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Is it possible to keep variables in php.ini file. Like that we do with the web.config in .net. I like to keep a flag type variable in the php.ini and use it to different projects.



It's not possible to set user-level variables within a plain php.ini file (or the .htaccess equivilents). There are some PECL modules that do allow that, such as hidef ( - though these would need to be installed on every installation you use.

Including (or pre-including) a file with auto_prepend_file is quite possible - though that would be on every PHP request.

What is frequently done is setting an environment variable as part of the webserver process, which can be read from PHP. In Apache this is quite easy, with the SetEnv module.


And accessing it in PHP:

if ($_ENV['PRODUCTION_SERVER']) {...}  // or getenv('PRODUCTION_SERVER')
Friday, November 11, 2022

When people talk about global variables in other languages it means something different to what it does in PHP. That's because variables aren't really global in PHP. The scope of a typical PHP program is one HTTP request. Session variables actually have a wider scope than PHP "global" variables because they typically encompass many HTTP requests.

Often (always?) you can call member functions in methods like preg_replace_callback() like this:

preg_replace_callback('!pattern!', array($obj, 'method'), $str);

See callbacks for more.

The point is that objects have been bolted onto PHP and in some ways lead to some awkwardness.

Don't concern yourself overly with applying standards or constructs from different languages to PHP. Another common pitfall is trying to turn PHP into a pure OOP language by sticking object models on top of everything.

Like anything else, use "global" variables, procedural code, a particular framework and OOP because it makes sense, solves a problem, reduces the amount of code you need to write or makes it more maintainable and easier to understand, not because you think you should.

Monday, August 8, 2022

Well, why don't you just test ? ;-)

Note: It is not as easy as you'd think -- read the full answer ;-)

Calling the hello_testing(); function, without setting the variable:


I get no output -- which indicates isset returned false.

Calling the function, after setting the variable:

$conditional_random = 'blah';

I get an output:

foo is inside

Which indicates global works as expected, when the variable is set -- well, one should not have any doubt about that ^^

But note that isset will return false if a variable is set, and null!

See the manual page of isset()

Which means that a better test would be:

function hello_testing() {
    global $conditional_random;


And this displays:


No Notice: the variable exists! Even if null.

As I didn't set the variable outside of the function, it shows that global sets the variable -- but it doesn't put a value into it; which means it's null if not already set outside the function.


function hello_testing() {
    //global $conditional_random;



Notice: Undefined variable: conditional_random

It proves that notices are enabled ;-)

And, if global didn't "set" the variable, the previous example would have given the same notice.

And, finally:

function hello_testing() {
    global $conditional_random;

$conditional_random = 'glop';


string 'glop' (length=4)

(This is to purely to demonstrate my example is not tricked ^^)

Saturday, October 8, 2022

You just need to declare a as a global in thread2, so that you aren't modifying an a that is local to that function.

def thread2(threadname):
    global a
    while True:
        a += 1

In thread1, you don't need to do anything special, as long as you don't try to modify the value of a (which would create a local variable that shadows the global one; use global a if you need to)>

def thread1(threadname):
    #global a       # Optional if you treat a as read-only
    while a < 10:
        print a
Saturday, December 24, 2022

Use built-in function globals().


Return a dictionary representing the current global symbol table. This is always the dictionary of the current module (inside a function or method, this is the module where it is defined, not the module from which it is called).

a = 'foo'

def my_func(a = 'bar'):
    globals()['a'] = a

BTW, it's worth mentioning that a global is only "global" within the scope of a module.

Monday, October 17, 2022
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