changing local namespace of a function

[Bo Peng]

Kent Johnson wrote:
> Bo Peng wrote:
> 
>>> Exec is slow since compiling the string and calls to globals() use a 
>>> lot of time.  The last one is most elegant but __getattr__ and 
>>> __setattr__ are costly. The 'evil hack' solution is good since 
>>> accessing x and y takes no additional time.
>>
>>
>>
>> Previous comparison was not completely fair since I could pre-compile 
>> fun2 and I used indirect __setattr__. Here is the new one:
>>  >>> # solution two: use exec
>> ... def makeFunction(funcStr, name):
>> ...   code = compile(funcStr, name, 'exec')
>> ...   def f(d):
>> ...     exec code in d
>> ...   return f
>> ...
>>  >>> def fun2(d):
>> ...   myfun = makeFunction('z = x + y', 'myfun')
>> ...   for i in xrange(0,N):
>> ...     myfun(d)
>> ...   del d['__builtins__']
> 
> 
> You are still including the compile overhead in fun2. If you want to see 
> how fast the compiled code is you should take the definition of myfun 
> out of fun2:
> 
> myfun = makeFunction('z = x + y', 'myfun')
> def fun2(d):
>   for i in xrange(0,N):
>     myfun(d)
>   del d['__builtins__']
> 
> Kent

I assumed that most of the time will be spent on N times execution of 
myfunc.

 >>> myfun = makeFunction('z = x + y', 'myfun')
 >>> def fun2(d):
...   # myfun = makeFunction('z = x + y', 'myfun')
...   for i in xrange(0,N):
...     myfun(d)
...   del d['__builtins__']
 >>> def fun21(d):
...   myfun = makeFunction('z = x + y', 'myfun')
...   for i in xrange(0,N):
...     myfun(d)
...   del d['__builtins__']

 >>> profile.run('fun2(a)')
          200003 function calls in 1.930 CPU seconds

    Ordered by: standard name

    ncalls  tottime  percall  cumtime  percall filename:lineno(function)
         1    0.000    0.000    1.930    1.930 <string>:1(?)
    100000    0.460    0.000    0.460    0.000 myfun:1(?)
         1    0.000    0.000    1.930    1.930 profile:0(fun2(a))
         0    0.000             0.000          profile:0(profiler)
    100000    0.980    0.000    1.440    0.000 python-162616Io.py:4(f)
         1    0.490    0.490    1.930    1.930 python-16261Ud0.py:1(fun2)

 >>> profile.run('fun21(a)')
          200004 function calls in 1.920 CPU seconds

    Ordered by: standard name

    ncalls  tottime  percall  cumtime  percall filename:lineno(function)
         1    0.000    0.000    1.920    1.920 <string>:1(?)
    100000    0.390    0.000    0.390    0.000 myfun:1(?)
         1    0.000    0.000    1.920    1.920 profile:0(fun21(a))
         0    0.000             0.000          profile:0(profiler)
         1    0.000    0.000    0.000    0.000 
python-162616Io.py:2(makeFunction)
    100000    0.930    0.000    1.320    0.000 python-162616Io.py:4(f)
         1    0.600    0.600    1.920    1.920 python-16261huu.py:1(fun21)