POSIX参数展开

这是一个创建Python库以从字符串中启用POSIX参数展开的实验。

明显的测试案例

    >>> from parameter_expansion import expand
    >>> foo = 'abc/123-def.ghi'
    >>> # Bland Expansion
    >>> expand('abc $foo abc')
    'abc abc/123-def.ghi abc'
    >>> expand('abc${foo}abc')
    'abcabc/123-def.ghiabc'
    >>>
    >>> # Default Value Expansion
    >>> expand('-${foo:-bar}-')
    '-abc/123-def.ghi-'
    >>> expand('-${bar:-bar}-')
    '-bar-'

默认值展开

    >>> foo = 'abc/123-def.ghi'
    >>> expand('abc $foo abc')
    'abc abc/123-def.ghi abc'
    >>> expand('abc${foo}abc')
    'abcabc/123-def.ghiabc'