On Sun, Oct 11, 2009 at 01:17:00PM -0700, Jim Lucas wrote:
> Stephan Ebelt wrote:
> > On Mon, Oct 05, 2009 at 05:48:32PM -0700, Jim Lucas wrote:
> >> Here is a problem that I have had for years now. I have been trying to come up
> >> with the perfect solution for this problem. But, I have come down to two
> >> different methods for solving it.
> >>
> >> Here is the problem...
> >
> > [...]
> >
> >> Now, we all have a function or method like this floating around somewhere.
> >>
> >> My question is, how do YOU go about setting the required entries of the $headers
> >> array() ?
> >>
> >
> > [...]
> >
> >> END of examples...
> >>
> >> Now, IMO, the last one is the simplest one and for me, I think it will be the
> >> new way that I solve this type of problem.
> >>
> >> But, my question that I put out to all of you is...
> >>
> >> How would you solve this problem?
> >
> > I have use this array_merge() approach mentioned in other posts for
> > quite some time but found that it introduced many bugs when fieldnames changed.
> > Ie. if the defaults come from a database table and I changed the schema it
> > caused undefined values during the merging and - worse - sometimes messed up the
> > inner workings of functions...
> >
> > Then I heard of the "value object" approach somewhere and found that much more
> > solid. One would basically define a class where default values are represented
> > by its properties. Ie:
> >
> > class vo_email extends vo {
> > public $to = '';
> > public $from = '';
> > public $subject = '(no subject)';
> > public $body = '';
> > ...
> > }
> >
> > the constructor can make sure that absolutly necessary values are required and
> > set properly - and could complain if something is not right. There could be
> > methods that add() or set() or change() things. These could also be inherited
> > from a very generic class "vo" so that this stuff is written once and applies
> > to all sorts of defaults in the program.
> > In my app the inherited constructor accepts arrays as parameter and assigns
> > their elements to the object properties and - by that - overwrites the default
> > settings. If elements do not match with the defined properties it will trigger
> > a very visible call trace.
> >
> > A function like sendEmail() would then require a object of type vo_email as
> > parameter and would work with its properties internally and can rely on it as
> > the vo's constructor should have catched anything bad.
> >
> > If additional logic for the input values is required, it can be added easily:
> >
> > class dao_email extends vo_email {
> > ...
> > public function encode_body() {
> > ...
> > }
> >
> > public function sanitize_mail_address() {
> >
> > }
> > ...
> > }
> >
>
> This is a very interesting approach. How would you initialize the class? Using
> a Singleton Method, or a Globally available class variable
as far as I understood/use it: I try to hardcode as many workable defaults in
the vo class as possible (ie. see $subject in the example). Then I create objects
by passing result records from the database (arrays) to the constructor. That
either returns a object or crashes the application if something is wrong.
Optionally I can create objects without any passed-in parameter which will give
one with only the defaults set. Depending on the class' definition those may
have empty properties. These can be set by subsequent code like
$object->empty_property='bla'. This way its not much different than using plain
arrays except that its still an object which might have additional functionality.
in the email example the constructor should probably refuse to return a object
unless $to and $from are given. I can't see much use without these two.
stephan
>
>
> > sendEmail() would then require a dao_email object (dao=data access object) as
> > input.
> >
> > stephan
> >
> >> TIA
> >>
> >> Jim Lucas
> >>
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