89b8360218
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>
89 lines
3.0 KiB
Objective-C
89 lines
3.0 KiB
Objective-C
// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#ifndef __GO_SEQ_HDR__
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#define __GO_SEQ_HDR__
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#include <Foundation/Foundation.h>
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#include "GoUniverse.h"
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#ifdef DEBUG
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#define LOG_DEBUG(...) NSLog(__VA_ARGS__);
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#else
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#define LOG_DEBUG(...) ;
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#endif
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#define LOG_INFO(...) NSLog(__VA_ARGS__);
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#define LOG_FATAL(...) \
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{ \
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NSLog(__VA_ARGS__); \
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@throw \
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[NSException exceptionWithName:NSInternalInconsistencyException \
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reason:[NSString stringWithFormat:__VA_ARGS__] \
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userInfo:NULL]; \
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}
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// GoSeqRef is an object tagged with an integer for passing back and
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// forth across the language boundary. A GoSeqRef may represent either
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// an instance of a Go object, or an Objective-C object passed to Go.
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// The explicit allocation of a GoSeqRef is used to pin a Go object
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// when it is passed to Objective-C. The Go seq package maintains a
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// reference to the Go object in a map keyed by the refnum. When the
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// GoSeqRef is deallocated, the Go seq package will clear the
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// corresponding entry in the map.
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// TODO(hyangah): update the doc as golang.org/issue/10933 is fixed.
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@interface GoSeqRef : NSObject {
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}
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@property(readonly) int32_t refnum;
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@property(strong) id obj; // NULL when representing a Go object.
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// new GoSeqRef object to proxy a Go object. The refnum must be
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// provided from Go side.
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- (instancetype)initWithRefnum:(int32_t)refnum obj:(id)obj;
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- (int32_t)incNum;
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@end
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@protocol goSeqRefInterface
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-(GoSeqRef*) _ref;
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@end
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// Platform specific types
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typedef struct nstring {
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void *ptr;
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int len;
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} nstring;
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typedef struct nbyteslice {
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void *ptr;
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int len;
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} nbyteslice;
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typedef int nint;
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extern void init_seq();
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// go_seq_dec_ref decrements the reference count for the
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// specified refnum. It is called from Go from a finalizer.
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extern void go_seq_dec_ref(int32_t refnum);
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// go_seq_inc_ref increments the reference count for the
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// specified refnum. It is called from Go just before converting
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// a proxy to its refnum.
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extern void go_seq_inc_ref(int32_t refnum);
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extern int32_t go_seq_to_refnum(id obj);
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// go_seq_go_to_refnum is a special case of go_seq_to_refnum
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extern int32_t go_seq_go_to_refnum(GoSeqRef *ref);
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extern GoSeqRef *go_seq_from_refnum(int32_t refnum);
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// go_seq_objc_from_refnum is a special case of go_seq_from_refnum for
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// Objective-C objects that implement a Go interface.
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extern id go_seq_objc_from_refnum(int32_t refnum);
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extern nbyteslice go_seq_from_objc_bytearray(NSData *data, int copy);
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extern nstring go_seq_from_objc_string(NSString *s);
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extern NSData *go_seq_to_objc_bytearray(nbyteslice, int copy);
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extern NSString *go_seq_to_objc_string(nstring str);
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#endif // __GO_SEQ_HDR__
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