Ever heard of SOLID code? Probably: It is a term describing a collection of design principles for "good code" that was coined by Robert C. Martin (aka "uncle bob"), our beloved evangelist of clean code. [...] So, why not approach the problem from the other side for once? Looking at what makes up bad code.

He goes through each part of his STUPID acronym and talks about how it can hurt your code and a few alternatives to help make your application more flexible and easier to maintain in the long run. He also mentions GRASP (General Responsibility Assignment Software Principles), another set of good practices to follow, some similar to SOLID, that can make your app better.

Their implementation adds a tainted or not flag for every byte so that it is possible on invocation of mysql_query() to determine any kind of injection.

Unfortunately, Stefan also mentions two big issues it might have from the get-go: the overhead for the memory needed can slow things down and an incorrect parsing in their query handler could lead to injection attacks.