go 언어의 selector

For a primary expression  x  that is not a package name, the selector expression

x.f

denotes the field or method  f  of the value  x  (or sometimes  *x ; see below). The identifier  f  is called the (field or method) selector; it must not be the blank identifier. The type of the selector expression is the type of  f . If  x  is a package name, see the section on qualified identifiers.
A selector  f  may denote a field or method  f  of a type  T , or it may refer to a field or method  f  of a nested anonymous field of  T . The number of anonymous fields traversed to reach f  is called its depth in  T . The depth of a field or method  f  declared in  T  is zero. The depth of a field or method  f  declared in an anonymous field  A  in  T  is the depth of  f  in  A  plus one.
The following rules apply to selectors:

For a value  x  of type  T  or  *T  where  T  is not an interface type,  x.f  denotes the field or method at the shallowest depth in  T  where there is such an  f . If there is not exactly one  f with shallowest depth, the selector expression is illegal.

For a variable  x  of type  I  where  I  is an interface type,  x.f  denotes the actual method with name  f  of the value assigned to  x . If there is no method with name  f  in the method set of  I , the selector expression is illegal.

In all other cases,  x.f  is illegal.

If  x  is of pointer type and has the value  nil  and  x.f  denotes a struct field, assigning to or evaluating  x.f  causes a run-time panic.

If  x  is of interface type and has the value  nil , calling or evaluating the method  x.f  causes a run-time panic.

Selectors automatically dereference pointers to structs. If  x  is a pointer to a struct,  x.y  is shorthand for  (*x).y ; if the field  y  is also a pointer to a struct,  x.y.z  is shorthand for  (*(*x).y).z , and so on. If  x  contains an anonymous field of type  *A , where  A  is also a struct type,  x.f  is shorthand for  (*x.A).f .
원문 http://golang.org/ref/spec#Selectors
 
다음으로 전송:https://www.cnblogs.com/fishincat/p/4116372.html