Question

我得到的输入文件只包含一个类定义（类只是常量容器，包含json的键，类似的文件用于Java客户端解码json）看起来像：

class Constants(object):

    VERSION= 'version'
    OS = 'os'
    PROGRAM = 'program'
    # more constants .....

如何获取Constants中定义的所有属性的字典，如何将文件解析为字典？我想压缩密钥并生成具有相同常量键但更短键的新.py和.java文件。

Answer 1

>>> [elem for elem in dir(Constants) if not elem.startswith("_")]
['OS', 'PROGRAM', 'VERSION']

Answer 2

导入模块
- 我在以下代码中使用imp.load_module代替__import__来导入abitrary文件路径。
找到类对象。
使用vars：

import imp
path = '/path/to/file'
with open(path, 'U') as f:
    mod = imp.load_module('temporary', f, path, ('.py', 'U', imp.PY_SOURCE))

builtins = vars(__builtins__)
cls = next(value for name, value in vars(mod).items() if name not in builtins)
const_dict = {name: value for name, value in vars(mod.Constants).items()
                          if not name.startswith('_')}
print(const_dict)

# => {'OS': 'os', 'VERSION': 'version', 'PROGRAM': 'program'}

在2.7.6,3.3.2,3.4.0b2上用Python测试。

Answer 3

扩大答案第一：

# dir(yourClass) will get you all the methods and properties of yourClass and parents wheather yourClass
# is a definition or an instance
elements = [elem for elem in dir(Constants) if not elem.startswith("_")]

# Using yourClass.__dict__.keys() will give you the same of dir if applied to a definition but only instance members 
# if applied to an instance
elements = [elem for elem in Constants.__dict__.keys() if not elem.startswith("_")]

# You can get to the values of the properties with
for el in elements:
    print Constants.__dict__[el]
    # plus whatever you want to do to those elements

# Or if you're using the __dict__ way
Constants.__dict__.items()

Answer 4

以下是使用execfile和python 2.6（我在Debian Wheezy上工作）的示例。还给出了为python 2.7及更高版本构建字典的较短版本。 constants.py文件可以定义几个类，所有这些类都将被解析。

#!/usr/bin/env python

d = {}
const_d = {}

execfile("constants.py", d)

for k,cls in d.items():
  if k not in vars(__builtins__):
    if type(cls) is type:
      # Python version < 2.7
      attributes = {}
      for name, value in vars(cls).items():
        if not name.startswith('__'):
          attributes[name] = value
      # Python version >= 2.7
      #attributes = {name: value for name, value in vars(cls).items() if not name.startswith('__')}
      const_d[cls.__name__] = attributes
      pass
    pass
  pass

print(const_d)

如何从.py文件中获取包含类定义的属性名称

4 个答案: