将结构变量/名称添加到：=的左侧

How to shorten this code

access_log, err := os.OpenFile("log/access.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0660);
w.access_log = access_log

To something like this

w.access_log, err := os.OpenFile("log/access.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0660);

You need to assign (=), not declare (:=):

var error
w.access_log, err = os.OpenFile("log/access.log", os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0660);

:= is for Short Variable declaration, and w.access_log is already declared (in w struct)

It is discussed in issue 6842.