Can Go Create Methods with Receivers Dynamically at Runtime?

Creating Functions with Receivers Dynamically in Go

In Go, a method is a function with a receiver, which represents the object on which the method is being called. The question arises as to whether it's possible to create a method at runtime.

Reflect Package

The reflect package provides facilities for manipulating types and values in Go. It offers the MakeFunc function, which allows dynamic function creation. However, MakeFunc cannot create functions with receivers.

Limitations of Runtime Method Creation

The answer is, unfortunately, no. This limitation stems from the way Go manages method sets. If methods could be created dynamically, the type's method set would change at runtime, conflicting with Go's compile-time type checking. Furthermore, runtime interface-implementation checks would be required for every function call involving interface arguments.

Alternative Approach: Forking the 'reflect' Package

In theory, one could fork the reflect package to create a value representing a method attached to any type. However, this would circumvent Go's type system and would not inherently alter the type's method set.

Swapping Method Pointers on an Object

Unlike certain other languages, Go does not embed virtual method dispatch tables in concrete values (only in interface values). However, it's possible to access and modify the itable field of a reflect.nonEmptyInterface, allowing for the swapping of method pointers on an object.

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