根据需要更改__call__ [英] changing __call__ on demand

问题描述

嗨！


这让我有些困惑：


Python 2.4（＃1，2005年2月3日，16：47：05）

[GCC 3.3.4（前3.3.5 20040809）] on linux2

输入help，copyright，credit等等。或许可证或欲了解更多信息。


..>>> class test（object）：

.... def __init __（self）：

.... self .__ call__ = self .__ call1

.... def __call1（个体经营）：

....打印1

.... def __call __（个体经营）：

....打印2

....

..>>> t = test（）

..>>> t（）

2


如果我完全取出__call__方法而只在__init__中设置它，我将获得一个
TypeError表示测试不可调用。

我想使用它来提供基于

对象配置的不同实现。计算正确的调用函数非常重要

并且调用频繁，所以我想更改__call__以便直接运行正确的

函数。


我知道，我可以使用另一个间接级别：


def __call __（自我）：

self.the_right_method（）


然后相应地设置the_right_method，但我发现有点

次优。有没有办法在课程创建后改变__call__？


Stefan

解决方案

我试过这个：< br>

class test（object）：
.... def __call1（self）：

....打印1

.... __ call__ = __call1

.... t = test（）
t（）
1

这就是你要找的东西吗？


-

Alan McIntyre

ESRG LLC
http：//www.esrgtech .com


Stefan Behnel写道：嗨！

这让我感到很困惑：

Python 2.4（＃1 ，2005年2月3日，16：47：05）
在Linux2上的[GCC 3.3.4（前3.3.5 20040809）]
类型帮助，版权，信用等。或许可证或了解更多信息。

。>>> class test（object）：
... def __init __（self）：
... self .__ call__ = self .__ call1
... def __call1（self）：
...打印1
... def __call __（自我）：
...打印2
...
。>>> t = test（）
。>>> t（）
2
如果我完全取出__call__方法并且只在
__ init__中设置它，我会得到一个TypeError，说测试不可调用。

我想使用它来为对象配置提供基于
的不同实现。计算正确的调用函数是非常重要的，并且调用很频繁，所以我想在
命令中更改__call__以直接运行正确的函数。

我知道，我可以使用另一个间接级别：

def __call __（self）：
self.the_right_method（）

然后相应地设置the_right_method，但我发现有点<次优的。有没有办法在课程创建后改变__call__？

Stefan

Stefan Behnel写道：

有没有办法在课程创建后更改__call__？

__call__，如__getitem__，而__getattr__在
$ b $上调用b类对象，而不是实例对象。所以，不，不是我想知道的，而不是使用元类欺骗。最简单的选择

IMO将按照你的建议使用另一个间接级别。

-

Michael Hoffman

Alan McIntyre写道：

class test（object）：

... def __call1（个体经营）：
...打印1
... __call__ = __call1
这就是你要找的吗？

这仍然只允许他每班有一个电话功能。

-

Michael Hoffman

Hi!

This somewhat puzzles me:

Python 2.4 (#1, Feb 3 2005, 16:47:05)
[GCC 3.3.4 (pre 3.3.5 20040809)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

..>>> class test(object):
.... def __init__(self):
.... self.__call__ = self.__call1
.... def __call1(self):
.... print 1
.... def __call__(self):
.... print 2
....
..>>> t = test()
..>>> t()
2

If I take out the __call__ method completely and only set it in __init__, I
get a TypeError saying that test is not callable.

I want to use this in order to provide different implementations based on the
object configuration. Calculating the right function to call is non-trivial
and calls are frequent, so I want to change __call__ in order to run the right
function directly.

I know, I could use another level of indirection:

def __call__(self):
self.the_right_method()

and then set the_right_method accordingly, but I find that somewhat
sub-optimal. Is there a way to change __call__ after class creation?

Stefan

解决方案

I tried this:

class test(object): .... def __call1(self):
.... print 1
.... __call__ = __call1
....t = test()
t() 1

Is that what you were looking for?

--
Alan McIntyre
ESRG LLC
http://www.esrgtech.com

Stefan Behnel wrote: Hi!

This somewhat puzzles me:

Python 2.4 (#1, Feb 3 2005, 16:47:05)
[GCC 3.3.4 (pre 3.3.5 20040809)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

.>>> class test(object):
... def __init__(self):
... self.__call__ = self.__call1
... def __call1(self):
... print 1
... def __call__(self):
... print 2
...
.>>> t = test()
.>>> t()
2

If I take out the __call__ method completely and only set it in
__init__, I get a TypeError saying that test is not callable.

I want to use this in order to provide different implementations based
on the object configuration. Calculating the right function to call is
non-trivial and calls are frequent, so I want to change __call__ in
order to run the right function directly.

I know, I could use another level of indirection:

def __call__(self):
self.the_right_method()

and then set the_right_method accordingly, but I find that somewhat
sub-optimal. Is there a way to change __call__ after class creation?

Stefan

Stefan Behnel wrote:

Is there a way to change __call__ after class creation?

__call__, like __getitem__, and __getattr__ is called on the
class object, not the instance object. So, no, not as far as I
am aware, without using metaclass trickery. The simplest option
IMO is to use another level of indirection as you suggest.
--
Michael Hoffman

Alan McIntyre wrote:

class test(object):

... def __call1(self):
... print 1
... __call__ = __call1
Is that what you were looking for?

That still only allows him to have one call function per class.
--
Michael Hoffman

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