Implementing #define macros similar to C on python

Chris Angelico rosuav at gmail.com
Fri Nov 15 05:57:05 CET 2013


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.)

ChrisA



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