Update: this article is mentioned in a few places as a practical example of using closures.
Some languages pass variables into a closure automatically. In PHP it needs to be done explicitly using the use keyword. See line #6 of the code example.

I was inspired by a question that I was asked on Twitter to write a quick code snippet.

As you may know, set_error_handler can be used to set a custom error handler in PHP. It will catch any errors that happen in the script (with a few notable exceptions). If the function returns false then error handling resumes as normal; otherwise it is assumed that the custom handler took care of things. The problem is that you can only have one error handler active at one time. The purpose of this code is to provide a error handeling stack for PHP.

Using this code you can have more than one error handler while taking advantage of the set_error_handler function.
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