Help talk:Parser functions in templates

logical error

I think there's a logical error here. It's easiest to see in the table at the bottom. In sample 1, {{{1}}} is true for both being defined and for being not defined. How can it both be defined and not defined? -Khono

I think it is right. If you call {{foo | bar}}, then both {{{1}}} and {{{1|}}} will return "bar" (in template:foo), why the #if statement treat both as true. --79.136.98.249 23:13, 1 September 2009 (UTC)

White spaces

Is there any parser function that strip leading and tailing white spaces, or one that change them into "%20" or "_"? I try to make a template that includes a link to wikipedia.

• {{Wikipedia | phoo}} givs: See phoo Wikipedias article - NOK (.../wiki/).
• {{Wikipedia |phoo}} givs: See Wikipedias article - OK (.../wiki/phoo).
• {{Wikipedia |phoo bar}} givs: See bar Wikipedias article - NOK (.../wiki/phoo).
• {{Wikipedia}} givs: See functions in templates Wikipedias article - NOK (../wiki/Parser).

--Petter Källström, 79.136.98.249 23:13, 1 September 2009 (UTC)

parameter specified or not

One way to test whether a parameter was specified in a template call is thus: {{#ifeq:{{{v|}}}|{{{v|-}}}| v was specified (and may be empty) | v was not specified }}

Could an expert please check whether this is true? I find it returns "v was specified (and may be empty)" only when "|v=" or "|v=text" is in the template call code, otherwise "|v" (without any =) returns "v was not specified ". The latter behaviour is unexpected. -84user 18:20, 27 September 2009 (UTC)

I may have misunderstood, but why is the latter behaviour unexpected? When = is missing, v is interpreted as an unnamed parameter, not as parameter v, so parameter v is missing. I believe that is the correct behaviour. Hamilton Abreu 00:09, 24 January 2010 (UTC)

Inconsistency → Incomprehensibility

I can't even figure out what's supposed to happen. There are two examples given with different syntax

• Sample A
  {{{1}}} (no parameter, no pipe)
• Sample B
  {{{1|}}} (no parameter, has pipe)

and different outputs for both conditions:

• Sample A
  • condition true
    Parameter 1 is not defined, or is defined and non-null/non-empty.
  • condition false
    Parameter 1 is null. It contains only empty string(s) or breaking space(s) etc.
• Sample B
  • condition true
    Parameter 1 is defined and non-null/non-empty.
  • condition false
    Parameter 1 is not defined, or is defined but null. It contains only empty string(s) or breaking space(s) etc.

But only one result is shown for each sample: the if-true output for Sample A, and the if-false output for Sample B.

If I get the general idea correctly, the presence or absence of the pipe should affect the test. But the paragraph doesn't even say whether parameter 1 is being supplied, and if so whether it's null or blanks only or nonblank or what. --Thnidu (talk) 17:52, 2 October 2012 (UTC)

Max depth of nested #if parser functions.

I have a rather large set of nested #ifexpr: tests (48 so far, with intent to add another 30), and I have found that it is not returning the correct values for anything that is past the 40th response. Is there a max nest limit of 40 for this function? -- ShoeMaker   ( Contributions • Message )   22:35, 30 December 2012 (UTC)

After some in depth testing on a wiki running MediaWiki 1.19.1 with ParserFunctions (Version 1.4.1) there is a nesting limit of 40. I managed to rework my template and section it into chunks. There should be a note added to the Help page itself if anyone can confirm this to be true (my personal testing is not proof to me, could be a bug on my wiki). -- ShoeMaker   ( Contributions • Message )   03:32, 31 December 2012 (UTC)

Where is my mistake?

{{#if:{{{image}}}|{{|}}[[File:{{{image}}}{{|}}size{{|}}100x100px]]|{{|}} }}

I am trying for 2 hours now, but the part of "true" won't come out as it should be.