☀ ⛱ eevee  ⛱ ☀

i guess the case inheritance is best suited for is deep hierarchy. biggest example that comes to mind is GUI libs.

the question, then, is: how would you rearrange wx or qt to use traits instead?

worst case is where each level adds extra behavior to the same method — can't exactly ask each trait for its input on some operation

or what if you could? idk what it'd look like but that's the basis of most plugin systems, except they have to reinvent it at runtime

.@eevee On the subject of inheritance: How often do you want to override a method... except you want superclass functionality to "wrap" it?

.@eevee How about methods which work "backwards", i.e. instead of child doing "super.method(blah)", the parent does "child.method(blah)"?

.@eevee It seems like a really desirable feature that no language that I'm aware of supports

@eevee Behavior specialization. otherwise I just use interfaces. This seems to be something Rust gets really correct

@atweetingtwit can you think of a case where rust's traits and default methods wouldn't work?

@eevee i'm not sure you can do stuff like dynamic downcasting with traits objects?

@ben0x539 since i'm making the language i could just say you totally can ;)

@eevee does the default method encoding of overridable methods break down immediately when you inherit again and override the non-default

@eevee @glyph allowing a caller to treat elements of different but related classes the same (in a strongly typed language).

@eevee @glyph allowing common behavior and structure of different but related classes to only be implemented once.

@cathodion @glyph well yeah but you can always make any behavior only be implemented once, by writing a function ;)

@eevee @glyph that's what the superclass constructor is :)

@eevee @glyph TBH, i'm having trouble thinking of an example where it's inheritance and not polymorphism that's useful.

@cathodion @glyph yeah you can get polymorphism with traits. rust is considering inheritance, but again, mostly for tall hierarchies

@eevee @glyph example that springs to mind is Django's ORM. every model class gets a lot of behavior from db.Model or whatever.