On Thu, May 21, 2015 at 06:51:34PM -0700, Andrew Barnert via Python-ideas wrote:
On May 21, 2015, at 18:18, Ben Hoyt <benhoyt@gmail.com> wrote:
(I know that there's the "ast" module and ast.parse(), which can give you an AST given a *source string*, but that's not very convenient here.)
Why not? Python modules are distributed as source.
*Some* Python modules are distributed as source. Don't forget that byte-code only modules are officially supported. Functions may also be constructed dynamically, at runtime. Closures may have source code available for them, but functions and methods constructed with exec (such as those in namedtuples) do not. Also, the interactive interpreter is a very powerful tool, but it doesn't record the source code of functions you type into it. So there are at least three examples where the source is not available at all. Ben also talks about *convenience*: `func.ast` will always be more convenient than: import ast import parse ast.parse(inspect.getsource(func)) not to mention the wastefulness of parsing something which has already been parsed before. On the other hand, keeping the ast around even when it's not used wastes memory, so this is a classic time/space trade off.
You can pretty easily write an import hook to intercept module loading at the AST level and transform it however you want.
Let's have a look at yours then, that ought to only take a minute or three :-) (That's my definition of "pretty easily".) I think that the majority of Python programmers have no idea that you can even write an import hook at all, let alone how to do it. -- Steve