How can you compare functions in Go if standard comparison operators don\'t work?

Comparing Functions in Go

In Go, comparing two function values using standard comparison operators is not feasible. However, there are alternative methods for checking if functions are equivalent.

Using Function Addresses

Function values themselves are not comparable. Instead, you can compare the addresses of the function values to determine if they refer to the same function. To obtain the function's address, you can use the fmt package's Sprintf("%v") function:

<code class="go">hand := &Handler{Undefined, Defined}
p1 := fmt.Sprintf("%v", Undefined)
p2 := fmt.Sprintf("%v", hand.Get)

if p1 == p2 {
    // Undefined and hand.Get refer to the same function.
}</code>

Using reflect.Value

Another approach is to use the reflect.Value type to obtain the underlying function pointer. This is precisely what the fmt package does internally:

<code class="go">value := reflect.ValueOf(Undefined)
ptr := value.Pointer()</code>

You can then compare the ptr values to determine if the functions are equal.

Caution

However, it's important to note that comparing function addresses is not a reliable method for all scenarios. Function closures and dynamically generated functions can have different addresses even if they perform the same task.

Therefore, it's generally recommended to avoid comparing function addresses and instead consider alternative approaches for comparing function behavior, such as testing their input and output values.

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