Topic on Help talk:Extension:ParserFunctions/2020-2024

I've done a lot, but I can't seem to figure out why can't we just use

{{#explode:{{PAGENAME}}|:}}

It just doesn't work. On the other hand, writing the actual words (not substituting them):

{{#explode:Extension:ParserFunctions|:}}

will work. Why is that and what can be done?

{{PAGENAME}} only returns the name of the current page, without the namespace. For example, (on this wiki) for the page Extension:ParserFunctions, it returns ParserFunctions. Therefore, {{ #explode: {{PAGENAME}} | : }} will only return something different from {{PAGENAME}} if the page name itself contains a colon. If you want to get the namespace of a page, you should instead use {{NAMESPACE}}: for Extension:ParserFunctions (again, on this wiki), it returns Extension. Alternatively, you could use {{FULLPAGENAME}}, which will return the namespace and page name together, but there's no point in doing that just to #explode it to get the namespace.

I was thinking without the namespace. It's more about removing extra characters from the title, like getting "car" from "John's car" if the page is named "John's car".

For that specific case, you can just do {{ #explode: {{PAGENAME}} || 1 }}: #explode will operate on spaces if you omit or leave blank the second parameter.

If this still doesn't help for what you're trying to do, please post an actual use case from your wiki and I'll see if I can give you better/more tailored advice.

Don't forget that {{NAMESPACE}}, {{FULLPAGENAME}} and {{PAGENAME}} can take an optional parameter after a colon and before the closing braces. This simplifies a lot the design of templates without having to perform lot of tests:

• You can use {{PAGENAME:{{{1|}}}}} to strip the leading whitespaces and colon and the namespace prefix from the value of {{{1|}}}. It will also strip the trailing whitespaces, and other whitespaces and underscores are normalized and compressed to their default meaningful presentation form (the form displayed in the rendered page titles, and in links to members of categories).
• Or {{FULLPAGENAME:{{{1|}}}}} to just strip the leading whitespaces and colon (the namespace prefix will be kept). It will also strip the trailing whitespaces.

  A valid pagename (without the namespace or any interwiki/language prefix) may still contain a colon, if what is before that colon it is not recognized as a valid namespace or wiki prefix. Using {{#explode:}} will not make this difference and may strip too much in that case...

• As well, {{NAMESPACE:{{{1|}}}}} will strip the leading colon and the pagename (containing interwiki prefixes followed by a possible remote namespace), keeping only a leading namespace recognized on the local wiki (with its trailing colon if that namespace is not the empty string for the default namespace).

  The form of the namespace (when it is not empty) present in the value returned by {{NAMESPACE:}} or {{FULLPAGENAME:}} is canonicalized to its default letter case (with a single capital initial), and recognized aliases are converted to the canonical name (e.g. the Image: alias will be converted to the canonical File: namespace).

  This allows comparing namespaces directly, e.g. in test labels of {{#switch:...}} or with {{#ifeq:...}}, without having to convert them to a unique letter case form (with {{UCFIRST:{{LC:...}}}}, or {{UC:...}}).

  This canonical form of any namespace may be localized in the default language of the local wiki. If you intend to write code that would work the same in different wikis, e.g. between English Wikipedia (which uses "Template:") and French Wikipedia (which uses "Modèle:" and recognizes "Template:" only as an alias), you may want to compare with namespace names returned by namespace numbers (using {{NS:number}}, where {{NS:0}} is the empty string for the main namespace of the wiki) instead of comparing them with explicit canonical namespace names (the namespace number for the "Template:" namespace in English is the same as the namespace number for the "Modèle:" namespace in French).

• None of these three functions will touch/remove/canonicalize the namespaces and pagenames if they occur after any "interwiki:" prefix recognized by the local wiki. The links to external wikis will still work, but will be resolved and canonicalized externally by the target wiki itself when visiting them (as well the target wiki will resolve itself any resulting page redirect); such remote resolution may change over time (extremely rarely, hopefully, generally only during the early development phases of a starting wiki, when the localization to its default language is not finalized; but redirects on the target wiki may occur and change quite frequently). As well no test of existence of the target page on the target wiki is done when using any interwiki prefix, it is assumed to exist for the local wiki, which just validates its locally known interwiki prefix.