[nojvek]

I've re-written a couple of systems. I think sometimes a refactor is a lot more expensive. e.g old system was written in actionscript/flash. The old devs left and lots of little bugs. Best to just rewrite in HTML/JS that works on mobile and you have full control.

Another example. This dude had a giant wordpress site with a bazillion plugins. It worked but when something went wrong he couldn't figure jack shit and couldn't add more. Re-wrote it with a CMS, he got a 100x boost on how fast he could get things done.

Sometimes the old just needs to be replaced with the new.

[GFischer]

Are you sure you rewrote a "system"? Or a program?

Fred Brooks makes a distinction between a program, a product, a system, and a "programming system product" (what I believe Joel was thinking about when he was talking about Netscape)

"A product (more useful than a program):

can be run, tested, repaired by anyone

- usable in many environments on many sets of data.

- must be tested

- documentation

Brooks estimates a 3x cost increase for this.

To be a component in a programming system (collection of interacting programs like an OS):

- input and output must conform in syntax, semantics to defined interfaces

- must operate within resource budget

- must be tested with other components to check integration (very expensive since interactions grows exponentially in n).

Brooks estimates that this too costs 3x.

A combined programming system product is 9x more costly than a program.

http://www.cs.usfca.edu/~parrt/course/601/lectures/man.month...

http://books.cat-v.org/computer-science/mythical-man-month/t...