Newbie learning function, how do you use it?

Walle

Hi guys,

I just wonder how you handle your PHP function. Do you store all function in one php file and include it or you use function that needs in a file?

I also wonder how it works when include function-file to another file. Lets say if include a function-file and you only need one or two function from it then all code from all functions still will be includes anyway?

johanafm

Everything in the included file will be inserted in the code where it says to include that file. The end result is as if you only had everything in one single file.

As such, there is one major advantage to using it, and that is getting a good structure to your code. Group things together that you feel belong together, so it's easy for you to understand what happens where, even if you come back to the code one year later. Or if someone else has to go through your code for that matter.

E.g. you may want to keep session handling, login and logout functions in one file, db access in one file etc.

Also, files containing classes don't have to be explicitly included if you take advantage of the __autload function.

Walle

Then it is as I thought when include. I have seen some people include some function file but always wonder if that was good thing to do. But maybe it just was about session, login, logout functions etc as you mentioned. I have a connection function that I usually include. Only have one function right now but I had some plan if I should save future functions in one file and include it. But it sounds as its not god idea if everything will be inserted.

Is this a facts or maybe it only include functions that is called? Example if I add in a file somewhere function name(); then code from function "name" will be included when it called only? Or for example include function.php'; actually includes all code from this file?

johanafm

All the code in the included file is "copy pasted" into the place where it says "include file.ext". But normal rules apply, so code inside a function will not be run until you call the function.

file1.php

echo '1';
include 'file2.php';
echo '1';
file2_func();

echo $file2_var;
echo $file2_func_var;		// error

file2.php

$file2_var = 'b';					// scope of this var is still global
echo '2';

function file2_func() {
	$file2_func_var = 'func_b';		// scope of this var is still local to function
	echo '2_func';
}

Output:
1
2
1
2_func
b
Error...

And file1.php is equal to

echo '1';
// this is where it said to include file2.php. copy pasting contents from that file here
$file2_var = 'b';					// scope of this var is still global
echo '2';

function file2_func() {
	$file2_func_var = 'func_b';		// scope of this var is still local to function
	echo '2_func';
}
// end of the included file
echo '1';
file2_func();

echo $file2_var;
echo $file2_func_var;		// error

The ONLY thing that differs from included/required content to non-included content is that you can use return statements (pretty much as if you were inside a function). But, if you need to do this, you should probably restructure your code instead.
filea.php

if ((include 'fileb.php') == 2)
	echo 'fileb.php returned 2';

fileb.php

if ($something)
	return 1;
else
	return 2;

Walle

Thanks for that god explanation johanafm. I think I understand how include works little better now.