This page describes an internal function in PmWiki's engine called FmtPageName(). The contents are not intended for those with a weak heart ;-)
Also see: PmWiki.Functions
$fmt, with $variable and internationalisation substitutions performed, under the assumption that the current page is
pagename. As a rule is used to pre-process all variables which by convention have a "Fmt" suffix (like
$GroupFooterFmt), but also other strings that require interpolation, notably the page template (.tmpl) file. See PmWiki.Variables for an (incomplete) list of available variables, PmWiki.Internationalizations for internationalisation.
FmtPageName() applies internationalization-substitutions
and $Variable-substitions to the string $fmt under the assumption that the
current page is $pagename.
The substitutions go as follows:
$XyzFmtwith value of any corresponding global variable.
$[...]phrases (internationalized phrase), using the currently loaded translation tables.
$ScriptUrl(to defer processing to the URI processing phase)
$FmtP. Typically this is used to handle things like $Name and $Group etc that are specific to the name of the current page. ?? Appears to be used in robots.php to hide actions from robots.
$EnablePathInfoisn't set, convert
URIsto use the syntax
$ScriptUrl?n=<Group>.<Name> instead of
$ScriptUrl/<Group>/<Name>. In any case, replace
$ScriptUrlwith its value. If there are no more $-sequences, then return the formatted string and exit the function
FmtPageName() is automatically aware of any global
variables. However, since modifying global variables may be expensive, the
$FmtV exists as a way to avoid rebuilding the variable cache for
values that change frequently.
According to PM, as a general rule it's unwise to be calling FmtPageName() on strings that are coming from page markup, as this exposes the ability for people to view the values of variables that perhaps they shouldn't see. This is also why page variables (which come from markup) use PageVar() and PageTextVar() and don't go through FmtPageName().
To be very specific, here's what Pm wrote regarding different ways of defining a variable that can be used by FmtPageName (when it is formatting a string):
$FmtVas in the next item.
$FmtV['$MyVariable']='something' means to replace instances of '$MyVariable' with 'something'. Use this for variables that change value frequently over multiple calls to FmtPageName.
$FmtParray. This is normally done for substitutions that have to be dynamic somehow based on the pagename being referenced, such as '$Title', '$Group', '$Name', '$PageUrl', etc.
Also see: Cookbook:Functions#FmtPageName
Finally, here's something else Pm wrote that is related and explains why we have this function:
$ScriptUrl?n=$Group.$Name for sites that cannot handle PATH_INFO urls
$page = ReadPage($pagename); PCache($pagename, $page); $ptitle = FmtPageName('$Title', $pagename); $pauthor = FmtPageName('$LastModifiedBy', $pagename);