python - 相同的函数在 Python 中以相反的顺序给出不同的结果。为什么？

Question

我正在使用这段代码:

def copy_part_of_space(row,column,lenght):
    #Copy String to Presentation Space (15)
    #Prerequisite Connect Presentation Space
    #Prerequisite function: connect_pcomm(presentation_space)    
    function_number = c_int(8)
    data_string = create_string_buffer(lenght*2*2) #number of unicode char *2*2
    lenght = c_int(lenght)
    ps_position = c_int(((row - 1) * 80)+ column)
    foo = hllapi(byref(function_number), data_string, byref(lenght), byref(ps_position))
    data_string.value
    return {{
        0 : 'The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.',
        1 : 'Your program is not connected to a host session.',
        4 : 'The host presentation space contents were copied. The connected host     presentation space was waiting for host response.',
        5 : 'The host presentation space was copied. The keyboard was locked.',
        9 : 'A system error was encountered.',
        'x' : 'Undocumented error found. Run in circles.',
        }.get(foo, 'x'),data_string.value}

想法是从终端复制一些信息；函数需要返回状态信息(使用字典和 0,1,4,5,9,x 参数)和复制的信息 - 使用 data_string.value

为了运行一些测试，我使用了使用上述函数的代码:

for a in range(15,22):
    print copy_part_of_space(a,7,8)

这是结果:

   set(['The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.', '36343581'])
   set(['36343663', 'The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.'])
   set(['The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.', '36343708'])
   set(['36344673', 'The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.'])
   set(['36344740', 'The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.'])
   set(['The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.', '36344758'])
   set(['36344869', 'The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.'])

如您所见，有时我会在从主机应用程序复制内容之前获取状态信息 - 就像第一行。

但有时我会得到在状态信息之前复制的信息，比如第二行。

我不熟悉使用dict返回信息，所以我想这可能是个问题，特别是当我试图返回的事实混合在一起时两个变量。

谁能解释为什么会这样？

我知道我可以简单地使用 dict 并在返回之前将返回信息保存到一个变量，但我真的认为这是一个更优雅的解决方案 - 我错了吗？

Answer 1

set s 是无序的(或者更好的是，它们的顺序是任意的)。除了改用有序数据类型外，您无能为力。

例如，通过删除 set 构造函数 {...}:

return {
    0 : 'The host presentation space contents were copied to the application program. The target presentation space was active, and the keyboard was unlocked.',
    1 : 'Your program is not connected to a host session.',
    4 : 'The host presentation space contents were copied. The connected host     presentation space was waiting for host response.',
    5 : 'The host presentation space was copied. The keyboard was locked.',
    9 : 'A system error was encountered.',
    'x' : 'Undocumented error found. Run in circles.',
    }.get(foo, 'x'), data_string.value

现在这段代码返回一个 tuple相反(第一个元素是“错误消息字典”的查找结果，第二个元素包含在 data_string.value 中)。