Macros: why and/or when to use them?

[xigoi]

The conventional rule is: use the least powerful tool that does the job.

  * If a function works, use a function.
  * Elif a procedure works, use a procedure.
  * Elif a template works, use a template.
  * Elif a macro works, use a macro.
  * Else, make a problem-specific solution.