[racket-dev] Behavioral subtyping for editor<%> and its implementing classes

Sounds fine.

At Tue, 7 Dec 2010 15:20:54 -0500, Matthias Felleisen wrote:
> 
> 
> If we take it out of editor<%>, we should not encounter any problems 
> whatsoever. It is possible that additional implements-interface checks will 
> succeed, but I am doubtful. Other than that I can't think of any problems. 
> 
> Should Asumu try and just run the whole test suite and if it works you commit 
> the change? 
> 
> 
> 
> 
> On Dec 7, 2010, at 3:08 PM, Matthew Flatt wrote:
> 
> > I think the mismatch was not intentional.
> > 
> > Maybe `do-copy' originally had a consistent interface, or maybe it was
> > written down in `editor<%>' before it became apparent that its
> > interface would be be specific to each different kin of editor. I can't
> > think of any reason to have `do-copy' in its present form in
> > `editor<%>'.
> > 
> > At Thu, 2 Dec 2010 16:29:52 -0500, Asumu Takikawa wrote:
> >> Hi all,
> >> 
> >> While writing contracts for classes in racket/gui, I noticed that the
> >> implementations of text% and pasteboard% do not act as behavioral
> >> subtypes of editor<%>, which both classes implement.
> >> 
> >> In particular, consider the do-copy method from editor<%>. Its contract
> >> looks like this:
> >> 
> >> (send an-editor do-copy) → void?
> >> 
> http://pre.racket-lang.org/docs/html/gui/editor___.html?q=do-copy#(meth._(((lib
> >> ._mred/main..rkt)._editor~3c~25~3e)._do-copy))
> >> 
> >> However, the implementations have the following contracts:
> >> 
> >> (send a-text do-copy start end time extend?) → void?
> >> 
> http://pre.racket-lang.org/docs/html/gui/text_.html?q=do-copy#(meth._(((lib._mr
> >> ed/main..rkt)._text~25)._do-copy))
> >> 
> >> and
> >> 
> >> (send a-pasteboard do-copy time extend?) → void?
> >> 
> http://pre.racket-lang.org/docs/html/gui/pasteboard_.html?q=do-copy#(meth._(((l
> >> ib._mred/main..rkt)._pasteboard~25)._do-copy))
> >> 
> >> That is, do-copy in editor<%> has no mandatory arguments, do-copy in
> >> text% has four mandatory arguments, and do-copy in pasteboard% has
> >> two mandatory arguments. Thus, the do-copy methods in text% and
> >> pasteboard% do not implement the editor<%> interface (in the behavioral
> >> subtyping sense) nor do they implement a common interface despite
> >> claiming to.
> >> 
> >> There are several other examples of this issue in the same classes. (see
> >> do-paste, paste-x-selection, etc.)
> >> 
> >> Is there a design rationale for this? Is this method not meant to
> >> implement a common interface?
> >> 
> >> Cheers,
> >> Asumu
> > 
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