Posted by Bit Byte on 07/02/27 11:59

ZeldorBlat wrote:

> Bit Byte wrote:
>
>>Since the webserver loads a PHP script every time a request is issued
>>from a client, it seems that Singletons are unnessesary in PHP?, since
>>each time an object is invoked, it is (guaranteed?) to be the only
>>instance - at least for that thread that is handling the request ? No ?
>>
>>If I am missing something quite obvious, please let me know.
>
>
> <?php
> //Thread starts
>
> $a = new Foo();
> $b = new Foo();
>
> //Now have two instances of Foo, all in the same thread -- no
> guarantees here
>
> //Thread ends
> ?>
>

Hmm, yes, that was a rather obvious refudiation of the point I was
making. I obviously wasn't making myself clear. What I meant was to say
was that other than in cases (such as the one above) where the user
deliberately creates multiple instances of the same class, I can't see
the relevance of porting this Pattern to PHP - since each request is
handled in a new thread/(possibly) process.

Case in point. I have wrapped up all of my user management functionality
in a usermanger class which derives from a Singleton base class
(following logic I had used in my C++ program). Its only when I started
using this class that it became obvious to me that the logic was not
necessarily meaningful in the PHP space - each request to manage a user
- will (as I understand it) - fork a new process (or maybe just spawn a
new thread), which will have its own singleton class - blisfully unaware
of the other's existence - unless ofcourse - the Singleton objects are
being cached in shmem (shared memory) - otherwise, it all seems a bit
like a pointless exercise in futility (because in C++ etc, once you
create a Singleton, it notmally stays memory resident until program
termination - whereas in PHP, the Singleton is only alive for the
duration of the request?) - unless again, I am missing something.

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