[fpc-devel] "Friend" classes?

Peter J. Haas fpc.ml at pjh2.de
Sun Mar 20 19:07:51 CET 2005

Hi Ales,

on 2005-03-18T10:57:10+01:00 Ales wrote:
> C++ requires "friend" only because it lacks the idea of modularity.
> Since all classes are "apart" they need some way to tell each other "I 
> can use you"
> In pascal you simply put them into 1 unit.

But IMCO this is not really a good OOP-like solution. Above all
because every class in the unit have access to all sections of a other
class, including the private section (at least in Delphi). A real
private section is on my wish list since Delphi 1.

Sometimes is it not possible or meaninful to put all related classes
in 1 unit, e.g. to avoid monster units and split a problem in
surveyable parts, although this classes belong together and are
managed by a furthermore class. Then you need to publish more methods,
as you need for other resp. the actual usage, this softed the
information hiding concept.

Years ago I read a description of a object oriented pascal dialect,
which use a other concept, IIRC called view concept. The developer can
declare different views to a class, which only contain the methods,
which are needed for a concrete problem. I think such a concept would
be the better way.

The developer of a class or component don't need to consider, which
methods / fields he need to set in the protected part. A developer
which derive a class can define, which methods / fields he need and
write a view without any hacks or modification of the origin class.

wkr Peter.

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