选择要基于正则表达式调用的Python函数 [英] Choose Python function to call based on a regex

问题描述

是否可以在不先使用def为其命名的情况下将函数放入数据结构中?

Is it possible to put a function in a data structure, without first giving it a name with def?

# This is the behaviour I want. Prints "hi".
def myprint(msg):
    print msg
f_list = [ myprint ]
f_list[0]('hi')
# The word "myprint" is never used again. Why litter the namespace with it?

lambda函数的主体受到严格限制，因此我无法使用它们.

The body of a lambda function is severely limited, so I can't use them.

作为参考，这更像是我遇到问题的真实代码.

For reference, this is more like the real-life code where I encountered the problem.

def handle_message( msg ):
    print msg
def handle_warning( msg ):
    global num_warnings, num_fatals
    num_warnings += 1
    if ( is_fatal( msg ) ):
        num_fatals += 1
handlers = (
    ( re.compile( '^<\w+> (.*)' ), handle_message ),
    ( re.compile( '^\*{3} (.*)' ), handle_warning ),
)
# There are really 10 or so handlers, of similar length.
# The regexps are uncomfortably separated from the handler bodies,
# and the code is unnecessarily long.

for line in open( "log" ):
    for ( regex, handler ) in handlers:
        m = regex.search( line )
        if ( m ): handler( m.group(1) )

推荐答案

这基于我认为创建匿名函数的困难有点让人头疼.您真正想要做的是将相关代码保持在一起，并使代码整齐.因此，我认为装饰者可能会为您工作.

I think that the difficulty of creating anonymous functions is a bit of a red herring. What you really want to do is to keep related code together, and make the code neat. So I think decorators may work for you.

import re

# List of pairs (regexp, handler)
handlers = []

def handler_for(regexp):
    """Declare a function as handler for a regular expression."""
    def gethandler(f):
        handlers.append((re.compile(regexp), f))
        return f
    return gethandler

@handler_for(r'^<\w+> (.*)')
def handle_message(msg):
    print msg

@handler_for(r'^\*{3} (.*)')
def handle_warning(msg):
    global num_warnings, num_fatals
    num_warnings += 1
    if is_fatal(msg):
        num_fatals += 1

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