On Tue, Aug 13, 2019 at 8:10 AM Sathish VJ <sathis...@gmail.com> wrote:
> So doing *type X Y* is just a type declaration then? > > In a certain sense type X Y and type X = Y are both type declarations. They differ in that the first is generative, whereas the other is a synonym. In a generative pattern, you are generating, or minting, a new type X which differs from Y; whereas in the the synonym situation, the types X and Y admits equality at the type level. Historically, Go only had generative types. The second case was added to the language, because of a need to facilitate large scale program rewriting. By aliasing a type, you can point an older implementation to a new one or vice versa, until the work has been completed. This avoids the need of one large patch across several modules, and allows for a more partial approach in which the programmer can split the patch over multiple commits. As a simple example of why you would often prefer types to differ, consider something like type meter int type yard int Clearly, you don't want to admit the interchange of two different distance units (Even worse: Pound-Force to Newton's). This is by far the common case in programming, and they are crucial for producing modular code via encapsulation and isolation. -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/CAGrdgiXCSygqAC%3DyqPY%2But0Hm_MZ49qX2ZJnixuE1%2BLt6aVv-w%40mail.gmail.com.
