Many Matters

authors, admins (advanced)

Using the (:if:) Directive

The (:if:) directive allows portions of a page to be included or
excluded from processing. The generic form of the (:if:) directive is

 (:if cond param:) body (:ifend:)

where “cond” names a condition to be tested (described below), and “param”
is a parameter or other argument to the condition.

The built-in conditions include:

	(:if name PAGENAME:)	-	current page is named “PAGENAME”
	(:if group GROUPNAME:)	-	current group is named “GROUPNAME”
	(:if auth LEVEL:)	-	viewer is authorized at “LEVEL” where LEVEL can be: read, edit, upload, attr or admin
	(:if authid:)	-	current viewer is authenticated
	(:if true:)	-	always include text
	(:if false:)	-	always exclude text (same as a comment)
	(:if attachments:)	-	current page has attachments
	(:if date DATE:)	-	true if current date is DATE
	(:if date DATE..:)	-	true if current date is DATE or later (unlimited)
	(:if date DATE1..DATE2:)	-	true if current date is in range DATE1 to DATE2 (inclusive)
	dates are in the format yyyy-mm-dd or yyyymmdd
	(:if enabled VAR:)	-	true if PHP VAR is true
	(:if equal STRING1 STRING2:)	-	true if STRING1 equals STRING2
	(:if match REG_EXPRESSION:)	-	true if current page name matches the regular expression
	(:if exists PAGENAME:)	-	true if the page pagename exists

Negated forms of conditions also work:

	(:if !attachments:)	-	this page has no attachments
	(:if ! name PAGENAME:)		current page is NOT named “PAGENAME”
	(:if name -PAGENAME :)
	(:if name !PAGENAME :)

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

 (:if auth read:)* You can read
 (: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 in conditional markup,
thus:

	(:if name PmCal.2005* :)	-	current page is in group PmCal and begins with 2005
	(:if group PmWiki* :)	-	current page is in group PmWiki or a group beginning with Pmwiki
	(:if name Profiles.*,-Profiles.Profiles :)	-	current page is in group Profiles but not Profiles.Profiles

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
bracketed sub-expressions of regular conditions:

Nota:

• Spaces around operators and brackets are required.
• No specific feedback is given for syntaxic errors or unbalanced brackets.

Thus, writing:

 (:if expr auth admin || auth attr || auth edit :)
 [[Logout -> {$Name}?action=logout]]
 (:if:)

provides you a logout link only when authentified with rights higher than ‘read’.

admins (advanced)

Creating new conditions

See Cookbook:ConditionalMarkupSamples.

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