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PageVariableExtensions

Questions answered by this recipe

I've found the page variables very useful but I can't only rely on their plain values, I need to be able to manipulate them.

This recipe is *officially* deprecated by MarkupExprPlus and would not be maintained anymore --Dfaure September 13, 2007, at 03:49 AM

Note: Much of this functionality can be done with core methods provided in the latest 2.1.xbeta series (see the See Also: below)

How may I have my own?

Description

The extendvars.phpΔ script enhances the variable features in several ways, providing markup and suffixes functions to dynamically initialize and manipulate their values:

• The recipe provides the (:set ...:) markup directive to initialize/assign page variables.
• The general syntaxic form for variables becomes {pagename$variable:function arg ...}, where the function is applied to the variable's value before returning it to the page.

As a preliminary sample, on a page where {$Name} renders as PageVariableExtensions, you may write:

(:set msg='{$Name:toupper} is here!':)
''oyez, oyez, {$msg}''

Installation

Proceed to installation steps as usual for cookbook recipe scripts.

Warnings/Preliminary notes

User-defined page variables are very volatile things and only "page-local" and "page-wide" variables may be assigned with the (:set ...:) directive. Therefore:

• Variable's values can only be seen from within the page they have been assigned (page-local aspect).
• Conditional markup is ignored during value assignation (which occurs before):

(:set var='nice':)
(:if false:)(:set var='weird':)(:if:)
"Conditionals are {$var}"

...instead of "Conditionals are nice" (page-wide aspect).

Variable initialization

The (:set var1=value1 var2=value2 ...:) markup directive allows the definition of new variables, including using ones previously defined earlier in the same directive, as in:

(:set 1stname=Dominique:)
(:set surname=Faure user='{$1stname} {$surname}':)
Hello, I'm {$user}

During variable assignation, the directive is also able to recognize specific helper functions. The generic value syntax is

 '(=function arguments) params' (square brackets are also allowed).

The build-in helper functions include:

'(=if condition) value_if_TRUE "value if FALSE"'

'(=time H=... M=... S=... d=... m=... Y=...)'
'(=time specification reference)'

'(=http_get name) default_value'
'(=http_post name) default_value'
'(=http_request name) default_value'
'(=http_cookie name) default_value'
'(=session_data name) default_value'

The revisited conditional is then

(:set flag=1 mood='(=if equal {$flag} 1) "nice" "weird"':)
"Conditionals are {$mood}"

Variables could also be erased/removed with the (:set -VarToForget ...:) syntax.

Variable values manipulation functions

The following function suffixes are available to manipulate values as PmWiki renders them with the page text:

+ value
- value
* value
/ value

Function calls may be chained as in: {$Namespaced:tolower:replace ' ' '_'} (which would provides: page_variable_extensions if triggered as the first sample).

Variable values may be provided as function parameters using angle brackets, as in:

(:set var='abcdef' s1=2 s2=4:)
* {$var:sub <$s1> 3}
* {$var:sub <$s2> 3}

Miscellaneous

As another workaround to the volatile nature of the user defined page variables (cf. preliminary note), the $EnableUrlSetVar flag (set to 1, before including the recipe script) would allow one to define variables from an url with parameters like ?set_var1=value1&set_var2=value2&..., as in:

[[{$PageUrl}?set_VarSetFromUrl=This the value|Go to page with a value set]]

Nota: You should prefer use the http_... variable initializers, which provide a more powerful control and doesn't need the $EnableUrlSetVar flag set.

Two extra directives are available to set/erase cookie values and/or session data:

(:cookie name=... value=... expire=... path=... domain=...:)

(:session var1=value1 var2=value2 -removedVar ...:)

• The cookie directive takes account of the $CookiePrefix configuration option.
• When ommitted, cookie path defaults to '/'.

Technical hints (advanced user/admin.)

You may easily extend the recipe providing your own functions in your local configuration files to initialize variables from specific data-sources or manipulate variable's values. Please refer to the recipe source code itself for live samples:

Variable initializers are defined in the $PageVarSetters array with the following prototype:

$PageVarSetters['...']($pagename, $func, $param, $default)

$PageVarSetters is an array of functions, indexed by name. These functions get called to initialize variables using their parameters or the provided default value:

• $pagename - The name of the current page.
• $func - The function name which initiated the call.
• $param - The parameters provided in the call.
• $default - The default value provided in the call.

Variable functions are defined in the $PageVarFuncs array, an indexed by name array of evaluable expression strings. Function parameters and current variable value are made available in the $funcparm array and the $value variable. The string evaluation should result in the replacement text.

Contributors

Dfaure

See Also

• page variables
• conditional markup
• page text variables - another way to set text values to variable like things
• MarkupExpressions - another way to execute similar string functions
• Cookbook.HttpVariables - another method of accessing/setting GET/POST vars, COOKIES and SESSIONS
• Cookbook.MarkupExprPlus - Extends {(...)} expression markups

Release Notes

• 2006-05-04 Initial release.
• 2006-05-18 Allowed variables initialization from url parameters. Added (some) missing strftime date mapping for Win32.
• 2006-06-28 Introduced conditional assignation, function parameters passing and regular expression functions.
• 2006-07-07 Revamped assignation with helper functions, added arithmetic and wiki names functions.
• 2006-07-10 Corrected cookie/session handling bugs.
• 2006-07-13 Small function parsing bug fix. Added timestamp assignation.
• 2006-09-28 Made recipe PmWiki 2.2.0-beta? compatible.
• 2006-10-29 Added RecipeInfo data.

Comments

(:set cVar1='(=http_cookie Var1)' Var1='(=http_get Var1) {$cVar1}':)
...
(:cookie name="Var1" value="{$Var1}" expire="{$Now:+ 3600}":)

[[#titlecounttotal]]
(:set totalwords='(=if equal "{<$Group}" "") 0 "{$totalwords}"':)
* [[{=$FullName}|{=$Title}]] ({=$Words} words)
(:set totalwords='{$totalwords:+ {=$Words}}':)
(:if equal {>$Group}:)

->Total: {$totalwords} words(:if:)
[[#end]]