[Python-Dev] Passing compile(...,'exec') code to 'eval' (original) (raw)

Brett C. bac at OCF.Berkeley.EDU
Wed May 5 14:23:16 EDT 2004

In preparations for my coding my thesis I have been trying to figure out how a local variable could be assigned to without me explicitly knowing during compilation. Obviously 'exec' can. But I wasn't sure about 'eval'.

Reading the docs, I didn't think it could since 'eval', when taking a string, only evaluates expressions. But what about code objects? The docs say, "The code object must have been compiled passing 'eval' as the kind argument". But I didn't read that when I started testing.

This is when I discovered you can pass in something using 'compile' with the kind argument of "exec"::

x Traceback (most recent call last): File "", line 1, in ? NameError: name 'x' is not defined [16425 refs] eval(compile("x = 1", "", "exec")) [16426 refs] x 1

Is this a bug, or are the docs wrong? I am hoping it is the former since if it is the latter my thesis just got a big caveat pasted into it about how 'eval' can cause problems and invalidate the type inferencing in irreparable ways.

-Brett

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