## How to Convert a Slice of Interfaces to a Compatible Interface Slice in Go?

Converting Slices of Interfaces to Compatible Interface Slices

Implementing different interfaces that contain overlapping methods can provide flexibility in programming. However, passing a slice of one interface to a function expecting a different but compatible interface can result in errors. Let's explore how to address this issue in Go.

Suppose we have interfaces A and B, where A includes B. An implementation of A, Impl, satisfies both A and B.

<code class="go">type A interface {
    Close() error
    Read(b []byte) (int, error)
}

type Impl struct {}

func (I Impl) Read(b []byte) (int, error) {
    fmt.Println("In read!")
    return 10, nil
}

func (I Impl) Close() error {
    fmt.Println("I am here!")
    return nil
}</code>

Individual items can be passed across functions with ease. However, attempting to pass slices of A to functions expecting io.Reader may fail.

<code class="go">func single(r io.Reader) {
    fmt.Println("in single")
}

func slice(r []io.Reader) {
    fmt.Println("in slice")
}

im := &Impl{}

// works
single(im)

// FAILS!
list := []A{t}
slice(list)</code>

To resolve this, we can create a new slice of type []io.Reader and populate it with elements from []A. This is the workaround to bypass the limitation and ensure compatibility between different but overlapping interface types.

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