[fpc-devel] New language feature suggestion (probably not existing in Delphi)

Michael Van Canneyt michael at freepascal.org
Fri Nov 26 10:38:46 CET 2010

On Fri, 26 Nov 2010, Max Vlasov wrote:

> Hi,
> I thought about OOP recently, as many sometimes wonder that it's not as good as it can be in some areas. For example, the OOP encapsulation is good, but
> sometimes the developer doesn't track the context completely or makes other "bad" things related to the hidden nature of encapsulation context. The
> notion of name the variables with "f" at the start also speaks itself about these problems.
> An idea here is to introduce a directive (maybe something else, but directive looks more straightforward), let's call it readonly that forces the method
> to be able only to read the fields and properties of the object it belongs to and forbid any writing. Sure in this case it only can call only the methods
> also containing such directive.
> One of example of possible usage: TBitmap contains PixelFormat, when user changes it, there should be a conversion, but to be more sure that it will be
> accurate and there are no side effects I'd mark the method for conversion with this directive so it will only read existing properties and create some
> new one to return in variable passed by reference. With this directive on, any attempt of this method to change the fields related to bits or handle will
> be stopped by the compiler, also if it tries to call a read/write method, the compiler will also stops. There are others examples that come to mind, all
> allowing oop programming to be more controlled.
> I thing there might be some logical contradictions I'm not aware at the moment, but I think they can be resolved with general oop inheritance logic.
> What do you think? Is anyone aware of similar concept in any other OOP language? Apart from the idea (worth it or not), there's also a question about
> introducing brand-new features in fpc. Are developers (read "Florian" :) is open to introducing new features that later possible other parties (read
> Embarcadero :) will be willing to adapt?

Everything we introduced first Embarcadero has consistently done different, so I would not hope for that.


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