The very rough example I imagine will still have some lines of code in each method
<?php
class Chain {
private $_register = array();
public function foo () {
$this->register(__METHOD__);
return $this;
}
public function bar () {
$this->register(__METHOD__);
return $this;
}
public function some () {;
$this->verify('foo'); // foo() should be called before some();
$this->register(__METHOD__);
echo 'it's ok';
return $this;
}
public function verify($method) {
if(array_key_exists($method, $this->_register) && $this->_register[$method] == true) {
return true;
}
else {
throw new Exception('Some exception');
}
}
public function register($method) {
$method = str_replace(__CLASS__.'::', '', $method);
$this->_register[$method] = true;
}
}
What do we do here - we have a register()
and verify()
methods. (they can be helpers, but for the current purpose I added them in the class.
Each method should have before it's returning value a register to itself. Calling $this->register(__METHOD__)
from foo()
will add in the private array 'foo' => true
.
The verify()
method checks if foo
exist as array key and if its value is true
. If it is - the script will continue. Otherwise - throws exception.
In this case:
$chain = new Chain();
$chain->bar()->some()->foo(); //throws an exception
Fatal error: Uncaught exception 'Exception' with message 'Some
exception' in ...
$chain = new Chain();
$chain->foo()->some()->foo(); // ok
it's ok
The problem here is that we establish a "convention". You need to pass __METHOD__
to the register function so after it replace the classname it will add only the method name in the array. So later, in the function where you need to verify if one or more functions are called before this, you need to use the method name as string i.e. $this->verify('foo');
Ofcourse you can play different scenarios without stripping and testing with strpos()
or adding ()
after the methodname for easier recognition if you are verifying a method or smth else.
But at least it will save you from making for each method, different variable to fill i.e.
function foo() {
$this->_foo = true;
return $this;
}
function bar() {
$this->_bar = true;
return $this;
}
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