Template:If empty/doc

This is a documentation subpage for Template:If empty.

It contains usage information, categories, and other content that is not part of the original template page.

Template:If empty invokes function main in Module:If empty using Lua.

This template is imported from Template:If empty/doc on Wikipedia.

This template is imported from the English Wikipedia. Although the visual appearance might be different, the functionality is identical. Please refer to the Template:If empty/doc page on Wikipedia for detailed documentation.

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".