当我们记得自己插入空间时，我们如何防止Python自动插入空间字符

Question

假装" ."是一个空间字符。然后，Python的打印功能的行为如下：

   print("ham is", 5)    "ham.is.5"
   print("ham is ", 5)   "ham.is..5"

Python的print功能总是在相邻对象之间插入空格。

我们试图编写具有以下行为的函数sprint：

   sprint("ham is", 5)    "ham.is.5"
   sprint("ham is ", 5)   "ham.is.5"

给定 sprint(left, right)，我们仅在 left和 right之间插入一个空间，而 left以白色空间char或 right结束，以白色空间char开始。

• sprint需要接受任何数量的参数，就像print一样。
• sprint是关键字参数end所需的，就像print一样。
。
• sprint应该尽可能像print，除了何时插入空间的决定。

Answer 1

以下代码执行技巧

import itertools as itts
import sys
def sprint(*args, **kwargs):
    """
   If you do *not* insert the space between strings, then sprint will insert one for you
        if you *do* insert the space, then sprint won't insert a space
    sprint("ham is", 5)    "ham.is.5"
    sprint("ham is ", 5)   "ham.is.5"
    sprint mostly behaves like print.
    However, unlike ....
        print("", end = "")
    we have ...
        sprint("", end = "")
    ... will cause an error
    """
    try:
        # suppose someone input a keyword argument for `end`
        # We wish to append that string to the end of `args`
        # if `end == "t"`, then the new argument list will have
        # a tab character as the very last argument 
        args = itts.chain(args, itts.repeat(kwargs["end"], 1))
    except KeyError:
        # in this case, no keyword argument `end` was used
        # we append nothing to the end of `args`
        pass
    # convert everything into a string
    sargs = (str(x) for x in args)
    # sargs = filter out empty strings(sargs)
    sargs = filter(lambda x: x != "", sargs)
    try:
        while True:
            got_left = False
            left = next(sargs)
            got_left = True
            right = next(sargs)
            sprint_two(left, right)
    except StopIteration:
        if got_left:
            # if an odd number of arguments were received
            sprint_one(left)
    return None
def sprint_two(left, right):
    """
    print exactly two items, no more, and no less.
    """
    # assert (left and right are strings)
    assert(isinstance(left, str) and isinstance(right, str))
    # if (left ends in white space) or (right begins with white space)
    whitey = " fnrtv"
    if (left[-1] in whitey) or (right[-1] in whitey):
        # print (left, right) without space char inserted in-between
        r = sprint_one(left, right)
    else:
        r = sprint_one(left, " ", right)
    return r
def sprint_one(*args):
    """
    PRECONDITION: all input arguments must be strings
    mainly wrote this function so that didn't have to repeatedly
    `sys.stdout.write(''.join(args))`, which looks very ugly 
    """
    sys.stdout.write(''.join(args))