Task tracking numbers are not a substitute for documentation

Do you think this is an appropriate and sufficient documentation for this function?

# 3978
sub is_contact_in_abook_for_user {

This number refers to the task number in a task/bug tracking system. The idea being, why write documentation, when that would simply duplicate what is already available.

There are a number of reasons why this sort of documentation is bad, but the main one is that a feature lives on a for a long time, as does reusable code which one creates in order to implement the particular feature. But a task is just a task, once it's done, no one cares about it any more. So if one sees e.g. a class modelling a user exposing methods such "fetch by user name", "fetch by id", "fetch by telephone number", it isn't really helpful to know that the first two were implemented as part of a "implement payment" feature, and the last for a "mobile phone shop" feature. There are so many aspects of those features which have nothing to do with a function which can be reused time and time again.

The other reasons are:

I think the solution is the task tracker should reference the code, not the other way around. E.g. a comment by a programmer "adrian 20th dec 2006: committed file MyClass.java in svn revision 2938".

This article is © Adrian Smith.
It was originally published on 11 Apr 2007
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