I am writing a simple prototype code to demonstrate & profile I/O schemes (HDF4, HDF5, HDF5 using parallel IO, NetCDF, etc.) for a physics code. Since focus is on IO, the rest of the program is very simple:

class Grid
{
public:
  floatArray x,y,z; 
};

class MyModel
{
public:
  MyModel(const int &nip1, const int &njp1, const int &nkp1, const int &numProcs);
  Grid grid;
  map<string, floatArray> plasmaVariables;
};

Where floatArray is a simple class that lets me define arbitrary dimensioned arrays and do mathematical operations on them (i.e. x+y is point-wise addition).

Of course, I could use better encapsulation (write accessors/setters, etc.), but that's not the concept I'm struggling with. For the I/O routines, I am envisioning applying simple inheritance:

• Abstract I/O class defines read & write functions to fill in the "myModel" object
  • HDF4 derived class
  • HDF5
  • HDF5 using parallel IO
  • NetCDF
  • etc...

The code should read data in any of these formats, then write out to any of these formats. In the past, I would add an AbstractIO member to myModel and create/destroy this object depending on which I/O scheme I want. In this way, I could do something like:

myModelObj.ioObj->read('input.hdf')
myModelObj.ioObj->write('output.hdf')

I have a bit of OOP experience but very little on the Design Patterns front, so I recently acquired the Gang of Four book "Design Patterns: Elements of Reusable Object-Oriented Software". OOP designers: Which pattern(s) would you recommend I use to integrate I/O with the myModel object? I am interested in answering this for two reasons:

• To learn more about design patterns in general
• Apply what I learn to help refactor an large old crufty/legacy physics code to be more human-readable & extensible.

I am leaning towards applying the Decerator pattern to myModel, so I can attach the I/O responsibilities dynamically to myModel (i.e. whether to use HDF4, HDF5, etc.). However, I don't feel very confident that this is the best pattern to apply. Reading the Gang of Four book cover-to-cover before I start coding feels like a good way to develop an unhealthy caffeine addiction. What patterns do you recommend?