PHP Includes and Memory

I hope this is not a completely stupid question. I have searched quite a bit for an answer, but I can't find (or recognise) on开发者_Python百科e exactly on point.

I understand that functions in PHP are not parsed until actually run. Therefore, if I have a large class with many functions, only one of which requires a large include file, will I potentially save memory if I only include the "include file" within the function (as opposed to at the top of the class file)?

I presume that, even if this would save memory, it would only do so until such time as the function was called, after which the memory would not be released until the current script stopped running?

Many Thanks,

Rob

I love this saying: "Make it work and then, if needed, make it fast." -some good programmer?

In most cases you would probably be better off focusing on good OOP structure and application design then speed. If you server is using something like Zend Optimizer having all your methods in a single file won't make any difference since it is all pre-compiled and stored in memory.(It's more complicated then this but you get the idea)

You can also load all your include files when apache starts. Then all the functions are loaded in memory. You wouldn't want to do that while developing unless you like to restart Apache every time you make a code change. But when done on production servers it can make a huge difference. And if you really want to make things fast you can write the code in C++ and load it as a module for Apache.

But in the end... do you really need that speed?

Yes it will, but be sure that the function doesn't depend on any other functions included in the parent. The memory consumption is also dependent on a couple things, from the size of the file itself to the amount of virtual memory it requires with variable setting and proper garbage collection protocols.

If the function is inside a class, it's called a method, and it might depend on its class to extend another class.

Just some things to consider. Always include the bare minimum.

Don't save memory on such cases unless you really need it, save development time. Memory is usually cheap but development/supoort time isn't. Use php opcode cacher like eAccelerator or APC, it will increase speed of execution because all files will be pre-compiled and stored in memory.