test_numbers.py 文件源码

def valid_ranges(*types):
    # given a sequence of numeric types, collect their _type_
    # attribute, which is a single format character compatible with
    # the struct module, use the struct module to calculate the
    # minimum and maximum value allowed for this format.
    # Returns a list of (min, max) values.
    result = []
    for t in types:
        fmt = t._type_
        size = struct.calcsize(fmt)
        a = struct.unpack(fmt, ("\x00"*32)[:size])[0]
        b = struct.unpack(fmt, ("\xFF"*32)[:size])[0]
        c = struct.unpack(fmt, ("\x7F"+"\x00"*32)[:size])[0]
        d = struct.unpack(fmt, ("\x80"+"\xFF"*32)[:size])[0]
        result.append((min(a, b, c, d), max(a, b, c, d)))
    return result