Include all functions in the php file I need or just the functions I need?

Question

So here is what I want to do.

1. The first option is to write each function in different php file each one and then include all of them in a php file that is called include functions.php and whenever I create a new page , let's say index.php I just include "functions.php";

   Why do I need to do that? Because I'll just have to include only one file and all the functions will be included. Now the problem probably will be the server load. I'm not sure how much uncalled functions affect the performance.

2. The second option is to create again the files I need, team them up and then whenever I need a function just call it. The drawback of this is that I'll have more work to do in order to categorize and I'll have to include a lot of files

So I want to ask, does the first option increase the cpu and memory load that much that I have to go to the second one? Are there any performance issues with the first way or the functions that are not being used are not parsed at all by the php ?

Mill

Answer 1

Disk is a slowest part of the server, so in this case variant "all functions in 1 file" will give you little more performance, theoretically.

But I don't recommend you to create "functions.php", better way is OOP. Create classes (objects) with methods, use autoloaders and PSR-0 standard and you will forget about "include" and "require" at all.

Applecart

Answer 2

This is a time to remember Donald Knuth's famous quote:

Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%."

In general, your development model should be tuned to match the needs and goals of the project. After you have met the goals, you can always return to such questions as the one you asked. When you do that, your question will probably answer itself. The program structure will dictate the best way to handle your includes.

You may wish to consider using object-oriented programming (OOP) if it is applicable to your project. Whenyou use OOP, this problem may even become a non issue if your objects handle their own dependency loading.

Pitanga

Also I can say: architecture, designed without thinking about performance, will require changing 100% of code in the future. We just should know, what will give us performance in practice and what only in theory. But we should never forget about optimization, just because of that Knuth's phrase. – Applecart

@OZ_: I think Knuth's point is that we should keep the main thing the main thing. Should the primary focus of a developer be on making a project accomplish the intended goals, or on making it run fast? The fastest-running program is useless if the objectives are not reached. Optimization is good, but is a secondary concern. – Pitanga

@[George Cummins], I understood Knuth's point and I agree with that point. But only with full paragraph. What is common mistake is to quote premature optimization is the root of all evil and repeat it like a mantra. Caching should be part of algorithms, architecture should be designed with thoughts about performance. Yes, we shouldn't waste 90% of development to achieve 0.01 sec improvement, but if we will not think about performance at all, page will be generated in more than 3 seconds and after that we will need to rebuild whole architecture. – Applecart

@ George: You suggest to stop thinking about it and just do it? And what if I notice huge performance issues later? I'll have to change the whole code as OZ said. After all I'm not sure how I can program with classes in php and cant find a decent book for people that have no clue about OOP. I know what it is but it is really confusing for me and I want a book that will even explain what is OOP. – Mill