object states

[Ali Çehreli]

On 10/07/2012 11:44 AM, Henning Pohl wrote:
> Imagine you want an image to keep the width of 512:
>
> void func(Image img) {
> assert(img.width == 512);
>
> img.doSomething();
> assert(img.width == 512);
>
> while (img.somethingElse()) {
> assert(img.width == 512)
>
> someFunc(img);
> assert(img.width == 512);
> }
> }
>
> In theory, every call to a function can change the width of the image.
> What do you think about this:
> https://dl.dropbox.com/u/34762907/temp/prop1.html
>
> I do know it can be implemented in D4 only.

Sounds good. You haven't mentioned the invariant keyword, so perhaps you 
are not aware of that feature?

   http://dlang.org/class.html#Invariant

   http://dlang.org/dbc.html

Although the docs seem to favor classes, invariant is available for 
structs as well.

Ali

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D Programming Language Tutorial: http://ddili.org/ders/d.en/index.html