data type polymorphism

[Scott Christley]

Hello,

This is more a generic Objective-C question versus GNUstep but maybe some experts here have a suggestion.

I have a bunch of code that looks l like this:

  if ([encode isEqual: [BioSwarmModel floatEncode]]) {

    // interpret as float matrix

    float (*grid)[height][width] = matrix;

    for (i = 0;i < height; ++i)

        for (j = 0;j < width; ++j)

            (*grid)[i][j] = 0.0;

  } else if ([encode isEqual: [BioSwarmModel doubleEncode]]) {

    // interpret as double matrix

    double (*grid)[height][width] = matrix;

    for (i = 0;i < height; ++i)

      for (j = 0;j < width; ++j)

          (*grid)[i][j] = 0.0;

   }

where I have a generic pointer void *matrix to some data, that I need to interpret as a specific data type, generally either int, float or double.  The part I don’t like is that the operation is essentially identical regardless of the data type, but I have to duplicate code in order to handle it.  In this example, the code is just zero’ing out the data.  This can be a pain for more complicated operations as I have to make sure I do the correct changes to each code piece.  What I would like is just to write the code once and have the compiler or whatever handle the data type for me:

    for (i = 0;i < height; ++i)

      for (j = 0;j < width; ++j)

          (*grid)[i][j] = 0.0;

So is there some new Objective-C feature that I’m unaware of which can do this for me?

I know at the C language level, there essentially has to be separate code generated for each data type.  I can do some trickery with C-preprocessor macros, or #include code snippets but I’ve avoided that at the moment.

cheers

Scott