在你看来,你遇到过的最令人惊讶、最怪异、最奇怪或最“WTF”的语言特性是什么?

请每个回答只回答一个特征。


当前回答

在Python中:

>>> a[0] = "hello"
NameError: name 'a' is not defined
>>> a[0:] = "hello"
NameError: name 'a' is not defined
>>> a = []
>>> a[0] = "hello"
IndexError: list assignment index out of range
>>> a[0:] = "hello"
>>> a
['h', 'e', 'l', 'l', 'o']

这些切片分配也会给出相同的结果:

a[:] = "hello"
a[42:] = "hello"
a[:33] = "hello"

其他回答

C的多个名称空间:

typedef int i;

void foo()
{
    struct i {i i;} i;
    i: i.i = 3;
    printf( "%i\n", i.i);
}

或与字符:

typedef char c;

void foo()
{
    struct c {c c;} c;
    c: c.c = 'c';
    printf( "%c\n", c.c);
}

我一直在想为什么最简单的程序是:

class HelloWorldApp {
    public static void main(String[] args) {
        System.out.println("Hello World!");
    }
}

然而它可以是:

print "Hello World!"

也许这是为了吓唬计算机科学专业的学生……

VBScript的With block:

With xml.appendChild(xml.createElement("category"))
  .setAttribute("id",id)
  .setAttribute("keywords",keywords)
  With .appendChild(xml.createElement("item"))
    .setAttribute("count",count)
    .setAttribute("tip",tip)
    .appendChild(xml.createTextNode(text))
  End With
End With

Javascript中有很多东西会让你流泪。

局部变量的作用域,举个简单的例子:

function foo(obj)
{
  for (var n = 0; n < 10; n++)
  {
    var t;        // Here is a 't'
    ...
  }
  t = "okay";     // And here's the same 't'
}

很简单,Erlang有很多。例如,标点符号的三种形式,

a_function(SomeVariable) ->
  statements_end_with_commas(),
  case PatternMatching of
    0 -> now_we_end_with_semicolon;
    true -> except_the_last_one
  end.

%%  Function definitions end with periods!