2db4579b6f
The long-form (with comma-ok) ones were already fixed but the short-form ones were not because they were in a completely different code path. This PR also refactors the code so that both short-form and long-form are now merged in the same function. N.B: even though most (all?) cases seem to now be supported, one of them still yields a result that does not satisfy reflect's Implements method yet. It does not prevent the resulting assertion to be usable though. N.B2: the code path for the third-form (_, ok) hasn't been fixed and/or refactored yet. Fixes #919
97 lines
1.8 KiB
Go
97 lines
1.8 KiB
Go
package main
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import (
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"fmt"
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"reflect"
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"time"
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)
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type MyWriter interface {
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Write(p []byte) (i int, err error)
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}
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type TestStruct struct{}
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func (t TestStruct) Write(p []byte) (n int, err error) {
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return len(p), nil
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}
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func usesWriter(w MyWriter) {
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n, _ := w.Write([]byte("hello world"))
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fmt.Println(n)
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}
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type MyStringer interface {
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String() string
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}
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func usesStringer(s MyStringer) {
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fmt.Println(s.String())
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}
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func main() {
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aType := reflect.TypeOf((*MyWriter)(nil)).Elem()
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var t interface{}
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t = TestStruct{}
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var tw MyWriter
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var ok bool
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tw, ok = t.(MyWriter)
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if !ok {
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fmt.Println("TestStruct does not implement MyWriter")
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} else {
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fmt.Println("TestStruct implements MyWriter")
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usesWriter(tw)
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}
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n, _ := t.(MyWriter).Write([]byte("hello world"))
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fmt.Println(n)
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bType := reflect.TypeOf(TestStruct{})
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fmt.Println(bType.Implements(aType))
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t = 42
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foo, ok := t.(MyWriter)
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if !ok {
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fmt.Println("42 does not implement MyWriter")
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} else {
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fmt.Println("42 implements MyWriter")
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}
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_ = foo
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var tt interface{}
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tt = time.Nanosecond
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var myD MyStringer
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myD, ok = tt.(MyStringer)
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if !ok {
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fmt.Println("time.Nanosecond does not implement MyStringer")
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} else {
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fmt.Println("time.Nanosecond implements MyStringer")
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usesStringer(myD)
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}
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fmt.Println(tt.(MyStringer).String())
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cType := reflect.TypeOf((*MyStringer)(nil)).Elem()
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dType := reflect.TypeOf(time.Nanosecond)
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fmt.Println(dType.Implements(cType))
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tt = 42
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bar, ok := tt.(MyStringer)
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if !ok {
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fmt.Println("42 does not implement MyStringer")
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} else {
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fmt.Println("42 implements MyStringer")
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}
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_ = bar
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}
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// Output:
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// TestStruct implements MyWriter
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// 11
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// 11
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// true
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// 42 does not implement MyWriter
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// time.Nanosecond implements MyStringer
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// 1ns
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// 1ns
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// true
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// 42 does not implement MyStringer
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