Re: [Corelinux-public] Bridge Implementation

[Frank V. C. <fr...@co...>]

Typo comment added to the end of this reply

"Frank V. Castellucci" wrote:
> 
> In light of the recent exchange here in regards to genericity in
> collections, it brought up an interesting conversation I had with Tom
> Maguire (a team member both here and on the job I have so my kids can
> milk me for every dime I have..., sorry), about the Bridge
> implementation.
> 
> As you all know, or maybe don't, I implemented the Bridge pattern where
> the base abstraction has the data member for the implementation:
> 
> class Bridge : public CoreLinuxObject
> {
>         ...
> 
> protected:
> 
>         CoreLinuxObjectPtr getImplementation( void );
> 
> private:
> 
>         CoreLinuxObjectPtr  theImplementation;
> };
> 
> This means that when a derivation is using the protected accessor, in
> order to perform the operation the bridge was called up to do, it would
> have to cast the implementation to the type that the derivation
> expected. In the example code, EngineBridge worked with Engine
> implementations.
> 
> Now, with Tom I mentioned his comment "Typically this is really ugly
> type checking code that is the hallmark of poor or  shortsighted
> analysis." in regards to the Java hashtable thread. I pointed out that
> Bridge requires the derivation to do exactley that!!!
> 
> So I am wondering, should we be offering a choice of implementation
> where possible? In the bridge case a possible scenario would be:
> 
> --------- In libcorelinux++ source -----------
> 
> // We keep the same Bridge we already have AND ADD
> 
> template < class Implementation >
>    class BridgeTemplate : public Bridge
>    {
>       ...
> 
>    protected:
> 
>         Implementation * getImplementation( void )
>         {
>                 return dynamic_cast<Implementation *>
>                         (Bridge::getImplementation());
>         }
> 
>    private:
> 
> };
> 
> // OR We keep the same Bridge we already have AND ADD
> 
> template < class Implementation >
>    class BridgeTemplate : public CoreLinuxObject
>    {
>       ...
> 
>    protected:
> 
>         Implementation * getImplementation( void )
>         {
>            return theImplementation;
>         }
> 
>    private:
> 
>         Implementation * theImplementation;
> };
> 
> ------------------------------------------------------

The above is wrong as I did not clarify that we would LOOSE the data
member in the base Bridge abstraction. Sorry.