Posted by petethebloke@googlemail.com on 10/03/07 17:01

On 3 Oct, 17:49, klenwell <klenw...@gmail.com> wrote:
> > > Thanks for that Jerry.
> > > I was trying to keep things simple (!).
>
> > Yea, but it's not always that way, unfortunately.
>
> > > At the moment I have 'design' and it does everything, but it has 30
> > > odd methods
> > > and I wanted to see if I could make things easier to manage. The idea
> > > was to have
> > > inheriting classes 'cushion', 'blind', 'pelmet', 'curtain' and so on
> > > (it's a soft
> > > furnishings site) where functions relevant only to cushions (or
> > > whatever) would be
> > > in the child class.
>
> > OK, that's reasonable enough.
>
> > > The reason I need to call design without knowing its type is that it
> > > has to speak up
> > > for itself in the shopping basket page.
>
> > > Mind you.... it works at the moment, so maybe I'm only making grief
> > > for myself.
>
> > > Thanks again.
>
> > > Pete
>
> > I suspect everything's in a single class right now, and some methods are
> > applicable to one object while not another. This would be a great use
> > of inheritance.
>
> > What I might recommend is to use the static function idea in the
> > 'hanging' class. Maybe pass it a database row id (or the contents of
> > the row, if you wish) and have it build the appropriate class from the data.
>
> > As I said - it's not perfectly clean, but if you want to use
> > inheritance, someone needs to know what the classes you're using are.
> > And keeping everything in this one function means you can easily add
> > more classes to the inheritance hierarchy later.
>
> > --
> > ==================
> > Remove the "x" from my email address
> > Jerry Stuckle
> > JDS Computer Training Corp.
> > jstuck...@attglobal.net
> > ==================
>
> Pete,
>
> I was wrestling with much the same issue recently with a form library
> I'm developing. I wanted there to be a Form class which would be
> responsible for managing all the elements in a webpage form and a
> FormElement class which the add_element method of the Form class would
> use to construct child object elements of specific form field types
> (e.g. ElementTextInput, an extension of FormElement).
>
> It doesn't involve a database, but I did want to validate element
> types against a central array. For that I ended up using the idea
> Jerry suggested here: a static method in the base element class (I may
> move it to the form class before I'm finished) that can be called
> statically to retrieve a valid list of element types:
>
> function get_valid_types()
> {
> $V = array(); // return
>
> // element families
> $V['INPUT_TEXT'] = array('input_text', 'input_email', 'input_url',
> 'input_password');
> $V['TEXTAREA'] = array('textarea');
>
> // all elements
> $V['TYPE'] = array_merge($V['INPUT_TEXT'],$V['TEXTAREA']);
>
> return $V;
>
> }
>
> So if I add a new subclass (say, a radio-button menu class), I can
> just update this method.
>
> Like you, I originally was dreaming of something simpler and more
> elegant for the library as a whole. The resulting code ended up being
> more complicated and required an additional Factory class to make
> everything work as transparently on the API end as I wished. But once
> I got that sorted out, implementation is pretty simple:
>
> $TestForm = new CeoForm($debug);
> $TestForm->add_element($name='text_input', $type='input_text',
> $label='input some text', $is_required=1, $maxlength=255,
> $minlength=4);
> $TestForm->add_element($name='email_input', $type='input_email',
> $label='email address', $is_required=1);
> $TestForm->add_element($name='url_input', $type='input_url',
> $label='web address', $is_required=0);
>
> if ( $TestForm->is_valid() )
> {
> // insert results in db or whatever...}
>
> else
> {
> $show_form = 1;
>
> }
>
> Anyway, your problem strikes me as the same basic problem. If
> interested, you can view the source for this library here:
>
> http://klenwell.googlecode.com/svn/trunk/PHP/ceo/php_ceo/ext/input/
>
> Tom

Thanks Jerry. Thanks Tom.
I'm diving off somewhere else at the moment but I'll take a look at
that code when I get back.
I appreciate you both having a look at this for me.

Pete

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