| Re: An overloading question [message #174501 is a reply to message #174492] |
Wed, 15 June 2011 03:41   |
Denis McMahon
Messages: 634
Registered: September 2010
Karma:
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Senior Member |
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On Tue, 14 Jun 2011 18:27:20 -0400, sheldonlg wrote:
>> This code:
>>
>> <?php
>>
>> abstract class A {
>>
>> public function x() {
>> print "x() In class A\n";
>> $this->y();
>> }
>>
>> public function y() {
>> print "y() In class A\n";
>> }
>>
>> public function a() {
>> print "a() In class A\n";
>> }
>>
>> }
>>
>> class B extends A {
>>
>> public function y() {
>> print "y() In class B\n";
>> }
>>
>> }
>>
>> print "instantiate\n";
>>
>> $x = new B();
>>
>> print "call function\n";
>>
>> $x->x();
>>
>> ?>
>>
>> gives:
>>
>> instantiate
>> a() In class A
>> call function
>> x() In class A
>> y() In class B
>>
>> Not sure, though, if that solves your problem or not?
> Why did your example print out that last line. It was never called.
> Why did it use it as a constructor? That doesn't seem to make sense.
OK, the calls as I understand it in my code.
First I print "instantiate"
Next, "$x = new B();" causes $x to be created, which instantiates b,
which extends a, which causes A::a() to be called as a constructor
function, which prints "a() In class A".
Then I print "call function"
Finally, "$x->x();" calls A::x() which prints the line "x() In class A"
and then calls $this->y() which finds B::y() which prints the line "y()
In class B".
I'm not sure if your complaint is about the sequence of call of the
constructor functions during instantiation of $x, or the call chain after
instantiation, which is why I gave the functions called after
instantiation different names (x and y) to the constructor function in
class A.
I believe that in your code, A::a() was being called as a constructor at
instantiation, and A::b() was calling B::a() after instantiation. That's
certainly suggested by:
<?php
abstract class A {
public function a() {
print "a() In class A\n";
}
public function b() {
print "b() In class A\n";
print "b() In class A calling \$this->a()\n";
$this->a();
print "b() In class A returned from \$this->a()\n";
}
}
class B extends A {
public function a() {
print "a() In class B\n";
}
}
print "instantiate\n";
$x = new B();
print "call function\n";
$x->b();
?>
giving:
instantiate
a() In class A
call function
b() In class A
b() In class A calling $this->a()
a() In class B
b() In class A returned from $this->a()
Note that A::a() is called as constructor during instantiation of $x
A::b() calling $this->a() after instantiation of $x calls B::a() and not
A::a().
Your initial complaint was about A::a() being called, is it possible that
the A::a() call that you observed was from instantiation and not the call
to $x->b()?
Rgds
Denis McMahon
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