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<title>6.28.3.4 Deferred translations</title>
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<H3><A NAME="SECTION0082834000000000000000">
6.28.3.4 Deferred translations</A>
</H3>

<P>
In most coding situations, strings are translated where they are coded.
Occasionally however, you need to mark strings for translation, but
defer actual translation until later.  A classic example is:

<P>
<div class="verbatim"><pre>
animals = ['mollusk',
           'albatross',
           'rat',
           'penguin',
           'python',
           ]
# ...
for a in animals:
    print a
</pre></div>

<P>
Here, you want to mark the strings in the <code>animals</code> list as being
translatable, but you don't actually want to translate them until they
are printed.

<P>
Here is one way you can handle this situation:

<P>
<div class="verbatim"><pre>
def _(message): return message

animals = [_('mollusk'),
           _('albatross'),
           _('rat'),
           _('penguin'),
           _('python'),
           ]

del _

# ...
for a in animals:
    print _(a)
</pre></div>

<P>
This works because the dummy definition of <tt class="function">_()</tt> simply returns
the string unchanged.  And this dummy definition will temporarily
override any definition of <tt class="function">_()</tt> in the built-in namespace
(until the <tt class="keyword">del</tt> command).
Take care, though if you have a previous definition of <tt class="function">_</tt> in
the local namespace.

<P>
Note that the second use of <tt class="function">_()</tt> will not identify ``a'' as
being translatable to the <b class="program">pygettext</b> program, since it is not
a string.

<P>
Another way to handle this is with the following example:

<P>
<div class="verbatim"><pre>
def N_(message): return message

animals = [N_('mollusk'),
           N_('albatross'),
           N_('rat'),
           N_('penguin'),
           N_('python'),
           ]

# ...
for a in animals:
    print _(a)
</pre></div>

<P>
In this case, you are marking translatable strings with the function
<tt class="function">N_()</tt>,<A NAME="tex2html47"
  HREF="#foot36714"><SUP>6.6</SUP></A> which won't conflict with any definition of
<tt class="function">_()</tt>.  However, you will need to teach your message extraction
program to look for translatable strings marked with <tt class="function">N_()</tt>.
<b class="program">pygettext</b> and <b class="program">xpot</b> both support this through the
use of command line switches.

<P>
<BR><HR><H4>Footnotes</H4>
<DL>
<DT><A NAME="foot36714">...N_(),</A><A
 HREF="node337.html#tex2html47"><SUP>6.6</SUP></A></DT>
<DD>The choice of <tt class="function">N_()</tt> here is totally
arbitrary; it could have just as easily been
<tt class="function">MarkThisStringForTranslation()</tt>.


</DD>
</DL>
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<span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span>
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