Steve Holden wrote: > Fuzzyman wrote: > > > The following two passages from the python documentation *appear* to > > contradict each other. Equally possible (or more likely !) is that I > > misunderstand it : > > > > eval : > > This function can also be used to execute arbitrary code objects (such > > as those created by compile()). In this case pass a code object instead > > of a string. The code object must have been compiled passing 'eval' as > > the kind argument. > > > > > > compile: > > The kind argument specifies what kind of code must be compiled; it can > > be 'exec' if string consists of a sequence of statements, 'eval' if it > > consists of a single expression, or 'single' if it consists of a single > > interactive statement (in the latter case, expression statements that > > evaluate to something else than None will be printed). > > > > The docs for compile say that if you are creating a code object from a > > sequence of statements you must use the kind argument 'exec'. Eval says > > that if you are using the eval function you must use 'eval' as your > > kind argument. > > > > In practise I have found that using the eval function with code objects > > compiled with 'exec' as the kind argument works fine. Is this a 'bug' > > in the docs ? > > Regards, > > > > "Dear List: > > I live close to a railroad, and the tracks are surrounded by a fence > with large signs saying 'Walking on the tracks can be dangerous'. > > I have walked on the tracks several times, however, and I don't see why > the railway company put those signs there. In fact I'm walking along the > tracks right now as I enter this post on my hand-held, and > > [message ends with sound of locomotive horn followed by an ugly squelch]." > > That's the kind of practice best avoided. Are you breaking the rules > just for the fun of it? >
Hmm.... documentation on code objects says : Code objects are returned by the built-in compile() function and can be extracted from function objects through their func_code attribute. A code object can be executed or evaluated by passing it (instead of a source string) to the exec statement or the built-in eval() function. It mentions no such restriction. I didn't properly absorb the 'must' in the eval description...... Hmmm... my code will *never* need to run on anything other than CPython because I use py2exe to turn it into a frozen python distribution. So if it was always safe in CPython then that would be fine for me. The reason I like eval is that "If both dictionaries are omitted, the expression is executed in the environment where eval is called". However I think exec might do the same thing anyway. I'll just switch to exec. Regards, Fuzzy http://www.voidspace.org.uk/python/index.shtml > regards > Steve > -- > Meet the Python developers and your c.l.py favorites March 23-25 > Come to PyCon DC 2005 http://www.python.org/pycon/2005/ > Steve Holden http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
