Why Are Methods on `T` Not Usable by `*T` in Go?

Why Go Discriminates Method Sets on T and *T

In Go, methods defined on a type T can be used by both T and T, while methods on T cannot be used by T. This raises the question of why this asymmetry exists.

Lack of Static Memory Addresses for T

Taking the address of a T value using the '&' operator is not always possible in Go. This is due to optimizations that can relocate the memory address of the value dynamically. For example, values stored in maps or returned from functions may not have a fixed address.

Guaranteed Access for *T

In contrast, dereferencing a pointer to a T value (T) always returns a T value with a known memory address. This allows methods defined on T to access and modify the actual data associated with the T value.

Asymmetry in Pointer Conversions

While it's possible to convert a T to T by dereferencing, it's not always feasible to convert T to T by taking an address. This asymmetry arises from the need to guarantee that method calls on *T will always have valid memory addresses to access the data.

Consequences

This design has both advantages and disadvantages:

Advantages:

• Enhances performance: Dynamic memory relocation allows for more efficient memory management.
• Simplifies code: Developers need not worry about memory addresses when using methods on *T.

Disadvantages:

• Limits code reusability: Methods on T cannot be directly used by *T, requiring duplication of code.
• Potential for errors: Developers must be aware of the distinction between methods on T and *T to avoid using methods that require pointer receivers.

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