Python：functools，方法的包装器装饰器：使ipython在使用时返回正确的定义'?'

Question

我使用functools来制作一个装饰器，这允许我记录方法调用的详细信息。

我在这里得到了很多帮助来写它…不是我自己的，我还学习它是如何工作的……

我经常使用python，当我使用:

import Tools
imagetools = Tools.Tools()
imagetools.save_new_image ?
Type:       instancemethod
String Form:<bound method ImageTools.save_new_image of <ImageTools.ImageTools object      at    0x305d1d0>>
File:       /fs/corpus6/dpc/workspace/python/Modules/MiscTools.py
Definition: imagetools.save_new_image(self, *args, **kwargs)
Docstring:  <no docstring>

这是我的问题线…除此之外，我还没有写文档字符串…: |

Definition: imagetools.save_new_image(self, *args, **kwargs)

我想是:

save_new_image_clone(self, data, header, outfile,  coordmap)

包装器:

import functools
def log_method(func):
@functools.wraps(func)
def wrapper(self, *args, **kwargs):
    self.__doc__ = func.__doc__
    # allows me to put the wrapper in helper methods that are sometimes major steps
    if check_for_True_in_last_arg(*args):
        log.debug('''Last arg is "True" which could indicate the caller 
intends the log to work on this method. For that behaviour, use the keyword arg:  log_this=True''')
    if 'log_this' in kwargs and kwargs['log_this'] is not False: 
        args_name = inspect.getargspec(func)[0][1:] #drop the 'self' arg
        args_dict = dict(list(itertools_izip(args_name, args)) + list(kwargs.iteritems()))
        method_name = wrapper.__name__
        args_dict_string = 'nMETHOD: ' + method_name + 'n'
        for k,v in args_dict.iteritems():
            if type(v) is not np.ndarray:
                args_dict_string += "%s: %sn" %(k,v)
            elif type(v) is np.ndarray:
                args_dict_string += "NUMPY ARRAY:%s nSHAPE:%sn" %(k, str(v.shape))
        args_dict_string += 'n'
        log.info(args_dict_string)
    return func(self, *args, **kwargs) 
return wrapper

更新:在python中，我这样做是为了看看发生了什么，但它还没有帮助我。

help??
Type:       _Helper
String Form:Type help() for interactive help, or help(object) for help about object.
File:       /usr/lib64/python2.7/site.py
Definition: help(self, *args, **kwds)
Source:
class _Helper(object):
"""Define the builtin 'help'.
This is a wrapper around pydoc.help (with a twist).
"""
def __repr__(self):
    return "Type help() for interactive help, " 
           "or help(object) for help about object."
def __call__(self, *args, **kwds):
    import pydoc
    return pydoc.help(*args, **kwds)
Call def:   help(self, *args, **kwds)

Answer 1

您要做的——创建一个调用签名与要装饰的函数相同的装饰器——并不是一件从头开始就能简单完成的事情。有一个叫做decorator的第三方模块可以做到这一点:

import decorator
@decorator.decorator
def log_method(func, *args, **kwargs):
    # allows me to put the wrapper in helper methods that are sometimes major steps
    if check_for_True_in_last_arg(*args):
        log.debug('''Last arg is "True" which could indicate the caller 
intends the log to work on this method. For that behaviour, use the keyword arg:  log_this=True''')
    if 'log_this' in kwargs and kwargs['log_this'] is not False: 
        args_name = inspect.getargspec(func)[0][1:] #drop the 'self' arg
        args_dict = dict(list(itertools_izip(args_name, args)) + list(kwargs.iteritems()))
        method_name = wrapper.__name__
        args_dict_string = 'nMETHOD: ' + method_name + 'n'
        for k,v in args_dict.iteritems():
            if type(v) is not np.ndarray:
                args_dict_string += "%s: %sn" %(k,v)
            elif type(v) is np.ndarray:
                args_dict_string += "NUMPY ARRAY:%s nSHAPE:%sn" %(k, str(v.shape))
        args_dict_string += 'n'
        log.info(args_dict_string)
    return func(self, *args, **kwargs) 
class Tools(object):
    @log_method
    def save_new_image(self, data, header, outfile, coordmap):
        """
        Jazz the snaz output baz
        """

Then from IPython:

In [14]: imagetools = Tools()
In [15]: imagetools.save_new_image?
Type:       instancemethod
String Form:<bound method Tools.save_new_image of <__main__.Tools object at 0xae1e20c>>
File:       /tmp/python-2973tNk.py
Definition: imagetools.save_new_image(self, data, header, outfile, coordmap)
Docstring:  Jazz the snaz output baz

---

如果你想查看实现此功能的Python代码，请参阅装饰器。FunctionMaker类。它使用inspect计算出原始函数的签名，然后使用字符串格式化编写定义修饰函数的def-statement。然后调用exec code in evaldict来执行字符串。