[AccessD] Class costs & benefits

The simplest illustration is to say that inheritance is the ability to define your own object as 
starting from something already in existence.

Inheritance in the programming world mimics inheritance in the genetic world except that in most 
languages you are only allowed to inherit properties from a single parent.

So.  I am my dad.  I get everything my dad has, his eyes, his height, his race, his ...

I add to what I inherited.

I add a bunch of extra pounds.  I add the experience of living in Mexico for five years.  I add the 
knowledge of building computers.

In programming.  I inherit a text control.  I add code to check my control source to see what data 
type it is.  I then add new method to make my display format depend on the data type I am bound to.

I have all of the normal properties of a text box.  I can generate all of the events that the text 
box generated.  But I have additional code to check my data type and format myself differently 
depending on the data type.  And other useful things.

That in a nutshell is inheritance.

Access does not have inheritance.  That doesn't Accesses classes useless however.  A class is far 
more than the ability to inherit another object, even in languages where inheritance is possible.

John W. Colby
www.ColbyConsulting.com


Rocky Smolin at Beach Access Software wrote:
> "I will promise to treat every opinion as valid and not go into rant mode.
> ;)" Gonna be a pretty dull thread.
> 
> For those of who don't know, can you define inheritance? 
> 
> 
> Rocky Smolin
> Beach Access Software
> 858-259-4334
> www.e-z-mrp.com
> www.bchacc.com
>  
>  
> 
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby
> Sent: Wednesday, February 25, 2009 7:48 AM
> To: Access Developers discussion and problem solving
> Subject: [AccessD] Class costs & benefits
> 
>  From Rocky's email I thought that perhaps a thread on what the costs and
> benefits are for classes.
> 
> Jim made a statement that he felt that "Access has no implementation
> inheritance and since inheritance really is the whole point of using
> classes, I think they are more or less a waste in Access".
> 
> So what are your feelings and opinions about classes?
> 
> I will promise to treat every opinion as valid and not go into rant mode.
> ;)
> 
> In fact I will promise to not respond to any message unless the author
> specifically asks me to for some reason.
> 
> --
> John W. Colby
> www.ColbyConsulting.com
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