Generics in Go enable type-safe, reusable functions and data structures. Introduced in Go 1.18, they reduce code duplication by allowing functions like func Max[T comparable](a, b T) T to work across multiple types while enforcing constraints. Type parameters in square brackets, such as [T comparable], define the acceptable operations, where comparable ensures support for comparison. Custom constraints using interfaces, like type Number interface { int | float64 | float32 }, restrict types to those supporting specific operations, such as addition in Sum[T Number](a, b T) T. Generic data structures, such as type Stack[T any] struct { items []T }, allow creation of flexible containers that work with any type, enhancing reusability without sacrificing performance or safety.
Generics in Go allow you to write functions and data structures that work with different types while maintaining type safety. Introduced in Go 1.18, they help reduce code duplication when the logic is the same across multiple types.
Define Generic Functions
To create a generic function, use type parameters inside square brackets [ ] before the regular function parameters.
For example, here’s a simple function that returns the larger of two values:
func Max[T comparable](a, b T) T {???if a > b {
??????return a
???}
???return b
}
The T is a type parameter, and comparable is a constraint that ensures T supports comparison operations like >. When calling this function, you can pass in types like int, float64, or string.
Use Type Constraints
Constraints define what operations a type parameter must support. You can use built-in constraints like comparable or any (which allows any type), or define your own using interfaces.
Example with a custom constraint:
type Number interface {???int | float64 | float32
}
func Sum[T Number](a, b T) T {
???return a b
}
This restricts T to only numeric types, ensuring the operation is valid.
Create Generic Data Structures
You can also define generic types, such as containers:
type Stack[T any] struct {???items []T
}
func (s *Stack[T]) Push(item T) {
???s.items = append(s.items, item)
}
func (s *Stack[T]) Pop() (T, bool) {
???if len(s.items) == 0 {
??????var zero T
??????return zero, false
???}
???item := s.items[len(s.items)-1]
???s.items = s.items[:len(s.items)-1]
???return item, true
}
This Stack[T] works with any type, like Stack[int] or Stack[string].
Using generics makes your Go code more reusable and safer without sacrificing performance. Just keep constraints clear and limit complexity to maintain readability.
Basically just add type parameters where needed and specify what those types should support.
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