回调函数不可调用 [英] Callback function not callable

问题描述

我已经阅读了python文档，可以从命令行调用函数，因此我使用optparse模块从函数返回大量文本，但是我的代码不起作用！我想我做对了所有事情.

I've read in python documentation that it is possible to call a function from command line, so I've used optparse module to return a huge text from a function but my code doesn't work! I think I've done everything right.

def HelpDoc():
     return """ SOME 
                   HUGE 
                      TEXT """

parser = OptionParser(usage="%prog ConfigFile")
parser.add_option("-g", "--guide", action = "callback", callback=HelpDoc(), help = "Show help documentation")

(options,args) = parser.parse_args()

追踪

    parser.add_option("-g", "--guide", action = "callback", callback=HelpDoc(), help = "Show help documentation")
  File "/Python-2.7.2/lib/python2.7/optparse.py", line 1012, in add_option
    option = self.option_class(*args, **kwargs)
  File "/Python-2.7.2/lib/python2.7/optparse.py", line 577, in __init__
    checker(self)
  File "/Python-2.7.2/lib/python2.7/optparse.py", line 712, in _check_callback
    "callback not callable: %r" % self.callback, self)

推荐答案

HelpDoc()是字符串，而不是回调函数，因此请使用callback=HelpDoc，即:

HelpDoc() is string, not a callback function, so use callback=HelpDoc instead, i.e.:

parser.add_option("-g", "--guide", action = "callback", callback=HelpDoc, help = "Show help documentation")

这里的区别可以通过以下方式看到:

The difference here can be seen by:

>>> type(HelpDoc())
str

>>> type(HelpDoc)
function

因此，这就是为什么抱怨是回调对象不可调用的原因.显然，字符串不能作为函数调用.

So, that is why the complaint is that the callback object is not callable. String clearly cannot be called as a function.

但是，对选项回调有一些进一步的要求，因此，使用上述修复程序，您将仅收到另一个错误(参数过多).有关更多信息和示例，请参见: https://docs.python .org/2/library/optparse.html#optparse-option-callbacks

However, there are certain further requirements for an option callback, so with the fix above you'll just receive another error (too many arguments). For more info and examples, see: https://docs.python.org/2/library/optparse.html#optparse-option-callbacks

所以，这要复杂得多.至少功能签名(可接受的参数)必须正确.

So, it is a bit more complicated than that. At least the function signature (accepted parameters) has to be right.

(正如Shadow9043在其评论中所述，不建议使用optparse，请改用argparse.)

(And as Shadow9043 says in its comment, optparse is deprecated, use argparse instead.)

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