Coverage for local/lib/python2.7/site-packages/sage/cpython/debug.pyx : 94%

""" 

Various functions to debug Python internals 

""" 

#***************************************************************************** 

# Copyright (C) 2017 Jeroen Demeyer <jdemeyer@cage.ugent.be> 

# 

# This program is free software: you can redistribute it and/or modify 

# it under the terms of the GNU General Public License as published by 

# the Free Software Foundation, either version 2 of the License, or 

# (at your option) any later version. 

# http://www.gnu.org/licenses/ 

#***************************************************************************** 

from cpython.object cimport PyObject, Py_TYPE, descrgetfunc, descrsetfunc 

cdef extern from "Python.h": 

# Helper to get a pointer to an object's __dict__ slot, if any 

PyObject** _PyObject_GetDictPtr(obj) 

from .getattr cimport AttributeErrorMessage 

def shortrepr(obj, max=50): 

""" 

Return ``repr(obj)`` bounded to ``max`` characters. If the string 

is too long, it is truncated and ``~~~`` is added to the end. 

EXAMPLES:: 

sage: from sage.cpython.debug import shortrepr 

sage: print(shortrepr("Hello world!")) 

'Hello world!' 

sage: print(shortrepr("Hello world!" * 4)) 

'Hello world!Hello world!Hello world!Hello world!' 

sage: print(shortrepr("Hello world!" * 5)) 

'Hello world!Hello world!Hello world!Hello worl~~~ 

""" 

r = repr(obj) 

if len(r) > max: 

r = r[:max-3] + "~~~" 

return r 

cdef object _no_default = object() # Unique object 

def getattr_debug(obj, name, default=_no_default): 

r""" 

A re-implementation of ``getattr()`` with lots of debugging info. 

This will correctly use ``__getattr__`` if needed. On the other 

hand, it assumes a generic (not overridden) implementation of 

``__getattribute__``. Note that Cython implements ``__getattr__`` 

for a cdef class using ``__getattribute__``, so this will not 

detect a ``__getattr__`` in that case. 

INPUT: 

- ``obj`` -- the object whose attribute is requested 

- ``name`` -- (string) the name of the attribute 

- ``default`` -- default value to return if attribute was not found 

EXAMPLES:: 

sage: _ = getattr_debug(list, "reverse") 

getattr_debug(obj=<type 'list'>, name='reverse'): 

type(obj) = <type 'type'> 

object has __dict__ slot (<type 'dict'>) 

did not find 'reverse' in MRO classes 

found 'reverse' in object __dict__ 

returning <method 'reverse' of 'list' objects> (<type 'method_descriptor'>) 

sage: _ = getattr_debug([], "reverse") 

getattr_debug(obj=[], name='reverse'): 

type(obj) = <type 'list'> 

object does not have __dict__ slot 

found 'reverse' in dict of <type 'list'> 

got <method 'reverse' of 'list' objects> (<type 'method_descriptor'>) 

attribute is ordinary descriptor (has __get__) 

calling __get__() 

returning <built-in method reverse of list object at 0x... (<type 'builtin_function_or_method'>) 

sage: _ = getattr_debug([], "__doc__") 

getattr_debug(obj=[], name='__doc__'): 

type(obj) = <type 'list'> 

object does not have __dict__ slot 

found '__doc__' in dict of <type 'list'> 

got "list() -> new empty list\nlist(iterable) -> ne~~~ (<type 'str'>) 

returning "list() -> new empty list\nlist(iterable) -> ne~~~ (<type 'str'>) 

sage: _ = getattr_debug(gp(1), "log") 

getattr_debug(obj=1, name='log'): 

type(obj) = <class 'sage.interfaces.gp.GpElement'> 

object has __dict__ slot (<type 'dict'>) 

did not find 'log' in MRO classes 

object __dict__ does not have 'log' 

calling __getattr__() 

returning log (<class 'sage.interfaces.expect.FunctionElement'>) 

sage: from ipywidgets import IntSlider 

sage: _ = getattr_debug(IntSlider(), "value") 

getattr_debug(obj=IntSlider(value=0), name='value'): 

type(obj) = <class 'ipywidgets.widgets.widget_int.IntSlider'> 

object has __dict__ slot (<type 'dict'>) 

found 'value' in dict of <class 'ipywidgets.widgets.widget_int._Int'> 

got <traitlets.traitlets.CInt object at ... (<class 'traitlets.traitlets.CInt'>) 

attribute is data descriptor (has __get__ and __set__) 

ignoring __dict__ because we have a data descriptor 

calling __get__() 

returning 0 (<type 'int'>) 

sage: _ = getattr_debug(1, "foo") 

Traceback (most recent call last): 

... 

AttributeError: 'sage.rings.integer.Integer' object has no attribute 'foo' 

sage: _ = getattr_debug(1, "foo", "xyz") 

getattr_debug(obj=1, name='foo'): 

type(obj) = <type 'sage.rings.integer.Integer'> 

object does not have __dict__ slot 

did not find 'foo' in MRO classes 

class does not have __getattr__ 

attribute not found 

returning default 'xyz' 

""" 

if default is not _no_default: 

try: 

return getattr_debug(obj, name) 

except AttributeError: 

print(f" returning default {shortrepr(default)}") 

return default 

name = str(name) 

print(f"getattr_debug(obj={shortrepr(obj)}, name={name!r}):") 

print(f" type(obj) = {type(obj)}") 

cdef object attr = None 

cdef object dct = None 

cdef PyObject** dictptr = _PyObject_GetDictPtr(obj) 

if dictptr is not NULL: 

if dictptr[0] is not NULL: 

dct = <object>(dictptr[0]) 

print(f" object has __dict__ slot ({type(dct)})") 

else: 

print(f" object has uninitialized __dict__ slot") 

else: 

print(f" object does not have __dict__ slot") 

cdef descrgetfunc get = NULL 

cdef descrsetfunc set = NULL 

# Look for name in dicts of types in MRO 

cdef bint attr_in_class = False 

for cls in type(obj).__mro__: 

if name in cls.__dict__: 

attr = cls.__dict__[name] 

print(f" found {name!r} in dict of {cls}") 

print(f" got {shortrepr(attr)} ({type(attr)})") 

get = Py_TYPE(attr).tp_descr_get 

set = Py_TYPE(attr).tp_descr_set 

if get is not NULL: 

if set is not NULL: 

print(f" attribute is data descriptor (has __get__ and __set__)") 

if dct is not None: 

print(f" ignoring __dict__ because we have a data descriptor") 

print(f" calling __get__()") 

attr = get(attr, obj, type(obj)) 

print(f" returning {shortrepr(attr)} ({type(attr)})") 

return attr 

else: 

print(f" attribute is ordinary descriptor (has __get__)") 

attr_in_class = True 

break 

if not attr_in_class: 

print(f" did not find {name!r} in MRO classes") 

if dct is not None: 

if name in dct: 

attr = dct[name] 

print(f" found {name!r} in object __dict__") 

print(f" returning {shortrepr(attr)} ({type(attr)})") 

return attr 

else: 

print(f" object __dict__ does not have {name!r}") 

if attr_in_class: 

if get is not NULL: 

print(f" calling __get__()") 

attr = get(attr, obj, type(obj)) 

print(f" returning {shortrepr(attr)} ({type(attr)})") 

return attr 

try: 

tpgetattr = type(obj).__getattr__ 

except AttributeError: 

print(f" class does not have __getattr__") 

else: 

print(f" calling __getattr__()") 

attr = tpgetattr(obj, name) 

print(f" returning {shortrepr(attr)} ({type(attr)})") 

return attr 

print(f" attribute not found") 

raise AttributeError(AttributeErrorMessage(obj, name))