找出_ast模塊的元素，它被導入ast.py

Question

我正在使用python 3.4.3，我正在使用python抽象語法樹（ast）模塊。我查看了ast.py模塊的源代碼，發現ast_py模塊導入了_ast模塊中的所有ast節點類。現在

from _ast import * 

，我想看看AST模塊的元素，讓我得到這個模塊中實現的所有類的名稱：

import _ast 
import inspect 
for element in inspect.getmembers(_ast) : 
    print(element) 

我得到的所有元素的名稱這個模塊：

('AST', <class '_ast.AST'>) 
('Add', <class '_ast.Add'>) 
('And', <class '_ast.And'>) 
('Assert', <class '_ast.Assert'>) 
('Assign', <class '_ast.Assign'>) 
('Attribute', <class '_ast.Attribute'>) 
('AugAssign', <class '_ast.AugAssign'>) 
('AugLoad', <class '_ast.AugLoad'>) 
('AugStore', <class '_ast.AugStore'>) 
('BinOp', <class '_ast.BinOp'>) 
('BitAnd', <class '_ast.BitAnd'>) 
('BitOr', <class '_ast.BitOr'>) 
('BitXor', <class '_ast.BitXor'>) 
('BoolOp', <class '_ast.BoolOp'>) 
('Break', <class '_ast.Break'>) 
('Bytes', <class '_ast.Bytes'>) 
('Call', <class '_ast.Call'>) 
('ClassDef', <class '_ast.ClassDef'>) 
('Compare', <class '_ast.Compare'>) 
('Continue', <class '_ast.Continue'>) 
('Del', <class '_ast.Del'>) 
('Delete', <class '_ast.Delete'>) 
('Dict', <class '_ast.Dict'>) 
('DictComp', <class '_ast.DictComp'>) 
('Div', <class '_ast.Div'>) 
('Ellipsis', <class '_ast.Ellipsis'>) 
('Eq', <class '_ast.Eq'>) 
('ExceptHandler', <class '_ast.ExceptHandler'>) 
('Expr', <class '_ast.Expr'>) 
('Expression', <class '_ast.Expression'>) 
('ExtSlice', <class '_ast.ExtSlice'>) 
('FloorDiv', <class '_ast.FloorDiv'>) 
('For', <class '_ast.For'>) 
('FunctionDef', <class '_ast.FunctionDef'>) 
('GeneratorExp', <class '_ast.GeneratorExp'>) 
('Global', <class '_ast.Global'>) 
('Gt', <class '_ast.Gt'>) 
('GtE', <class '_ast.GtE'>) 
('If', <class '_ast.If'>) 
('IfExp', <class '_ast.IfExp'>) 
('Import', <class '_ast.Import'>) 
('ImportFrom', <class '_ast.ImportFrom'>) 
('In', <class '_ast.In'>) 
('Index', <class '_ast.Index'>) 
('Interactive', <class '_ast.Interactive'>) 
('Invert', <class '_ast.Invert'>) 
('Is', <class '_ast.Is'>) 
('IsNot', <class '_ast.IsNot'>) 
('LShift', <class '_ast.LShift'>) 
('Lambda', <class '_ast.Lambda'>) 
('List', <class '_ast.List'>) 
('ListComp', <class '_ast.ListComp'>) 
('Load', <class '_ast.Load'>) 
('Lt', <class '_ast.Lt'>) 
('LtE', <class '_ast.LtE'>) 
('Mod', <class '_ast.Mod'>) 
('Module', <class '_ast.Module'>) 
('Mult', <class '_ast.Mult'>) 
('Name', <class '_ast.Name'>) 
('NameConstant', <class '_ast.NameConstant'>) 
('Nonlocal', <class '_ast.Nonlocal'>) 
('Not', <class '_ast.Not'>) 
('NotEq', <class '_ast.NotEq'>) 
('NotIn', <class '_ast.NotIn'>) 
('Num', <class '_ast.Num'>) 
('Or', <class '_ast.Or'>) 
('Param', <class '_ast.Param'>) 
('Pass', <class '_ast.Pass'>) 
('Pow', <class '_ast.Pow'>) 
('PyCF_ONLY_AST', 1024) 
('RShift', <class '_ast.RShift'>) 
('Raise', <class '_ast.Raise'>) 
('Return', <class '_ast.Return'>) 
('Set', <class '_ast.Set'>) 
('SetComp', <class '_ast.SetComp'>) 
('Slice', <class '_ast.Slice'>) 
('Starred', <class '_ast.Starred'>) 
('Store', <class '_ast.Store'>) 
('Str', <class '_ast.Str'>) 
('Sub', <class '_ast.Sub'>) 
('Subscript', <class '_ast.Subscript'>) 
('Suite', <class '_ast.Suite'>) 
('Try', <class '_ast.Try'>) 
('Tuple', <class '_ast.Tuple'>) 
('UAdd', <class '_ast.UAdd'>) 
('USub', <class '_ast.USub'>) 
('UnaryOp', <class '_ast.UnaryOp'>) 
('While', <class '_ast.While'>) 
('With', <class '_ast.With'>) 
('Yield', <class '_ast.Yield'>) 
('YieldFrom', <class '_ast.YieldFrom'>) 
('__doc__', None) 
('__loader__', <class '_frozen_importlib.BuiltinImporter'>) 
('__name__', '_ast') 
('__package__', '') 
('__spec__', ModuleSpec(name='_ast', loader=<class  '_frozen_importlib.BuiltinImporter'>, origin='built-in')) 
('alias', <class '_ast.alias'>) 
('arg', <class '_ast.arg'>) 
('arguments', <class '_ast.arguments'>) 
('boolop', <class '_ast.boolop'>) 
('cmpop', <class '_ast.cmpop'>) 
('comprehension', <class '_ast.comprehension'>) 
('excepthandler', <class '_ast.excepthandler'>) 
('expr', <class '_ast.expr'>) 
('expr_context', <class '_ast.expr_context'>) 
('keyword', <class '_ast.keyword'>) 
('mod', <class '_ast.mod'>) 
('operator', <class '_ast.operator'>) 
('slice', <class '_ast.slice'>) 
('stmt', <class '_ast.stmt'>) 
('unaryop', <class '_ast.unaryop'>) 
('withitem', <class '_ast.withitem'>) 

現在，我想看看這些類是如何在_ast模塊中實現的。但是，當我嘗試使用inspect.getsource方法獲取源文件，我得到一個錯誤：

>>inspect.getsource(_ast) 
Traceback (most recent call last): 
File "<pyshell#17>", line 1, in <module> 
inspect.getsource(_ast) 
File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/inspect.py", line 836, in getsource 
lines, lnum = getsourcelines(object) 
File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/inspect.py", line 825, in getsourcelines 
lines, lnum = findsource(object) 
File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/inspect.py", line 655, in findsource 
file = getsourcefile(object) 
File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/inspect.py", line 571, in getsourcefile 
filename = getfile(object) 
File "/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/inspect.py", line 518, in getfile 
raise TypeError('{!r} is a built-in module'.format(object)) 
TypeError: <module '_ast' (built-in)> is a built-in module 

爲什麼我得到這個錯誤。我如何獲得所有這些課程的來源？

在此先感謝

Answer 1

你不能說（不是_ast模塊，這是一個built-in模塊）做的。由於明確表示in the documentations -

inspect.getsourcefile（對象）

返回在其中定義的對象的Python源文件的名稱。 如果對象是內置模塊，類或函數，則這將失敗並出現TypeError錯誤。

（重點煤礦）

而且inspect.getsource()內部使用inspect.getsourcefile()，從回溯爲明顯。

由於_ast是一個內置的模塊，例 -

>>> import _ast 
>>> _ast 
<module '_ast' (built-in)> 

你不能得到通過該方法，它的來源。如果你真的想看看源代碼，Python的源代碼是開源的，可用here。我認爲你正在嘗試獲取源代碼的模塊完全是在C中編寫的。