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Posted by Jerry Stuckle on 11/15/07 04:25
Rob Wilkerson wrote:
> On Nov 14, 12:07 pm, Michael Fesser <neti...@gmx.de> wrote:
>> .oO(Rob Wilkerson)
>>
>>>> That's how singletons work in PHP.
>>> That's what I was afraid of. Kind of makes singletons worthless (at
>>> least for my case), doesn't it?
>> Partly. But they still assure that there's only a single instance to
>> work with, which is globally available from everywhere in your scripts.
>
> Yeah, I guess I was sort of (illogically) hoping that singletons could
> also manage to defy the fundamental nature of PHP and include a level
> of persistence that would allow me to perform certain operations only
> once. I suppose I just don't understand the concept of "globally
> available from everywhere in your scripts" if a "new" instance is
> actually being created with each request. If, somewhere between
> requests, I alter my config then I could have one user using an old
> version (until the next request) and another user using the new one.
>
> I'd like to have more control over when the config is read so that I
> can ensure that it's the only one in play at any given time, but the
> config is loaded in a pseudo front controller, so it's not like I'll
> ever encounter a condition under which it *doesn't* exist. That's
> something, I guess.
>
> Part of this is academic, too. It doesn't seem like much of a
> singleton if I have to keep loading it over and over and if there's no
> way for me to ensure that every user of my system is using precisely
> the same configuration. Instead, each user is running their own fully
> independent and fully functional instance of the "singleton" and
> creating a new instance on each separate request. In a distributed
> architecture more complex than what I need for this project, I suppose
> the singleton-like nature could come in handy when using the same
> instance in multiple components, but for my project its practical use
> is limited.
>
> Thanks for all of your help, guys. At least I have a better
> understanding of the PHP runtime.
>
>
Rob,
One of the things you may be missing is that web pages are basically a
transactional request system. That is, the client calls a web page.
That page opens the resources it needs, fetches them and closes the
resources. The web page (transaction) then ends (and frees all resources).
The next page is another transaction and needs to do it's thing, also.
This is very different from batch programs which can keep resources
available across requests to the UI. Those are running all the time,
and can maintain resources across multiple requests.
It's a different style of programming, and if you're used to writing
batch programs, it takes a bit of getting used to the differences.
--
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Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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