Accept ObjC API wrapper types as arguments and return values from
bound Go package functions and methods. Also, allow Go structs
to extend ObjC classes and implement ObjC protocols as well as override
and implement methods.
This is the third and final part of the implementation of the golang/go#17102
proposal.
Fixesgolang/go#17102
Change-Id: I601d90fb6d22b8d6f8b7d5fe0130daa1a4dd4734
Reviewed-on: https://go-review.googlesource.com/29175
Reviewed-by: David Crawshaw <crawshaw@golang.org>
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>
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>
Java classes must explicitly declare implemented interfaces. Bind
already declares all such interfaces within each package. Expand
the set of interfaces to include all bound packages.
In addition, let Java interfaces extend all possible interfaces in
the same way as Java classes. To avoid circular references, only
let interfaces extend compatible interfaces with fewer methods.
Before, each package was imported in its own importer, breaking the
assumption of types.AssignableTo that identical packages have
identical *types.Package. Fix that by using one importer for all
bound packages, replacing package path equality checks with direct
equality checks.
While we're here, add missing arguments to a few error messages.
Change-Id: I5eb58972a3abe918862ca99d5a203809699a3433
Reviewed-on: https://go-review.googlesource.com/20987
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
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>
Tests now pass on OS X.
Change-Id: Id2e6c5bd9ddd4070962ff9bc121d7902e8c9a647
Reviewed-on: https://go-review.googlesource.com/13694
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
This allows gomobile bind to stop copying seq.h to the destination.
Change-Id: I4a23613fe0407500ad483ae9d8f6bb823d82f082
Reviewed-on: https://go-review.googlesource.com/12300
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Before this change, func Hello() of mypkg package generated a function
GoMypkg_Hello to distinguish the prefix from the function name.
It seems the use of '_' is very rare in Objective-C though.
After this change, it generates GoMypkgHello.
Change-Id: Ic7aa2b667363a447a5ff3500262502d3137d6853
Reviewed-on: https://go-review.googlesource.com/11893
Reviewed-by: Damien Neil <dneil@google.com>
Translate error type to NSError.
Interface type is not supported yet.
Change-Id: I54abba2360cff41ef8ca08063b0120e7edd65a47
Reviewed-on: https://go-review.googlesource.com/10793
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
