無法獲取內建類型

Question

我試圖從__builtins__

if params.type in ["int", "long", "float"]: 
    vtype = getattr(__builtins__, params.type) 
    para = [vtype(para[0])] 

得到一個類型，我收到以下錯誤：

Traceback (most recent call last): 
    File "message_ajax_handler.py", line 267, in get 
    vtype = getattr(__builtins__, subset[i]) 
AttributeError: 'dict' object has no attribute 'int' 

但是當我測試，在命令行

vtype = getattr(__builtins__, 'int') 

它正在工作。我在哪裏犯錯誤。

Answer 1

您應該使用__builtin__ module代替：

import __builtin__ 

vtype = getattr(__builtin__, subset[i]) 

__builtins__（與s）可以是一個字典或模塊，根據上下文無論是。這個對象的存在實際上是一個實現細節。來自__builtin__文檔：

CPython implementation detail: Most modules have the name __builtins__ (note the 's') made available as part of their globals. The value of __builtins__ is normally either this module or the value of this modules’s __dict__ attribute. Since this is an implementation detail, it may not be used by alternate implementations of Python.