-2

My code :

package sort_test

type SortList []interface{}

type SortFunc func(interface{}, interface{}) bool


func Do(list SortList, function SortFunc)

main package

package main

import (
        "sort_test"
)

func main() {

    list := []int{3, 4, 5, 6, 6, 77, 4, 4, 5, 6, 8, 345, 45, 424, 2, 67, 7, 830}

slice := list[:]

sort_test.Do(slice, function)
}

compile error

src/algorithm/algorithm.go:32: cannot use slice (type []int) as type sort_test.SortList in argument to sort_test.Do
src/algorithm/algorithm.go:32: cannot use function (type func(int, int) bool) as type sort_test.SortFunc in argument to sort_test.Do
make: *** [algorithm] Error 2
leeor
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wangzun
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2 Answers2

3

Cannot. Interface is interface.

interface{} is not some kind of "any" type. But, any type implements interface{}. Interface is just a set of methods which should be implemented.

If you want to check whether the interface{} is slice or not, you can write it like this:

import "reflect"

t := reflect.TypeOf(list)
if t.Kind() == reflect.Slice {
    ...
}

I recommend you read this very helpful article: http://blog.golang.org/laws-of-reflection.

Additionally, it will be nice to read the code of sort package: https://golang.org/pkg/sort/. It is an example of golang-way implementation of sorting.

Edit: If you really really want use []interface{} as a parameter, actually you can do it like this:

vs := make([]interface{}, len(list))
for i, e := range list {
    vs[i] = e
}
Do(vs, f)

In fact, []interface{} is not an empty interface. It's a slice type whose elements are interface{}; []int is not []interface{}, but just implements interface{}.

I guess you want to write some kind of a general sorting method, like you write it by using generics in Java. I think it is a bad code.

Seonggi Yang
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0

The errors are telling you that you are trying to pass an int array (the slice variable) to the function Do, which is expecting it's first argument as type SortList.

Also, your interface definition does not look right. You have array syntax in there. It should look like this:

type SortList interface{}

I suggest you take a look at the gobyexample page on interfaces.

leeor
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