| commit | 89b83602188ee84018a2658a8f9f800b4bd80894 | [log] [tgz] |
|---|---|---|
| author | Elias Naur <elias.naur@gmail.com> | Mon Sep 19 12:44:13 2016 +0200 |
| committer | Elias Naur <elias.naur@gmail.com> | Tue Oct 04 09:11:42 2016 +0000 |
| tree | 465c275418237bba31a5848f759474aa9ac837cb | |
| parent | 84d710de2097bf402ede87a8cede037a5fe07716 [diff] |
bind: remove error wrappers to preserve error instance identity
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>
The Go mobile repository holds packages and build tools for using Go on mobile platforms.
Package documentation as a starting point:
The Go Mobile project is experimental. Use this at your own risk. While we are working hard to improve it, neither Google nor the Go team can provide end-user support.
This is early work and installing the build system requires Go 1.5. Follow the instructions on golang.org/wiki/Mobile to install the gomobile command, build the basic and the bind example apps.
Contributions to Go are appreciated. See https://golang.org/doc/contribute.html.