间隔的符号？

我想为实数区间创建一个 Python 类。与数学符号最密切相关的语法是Interval([a, b))或者，甚至更好，Interval[a, b)构造所有实数的区间x令人满意a <= x < b.

是否可以构造一个处理这种语法的类？

通过创建自定义类来“修复”语法无效的 python 是不可能的。

我认为你能得到的最接近Python中的数学区间表示法是

Interval('[a, b)')

如果您将间隔作为参数传递给函数，并且函数在使用它们之前将其参数转换为适当的类型，则这种方式变得更加轻量级。例子：

def do_foo(interval, bar, baz):
    interval = Interval(interval)
    # do stuff

do_foo('[3,4)', 42, true)

可能的实施:

import re

class Interval:
    def __init__(self, interval):
        """Initialize an Interval object from a string representation of an interval
           e.g: Interval('(3,4]')"""
        if isinstance(interval, Interval):
            self.begin, self.end = interval.begin, interval.end
            self.begin_included = interval.begin_included
            self.end_included = interval.end_included
            return
        number_re = '-?[0-9]+(?:.[0-9]+)?'
        interval_re = ('^\s*'
                       +'(\[|\()'  # opeing brecket
                       + '\s*'
                       + '(' + number_re + ')'  # beginning of the interval
                       + '\s*,\s*'
                       + '(' + number_re + ')'  # end of the interval
                       + '\s*'
                       + '(\]|\))'  # closing brecket
                       + '\s*$'
                      )
        match = re.search(interval_re, interval)
        if match is None:
            raise ValueError('Got an incorrect string representation of an interval: {!r}'. format(interval))
        opening_brecket, begin, end, closing_brecket = match.groups()
        self.begin, self.end = float(begin), float(end)
        if self.begin >= self.end:
            raise ValueError("Interval's begin shoud be smaller than it's end")
        self.begin_included = opening_brecket == '['
        self.end_included = closing_brecket == ']'
        # It might have been batter to use number_re = '.*' and catch exeptions float() raises instead

    def __repr__(self):
        return 'Interval({!r})'.format(str(self))

    def __str__(self):
        opening_breacket = '[' if self.begin_included else '('
        closing_breacket = ']' if self.end_included else ')'
        return '{}{}, {}{}'.format(opening_breacket, self.begin, self.end, closing_breacket)

    def __contains__(self, number):
        if self.begin < number < self.end:
            return True
        if number == self.begin:
            return self.begin_included
        if number == self.end:
            return self.end_included