Thursday, June 25, 2015

Go for Minor Utilities

I continue to play around with Google’s Go language, and I continue to have very mixed feelings about it.

It’s clearly not built for You and Me, i.e. for the programmers of the world; rather it’s built for Google and shared with us. This is fine as far as it goes, but as with so many other Google products the joy of the user is mostly “out of scope.”

Also, presumably because the whole Go ecosystem is so young, there are all kinds of quirky things being done in the many, many, many third-party packages scattered around the Githubbernets. I may write more later about the Goverse’s tendency towards Database Worst Practices and its shunning of the Null. (Ironic for a language in which every thirteenth line is a nil check.)

So far, I’m pretty sure I would not use Go for any big, complex, long-term project. But it’s good enough at some things that I’d definitely consider it for any straightforward, easy-to-run subcomponents of a big project. I wouldn’t choose Go for code shared with a bunch of other developers, but if I were dropped into such a project I’d probably do just fine. I might use Go if I planned on bringing in outside help, because as others have pointed out, one of the Google use-cases it seems optimized for is bringing inexperienced programmers into a project.

But there is one thing for which I absolutely love Go, and for which I could picture myself using it for a long time to come: Go is really great for writing simple utility programs.

Tonight I found myself needing some random-ish strings for a goofy little side-project I’m doing. After not finding quite what I wanted at the otherwise wonderful, I took an hour to throw together a little utility. It will probably only ever be utilitous to me, and I may or may not bother cleaning it up and testing it, but now at least it exists:

And that means I can, should I need to on some other computer, simply do this:

$ go get
$ which randstr
$ randstr --help

…assuming my $GOPATH is in order, and subject to dependencies I have not yet “vendored in,” and so on.

There are, I think, four things that make it especially attractive to write such programs in Go:

  1. It compiles, quickly no less, into a single binary.
  2. It’s reasonably cross-platform.
  3. The standard library, while sometimes bizarre, is very rich.
  4. Docopt!

The Joy of DocOpt

Command-line utilities, and Unix-like programs in general, usually take options and other arguments, and they usually have some rudimentary help text explaining these things.

DocOpt parses a structured, but very human-readable, help text in order to determine what the available options are. It’s not perfect but it more than covers the reasonable use-cases of most utilities I’ll ever need to write.

For any nerds who have not yet heard of DocOpt, here is the canonical example:

Naval Fate.

  naval_fate ship new <name>...
  naval_fate ship <name> move <x> <y> [--speed=<kn>]
  naval_fate ship shoot <x> <y>
  naval_fate mine (set|remove) <x> <y> [--moored|--drifting]
  naval_fate -h | --help
  naval_fate --version

  -h --help     Show this screen.
  --version     Show version.
  --speed=<kn>  Speed in knots [default: 10].
  --moored      Moored (anchored) mine.
  --drifting    Drifting mine.

There are many implementations of DocOpt, but the one I have been using with Go is the excellent docopt-go by Keith Batten et al.

I do still love the completeness and flexibility of Perl’s Getopt::Long, and I’ve not found anything similar for Go; but now that I’ve gotten used to DocOpt I would think twice before committing to anything more complicated.

With DocOpt in your toolkit, Go is an awesome language for writing quick little utilities. Whatever else it may be, and whatever it may lack, this is reason enough to know some Go.