Why Can\'t I Directly Assign a Go Struct Array to an Interface Array?

Why Assigning Struct Array to Interface Array Fails in Golang

Despite its flexibility and ease of use, the Go programming language poses a particular challenge when attempting to assign a struct array to an interface array. This inconsistency arises due to fundamental differences in the way structs and interfaces are stored in memory.

Understanding Interface Representation

An interface{} is a special type in Go that can represent any type in the language. Internally, it's stored as a two-word pair: one word contains type information, and the other references the actual value. This representation allows interface{} to hold and manipulate values of different types dynamically, making it a powerful and versatile tool.

Struct Memory Layout

Struct types, on the other hand, do not share this representation. Instead, structs are laid out sequentially in memory, with each field occupying its respective position. This direct and contiguous storage optimization ensures efficiency in memory consumption and access speed.

Addressing the Incompatible Representations

When attempting to assign a struct array to an interface array, a compilation error occurs because the two types are inherently different in terms of memory representation. The struct array has a collection of structs stored sequentially, while the interface array is intended to hold references to interface{} values. This fundamental mismatch prevents direct assignment between these two types.

Possible Solutions

To overcome this limitation, it's necessary to manually copy elements from the struct array to the interface array. This can be achieved by iterating through the struct array and assigning each element individually to the corresponding index in the interface array.

Alternatively, it's possible to declare a slice of interfaces that contains []MyStruct as its underlying type, or utilize an interface{} variable to hold the entire struct array. However, direct assignment of struct arrays to interface arrays remains an unsupported operation.

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