Idea: use go run in generate line

[zombiezen]

An idea suggested by @steebchen is to use //go:generate go run github.com/google/wire/cmd/wire as the automatically inserted generate line for Wire output. This would have the advantage of always using a version of the code generator that's the same as the library being used, at the cost of perhaps some running time.

EDIT (Hit send too early) I don't think we want to make this change until Go Modules is the default, thus I'm marking this issue blocked.

[ernado]

This probably should be blocked until golang/go#33468 is resolved.

Also, we can detect case when binary is started with go run, so there will be no backward compatibility issues at all. That is, if wired binary was started via go run we emit go:generate go run github.com/google/wire/cmd/wire, otherwise we fallback to current go:generate wired.

[steebchen]

Go modules is pretty much the default now, so that part should not be blocking anymore.

[steebchen]

I want to raise this again – go modules is the way to go by now.

[zombiezen]

With Go 1.16 having GO111MODULE=on by default, I agree. Happy to accept a PR to fix.

[steebchen]

Sounds good, I created #268

[odsod]

@zombiezen This is something we've been looking for too, to simplify our go generate invocations (we currently pre-build the correct version of the wire CLI and add it to $PATH before invoking go generate.

When this gets merged to master, we'd be happy to test this out and provide feedback before the next stable release.

[ernado]

Note that go run will be slower that direct call of wire because go run does not cache linked binary.

Also just simply changing from wire to go run can break some users, I've implemented backward compatible version in #239

[steebchen]

Note that go run will be slower that direct call of wire because go run does not cache linked binary.

That's negligible:

❯ time go run github.com/google/wire/cmd/wire
wire: api: wrote /Users/luca/projects/ws-api/wire_gen.go
go run github.com/google/wire/cmd/wire  5.27s user 1.60s system 274% cpu 2.503 total

❯ time wire
wire: api: wrote /Users/luca/projects/ws-api/wire_gen.go
wire  5.26s user 1.05s system 236% cpu 2.673 total

Also just simply changing from wire to go run can break some users, I've implemented backward compatible version in #239

Good point. However, I think either way the new default should be to use go generate, so that new users can make immediate use of it. Users who explicitly want the old behaviour should not upgrade, or set the option explicitly should they update.