Some of the top people in the software field spend a good deal of their time examining and improving the quality of existing code bases, and showing developers how to keep their code bases habitable.
Brian Marick kindly filled in a historical gap for me in response to the initial version of this post. He writes: “‘habitability’ was probably coined by Richard P. Gabriel in an article for Journal of Object-Oriented Programming. The article (‘Habitability and Piecemeal Growth’) is included in his 1996 book Patterns of Software (available at https://dreamsongs.com/Books.html). Thanks for the history lesson, Brian!
It’s worth noting that “legacy” doesn’t automatically mean “bad”. Code that is currently used by numerous people, companies, and government agencies to support activities that are important to them clearly brings value. That value is part of the legacy of the code. But we need a shorthand way to categorize code whose internal design could benefit from improvement, and the word “legacy” has penetrated the market in that sense.
One might expect that after all these years of harping on “code quality” and “clean code” and “software design principles” that the problem of poorly-designed code would have faded into the background by 2020. Sadly, the problem is more profound than ever.
Why might that be the case? I think there are four main reasons.