Gobind uses strings for passing errors across the language barrier.
However, since Gobind doesn't have a concept of a nil string, it
can't separate an empty native string from a nil string.
In turn, that means that empty errors, exceptions or NSError * with
an empty description are treated as no error. With ObjC, empty errors
are replaced with a default string to workaround the issue, while
with Java empty errors are silently ignored.
Fix this by replacing strings with actual error objects, wrapping
the Go error, Java Throwable or ObjC NSError *, and letting the
existing bind machinery take care of passing the references across.
It's a large change for a small corner case, but I believe objects
are a better fit for exception that strings. Error objects also
naturally leads to future additions, for example accessing the
exception class name or chained exception.
Change-Id: Ie03b47cafcb231ad1e12a80195693fa7459c6265
Reviewed-on: https://go-review.googlesource.com/24100
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Multiple packages are already supported, but only as if each packages
were bound in isolation. This CL lets a bound package refer to other
bound packages in its exported functions, types and fields.
In Java, the JNI class jclass and constructor jmethodID are exported
so other packages can construct proxies of other packages' interfaces.
In ObjC, the class @interface declarations are moved from the package
.m file to its .h file to allow other packages to constructs its
interface proxies.
Add a supporting test package, secondpkg, and add Java and ObjC tests
for the new cross package functionality. Also add simplepkg for
testing corner cases where the generated Go file must not include its
bound package.
While we're here, stop generating Go proxy types for struct types;
only Go interfaces can be implemented in the foreign language.
Change-Id: Icbfa739c893703867d38a9100ed0928fbd7a660d
Reviewed-on: https://go-review.googlesource.com/20575
Reviewed-by: David Crawshaw <crawshaw@golang.org>
