How to pass generic type of array as the parameter for the function in Golang

Question

I'm new to Golang, My question is how to make function accept generic type of parameter. Here is the specific problem I met recently:

I defined a struct which contains a function

type TestArgs struct {
    name string
    ...
    customAssertForTypeA func(array []*pb.TypeA)
    customAssertForTypeB func(array []*pb.TypeB)
}

// Define the test case with TestArgs.
tests := []TestArgs{
        {
            name: "Test A",
            customAssertForTypeA: func(array []*pb.TypeA) {
                // Some code
            }
        },
        {
            name: "Test B",
            customAssertForTypeB: func(array []*pb.TypeB) {
                // Some code
            }
        },
}

My question is how to make customerAssert function accept generic type of parameter? I saw some similar question with solution interface{}, so I tried

customAssert func(array interface{})

and it doesn't work.

blackgreen · Accepted Answer · 2021-08-10 07:06:01Z

3

Type assertions ( https://tour.golang.org/methods/15 ) is what you need when you have an interface{} and want to access to the concrete value:

type TestArgs struct {
    name         string
    customAssert func(interface{})
}

// Define the test case with TestArgs.
tests := []TestArgs{
    {
        name: "Test A",
        customAssert: func(param interface{}) {
            // Some code
            array, ok := param.([]*pb.TypeA)
            if !ok {
                t.Fatal("assertion error TypeA")
            }
            // use array
        },
    },
    {
        name: "Test B",
        customAssert: func(param interface{}) {
            // Some code
            array, ok := param.([]*pb.TypeB)
            if !ok {
                t.Fatal("assertion error TypeB")
            }
            // use array
        },
    },
}

edited Aug 10, 2021 at 7:06

blackgreen♦

46.8k29 gold badges171 silver badges162 bronze badges

answered Aug 9, 2021 at 23:05

wakumaku

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