Variable Interpolation - status of PEP 215
andrewm at object-craft.com.au
Thu Jun 20 00:40:38 EDT 2002
>> I am a relative newbie to Python. I have a reasonably good perl background
>> (don't worry I am not about to start a language flame war :-), and one of
>> the things I really miss is variable interpolation in strings. I searched
>> the net and found PEP 215 (http://www.python.org/peps/pep-0215.html). This
>> seems to be exactly what I need. The proposal seems to be quite old, so I'd
>> like to know if it's still in consideration or has it been dropped
>>>> foo = "trick"
>>>> bar = 95.5
>>>> print "This %(foo)s is loved by %(bar)s%% of programmers." % locals()
>This trick is loved by 95.5% of programmers.
>You can use any dictionary, but locals() or globals() can be handy
>in many cases.
It took me a while to come to love the % operator - it really is a
neat idea. It means that you don't have to worry about escaping the
interpolation characters unless you explicitly want interpolation. In
perl, I seemed to be forever forgetting to escape them, producing obscure
bugs as a result. And it doesn't require any special rules in the grammer -
it's just another operator.
And in C, the problem is even worse (although it's not a fair comparison) -
you have to allocate the memory first, worry about bounds checking,
call sprintf (really snprintf), then worry about releasing the memory.
Andrew McNamara, Senior Developer, Object Craft
More information about the Python-list