具有方法/功能的Golang逗号[关闭]

Question

Why are we allowed to put a comma at the end of a receiver in the method declaration, or in the parameter lists or the return lists. Like so:

func (ds *dasa,) yoooooolo (dsa dasa,) (dsaa dasa,) 

Why is this allowed? All those commas at the end?

Answer 1

Golang allows trailing commas after many declarations.

This was likely an explicit design choice by the designers of the language to be more permissive of irrelevant syntax errors; however, only they can explain their motivations.

func (f *Foo,) Bar(x, y int,) (int, error,) { //...
f.Bar(1, 2, 3,)
xs := []int{1, 2, 3,}

In fact, in some multiline literal declarations it requires trailing commas (presumably to simplify reordering of elements):

ys := []int{
  1,
  2, // <-- required comma.
}
m := map[string]int{
  "foo": 1,
  "bar": 2, // <-- required comma.
}

Note that the go fmt command automatically removes extraneous, optional trailing commas. You should always run that tool before building your code.