Can You Compare Functions in Go?

Comparing Functions in Go

In Go, function values are not comparable. However, it's possible to compare the addresses of function values, which can be useful in certain scenarios.

Limitations of Function Value Comparison

As per the Go specification, "Function values are not comparable." This means that you can't directly compare two function values using comparison operators such as == or !=.

Comparing Function Value Addresses

To compare function value addresses, you can use the fmt.Sprintf() function to obtain the function address. The p1 and p2 variables in the code below contain the addresses of the Undefined and hand.Get functions, respectively.

<code class="go">p1 := fmt.Sprintf("%v", Undefined)
p2 := fmt.Sprintf("%v", hand.Get)</code>

You can then use the == operator to compare the function value addresses:

<code class="go">fmt.Println("Expecting true:", p1 == p2)</code>

Address Comparisons vs. Refactoring

While it's technically possible to compare function value addresses, it's generally not a good practice. Function values can change over the lifetime of a program, which can make address comparisons unreliable.

Instead of comparing function value addresses, it's better to refactor your code to avoid the need for such comparisons. For example, you could create a map of function values and compare the keys to determine which function is being used.

Alternative Method Using Reflection

Another option for comparing function values is to use reflection. The reflect.Value.Pointer() method allows you to obtain the address of a function value. However, this approach is also not recommended as it's more complex and error-prone than the address comparison technique described above.

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