Python Essential Reference, Second Edition

eval(), exec, execfile(), and compile()

The eval(str [,globals [,locals ]]) function executes an expression string and returns the result. For example:

a = eval('3*math.sin(3.5+x) + 7.2') 

Similarly, the exec statement executes a string containing arbitrary Python code. The code supplied to exec is executed within the namespace of the caller as if the code actually appeared in place of the exec statement. For example:

a = [3, 5, 10, 13] 
exec "for i in a: print i" 

Finally, the execfile(filename [,globals [,locals ]]) function executes the contents of a file. For example:

execfile("foo.py") 

All these functions execute within the namespace of the caller (which is used to resolve any symbols that appear within a string or file). Optionally, ...