PHP - Access a function from another class

Question

How can I access function b from within function a?

This is what I have so far, and I'm getting this error: PHP Fatal error: Call to undefined method a::b()

class test {
 function a($x) {
   switch($x)
   {
    case 'a'://Do something unrelated to class test2
      break;
    case 'b':
      $this->b();       
      break;
   }
 }
}

class test2 extends test {
 function b() {
  echo 'This is what I need to access';
 }
}

$example=new test();
$example2=new test2();
$example->a(b);

For background information - function a is a switch for requests sent via AJAX. Depending on the request, it calls a function to add a record to a database, edit it etc.

Thanks!

it was hard to write an answer that's easily understandable because you reuse your names a lot. I had to distinguish between the class test and the object test, and also you have a mysterious parameter called "b" passed to function "a", while also having a function called "b". For clarity sake you should use more descriptive and unique names in your examples. — Tesserex
– Tesserex, Commented Feb 18, 2010 at 15:57

user253984 · Accepted Answer · 2010-02-18 15:57:41Z

4

You have to define an abstract method b in the base class test (which makes this class abstract, so you cannot have instances of it) to call this method, otherwise the function b is not defined in this class, only in it's subclass of which the base class knows nothing (and should not have to know anything).

Read up on inheritance.

Another thing: a and b are not defined, use quotes. (But this might be just lazyness in your example)

answered Feb 18, 2010 at 15:57

user253984

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1 Comment

Matt Over a year ago

Yeah, I left the quotes out for the example. Thanks for the answer!

Tesserex · Accepted Answer · 2010-02-18 15:54:51Z

3

You can't, $test is not an instance of the test2 class, so it doesn't have method b. If you call $test2->a(b) instead, it could work, as long as you define b() in class test as well. That way the definition of b in class test2 overrides it.

answered Feb 18, 2010 at 15:54

Tesserex

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Comments

hsz · Accepted Answer · 2010-02-18 15:54:04Z

1

You cannot do this.

answered Feb 18, 2010 at 15:54

hsz

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3 Comments

Matt Over a year ago

So the only way to do it would be to call $test2->b(); ?

thetaiko Over a year ago

$test2 is a 'test' and has access to methods a() and b(); $test1 is a 'test' but not a 'test2' so only has access to method a()

thetaiko Over a year ago

also, $test1->a('b') will fail

Community · Accepted Answer · 2023-11-20 22:45:59Z

1

If your function can be called in static context, you can use

test2::b();

otherwise you'll need to do a

test2Obj = new test2();
test2Obj->b();

The following contains some appropriate documentation: https://www.php.net/manual/en/language.oop5.paamayim-nekudotayim.php

edited Nov 20, 2023 at 22:45

CommunityBot

11 silver badge

answered Feb 18, 2010 at 15:55

Dominik

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