英文:
I think I'm misunderstanding Go polymorphism/interfaces/structs
问题
我不明白为什么以下代码无法编译。
我对Go语言为什么说HistoryReader没有正确实现IReader感到困惑。HistoryBook实现了IBook。为什么在尝试将HistoryReader添加到IReader切片时，Read(book IBook)和Read(book HistoryBook)不能一起使用？
package main
type IReader interface {
Read(book IBook)
}
// HistoryReader implements IReader
type HistoryReader struct{}
func (r *HistoryReader) Read(book HistoryBook) {
// ...
}
type IBook interface{}
// HistoryBook implements IBook
type HistoryBook struct{}
func main() {
var readerSlice []IReader
_ = append(readerSlice, &HistoryReader{})
}
./main.go:28:26: cannot use &HistoryReader{} (value of type *HistoryReader) as type ReaderInterface in argument to append:
*HistoryReader does not implement ReaderInterface (wrong type for Read method)
have Read(book HistoryBook)
want Read(book BookInterface)
英文:
I don't understand why the following code does not compile.
I am confused why Go is saying HistoryReader does not correctly implement IReader. HistoryBook implements IBook. Why are Read(book Ibook) and Read(book HistoryBook) not acceptable together when trying to add a HistoryReader to a slice of IReaders?
package main
type IReader interface {
Read(book IBook)
}
// HistoryReader implements IReader
type HistoryReader struct{}
func (r *HistoryReader) Read(book HistoryBook) {
// ...
}
type IBook interface{}
// HistoryBook implements IBook
type HistoryBook struct{}
func main() {
var readerSlice []IReader
_ = append(readerSlice, &HistoryReader{})
}
./main.go:28:26: cannot use &HistoryReader{} (value of type *HistoryReader) as type ReaderInterface in argument to append:
*HistoryReader does not implement ReaderInterface (wrong type for Read method)
have Read(book HistoryBook)
want Read(book BookInterface)
答案1
得分: 6
IReader要求Read接受任何IBook。
但是HistoryReader.Read只接受一个HistoryBook，而不是任何IBook。因此，HistoryReader不满足IReader的要求。
英文:
IReader requires that Read takes any IBook.
But HistoryReader.Read only accepts a HistoryBook, not any IBook. Therefore, HistoryReader does not satisfy IReader.
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