看到了一个python_pipe的实现

这个实现的代码在这里:

代码我在这里也照样给抄过来了

def pype(x, *fs):
    """
    Pipe function. Takes an initial value and any number of functions/methods.
    Methods as strings. Additional args are supported for functions & methods
    by suppling a step as a tuple/list with function/method as the first
    element and the args as the rest. The pipe input is used as the last
    argument in this case. Currently no kwargs.
    """
    while fs:
        f = fs[0]
        args = []
        if isinstance(f, (list, tuple)):
            args = list(f[1:])
            f = f[0]
        if isinstance(f, str):
            if f.startswith('.'):
                x = getattr(x, f[1:])(*args)
            else:
                x = x[f]
        elif isinstance(f, int):
            x = x[f]
        else:
            x = f(*args + [x])
        fs = fs[1:]
    return x

我比较感兴趣的是这一句代码：
x = f(*args + [x])，　所以我将这个代码给修改了下,
x = f(*args, x), 得到的结果完全一样。不知道为什么他会那么写。搞不懂。
如果写成 x = f(*args, [x]) ,得到的结果也很有趣。　
下面就是比较：　

def pype_2(x, *fs):
    """
    Pipe function. Takes an initial value and any number of functions/methods.
    Methods as strings. Additional args are supported for functions & methods
    by suppling a step as a tuple/list with function/method as the first
    element and the args as the rest. The pipe input is used as the last
    argument in this case. Currently no kwargs.
    """
    while fs:
        f = fs[0]
        args = []
        if isinstance(f, (list, tuple)):
            args = list(f[1:])
            f = f[0]
        if isinstance(f, str):
            if f.startswith('.'):
                x = getattr(x, f[1:])(*args)
            else:
                x = x[f]
        elif isinstance(f, int):
            x = x[f]
        else:
            #difference lies here
            x = f(*args, x)
        fs = fs[1:]
    return x


def pype_3(x, *fs):
    """
    Pipe function. Takes an initial value and any number of functions/methods.
    Methods as strings. Additional args are supported for functions & methods
    by suppling a step as a tuple/list with function/method as the first
    element and the args as the rest. The pipe input is used as the last
    argument in this case. Currently no kwargs.
    """
    while fs:
        f = fs[0]
        args = []
        if isinstance(f, (list, tuple)):
            args = list(f[1:])
            f = f[0]
        if isinstance(f, str):
            if f.startswith('.'):
                x = getattr(x, f[1:])(*args)
            else:
                x = x[f]
        elif isinstance(f, int):
            x = x[f]
        else:
            #difference lies here
            x = f(*args, [x])
        fs = fs[1:]
    return x

def add_suffix(number, s):
    return '{} is {} cool!'.format(
        s,
        ' '.join('very' for _ in range(number))
    )

print(pype(
    '   abc: {}   ',
    '.strip',
    ('.format', 3),
    (add_suffix, 2),
    '.upper',
))

print(pype_2(
    '   abc: {}   ',
    '.strip',
    ('.format', 3),
    (add_suffix, 2),
    '.upper',
))

print(pype_3(
    '   abc: {}   ',
    '.strip',
    ('.format', 3),
    (add_suffix, 2),
    '.upper',
))

结果如下：非常有意思

In [6]: %run -i /usr/local/src/py/pype.py
				
 
				
					ABC: 3 IS VERY VERY COOL!
				
				
					ABC: 3 IS VERY VERY COOL!
				
				
					['ABC: 3'] IS VERY VERY COOL!