On 02/29/2012 07:06 PM, Stewart Gordon wrote:
On 29/02/2012 17:01, Timon Gehr wrote:
<snip>
The official website, d-programming-language.org or dlang.org. You
have to click on "See
example". It is at the first bulb of "Power".
But the comment "// <-- assumed to inherit contract" isn't actually
there, so what's "quite explicit" about it?
That was just for documentation... The part that is explicit is:
// Single inheritance of state
class ExtendedWidget : Widget {
override void print(uint level)
in { /* weakening precondition is okay */ } body {
... level may be 0 here ...
}
}
The fact that this weakens the precondition tells us that it was not
weakened before.
Besides, the interface
declaration there isn't allowed by the grammar.
The compiler implements it.
<snip>
Language level contracts as in D are (basically) a way to introduce
runtime checks into
interfaces. If the interface is redefined then that potentially breaks
all code that
implements the interface, even if this is not explicitly stated in
form of contracts.
You mean the fault lies on the part of the library creator for widening
the in contract of a non-final method?
Sure. This adds additional requirements that any deriving class needs to
fulfill. It is not a backwards-compatible change.
<snip>
Obviously there can be additional changes without redefining what an
existing part of the
API does.
<snip>
So you consider illegal inputs to a function to be part of the API?
Yes. Put differently, I consider legal inputs to a overridable virtual
function to be part of the API.
