是否将字段导出到匿名结构中有什么不同？

Question

Does exporting (or not exporting) a field in an anonymous struct in golang make any difference? In other words are the following two blocks of code different from each other in any way? Considering it's an anonymous struct, you can't use the struct outside the variable itself so I would assume the capital F doesn't make a difference when compiling (no compilation speed or run time memory differences).

Block 1:

var test = struct {
   FieldOne string
   FieldTwo string
} {
   FieldOne: "some string",
   FieldTwo: "some other string",
}

Block 2:

var test = struct {
   fieldOne string
   fieldTwo string
} {
   fieldOne: "some string",
   fieldTwo: "some other string",
}

Answer 1

Sure does, due to reflection. Try calling json.Marshal(test) after each of your declarations. In the first case, you will get {"FieldOne":"some string","FieldTwo":"some other string"}, but in the second case you will get {}. That's because the JSON marshaler only "sees" exported struct fields. More generally, even though the type of test doesn't have a name, doesn't mean that the type itself is inaccessible; it is accessible to anything with reflection.