There are several methods to producing code suitable for different generations of computer:

Method A: Using generic code

This is the preferred method of coding.

/* This code runs on all generations of computer */
genericcode

Pros

• Code is lightweight, because there is only one code branch
• Compiled executables are lightweight, since only code relevant to the machine is included
• Program behaves the same on all machines
• Programs are easy to debug because the same code is used on all machines
• Programs are portable across machines

Cons

• Machine specific features cannot be utilized

Method B: Using conditional branches

if machinetype=A then
  do this
else
  do that
endif

Pros

• Program is portable across machines
• Machine specific features can be utilized

Cons

• Code is bloated because there are multiple code branches
• Code is difficult to debug due to redundancies and differences in behaviour across machines
• Programs are bloated and contain redundancies that are not ever utilized on the machine
• Programs may behave differently depending on which computer they run on

Method C: Using conditional compilation

#IF MACHINETYPEA
  do this
#ENDIF
#IF MACHINETYPEB
  do that
#ENDIF

Pros

• Programs are lightweight, since only code relevant to the machine is included
• Machine specific features can be utilized

Cons

• Code is bloated because there are multiple code branches
• Code is difficult to debug due to redundancies and differences in behaviour across machines
• Programs are not portable and require recompilation when moving across machines

---

© Copyright 2008 Mark Hobley