eval, exec and execfile dilemma
gandalf at shopzeus.com
Sat Jul 30 15:48:56 EDT 2011
I have a program that generates source code for a function. I need to
compile that function so that it can be executed (relatively) fast
later. In most cases, I'll be generating about 10 functions per second,
and evaluate them frequently. But sometimes I'll have to generate 100
functions per second (upper limit). I also need to change the dict of
global variables that are accessible from that function. Here is the
* the eval function can only be used to evaluate expressions. The
source code of the generated function is too complex to be put
into a lambda expression. The def statement is not handled by
eval(), so I cannot use eval().
* the exec statement can be used to execute a def statement.
However, I see no way to change the globals, so I cannot use the
* the execfile statement could do everything that I want (e.g.
support statements + changing globals). But.... I cannot pass the
source code as a string. Looks like I MUST give a file name as the
first argument. Even worse, this can't be a temporary file
(because it has no name on some systems). This I consider a
security problem. Yes, I know that I might be able to create a
directory with good permissions, and then write out 10-100 files
in every second for compiling... but it seems a waste of time, and
why would I create 100 files per second on an unknown filesystem
when I only need to pre-compile some functions?
Are there any other options? (Python 2.7 + numpy, should be compatible
with Windows, Linux and FreeBSD)
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