[Tutor] eval and exec
alan.gauld at freenet.co.uk
Sat Dec 4 10:34:49 CET 2004
> I'm having trouble understanding the difference between eval and
eval evaluates an *expression* - that is something that returns a
exec executes a piece of code, it need not return a value.
eval is slightly safer than exec (but not much).
print 'hello' # use exec for this
6+7-9/3 # use eval for this
myfunction(42) # use eval for this
to make eval useful you need to assign the result to a variable:
res = eval('6+7-9/3')
but exec is just executed on its own:
Both are extremely dangerous functions from a security
and maintenance/reliability pouint of view and should be
used very rarely.
Was there anything more specific you wanted to know?
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