Question

我正在使用此代码：

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

要运行一些测试，我使用的代码使用上面的函数：

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

结果如下：

   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.'])

正如您所看到的，有时我会在从主机应用程序复制之前获取状态信息 - 就像第一行一样。

但有时我会获得在状态信息之前复制的信息，如第二行。

我不熟悉使用dict来返回信息，所以我想这可能是一个问题，特别是在混合我试图返回两个变量的事实时。

任何人都可以解释为什么会这样吗？

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变量中，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（或更好，它们的顺序是任意的）。除了使用有序的数据类型之外，你无能为力。

例如，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（第一个元素是来自＆＃34的查询结果;错误消息字典＆＃34;，第二个是data_string.value中包含的内容）。

Answer 2

您专门返回set，它被定义为无序数据类型。也就是说，可以以任何顺序返回集合的元素。集合已针对成员资格测试进行了优化（if x in set:）。集合类似于字典的键：它们可以按任何顺序迭代。

我怀疑为您提供更好的数据类型是一个元组：return (a, b)

然后结果将始终保持相同的顺序。

请注意文字符号的差异：

字典有冒号来配对项目：{'a': 'b', 'c': 'd')。
Set没有冒号，只是任意订购的商品：{'a', 'b', 'c', 'd'}
元组使用括号：('a', 'b', 'c', 'd')
List使用方括号，并且是可变的：['a', 'b', 'c', 'd']

相同的函数在Python中以相反的顺序给出不同的结果。为什么？

2 个答案: