why you might use reflect.TypeFor instead of reflect.TypeOf in Go.

Background

In Go, the reflect package provides two similar-looking functions:

• reflect.TypeOf(x)
  Takes a value x and returns its reflect.Type.
  Example:

  t := reflect.TypeOf(123) // type: int

• reflect.TypeFor[T]() (introduced in Go 1.22)
  A generic function that returns the reflect.Type for a type parameter T without needing a value.
  Example:

  t := reflect.TypeFor[int]() // type: int

Why use reflect.TypeFor instead of reflect.TypeOf?

1. No value needed

   • reflect.TypeOf requires an actual value at runtime.
     If you only know the type (not a value), you have to create a dummy value:

     t := reflect.TypeOf((*MyStruct)(nil)).Elem()

   • reflect.TypeFor works directly with the type parameter:

     t := reflect.TypeFor[MyStruct]()

     This is cleaner and avoids allocating or creating dummy values.

2. Compile-time type safety

   • With reflect.TypeOf, the type is determined from a runtime value, so mistakes may only show up at runtime.
   • With reflect.TypeFor, the type is determined at compile time from the generic type parameter, so it’s safer and clearer.

3. Better for generic code

   • In generic functions, you often have a type parameter T but no value of type T.
     reflect.TypeOf can’t be used without creating a zero value:

     func PrintType[T any]() {
         var zero T
         fmt.Println(reflect.TypeOf(zero))
     }

     With reflect.TypeFor, you can simply do:

     func PrintType[T any]() {
         fmt.Println(reflect.TypeFor[T]())
     }

4. Avoids unnecessary allocations

   • Creating a dummy value for reflect.TypeOf may allocate memory (especially for composite types).
   • reflect.TypeFor avoids this overhead entirely.

Summary Table

✅ Recommendation:
Use reflect.TypeFor when:

• You know the type at compile time (especially in generic code).
• You don’t have or don’t want to create a value.
• You want cleaner, safer, and allocation-free code.

Use reflect.TypeOf when:

• You already have a value and want its type at runtime.