Python是一門非常容易入門，但非常難以精通的一門編程語(yǔ)言。難在面向?qū)ο?繼承集合、多態(tài)、組合等等)，難在抽象(設(shè)計(jì)模式)，難在語(yǔ)法糖，難在元編程，難在代碼可以非常非常靈活的組合。
當(dāng)我遇到瓶頸需要通過(guò)閱讀大量框架代碼來(lái)提升編程水平的過(guò)程中，由于框架性代碼過(guò)于靈活或抽象，很多時(shí)候沒(méi)辦法僅通過(guò)閱讀源代碼就能理解，而是需要加入日志去運(yùn)行、調(diào)試來(lái)查看當(dāng)前對(duì)象是什么類，當(dāng)前對(duì)象有哪些屬性，當(dāng)前對(duì)象是被誰(shuí)調(diào)用的。
下面分享兩個(gè)我在閱讀開(kāi)源框架源碼時(shí)常用的分析工具：
裝飾器
查看調(diào)用者的文件位置路徑和代碼調(diào)用所在的行數(shù)，通過(guò)這種方式我可以一層一層的追蹤代碼執(zhí)行的源頭在哪里。
也就是說(shuō)一般使用它的場(chǎng)景是理解代碼線性處理過(guò)程。
utils.py
# -.- coding:utf-8 -.-
from __future__ import print_function
def findcaller(func):
def wrapper(*args,**kwargs):
import sys
f=sys._getframe()
filename=f.f_back.f_code.co_filename
lineno=f.f_back.f_lineno
print('{} {!s:<20} {} {} {} {} {}'.format(func.func_name, 'Called By ', filename, '', lineno, args, kwargs))
return func(*args,**kwargs)
return wrapper
使用方法
earth.py
# -.- coding:utf-8 -.-
import utils
@utils.findcaller
def golden():
return 'metal'
@utils.findcaller
def wood():
return golden()
@utils.findcaller
def water():
return wood()
@utils.findcaller
def fire():
return water()
@utils.findcaller
def land():
return fire()
print(land())
輸出結(jié)果
land Called By C:/Users/zhengtong/earth.py 31 () {}
fire Called By C:/Users/zhengtong/earth.py 28 () {}
water Called By C:/Users/zhengtong/earth.py 23 () {}
wood Called By C:/Users/zhengtong/earth.py 18 () {}
golden Called By C:/Users/zhengtong/earth.py 13 () {}
metal
參考網(wǎng)址:
Stansosleepy的簡(jiǎn)書(shū)博客
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內(nèi)省函數(shù)
很多時(shí)候開(kāi)源框架的文檔并沒(méi)有細(xì)致到告訴你每一個(gè)方法是什么意思，怎么用。
通常我在使用一個(gè)框架的某個(gè)組件功能時(shí)，習(xí)慣看看調(diào)用某個(gè)方法返回的結(jié)果，并分析一下該結(jié)果對(duì)象中包含有哪些可調(diào)用的方法，每個(gè)方法綁定的是哪些類對(duì)象，通過(guò)這些屬性對(duì)象可以使我對(duì)整個(gè)框架的功能和理解更全面。
utils.py
# -.- coding:utf-8 -.-
from __future__ import print_function
class ObjectAttrs(object):
"""
一般用于調(diào)試某個(gè)對(duì)象時(shí)使用，當(dāng)前這個(gè)工具類會(huì)將調(diào)試對(duì)象和其所屬的所有繼承對(duì)象的屬性依次羅列出來(lái)。
變量 showed_list 它是一個(gè)類變量, 用于記錄已顯示過(guò)的對(duì)象.
使用方法:
ObjectAttrs.show(調(diào)試對(duì)象)
"""
showed_list = []
@classmethod
def show(cls, _class, show_attr=True, show_doc=False, _parent_class=None):
"""
:param _class: 必填, 任意對(duì)象.
:param show_attr: 是否顯示_class對(duì)象的所有attribute.
:param show_doc: 是否顯示_class對(duì)象的__doc__屬性.
:param _parent_class: 內(nèi)部使用的參數(shù), 用來(lái)傳遞_class對(duì)象的父類.
:return:
"""
def _show(class_name):
if class_name in cls.showed_list:
return
else:
cls.showed_list.append(class_name)
parent_class_name = ' inherited by {}'.format(_parent_class) if _parent_class else ''
blank_lines = '\n' * 5 if show_attr else ''
print(blank_lines, class_name, parent_class_name, sep='')
if not show_attr: return
for x in dir(class_name):
if not show_doc:
if x == '__doc__':
continue
try:
attr_name = x
attr_type = type(getattr(class_name, attr_name))
attr_object = getattr(class_name, attr_name)
print('{!s:<60}{!s:<60}{}'.format(attr_name, attr_type, attr_object))
except:
print('{!s:<60}{}'.format(attr_name, 'error'))
_show(class_name=_class)
parents = list(getattr(_class, '__bases__', ''))
parents.append(getattr(_class, '__class__', ''))
parents = [i for i in parents if i is not object and i is not type and i]
for i in parents:
cls.show(_class=i, _parent_class=_class, show_doc=show_doc, show_attr=show_attr)
源代碼文件
fox.py
# -.- coding:utf-8 -.-
import utils
class Base(object):
def breathe(self):
return 'breathe'
class Animal(Base):
def run(self):
return 'run'
def walk(self):
return 'walk'
def sleep(self):
return 'sleep'
class FoxManager(object):
def find_other_fox(self):
return 'find_other_fox'
def drink(self):
return 'drink water'
def eat(self):
return 'eat meat'
class Fox(Base):
def __init__(self):
self.name = 'aurora fox'
self.sex = 'male'
self.actions = FoxManager()
使用方法1： 僅顯示對(duì)象的所有繼承關(guān)系
import utils
utils.ObjectAttrs.show(Fox(), show_attr=False)
# 輸出結(jié)果
<__main__.Fox object at 0x035D2B30>
<class '__main__.Fox'> inherited by <__main__.Fox object at 0x035D2B30>
<class '__main__.Base'> inherited by <class '__main__.Fox'>
使用方法2： 僅顯示當(dāng)前對(duì)象的所有屬性
import utils
utils.ObjectAttrs.show(Fox(), show_parent=False)
# 輸出結(jié)果
<__main__.Fox object at 0x030F2910>
__class__ <type 'type'> <class '__main__.Fox'>
__delattr__ error
__dict__ <type 'dict'> {'name': 'aurora fox', 'actions': <__main__.FoxManager object at 0x030F2F50>, 'sex': 'male'}
__format__ <type 'builtin_function_or_method'> <built-in method __format__ of Fox object at 0x030F2910>
__getattribute__ error
__hash__ error
__init__ <type 'instancemethod'> <bound method Fox.__init__ of <__main__.Fox object at 0x030F2910>>
__module__ <type 'str'> __main__
__new__ <type 'builtin_function_or_method'> <built-in method __new__ of type object at 0x51FA68B8>
__reduce__ <type 'builtin_function_or_method'> <built-in method __reduce__ of Fox object at 0x030F2910>
__reduce_ex__ <type 'builtin_function_or_method'> <built-in method __reduce_ex__ of Fox object at 0x030F2910>
__repr__ error
__setattr__ error
__sizeof__ <type 'builtin_function_or_method'> <built-in method __sizeof__ of Fox object at 0x030F2910>
__str__ error
__subclasshook__ <type 'builtin_function_or_method'> <built-in method __subclasshook__ of type object at 0x030F9968>
__weakref__ <type 'NoneType'> None
actions <class '__main__.FoxManager'> <__main__.FoxManager object at 0x030F2F50>
name <type 'str'> aurora fox
run <type 'instancemethod'> <bound method Fox.run of <__main__.Fox object at 0x030F2910>>
sex <type 'str'> male
sleep <type 'instancemethod'> <bound method Fox.sleep of <__main__.Fox object at 0x030F2910>>
walk <type 'instancemethod'> <bound method Fox.walk of <__main__.Fox object at 0x030F2910>>
使用方法3： 顯示當(dāng)前對(duì)象的所有屬性 以及 顯示當(dāng)前對(duì)象所有繼承關(guān)系
import utils
utils.ObjectAttrs.show(Fox())
# 輸出結(jié)果
<__main__.Fox object at 0x02ED2B50>
__class__ <type 'type'> <class '__main__.Fox'>
__delattr__ error
__dict__ <type 'dict'> {'name': 'aurora fox', 'actions': <__main__.FoxManager object at 0x02ED2F50>, 'sex': 'male'}
__format__ <type 'builtin_function_or_method'> <built-in method __format__ of Fox object at 0x02ED2B50>
__getattribute__ error
__hash__ error
__init__ <type 'instancemethod'> <bound method Fox.__init__ of <__main__.Fox object at 0x02ED2B50>>
__module__ <type 'str'> __main__
__new__ <type 'builtin_function_or_method'> <built-in method __new__ of type object at 0x51FA68B8>
__reduce__ <type 'builtin_function_or_method'> <built-in method __reduce__ of Fox object at 0x02ED2B50>
__reduce_ex__ <type 'builtin_function_or_method'> <built-in method __reduce_ex__ of Fox object at 0x02ED2B50>
__repr__ error
__setattr__ error
__sizeof__ <type 'builtin_function_or_method'> <built-in method __sizeof__ of Fox object at 0x02ED2B50>
__str__ error
__subclasshook__ <type 'builtin_function_or_method'> <built-in method __subclasshook__ of type object at 0x02ED9968>
__weakref__ <type 'NoneType'> None
actions <class '__main__.FoxManager'> <__main__.FoxManager object at 0x02ED2F50>
name <type 'str'> aurora fox
run <type 'instancemethod'> <bound method Fox.run of <__main__.Fox object at 0x02ED2B50>>
sex <type 'str'> male
sleep <type 'instancemethod'> <bound method Fox.sleep of <__main__.Fox object at 0x02ED2B50>>
walk <type 'instancemethod'> <bound method Fox.walk of <__main__.Fox object at 0x02ED2B50>>
<class '__main__.Fox'> inherited by <__main__.Fox object at 0x02ED2B50>
__class__ <type 'type'> <type 'type'>
__delattr__ <type 'wrapper_descriptor'> <slot wrapper '__delattr__' of 'object' objects>
__dict__ <type 'dictproxy'> {'__module__': '__main__', '__doc__': None, '__init__': <function __init__ at 0x02ECBCB0>}
__format__ error
__getattribute__ <type 'wrapper_descriptor'> <slot wrapper '__getattribute__' of 'object' objects>
__hash__ <type 'wrapper_descriptor'> <slot wrapper '__hash__' of 'object' objects>
__init__ <type 'instancemethod'> <unbound method Fox.__init__>
__module__ <type 'str'> __main__
__new__ <type 'builtin_function_or_method'> <built-in method __new__ of type object at 0x51FA68B8>
__reduce__ error
__reduce_ex__ error
__repr__ <type 'wrapper_descriptor'> <slot wrapper '__repr__' of 'object' objects>
__setattr__ <type 'wrapper_descriptor'> <slot wrapper '__setattr__' of 'object' objects>
__sizeof__ error
__str__ <type 'wrapper_descriptor'> <slot wrapper '__str__' of 'object' objects>
__subclasshook__ <type 'builtin_function_or_method'> <built-in method __subclasshook__ of type object at 0x02ED9968>
__weakref__ <type 'getset_descriptor'> <attribute '__weakref__' of 'Base' objects>
run <type 'instancemethod'> <unbound method Fox.run>
sleep <type 'instancemethod'> <unbound method Fox.sleep>
walk <type 'instancemethod'> <unbound method Fox.walk>
<class '__main__.Base'> inherited by <class '__main__.Fox'>
__class__ <type 'type'> <type 'type'>
__delattr__ <type 'wrapper_descriptor'> <slot wrapper '__delattr__' of 'object' objects>
__dict__ <type 'dictproxy'> {'__module__': '__main__', 'run': <function run at 0x02ECBBB0>, 'walk': <function walk at 0x02ECBBF0>, 'sleep': <function sleep at 0x02ECBC30>, '__dict__': <attribute '__dict__' of 'Base' objects>, '__weakref__': <attribute '__weakref__' of 'Base' objects>, '__doc__': None}
__format__ error
__getattribute__ <type 'wrapper_descriptor'> <slot wrapper '__getattribute__' of 'object' objects>
__hash__ <type 'wrapper_descriptor'> <slot wrapper '__hash__' of 'object' objects>
__init__ <type 'wrapper_descriptor'> <slot wrapper '__init__' of 'object' objects>
__module__ <type 'str'> __main__
__new__ <type 'builtin_function_or_method'> <built-in method __new__ of type object at 0x51FA68B8>
__reduce__ error
__reduce_ex__ error
__repr__ <type 'wrapper_descriptor'> <slot wrapper '__repr__' of 'object' objects>
__setattr__ <type 'wrapper_descriptor'> <slot wrapper '__setattr__' of 'object' objects>
__sizeof__ error
__str__ <type 'wrapper_descriptor'> <slot wrapper '__str__' of 'object' objects>
__subclasshook__ <type 'builtin_function_or_method'> <built-in method __subclasshook__ of type object at 0x02ED95B8>
__weakref__ <type 'getset_descriptor'> <attribute '__weakref__' of 'Base' objects>
run <type 'instancemethod'> <unbound method Base.run>
sleep <type 'instancemethod'> <unbound method Base.sleep>
walk <type 'instancemethod'> <unbound method Base.walk>
