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Posted by Josse Barrera on 12/30/05 12:46
Lüpher Cypher wrote:
> Hi,
>
> Suppose we have a hierarchical class structure that looks something like
> this:
>
> Object
> |
> +-- Main
> |
> +-- Object1
> | |
> | +-- Object11
> | |
> | +-- Object 12
> |
> +-- Object2
> |
> +-- Object3
> |
> +-- Object4
> |
> +-- Object41
> | |
> | +-- Object 411
> |
> +-- Object 42
>
> Now, the application looks like this:
>
> <?php
> $app = new Main(...);
> $app->doSomething();
> ?>
>
> Class Main() is instantiated only once, however it works with all other
> classes, which may be instantiated a number of times.
>
> Now suppose there is a scenario:
>
> Main creates Object11.
> Object11 calls Object1::foo(), which creates Object2.
> Object2 may then create Object1, in which case
> Object1 calls its foo(), which creates Object2.
> Object2 may then create Object1
> ..etc. until Object2 decides not to create Object1..
>
> So, basically we'd get:
>
> Main
> Object11->foo()
> Object2
> Object1->foo()
> Object2
> ...
>
> Now, when Object2 instantiates, it assigns a value to its variable, say,
> Object2::var, which should be unique. So, after assigning the value,
> Object2 has to check it against any other Object2::var.
> However, Object2 is not necessarily instantiated under Object1, so,
> let's say we have
>
> Main
> $obj11 = Object11
> $obj2 = Object2
> $obj1 = Object1
> $obj2 = Object2
> $obj3 = Object3
> $obj2 = Object2
> $obj411 = Object411
> $obj42 = Object42
> $obj1 = Object1
> $obj2 = Object2
>
>
> Assume $app->obj11->obj2->obj1->obj2::var should be checked against
>
> $app->obj11->obj2::var
> $app->obj3->obj2::var
> $app->obj411->obj42->obj1->obj2::var
>
> I assumed the easiest way would be to have a global array of all objects
> descending from Object and update it in Object's constructor:
>
> function Object() {
> global $objects;
> $objects[count($objects)] = &$this;
> ...
> }
>
> Then we could simply iterate through $objects, and if object's class is
> Object2, compare the var's.
> However, this does not work, even through the object is passed by
> reference - if the object's variables are updated (by the object itself
> or by another object), the global array apparently has a copy of the
> initial object state:
>
> $obj2 = new Object2();
> results in
> $obj2 = Object2( var => 1 )
> $objects[0] = Object2( var => 1 )
>
> $obj2->var++;
> results in
> $obj2 = Object2( var => 2 )
> $objects[0] = Object2( var => 1 )
>
> So, I guess, some other mechanism should be used.
>
>
> Any ideas?
>
> Thanks,
> luph
This is a textbook case of a badly designed set of classes. Their
relationships are so complicated that even you the architect, are having
problems explaining yourself. I think you'll need to go back to the
drawing board on this one.
Extract the common features into a set of interfaces which should help
clarify the class relationships and clean up the design. Also wherever
possible, try to use (design) patterns, that way, your code will be
reusable (not to mention easir to maintain). Incidentally, your Main
class looks like a Singleton pattern, but only you the archiect, can
know that for sure since your description given here is not very lucid.
hope that helps
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