Decorators can be nested, and what you can do in this case is to find the most inner-wrapped function by traversing the '__wrapped__' attributes (and check that the function you found is the actual original function). After that you can play with its attributes, but you can't simply substitute the function object, as the inner decorator won't use it. So sometimes you have to work with the function object without a way of substituting it. - Yury On 2012-03-16, at 2:37 PM, Mark Shannon wrote:

Yury Selivanov wrote:

...

Can we make the __closure__ attribute writeable? Since __code__ already is, and it is possible to tackle with the opcodes, having no way of rewriting __closure__ (except creating a completely new function) is annoying.

What's wrong with using a decorator?

...

I don't think it will somehow harm python, as those who want to break it can do it already in multiple ways, easier than playing with __closure__. - Yury _______________________________________________ Python-ideas mailing list Python-ideas@python.org http://mail.python.org/mailman/listinfo/python-ideas

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On 26 March 2012 11:32, Victor Stinner <victor.stinner@gmail.com> wrote:

2012/3/16 Yury Selivanov <yselivanov.ml@gmail.com>:

...

Can we make the __closure__ attribute writeable? Since __code__ already is, ...

I never understood why __code__ is writable. What is the usecase of modifying the code of an existing function?

There are many things you can do with bytecode manipulation (whether you should is another question). Among other things, I've used it for optimisation (e.g. my optimised self.super recipe that probably isn't actually available online anymore). Instrumentation of code is another thing, although these days you're probably better off using a decorator. There aren't a lot of real use cases, but if nothing else it can be a lot of fun :) Tim Delaney

On 29 March 2012 19:05, Mark Shannon <mark@hotpy.org> wrote:

Tim Delaney wrote:

...

There are many things you can do with bytecode manipulation (whether you should is another question). Among other things, I've used it for optimisation (e.g. my optimised self.super recipe that probably isn't actually available online anymore). Instrumentation of code is another thing, although these days you're probably better off using a decorator.

There aren't a lot of real use cases, but if nothing else it can be a lot of fun :)

You can do all of those things without changing the __code__ attribute. Just create a new function instead.

Not if you want anything that holds an existing reference to the function to get the new behaviour. Sometimes you need to change things in-place. Tim Delaney