Can I include code into a PHP function or method?

Question

I want to make a kind of "generic" function which gets executed and - depending on what to do - includes it's implementation file via include(). So for example, I might have exactly one function and exactly 20 procedure files for that function. The procedure files may look like do_this_procedure.php, do_that_procedure.php, etc.

As I'm new to PHP I'd like to know from PHP expertes wether this is fine with PHP or not, before I try it and only "believe" it works, and in reality a lot of things go wrong. So what do you think? Currently I think of an include just as an insertion of code right into that place before it gets compiled for execution.

Answer 1

You may try this too:

PHP Tokenizer.

//from external script:

<?php
  var_dump(token_get_all(file_get_contents('myscript.php')));
?>

Answer 2

From the include statement documentation:

If the include occurs inside a function within the calling file, then all of the code contained in the called file will behave as though it had been defined inside that function. So, it will follow the variable scope of that function. An exception to this rule are magic constants which are evaluated by the parser before the include occurs.

So yes, you can call include from within a function and use that to define the body of the function. You can even have the file that you include vary with each call to the function. The downside is the include will be evaluated with each call to the function; if the function is called many times, it could seriously impact performance.

Depending on exactly what you're trying to accomplish, an alternative is to follow a functional programming paradigm, which lets you construct functions at runtime. Before PHP 5.3, it's ugly, so I wouldn't recommend it unless you can require at least PHP 5.3.

Answer 3

Including such file will be done on runtime, I believe. Basically, when PHP hits the include/require function, it will eval that file as an independent one.

I'm not sure whether variables passed to the function will be usable in the included file, but global-ing them should work fine.

Answer 4

@outis hit the nail on the head, but an alternative approach would be to create the function as a static method in a class and create an autoloader (via spl_autoload_register, etc.) to include and call the class method at runtime.

Then again, this really wouldn't really buy you anything unless you're already using an OO approach.

Answer 5

outis is correct, however this strikes me as a very ugly and messy way to implement the code. Why not just have different files with different declarations of a function including the function declaration.

Functions should be as short as possible - as a general rule of thumb I will go back and see if it is practical to refactor any function longer than 20 lines. Bearing this in mind, where's the benefit in including the body of a function from a seperate file?

C.