"साँचा:If empty/doc" के अवतरणों में अंतर
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imported>SM7 छो (en:Template:If_empty/doc से 45 अवतरण आयात किये गए) |
छो (१ अवतरण आयात किया गया) |
||
| (एक अन्य सदस्य द्वारा किया गया बीच का एक अवतरण नहीं दर्शाया गया) | |||
| पंक्ति १: | पंक्ति १: | ||
{{Documentation subpage}} | {{Documentation subpage}} | ||
{{Template | <!----PLEASE ADD TEMPLATE CATEGORIES WHERE INDICATED AT THE BOTTOM OF THIS PAGE----> | ||
{{Template redirect |Ifempty |First nonempty |Use first nonempty |Firstdata}} | |||
{{Lua|Module:If empty}} | {{Lua|Module:If empty}} | ||
{{High- | {{High-use|all-pages = yes}} | ||
This is the {{ | This template is used inside other templates. It takes any number of parameters and returns the first found to be defined and non-empty. If none is found, nothing is returned. By writing <code><nowiki>{{if empty|a|b|c}}</nowiki></code> instead of <code><nowiki>{{#if:a|a|{{#if:b|b|c}}}}</nowiki></code>, expression a and b do not have to be [[Don't repeat yourself|repeated]] and evaluated twice. The template provides a [[fallback]] order, similar to a [[try catch]] based "It is easier to ask for forgiveness than permission" ([[EAFP]]) programming style. | ||
Typical usage is like this: | |||
: <code><nowiki>{{If empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}</nowiki></code> | : <code><nowiki>{{If empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}</nowiki></code> | ||
: <nowiki>("Return {{{logo|}}} if it has a value; else {{{image|}}} if it has a value; else {{{picture|}}} if it has a value; else return "default.svg".")</nowiki> | : <nowiki>("Return {{{logo|}}} if it has a value; else {{{image|}}} if it has a value; else {{{picture|}}} if it has a value; else return "default.svg".")</nowiki> | ||
This returns the first of the parameters ''logo'' and '' | This returns the first of the parameters ''logo'', ''image'' and ''picture'' that is defined and non-empty, otherwise "default.svg". | ||
===Rationale=== | ===Rationale=== | ||
| पंक्ति २३: | पंक्ति २१: | ||
But this becomes complex when several parameters are to be checked: | But this becomes complex when several parameters are to be checked: | ||
: <code><nowiki>{{#if:{{{logo|}}} |{{{logo}}} |{{#if:{{{image|}}} |{{{image}}} |{{#if:{{{picture|}}} |{{{picture}}} |default.svg}} }} }}</nowiki></code> | : <code><nowiki>{{#if:{{{logo|}}} |{{{logo}}} |{{#if:{{{image|}}} |{{{image}}} |{{#if:{{{picture|}}} |{{{picture}}} |default.svg}} }} }}</nowiki></code> | ||
: <nowiki>("If {{{logo}}} has a value, return it; else if {{{image}}} has a value, return that; else if {{{picture}}} has a value, return that; else return "default.svg".)</nowiki> | : <nowiki>("If {{{logo}}} has a value, return it; else if {{{image}}} has a value, return that; else if {{{picture}}} has a value, return that; else return "default.svg".")</nowiki> | ||
In these cases, {{tlf|if empty}} produces the simpler syntax (as above): | In these cases, {{tlf|if empty}} produces the simpler syntax (as above): | ||
: <code><nowiki>{{if empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}</nowiki></code> | : <code><nowiki>{{if empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}</nowiki></code> | ||
====Piping==== | ====Piping==== | ||
Parameters used with {{tlf|if empty}} must be [[Pipe (Unix)|pipe]]d – i.e. include the [[Vertical bar|vertical bar (pipe) symbol]] {{nowrap|("{{ | Parameters used with {{tlf|if empty}} must be [[Pipe (Unix)|pipe]]d – i.e. include the [[Vertical bar|vertical bar (pipe) symbol]] {{nowrap|("{{thin space}}|{{thin space}}")}} as a trailing character – so that empty or undefined parameters aren't treated as text and returned incorrectly. Hence, for example, <code><nowiki>{{{logo|}}}</nowiki></code>, <code><nowiki>{{{image|}}}</nowiki></code> and <code><nowiki>{{{picture|}}}</nowiki></code> rather than {{param|logo}}, {{param|image}} and {{param|picture}} in the above examples. | ||
===Examples=== | ===Examples=== | ||
| पंक्ति ३५: | पंक्ति ३३: | ||
|row1style=background:whitesmoke;padding-left:0.5em;font-weight:bold; | |row1style=background:whitesmoke;padding-left:0.5em;font-weight:bold; | ||
| Code | Result | | | Code | Result | | ||
| {{ | | {{tlc|if empty}} | {{if empty}} | Returns an empty string. | ||
| {{ | | {{tlc|if empty|one}} | {{if empty|one}} | Returns the first parameter that is defined and not empty. | ||
| {{ | | {{tlc|if empty|one|two}} | {{if empty|one|two}} | | ||
| {{ | | {{tlc|if empty|one|two|three|four}} | {{if empty|one|two|three|four}} | | ||
| {{ | | {{tlc|if empty||two}} | {{if empty||two}} | The first parameter is empty/undefined, so is passed over. | ||
| {{ | | {{tlc|if empty||two|three|four}} | {{if empty||two|three|four}} | | ||
| {{ | | {{tlc|if empty||two||four}} | {{if empty||two||four}} | | ||
| <code><nowiki>{{if empty||||||||||ten}}</nowiki></code> | {{if empty||||||||||ten}} | Unlike in previous versions, this template is no longer limited by 9 parameters. | | <code><nowiki>{{if empty||||||||||ten}}</nowiki></code> | {{if empty||||||||||ten}} | Unlike in previous versions, this template is no longer limited by 9 parameters. | ||
| {{ | | {{tlc|if empty{{!}}}} | {{if empty|}} | The only parameter is empty or undefined, so returns an empty string. | ||
| {{ | | {{tlc|if empty|{{!}}{{!}}{{!}}{{!}}}} | {{if empty||||}} | Returns an empty string. | ||
| <code><nowiki>{{if empty|{{{1|}}}|{{{2|}}}|three}}</nowiki></code> | {{if empty|{{{1|}}}|{{{2|}}}|three}} | | | <code><nowiki>{{if empty|{{{1|}}}|{{{2|}}}|three}}</nowiki></code> | {{if empty|{{{1|}}}|{{{2|}}}|three}} | | ||
| <code><nowiki>{{if empty|{{{1}}}|{{{2}}}|three}}</nowiki></code> | {{if empty|{{{1}}}|{{{2}}}|three}} | No pipe-characters following the names of the first two parameters ("1" and "2"), so the first of these returned as text ("{{{1}}}"). | | <code><nowiki>{{if empty|{{{1}}}|{{{2}}}|three}}</nowiki></code> | {{if empty|{{{1}}}|{{{2}}}|three}} | No pipe-characters following the names of the first two parameters ("1" and "2"), so the first of these returned as text ("{{{1}}}"). | ||
| पंक्ति ५६: | पंक्ति ५४: | ||
* {{tl|if either}} | * {{tl|if either}} | ||
* [[Help:Parameter default]] | * [[Help:Parameter default]] | ||
* {{tl|Category see also if exists 2}} | |||
<includeonly>{{ | <includeonly>{{Sandbox other| | ||
| <!-- ADD CATEGORIES BELOW THIS LINE, PLEASE: --> | | <!-- ADD TEMPLATE CATEGORIES BELOW THIS LINE, PLEASE: --> | ||
[[Category:If-then-else templates]] | [[Category:If-then-else templates]] | ||
[[Category:Parameter selection templates]] | |||
}}</includeonly> | }}</includeonly> | ||
१३:२९, १ जुलाई २०२२ के समय का अवतरण
{{
साँचा:namespace detect
| type = notice
| image = 
| imageright =
| class =
| style = margin-bottom:1.0em;
| textstyle =
| text = साँचा:strong for साँचा:terminate sentence
It contains usage information, categories and other content that is not part of the original साँचा page.
| small =
| smallimage =
| smallimageright =
| smalltext =
| subst =
| date =
| name =
}}
 | This template uses Lua: |
 | This template is used on approximately २७,३०,००० pages, or roughly 906% of all pages. To avoid major disruption and server load, any changes should be tested in the template's /sandbox or /testcases subpages, or in your own user subpage. The tested changes can be added to this page in a single edit. Consider discussing changes on the talk page before implementing them. |
This template is used inside other templates. It takes any number of parameters and returns the first found to be defined and non-empty. If none is found, nothing is returned. By writing {{if empty|a|b|c}} instead of {{#if:a|a|{{#if:b|b|c}}}}, expression a and b do not have to be repeated and evaluated twice. The template provides a fallback order, similar to a try catch based "It is easier to ask for forgiveness than permission" (EAFP) programming style.
Typical usage is like this:
{{If empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}- ("Return {{{logo|}}} if it has a value; else {{{image|}}} if it has a value; else {{{picture|}}} if it has a value; else return "default.svg".")
This returns the first of the parameters logo, image and picture that is defined and non-empty, otherwise "default.svg".
Rationale
The MediaWiki parameter default function doesn't return the default value for empty parameters. That is, {{{logo|default.svg}}} does not return "default.svg" if the template was called like this: {{template|logo=}}.
The usual workaround for a single parameter is:
{{#if:{{{logo|}}} |{{{logo}}} |default.svg}}- ("If {{{logo}}} has a value, return it, else return "default.svg".")
But this becomes complex when several parameters are to be checked:
{{#if:{{{logo|}}} |{{{logo}}} |{{#if:{{{image|}}} |{{{image}}} |{{#if:{{{picture|}}} |{{{picture}}} |default.svg}} }} }}- ("If {{{logo}}} has a value, return it; else if {{{image}}} has a value, return that; else if {{{picture}}} has a value, return that; else return "default.svg".")
In these cases, साँचा:tlf produces the simpler syntax (as above):
{{if empty |{{{logo|}}} |{{{image|}}} |{{{picture|}}} |default.svg}}
Piping
Parameters used with साँचा:tlf must be piped – i.e. include the vertical bar (pipe) symbol साँचा:nowrap as a trailing character – so that empty or undefined parameters aren't treated as text and returned incorrectly. Hence, for example, {{{logo|}}}, {{{image|}}} and {{{picture|}}} rather than साँचा:param, साँचा:param and साँचा:param in the above examples.
Examples
स्क्रिप्ट त्रुटि: "aligned table" ऐसा कोई मॉड्यूल नहीं है।
See also