Hi,
I am still quite inexperienced in go programming, and I find it quite
frustrating, sometimes, to find what will actually be executed by a call to
an interface method found in some arbitrary code.
Here I have traced the process of finding the definition of "conn.Close()"
an instance of an interface method call. This is what I would like to have
automatized by godef, for instance.
Is there anything like that out there that does it with one command / key
stroke, etc, automagically ?
Godef and go-guru does not, as far as I know.
BR,
David
Here follows some anonymized code:
(please forgive me if I've made some errors, I hope you get the idea anyway)
In the file file1.go:1234 in the library lib1, I found a call:
: _ = conn.Close()
How do i figure out what happens when this line is executed?
Here is a list of steps to find it "mechanically", so to say:
1. file1.go:1234
: func returnConn(conn lib2.Conn) {
: _ = conn.Close()
: }
Using godef-jump on the Close() will just give me the interface
declaration. I can use go-guru-implements, and get a list of
possible implementations of Close, but how do I know which one will
actually be used? So, let's figure out the actual type of conn.
I use go-guru-referrers on returnConn, and choose one of the hits,
which is file1.go:206
2. file1.go:206
: func (r *Record) Release(foo bar.T1) error {
: ...
: var conn lib2.Conn
: if conn, err = r.foo.getConn(baz); err != nil {
: return err
: }
: defer returnConn(conn)
conn gets its value from getConn, so I end up in file1.go:1074
3. file1.go:1074
: func (foo *FOO) getConn(mu T2) (lib2.Conn, error) {
: ...
: conn := foo.connBax.Get()
: ...
: return conn, nil
conn gets its value from Get(), so I go to file3.go:178
4. file3.go:178
: func (p *Bax) Get() Conn {
: ...
: return &xooConn{x: p, xc: xc}
I find the return value and go to its definition in file3.go:371
5. file3.go:371
: type xooConn struct {
: x *Bax
: xc *baxConn
: s T3
: }
Aaah! This is the type of conn at file1.go:1234!
6. file1.go:1234
: _ = conn.Close()
Now I can follow the "definition" of Close() using godef-jump, and
end up in file1.go:30:
7. file1.go:30
: type Conn interface {
: Close() error
I use go-guru-implements to see a list of possible implementations:
: PATH1/lib2/dir1/file1.go:30.2-30.6: abstract method func
(ConnWithTimeout).Close() error
: PATH1/lib2/dir1/file3.go:394.23-394.27: is implemented by method
(*xooConn).Close
: PATH1/lib2/dir1/conn.go:304.16-304.20: is implemented by method
(*conn).Close
: PATH1/lib2/dir1/boo.go:12.3-45.6: is implemented by method
(*booingConn).Close
: PATH1/lib2/dir1/file3.go:510.21-510.25: is implemented by method
(errorConn).Close
: PATH1/lib2/dir1/file1.go:30.2-30.6: implements method (Conn).Close
: PATH2/bah.go:78.9-101.2: implements method (bah.Closer).Close
Now, since I know the type is *xooConn, I can jump to the right hit,
and go to file3.go:394.
8. file3.go:394
: func (ac *xooConn) Close() error {
: pc := ac.pc
: ...
: return nil
Yes, here it is, at step 8!!!!
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