Life Before Templates

Recently functional languages are exploding on the scene. Old languages are slowly but steadily gaining new features. C++ 11 has a whole lot of new stuff. But, in this post I want to go back to some good old code. Code that was probably written when I was crawling as a toddler. C++ templates were introduced in mid-80s, so how did programmers code before that? Pre-processor

Have a look at http://docs.libreoffice.org/svl/html/svarray_8hxx.html It contains a lot of macros which create whole classes! (If you have time, see where each macro is being called, and do the whole stuff on your own to get the final class, and you'll appreciate the ingenuity of the programmers of old).

I have never used complex macros since in C and C++ since use of macros are kindaa frowned upon, so I decided to post a small and ugly use of these macros.

If I had been a programmer before C++ had templates, this is what I'd have done to add ;)

#define ADD_FUNC(ret,typedesc) \
typedesc add##ret(typedesc a, typedesc b){\
        typedesc c; \
        c = a + b; \
        return c;\
    }
The above code can be used by the following macro calls,
ADD_FUNC(int,int);
ADD_FUNC(float,float);

This would get me two neat functions for addition - addint(int,int), addfloat(float,float)

I can use these functions directly as,
cout<<addint(4,5)<<endl;
cout<<addfloat(4.3,5.2)<<endl;

Note that the above macro is very different from a normal macro function like,
#define MACRO_ADD(a,b) (a+b)

The first macro *creates new functions* which are then called directly by name. The second macro will be called differently,
cout<<macro_add(1,5)<<endl;
cout<<macro_add(2.2,3.1)<<endl;

Here is a full file to make everything very clear,

In LibreOffice code, you'll find that the calls to the macro generated functions/classes are themselves created using other macros. However all the old stuff is now being replaced by STL containers, so hurry you might miss some beautiful/ugly old code. (Its ugly in 2012, but it shows the ingenuity of the programmers of old! So that's the jackassery that was going on there!