[go-nuts] why go run can not check pkg cache just like go install?

Build and run don't do that by design. Run shouldn't modify anything in
your workspace. Build should only produce the executable you asked for. If
you want the benefits of go install, I'd say you should use go install. Are
there any reasons why you aren't?

I got your point.
The reason is that go install can not build a single golang file,and go
install can not run the compiled files.

So I can write my own version of go run to get better performance.
I can put my single golang file in to a temporary package,and go install
that package,and run the compiled files.

Of course, building a single file is what go run is good at. But usually
thoses files are not the ones taking multiple seconds build times. If you
have a project I assume you have split this project in multiples files,
with packages and all. The fact that go install doesn't run the binary is a
simple matter of "go install && $GOPATH/bin/mybinary" on Linux, "go install
&& %GOPATH/bin/mybin.exe" on Windows etc.

As I understand, you are using the single file for testing a non main
package? I would suggest the use of the test facilities of go so you get
reuseable tests after that. That would remove the need for go run.
See http://golang.org/doc/code.html#Testing
and http://golang.org/pkg/testing/ for more details on that.

Thanks for your reply.

I have a enter point of my project which is a main file import 10+ packages
with 20+ subcommand.The whole project should have 100+ packages which is in
GOPATH.One package have 2MB ip location data in source file which need
compile 1s~.

When I edited something to print something to debug and restart my server ,
it takes 7s~ to compile that enter point file on my one core vps, and that
is my problem.

I think a single enter point of the project simplify many things.

I'm sorry, at that point I do not understand what prevents you from using
go install? After your change you can simply do the "go install" and
restart the process, which will now use the new binary. Only the changed
code and the main package will be compiled. I'm having trouble seeing what
go run is doing there that go install wouldn't?

Thanks for your advice.
I will write a new command line tool that replace go run.

If you really want to keep using `go run`, for whatever reason, at least
`go install` the libraries/packages. If you run `go run -v yourfile.go` it
will show you which packages it compiled. Make sure you've `go install`-ed
those.

Thanks for your advices.
I am using `kmg gorun` to work around setting GOPATH problem.
I just need to add some code to kmg. It should be easy.

Try adding the -x flag when you run go run/build/install to see commands are being run.

At least on my machine, the first time I run 'go install -x .' it shows all the libraries that are not fresh being recompiled and cached in the $GOPATH/pkg directory. Later when changing just the main func and re-running with 'go run -x main.go' (or build) only the main package is recompiled, all other libraries have their cached version used. If you change a library you import go build/run will always recompile it but not cache it. As others have said, use go install to get the caching functionality.