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PageTextVariables-Talk

Nested page text variables

Note: The following examples in this section describe a behavior, which was not defined as a feature by design, but which is more like a side effect. Be advised not to rely on nested PTVs, as their processing may change in the future. --Petko June 19, 2010, at 07:54 PM

Oops! I hope it doesn't change too much. I make extensive use of the 2nd type of PTV nesting... —Peter Bowers February 23, 2011, at 01:39 AM

Page text variables can be nested

: MailingAddress : {$:Address}, {$:City}, {$:Country}
"{$:MailingAddress}"

Another way you may nest PTVs is to make (part of) the variable name a variable in itself:

x:Test/Ptvb
Contents of y on page {$:x}:
{{$:x}$:y}

Usage - other

Data relevant to a page (the "Base" page) may now also be found in other groups. If the Base page is Main/HomePage, the data page could be Data-Main/HomePage. A new variable called $BaseName, which automatically calculates the Base page name from the Data page name, and can be defined by including the following in config.php:

// The pattern for figuring out the basename of a page
$BaseNamePatterns['/^Data-/'] = '';

Your pattern may vary.

Use page text variables in conditional markup

Page text variables will be assigned/evaluated before any conditional markup is evaluated. This effectively means that you cannot declare a PTV within an if...else condition; and also that a PTV will have a value even if it is set within a (:if false:)....(:if:) condition.

Note: The following examples in this section describe a behavior, which was not defined as a feature by design, but which is more like a side effect. Be advised not to rely on conditionals when you set a PTV, as their processing may change in the future. --Petko June 19, 2010, at 07:54 PM

In the example below, the condition will output the text '1 is equal to 1'; however, the value of 'cond1' will be 23, since both PTV assignments are evaluated (before the conditional), but the cond1:23 is evaluated last, and overrides the initial cond1:19.

(:if equal 1 1:)1 is equal to 1 (:cond1:19:)
(:else:)1 is NOT equal to 1?! (:cond1:23:)
(:if:)

The value of 'cond1' is {$:cond1}

You can however embed a conditional in a PTV assignment. Notice the format of the declaration below uses the non-hidden assignment form.

cond2:(:if equal 1 1:)19(:else:)23(:if:)

The value of 'cond2' is {$:cond2}

You cannot use the hidden form of PTV assignments, with an embedded condition. You basically get garbage output:

(:cond3:(:if equal 1 1:)19(:else:)23(:if:):)

The value of 'cond3' is {$:cond3}

But, you can take advantage of the fact that PTV assignments are made before conditions are evaluated, and hide the PTV assignment within a condition which evaluates to false, and thus is not displayed. In the example below we're using embedded conditions, and so we number the if statements:

(:if1 false:)
cond4:(:if2 equal 1 1:)19(:else2:)23(:if2:)
(:if1:)

The value of 'cond4' is {$:cond4}

Other information:

• Pm's post about line breaks documents use of the directive and mentions customization of the markup.
• Pm's post responding to a request for a summary in response to a request for documentation.
• Pm's post announcing the release of 2.2.0 beta 2 and providing examples.
• Pm's post planning for 2.2.0
• Lots of older posts with references to "PData" including an some extensive threads with lots of brainstorming about markup including, specifically, the WikiPaths thread started by Martin. (wikipath recipe finally released)

Usage notes

List names can be separated with leading spaces (a la Site.Blocklist or Site.InterMap), but list values may only have one leading space.

 Sea: Tasman
  Ocean:  Southern

-> @@"{$:Sea}"@@
-> @@"{$:Ocean}"@@

(:Continent: Antartica:)
-> @@"{$:Continent}"@@

 Sea: Tasman
  Ocean:  Southern

Lists can have leading or trailing spaces around the page variable name

Insect : Weta
:Bird  : Kiwi
: Tree: Kauri
:  Flower : Kowhai

"@@{$:Insect}@@"
"@@{$:Bird}@@"
"@@{$:Tree}@@"
"@@{$:Flower}@@"

What you can't do

Mismatch case in the page variable name

river: Whanganui
Range: Southern Alps

->[-(lowercase)-] "{$:river}"
->[-(uppercase)-] "{$:River}"
->[-(lowercase)-] "{$:range}"
->[-(uppercase)-] "{$:Range}"

Have embedded (you really didn't expect that did you) spaces in the page variable name

:Big bird:Moa

"@@{$:Big bird}@@" "@@{$:Bigbird}@@" 

Note that leading and trailing spaces in the page variable text are retained

:Island:       Rakiura
:Volcano:               Ngauruhoe                                   
:Caldera:Rotorua                                         

"@@{$:Island}@@"
"@@{$:Volcano}@@"
"@@{$:Caldera}@@"

Use natural page names, ie normal page name preprocessing does not occur

-<[[PmWiki.Page text variables]] "{PmWiki.Page text variables$:Summary}"
-<[[PmWiki.PageTextVariables]] "{PmWiki.PageTextVariables$:Summary}"

To use with conditional markup put the conditional markup in the variable

LinkUrl: (:if TRUE:)https://dilbert.com(:else:)[[Cookbook:Quotes]](:ifend:)

"{$:LinkUrl}"
>>green<<
Wrong answer because [={$:LinkUrl}=] gets redefined in another example below.

This works:

AnotherLinkUrl: (:if TRUE:)https://dilbert.com(:else:)[[Cookbook:Quotes]](:ifend:)

"{$:AnotherLinkUrl}"

-> [-[[~ChuckG]] February 24, 2017, at 03:47 AM-]
>><<

This won't work as page text variables are calculated prior to expressions.

(:if TRUE:)
  LinkUrl: https://dilbert.com
(:else:)
  LinkUrl: [[Cookbook:Quotes]]
(:ifend:)

"{$:LinkUrl}"

  LinkUrl: https://dilbert.com

See more examples at Test.Ptv

Usage in code

Defining new patterns for PTV (examples : bulleted lists, anchors, triple angle brackets)

PageTextVar relies on the $PageTextVarPatterns variable (which can be used to extend the recognized formats for page text variables in a page). In the older 2.2.0 Beta versions of PmWiki, this variable wasn't initialized until stdmarkup.php was run, after config.php was executed. Thus, if you needed to use page text variables inside config.php, you had to initialize it yourself. This is no longer necessary, but for those who are still running earlier versions of the beta series, here's the value to use:

SDVA($PageTextVarPatterns, array(
  'var:' => '/^:*\\s*(\\w[-\\w]*)\\s*:[ \\t]?(.*)$/m',
  '(:var:...:)' => '/\\(: *(\\w[-\\w]*) *:(?!\\))\\s?(.*?):\\)/s'));

Bulleted lists. For enabling PTV definition in bulleted lists, use this line in config.php (EemeliAro in Mailing list)

Anchors. For enabling multiline PTV definition delimited with anchors, use these lines in config.php (HansB in Mailing list). « The advantage of using anchors as PTVs is that you could reference those sections as PTVs and also as anchor sections, use them in urls for instance. The markers are also invisible. »

# make it possible to treat [[#section]] .... [[#sectionend]] as a PTV of name 'section'
$PageTextVarPatterns['[[#anchor]]'] =   "/(\\[\\[#(\\w[-\\w]*)\\]\\](?: *\n)?)(.*?)(\\[\\[#\\2end\\]\\])/s";

<<< (myvar) angle brackets >>>. For enabling multiline PTV definition delimited with triple angle brackets, use these lines in config.php (HansB in Mailing list).

Markup('<<<var', '<split', '/<<<\\s*?\\((\\w[-\\w]*) *\\)(.*?)>>>/s', '$2' );
$PageTextVarPatterns['<<<var...>>>'] = '/(<<<\\s*?\\(*(\\w[-\\w]*) *\\)(?!\\))\\s?)(.*?)(>>>)/s';

Page Text Variable calls & Markup Expressions

You can use a PTV call in a markup expression, but due to order of processing, you cannot use a markup expression inside of a PTV variable name. The following will fail:

Instead create a Page Variable in config.php, and use it in the PTV:

Then this will work:

(:Abstract:{Programme.Abstracts$RandomSection}:)
(:include {$:Abstract} lines=4:)
->[[{$:Abstract} | more ...]]

:Quote:{Cookbook.Quotes$RandomSection}
{$:Quote}
{$:Quote}
{$:Quote}

(:parameter:value1:)
(:include TemplateThatUsesParameter:)
(:parameter:value2:)
(:include TemplateThatUsesParameter:)

(:div id={{=$Name}$:project}}_small :)

(:project:bob:)
(:div id='{$:project}_small':)
blah
(:divend:)

[[#singleline]]
[-[[{=$FullName}|+]],-] \
[[#singlelineend]]

(:PtvOne: some
thing:)
(:if ! equal "{$:PtvOne}" "":)something(:else:)nothing(:ifend:)\\
but markup works: {$:PtvOne}

# {(ptvlen "{$FullName}" "MyPTV")} # not $:MyPTV
# useful to test for a ptv that contains multiple lines or quotes that might break the markup
# E.G. (:if !equal {(ptvlen "{$FullName}" "MyPTV")} 0:) tests whether a non-empty MyPTV exists
# This is similar to strlen in PmWiki:MarkupExpressions, 
# but avoids breaking conditionals if PTV is multiline
  $MarkupExpr['ptvlen'] = 'PTVlen($args[0],$args[1])';
  function PTVlen ($page, $ptv) {
    $var=PageTextVar($page,$ptv); # no $: or quotes
    return strlen($var);   
  }