CL 24800 changed the error representation from strings to objects.
However, since native errors types are not immediately compatible
across languages, wrapper types were introduced to bridge the gap.
This CL remove those wrappers and instead special case the error
proxy types to conform to their language error protocol.
Specifically:
- The ObjC proxy for Go errors now extends NSError and calls
initWithDomain to store the error message.
- The Go proxy for ObjC NSError return the localizedDescription
property for calls to Error.
- The Java proxy for Go errors ow extends Exception and
overrides getMessage() to return the error message.
- The Go proxy for Java Exceptions returns getMessage whenever
Error is called.
The end result is that error values behave more like normal objects
across the language boundary. In particular, instance identity is
now preserved: an error passed across the boundary and back will
result in the same instance.
There are two semantic changes that followed this change:
- The domain for wrapped Go errors is now always "go".
The domain wasn't useful before this CL: the domains were set to
the package name of function or method where the error happened
to cross the language boundary.
- If a Go method that returns an error is implemented in ObjC, the
implementation must now both return NO _and_ set the error result
for the calling Go code to receive a non-nil error.
Before this CL, because errors were always wrapped, a nil ObjC
could be represented with a non-nil wrapper.
Change-Id: Idb415b6b13ecf79ccceb60f675059942bfc48fec
Reviewed-on: https://go-review.googlesource.com/29298
Reviewed-by: David Crawshaw <crawshaw@golang.org>
When the Java class parser began culling unused constructors, the
logic for determining whether a given Java class has a no-arg
constructor broke when the no-arg constructor is culled. Add
an explicit field for tracking the no-arg constructor property.
Change-Id: Ib68929ae1108bd6fa1fd23de1d134332eb0d97a2
Reviewed-on: https://go-review.googlesource.com/29875
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Accept Java API interface types as arguments and return values from
bound Go package functions and methods. Also, allow Go structs
to extend Java classes and implement Java interfaces as well as override
and implement methods.
This is the third and final part of the implementation of the golang/go#16876
proposal.
Fixesgolang/go#16876
Change-Id: I6951dd87235553ce09abe5117a39a503466163c0
Reviewed-on: https://go-review.googlesource.com/28597
Reviewed-by: David Crawshaw <crawshaw@golang.org>
