After reading a related question about using slices in maps, I became curious about equality in Go.
I know it's possible to override the equals method of a Java Object. Is there a similar way to define how Go checks user defined types/structs for equality? If so, there would be a workaround for the issue referenced above. I thought using interface{} values might offer a solution but I received the error message panic: runtime error: hash of unhashable type []int.
分享 Go supports equality checking structs.
type Person struct {
Name string
}
a := Person{"Bill DeRose"}
b := Person{"Bill DeRose"}
a == b // true
It won't work with pointer fields (in the way you want) because the pointer addresses are different.
type Person struct {
Friend *Person
}
a := Person{Friend: &Person{}}
b := Person{Friend: &Person{}}
a == b // false
You can't modify the equality operator and there is no built-in way to add support for custom types to use == syntax. Instead you should compare the pointer values using reflect.DeepEqual.
import "reflect"
a := Person{Friend: &Person{}}
b := Person{Friend: &Person{}}
reflect.DeepEqual(a, b) // true
Keep in mind there are caveats.
In general DeepEqual is a recursive relaxation of Go's == operator. However, this idea is impossible to implement without some inconsistency. Specifically, it is possible for a value to be unequal to itself, either because it is of func type (uncomparable in general) or because it is a floating-point NaN value (not equal to itself in floating-point comparison), or because it is an array, struct, or interface containing such a value.
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