94 lines
3.2 KiB
Python
94 lines
3.2 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Copyright © 2018 Simon Forman
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#
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# This file is part of Joypy
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#
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# Joypy is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# Joypy is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with Joypy. If not see <http://www.gnu.org/licenses/>.
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#
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'''
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I really want tracebacks to show which function was being executed when
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an error in the wrapper function happens. In order to do that, you have
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to do this (the function in this module.)
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Here's what it looks like when you pass too few arguments to e.g. "mul".
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>>> from joy.library import _dictionary
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>>> m = _dictionary['*']
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>>> m((), (), {})
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Traceback (most recent call last):
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File "<pyshell#49>", line 1, in <module>
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m((), (), {})
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File "joy/library.py", line 185, in mul:inner
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(a, (b, stack)) = stack
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ValueError: need more than 0 values to unpack
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>>>
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Notice that line 185 in the library.py file is (as of this writing) in
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the BinaryBuiltinWrapper's inner() function, but this hacky code has
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managed to insert the name of the wrapped function ("mul") along with a
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colon into the wrapper function's reported name.
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Normally I would frown on this sort of mad hackery, but... this is in
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the service of ease-of-debugging! Very valuable. And note that all the
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hideous patching is finished in the module-load-stage, it shouldn't cause
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issues of its own at runtime.
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The main problem I see with this is that people coming to this code later
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might be mystified if they just see a traceback with a ':' in the
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function name! Hopefully they will discover this documentation.
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'''
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def rename_code_object(new_name):
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'''
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If you want to wrap a function in another function and have the wrapped
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function's name show up in the traceback, you must do this brutal
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hackery to change the func.__code__.co_name attribute. See:
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https://stackoverflow.com/questions/29919804/function-decorated-using-functools-wraps-raises-typeerror-with-the-name-of-the-w
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https://stackoverflow.com/questions/29488327/changing-the-name-of-a-generator/29488561#29488561
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I'm just glad it's possible.
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'''
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def inner(func):
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name = new_name + ':' + func.__name__
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code_object = func.__code__
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return type(func)(
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type(code_object)(
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code_object.co_argcount,
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code_object.co_nlocals,
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code_object.co_stacksize,
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code_object.co_flags,
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code_object.co_code,
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code_object.co_consts,
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code_object.co_names,
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code_object.co_varnames,
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code_object.co_filename,
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name,
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code_object.co_firstlineno,
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code_object.co_lnotab,
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code_object.co_freevars,
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code_object.co_cellvars
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),
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func.__globals__,
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name,
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func.__defaults__,
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func.__closure__
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)
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return inner
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