JasonB (no@spam.com) on 2/15/08 wrote:
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>David Kanter (dkanter@realworldtech.com) on 2/15/08 wrote:
>---------------------------
>>>Of course "easy" and "efficient" are opposed goals.
>>
>>Of course, but python is a reasonably efficient language and it is easy.
>
>Although Python definitely has its place, and is relatively easy, I think
>it is more of an example in support of Howard's point than a counter-example that you can have both:
>
>http://shootout.alioth.debian.org/gp4/benchmark.php?test=all&lang=python&lang2=gcc
>
>It is definitely efficient enough for a whole bunch of tasks, just like
>a classic Pentium running C code is, but I don't consider
an average of 50 times slower to be "reasonably efficient".

I do performance sensitive work in python, and it is possible to get within shouting distance of C with a little extra work. The numeric and scientific libraries are pretty efficient, so any problem that spends most of its time crunching large arrays is easy to do efficiently in python. For other problems I use psyco or pyrex. Psyco is a JIT specializing recompiler that usually speeds up python code by a factor of two to three. Pyrex lets you interace to C code quickly and easily, or to write a static version of python code that gets compiled to C, but is seen by the rest of your code as a python object.

There is also the "Instant" library that lets you inline C code into your python code.

Usually it is only necessary to optimize a few bottlenecks to speed up the entire program substantially.

For a nice writeup, have a look at:
http://scipy.org/PerformancePython

I have no stake in the current thread, but I think it worth pointing out that the "python is 50x slower than C" argument is somewhat misleading, as it is only true for first-cut solutions to a problem. For not very much effort it is possible to get large speed gains. For me at least, I spend far less time programming in python than I would in C, including the extra time taken to optimize my code.

-Ray
(Who has written more lines of C in his life than in any other language, regrettably)