ruby中的隐含变量\constants和可变常量

Python的三元操作符

在Python中，C三元操作符(c++示例:bool isNegative = i < 0 ?True: false;)可用作语法糖:

>>> i = 1
>>> "It is positive" if i >= 0 else "It is negative!"
'It is positive'
>>> i = -1
>>> "It is positive" if i >= 0 else "It is negative!"
'It is negative!'

这并不奇怪，而是一种特征。奇怪的是，与C中的顺序(条件?答:b)。

在Python中，函数参数的“编译时”(或声明时)计算可能令人困惑:

def append(v, l = []):
    l.append(v)
    return l


print append(1)
print append(2)

>>> [1]
>>> [1,2]

其意图可能是:

def append(v, l = None):
    if l is None:
        l = []
    l.append(v)
    return l

print append(1)
print append(2)

>>> [1]
>>> [2]

这种行为对于缓存之类的事情很有用，但它可能是危险的。

附加特性:具有可变内容的元组:

a = (1,2,[3])
a[2][:] = [4] # OK
a[2] = [2] # crashes

我有点纠结:

1;

在perl中，模块需要返回true。

我很惊讶居然没有人提到Visual Basic的7个循环结构。

For i As Integer = 1 to 10 ... Next
While True ... End While
Do While True ... Loop
Do Until True ... Loop
Do ... Loop While True
Do ... Loop Until True
While True ... Wend

因为粘!你面前的条件实在是太复杂了!

我最喜欢的奇怪的C语言是5[“Hello World”]，但因为已经发布了，我最喜欢的第二个奇怪的是Windows版本结构初始化黑客:

void someWindowsFunction() {
    BITMAPINFOHEADER header = {sizeof header};

    /* do stuff with header */
}

这条微妙的线条达到了以下效果:

Declares a BITMAPINFOHEADER structure Concisely sets the "size" member of the structure, without hardcoding a size constant (since many Window structures, including BITMAPINFOHEADER, follow the convention of specifying the size of the structure as the first member} Declares the version of the structure (since many Windows structures, including BITMAPINFOHEADER, identify their version by the declared size, following the convention that structures definitions are append-only) Clears all other members of the structure (a C standard behavior when a structure is incompletely initialized).