How to add a new syntactic feature to PHP

This is, quite frankly, beautiful.

Huge kudos to Nikita Popov for providing such a great illustration of how PHP works, internally, from the tokenization process, to the parsing, and finally the execution.

I have always been curious about the process and have read other documentation that provides some insight but none of it has come close to this.

Even if you aren't interested in PHP or providing features to PHP, you should give this a read to understand how programming languages like PHP work.

However, I think that the title and the concept behind the post demonstrates how PHP got the way it is. Note how it's focussed on the syntax - this isn't a guide to ensuring that your feature has good semantics, or that it works well with existing features, or how to avoid creating new syntax by extending existing hook points in the language.

Nearly every PHP internals discussion about creating a new language feature has started and ended with "what will the syntax be" (sometimes even with a _vote_ about it!). Some more emphasis on the other aspects of language design would be welcome.

It's a useful post, but I'd like a but more warning that you really don't want to do this unless your proposing on either contributing this back into the core codebase, or forking php - something that can't be done likely. It reads a bit too much like this is something everyone should be doing.

If you are smart enough to do this to PHP, then you are hopefully smart enough to know you should probably not be writing your large system in PHP. There are many better base languages, as opposed to one which has the consistency of perl combined with the string handling power of C (a mild exaggeration, but not by as much as I wish it were). PHP's main advantage is that it is installed everywhere and just works. This breaks that, and therefore renders PHP's main advantage moot.