On Fri, Aug 28, 2015 at 3:50 PM, wrote:
Yes, but that really isn't at the crux of the problem or the fix.
The strange looking thing is that by adding an '&' in the var assignment,
sync.Locker in the method set Y suddenly accepts the structure X as
implementing Y independent of whether the embedded field sync.Mutex is
direct or pointer.
Requiring an embedded pointer field to satisfy the pointer-receiver
requirement of a method set member seems logically correlated. The
obliteration of that correlation by a distant var assignment (spooky action
at a distance) is, well, strange. Guessing it has something to do with the
heuristics of the type-inferencing system, but a guess is far shy of a
comfortable understanding.
Yes, but that really isn't at the crux of the problem or the fix.
The strange looking thing is that by adding an '&' in the var assignment,
sync.Locker in the method set Y suddenly accepts the structure X as
implementing Y independent of whether the embedded field sync.Mutex is
direct or pointer.
Requiring an embedded pointer field to satisfy the pointer-receiver
requirement of a method set member seems logically correlated. The
obliteration of that correlation by a distant var assignment (spooky action
at a distance) is, well, strange. Guessing it has something to do with the
heuristics of the type-inferencing system, but a guess is far shy of a
comfortable understanding.
type implements an interface is based on the type's method set.
http://golang.org/ref/spec#Method_sets
People often get confused about Method sets because of how the dot
selector will automatically take the address of receiver, so they
assume that T and *T both have the same method set.
http://golang.org/ref/spec#Selectors
The difference matter with interfaces because a value isn't
addressable while it's in an interface.
So if you want to call a method with a pointer receiver on a value in
an interface then the value must a pointer because the dot selector
can't just get you the address of that value.
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