I just had an idea, and did a quick search and didn't find any information. I was inspired by this issue in one of my modules. Basically the problem is that the Php5 function "array_combine" doesn't exist in Php4.
What if you could as a user, install a module (when asked to do so by another module) that allowed the developer to use their fancy Php5 functions and the user to reap the benefits in Php4?
We'd have to create a library of Php5 functions which have straight forward backports to Php4, etc... and include good documentation about the module.
Is this just silly? I understand that Php4 is soon going to be losing support and that users should be upgrading etc..., but this process takes time and as a developer I much prefer the Php5 function (in a lot of cases). This won't allow us to change Php4 and Php5 function behaviours, but it would allow us to include some nice and straight forward functions for our module.
Dave