ) :)

Conditions are combined into expressions with boolean operators and brackets. In the next table, A and B are either regular conditions or (round-)bracketed sub-expressions of regular conditions:

Nota:

• Spaces around operators and brackets are required.
• No specific feedback is given for syntax errors or unbalanced brackets.
• Use round brackets (not square) for nested expressions.

Thus, the following is a valid way of building an expression that shows the following contents only when the user is either the administrator, or is logged in and the time is later than the given date:

Nesting with square brackets will silently fail to work as expected:

A common use of these complex tests are for expressions like:

which provides a logout link only when the browser has admin, attr, or edit permissions.

admins (advanced)

Creating new conditions

See Cookbook:ConditionalMarkupSamples.

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