I want to look at two PHP functions: eval and exec. They’re so often thrown under the sensible-developers-never-use-these bus that I sometimes wonder how many awesome applications we miss out on.
Like every other function in the standard library, these have their uses. They can be abused. Their danger lies in the amount of flexibility and power they offer even the most novice of developers. Let me show you some of the ways I’ve seen these used, and then we can talk about safety precautions and moderation.
He then talks about some of the "interesting" things you can do with these two pieces of functionality including:
- Dynamic Class Creation
- [Creating] Domain Specific Languages
- Parallelism (with exec)
He ends the post with some advice how to avoid issues with the topics he's mentioned and how to "stay safe" while still using these two dangerous pieces of functionality.