[edit] Template documentation

This is a subtemplate of {{dialog/button}}. Given the specification of a single dialog parameter for the button, it extracts the literal value provided for the parameter, if any. Uses {{evalx}}.

Internals

When a template returns a string starting with colon, as this subtemplate is sometimes ordinarily expected to do, the wiki platform prefixes a linebreak to it. Functions within a Wikilisp expression are not subject to this limitation since the entire Wikilisp expression is within a single template call; the result from this template can therefore be renormalized by Wikilisp function trim, stripping off the prefixed linebreak, but must then be further processed within the Wikilisp expression to avoid re-prefixing by the wiki platform.