Jan 21, 2019

Giving Go another chance: command line arguments

To make a usable command line tool one has to parse the arguments first. I shopped around for a command line parsing library and found cli and cobra. I tried cli briefly and then switched to cobra. You gotta go with the stars, Github stars. Cobra’s got more of them.

Cobra comes with a cogeden tool which is nice, I guess. Since I’m still shaky with even basic Go concepts, I decided to run and not type up everything from scratch.

$ ~/go/bin/cobra init klk
Your Cobra application is ready at
/Users/detunized/go/src/klk

Why? I ran it in a different folder. And then I have a flashback and I realize why I had that bitter taste in my mouth the last time I used go. It’s the $GOPATH thing. No other language I know does anything like it. Apparently I cannot have my code where I want it. It has to be where Rob Pike wants it. Okay, I thought to myself, I can just copy the generated files to where I want them and I’m done. And I did.

Cobra provides a way to add a new command with the codegen tool like this:

$ ~/go/bin/cobra add in
in created at /Users/detunized/go/src/klk/cmd/in.go

This adds the subcommand called in. To be used like this: klk in. So far so good. I copied the newly created file to my repo and kept poking around, editing, running, see what my changes do. And then I had a first WTF moment. I change some files, but Go doesn’t pick up the changes and it seems like it runs the old executable. I spent lots of time trying to figure out why the build silently fails and I don’t see any error messages. And then it hit me: it keeps building some of the files from the $GOPATH and some from my project folder. So copying files from the default place to an external folder is not really an option.

Mmkay. But I still wanted my files in my project folder. Let’s see if symlinking my folder into $GOPATH/src would trick the compiler:

$ ln -s `pwd` /Users/detunized/go/src/klk

So far it’s working and I’m able to use cobra tool and the compiler is happy. But let’s finally get to coding next time. This time it didn’t happen.

Google searches that went into getting this to work:

  • go cli
  • go cli parser
  • go cli vs cobra
  • cobra Error: Rel: can’t make relative to
  • gopath
  • gopath vs goroot
  • go package init
  • go build without gopath
  • no gopath
  • vgo
  • Time spent: 2 hours
  • Total time spent: 5 hours