Frank Heckenbach wrote:
Adriaan van Os wrote:
Prof A Olowofoyeku (The African Chief) wrote:
What you are describing is almost equal to the "new" style Delphi Classes (actually, this is already over 7 years old, so it is not so new - but I use "new" here to distinguish it from the original BP object model). That type of Delphi compatibility, is, I believe, on the to-do list - but perhaps not a high priority.
There is also the "Object-Oriented Extensions to Pascal" proposal, of the Technical Committee X3J9, see http://www.pascal-central.com/OOE-stds.html.
I have heard that this is quite similar to Delphi's model. (I can only hope that's true, otherwise we might have 4 object models ...)
Although there are quite a few similarities between Delphi and OOE, there are some significant differences which I don't think can be handled in the same object model. For example, Delphi's object model is single inheritance only whereas OOE provides for a limited form of multiple inheritance with the mix-in type property class. Unfortunately, Borland choose to use the property word-symbol for a different feature (which isn't in OOE) so there is a clash in word-symbol useage between the two.
As far a model similarities go, there is a closer similarity between the Mac object mode and OOE's object model than there is between Delphi's and OOE's object models. In many aspects, you could view OOE's object model (and language extensions) as the much improved version 2 of Apple's version 1 Mac Object Pascal which was created in consultation with Wirth in the 1984/85 time period. (If GPC already had the planned for support for OOE, I don't think there would be any need to worry about supporting a separate Mac object model. Although there are a few differences, the differences are relatively minor and could be easily handled with a relatively few conditional compilation directives to handle the object versus class key-word syntax and new/dispose versus constructor/destructor methods for object instantiation and destruction.)
In passing, I have to mention that I personally prefer the BP object model, see section "E.6.5.1 The Object Model. ... The reference model has the following disadvantages: ...". Still, it is a given fact that traditional Macintosh Pascal compilers implemented the reference model.
To gain a more balanced assessment between the two models, one also needs to see section "D.1 Record Extensions ... The value model has many disadvantages ...".
Gale Paeper gpaeper@empirenet.com