Strategy for developing namespaced and non-namespaced versions of same PHP code

user_27009 0
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I'm maintaining library written for PHP 5.2 and I'd like to create PHP 5.3-namespaced version of it. However, I'd also keep non-namespaced version up to date until PHP 5.3 becomes so old, that even Debian stable ships it ;)

I've got rather clean code, about 80 classes following Project_Directory_Filename naming scheme (I'd change them to \Project\Directory\Filename of course) and only few functions and constants (also prefixed with project name).

Question is: what's the best way to develop namespaced and non-namespaced versions in parallel?

  • Should I just create fork in repository and keep merging changes between branches? Are there cases where backslash-sprinkled code becomes hard to merge?

  • Should I write script that converts 5.2 version to 5.3 or vice-versa? Should I use PHP tokenizer? sed? C preprocessor?

  • Is there a better way to use namespaces where available and keep backwards compatibility with older PHP?

Update: Decided against use of namespaces after all.

compatibility namespaces migration php
9 Answers

I don't think preprocessing the 5.3 code this is a great idea. If your code is functionally identical in both PHP 5.2 and 5.3 with the exception of using namespaces, instead of underscore-separated prefixes, why use namespaces at all? In that case it sounds to me like you want to use namespaces, for the sake of using namespaces..

I do think you'll find that as you migrate to namespaces, you will start to 'think a bit differently' about organizing your code.

For this reason, I strongly agree with your first solution. Create a fork and do backports of features and bugfixes.

Good luck!

user_809110

Here's what I've found:

Doing this with regular expressions is a nightmare. You can get most of it done with just a few simple expressions, but then edge cases are a killer. I've ended up with horrible, fragile mess that barely works with one codebase.

It's doable with built-in tokenizer and simple recursive descent parser that handles only simplified subset of the language.

I've ended up with rather ugly design (parser and transformer in one – mostly just changing or re-emitting tokens), because it seemed too much work to build useful syntax tree with whitespace maintained (I wanted resulting code to be human-readable).

I wanted to try phc for this, but couldn't convince its configure that I have built required version of Boost library.

I haven't tried ANTLR for this yet, but it's probably the best tool for that kind of tasks.

user_270090

Well, I don't know if it is the "best" way, but in theory, you could use a script to take your 5.3 migrate code and backport it into 5.2 (potentially even using PHP).

On your namespace files you would want to do something convert:

namespace \Project\Directory\Filename;

class MyClass {
  public $attribute;

  public function typedFunction(MyClass $child) {
    if ($child instanceof MyClass) {
      print 'Is MyClass';
    }
  }
}

To something like:

class Project_Directory_Filename_MyClass {
  public $attribute;

  public function typedFunction(Project_Directory_Filename_MyClass $child) {
    if ($child instanceof Project_Directory_Filename_MyClass) {
      print 'Is MyClass';
    }
  }
}

And in your namespace code you would need to convert from:

$myobject = new Project\Directory\Filename\MyClass();

To:

$myobject = new Project_Directory_Filename_MyClass();

While all your includes and requires would stay the same, I think you would almost need to keep some sort of Cache of all your classes and namespace to do the complex conversion around the 'instanceof' and typed parameters if you use them. That is the trickiest thing I can see.

user_1452140
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