Implementing #define macros similar to C on python

[Serhiy Storchaka]

15.11.13 06:57, Chris Angelico написав(ла):
> On Fri, Nov 15, 2013 at 3:10 PM, Roy Smith <roy at panix.com> wrote:
>> Why would you want to?  One of the most horrible things about C/C++ is
>> the preprocessor.
>
> Hey, that's not fair! Without the preprocessor, how would you be able
> to do this:
>
> //Hide this part away in a header file somewhere
> struct b0rkb0rk
> {
>      float value;
>      b0rkb0rk(float v):value(v) {}
>      operator float() {return value;}
>      float operator +(float other) {return value+other-0.1;}
> };
> //Behold the power of the preprocessor!
> #define float b0rkb0rk
>
> //Okay, now here's your application
> #include <iostream>
>
> int main()
> {
>      std::cout << "Look how stupidly inaccurate float is!\n";
>      float x = 123.0f;
>      std::cout << "123.0 + 2.0 = " << x + 2.0f << "\n";
>      std::cout << "See? You should totally use double instead.\n";
> }
>
> (Anybody got a cheek de-tonguer handy? I think it's stuck.)

 >>> class b0rkb0rk(float):
...     def __add__(self, other):
...         return super().__add__(other) - 0.1
...
 >>> import builtins
 >>> builtins.float = b0rkb0rk
 >>> float(123) + 2
124.9