You Ain't Gonna Need IT - Rationale

Rationale

According to those who advocate the YAGNI approach, the temptation to write code that is not necessary at the moment, but might be in the future, has the following disadvantages:

• The time spent is taken from adding, testing or improving necessary functionality.
• The new features must be debugged, documented, and supported.
• Any new feature imposes constraints on what can be done in the future, so an unnecessary feature may preclude needed features from being added in the future.
• Until the feature is actually needed, it is difficult to fully define what it should do and to test it. If the new feature is not properly defined and tested, it may not work correctly, even if it eventually is needed.
• It leads to code bloat; the software becomes larger and more complicated.
• Unless there are specifications and some kind of revision control, the feature may not be known to programmers who could make use of it.
• Adding the new feature may suggest other new features. If these new features are implemented as well, this may result in a snowball effect towards feature creep.