[fpc-pascal] random question

[Michael Van Canneyt]

On Fri, 4 Jun 2010, spir wrote:

> Hello Pascaleers,
>
>
> -1- class wrappers
> Are there in stock implementations of class wrappers for primitive types: such as TInteger, TString, etc? (that would for instance just hold a .value attr and delegate operations to builtin funcs or procs) This would save me some work :-)

No. They are planned. They partially exist for the objectivec import layer.
(although they may be semantically different there)

>
> -2- [] operator
> How to implement a class that manages this operator (did not find it in the operator overloading section). Pointer welcome (including to the implementation of eg TFPList).

[] is not an operator. It is a set notation.

Or it is used as a notation for selecting elements from an array. 
But that also is not an operator.

>
> -3- List specialization
> What is actually needed to specialise TFPList or TObjectList, in order for
> an instance of the new list class to hold as elements instances of a
> subclass of TObject.  (The main purpose for this specialisation is to
> avoid systematically casting back elements to TMyObject).  I guess I only
> need to redefine the .List or .Items property, but to do what, actually
> (maybe the main issue jumps back to question -2-)?

What you want - no typecasts - needs to be accomplished using generics,
see the fgl unit.

If typecasts are OK: just look at the contnrs unit, there you have several
descendents of the TList class.

Michael.