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<H3><A NAME="SECTION0082334000000000000000">
6.23.3.4 Deferred translations</A>
</H3>
<P>
In most coding situations, strings are translated were they are coded.
Occasionally however, you need to mark strings for translation, but
defer actual translation until later. A classic example is:
<P>
<dl><dd><pre class="verbatim">
animals = ['mollusk',
'albatross',
'rat',
'penguin',
'python',
]
# ...
for a in animals:
print a
</pre></dl>
<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>
<dl><dd><pre class="verbatim">
def _(message): return message
animals = [_('mollusk'),
_('albatross'),
_('rat'),
_('penguin'),
_('python'),
]
del _
# ...
for a in animals:
print _(a)
</pre></dl>
<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>
<dl><dd><pre class="verbatim">
def N_(message): return message
animals = [N_('mollusk'),
N_('albatross'),
N_('rat'),
N_('penguin'),
N_('python'),
]
# ...
for a in animals:
print _(a)
</pre></dl>
<P>
In this case, you are marking translatable strings with the function
<tt class="function">N_()</tt>,<A NAME="tex2html19"
HREF="#foot17314"><SUP>6.4</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="foot17314">...N_(),</A><A NAME="foot17314"
HREF="node154.html#tex2html19" tppabs="http://www.python.org/doc/current/lib/node154.html#tex2html19"><SUP>6.4</SUP></A>
<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>.
</DL>
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