(gettext.info)Interpolation II

---

Next: Parentheses Prev: Interpolation I Up: Perl

---

Enter node , (file) or (file)node

15.5.18.6 Valid Uses Of String Interpolation
............................................

   Perl is often used to generate sources for other programming
languages or arbitrary file formats.  Web applications that output HTML
code make a prominent example for such usage.

   You will often come across situations where you want to intersperse
code written in the target (programming) language with translatable
messages, like in the following HTML example:

     print gettext <<EOF;
     <h1>My Homepage</h1>
     <script language="JavaScript"><!--
     for (i = 0; i < 100; ++i) {
         alert ("Thank you so much for visiting my homepage!");
     }
     //--></script>
     EOF

   The parser will extract the entire here document, and it will appear
entirely in the resulting PO file, including the JavaScript snippet
embedded in the HTML code.  If you exaggerate with constructs like the
above, you will run the risk that the translators of your package will
look out for a less challenging project.  You should consider an
alternative expression here:

     print <<EOF;
     <h1>$gettext{"My Homepage"}</h1>
     <script language="JavaScript"><!--
     for (i = 0; i < 100; ++i) {
         alert ("$gettext{'Thank you so much for visiting my homepage!'}");
     }
     //--></script>
     EOF

   Only the translatable portions of the code will be extracted here,
and the resulting PO file will begrudgingly improve in terms of
readability.

   You can interpolate hash lookups in all strings or quote-like
expressions that are subject to interpolation (see the manual page ‘man
perlop’ for details).  Double interpolation is invalid, however:

     # TRANSLATORS: Replace "the earth" with the name of your planet.
     print gettext qq{Welcome to $gettext->{"the earth"}};

   The ‘qq’-quoted string is recognized as an argument to ‘xgettext’ in
the first place, and checked for invalid variable interpolation.  The
dollar sign of hash-dereferencing will therefore terminate the parser
with an “invalid interpolation” error.

   It is valid to interpolate hash lookups in regular expressions:

     if ($var =~ /$gettext{"the earth"}/) {
        print gettext "Match!\n";
     }
     s/$gettext{"U. S. A."}/$gettext{"U. S. A."} $gettext{"(dial +0)"}/g;