某些方法的 python backports

Question

是否有以下方法可以与 python 2.4 一起使用的任何反向移植:

any, all, collections.defaultdict, collections.deque

Answer 1

好吧，至少对于 any 和 all 这很简单:

def any(iterable):
    for element in iterable:
        if element:
            return True
    return False

def all(iterable):
    for element in iterable:
        if not element:
            return False
    return True

deque 已经在 2.4 中了。

至于 defaultdict，我想您可以使用 setdefault() 轻松模拟它。

强烈推荐来自 Alex Martelli(和其他人)的引述 Python Cookbook :

This is what the setdefault method of dictionaries is for. Say we’re building a word-to-page-numbers index, a dictionary that maps each word to the list of page numbers where it appears. A key piece of code in that application might be:

def addword(theIndex, word, pagenumber):
    theIndex.setdefault(word, [ ]).append(pagenumber)

This code is equivalent to more verbose approaches such as:

def addword(theIndex, word, pagenumber):
    if word in theIndex:
        theIndex[word].append(pagenumber)
    else:
        theIndex[word] = [pagenumber]

and:

def addword(theIndex, word, pagenumber):
    try:
        theIndex[word].append(pagenumber)
    except KeyError:
        theIndex[word] = [pagenumber]