July 11, 2013

Go+

Compared to other languages go has some strange behavior regarding its project root settings. If you import a library called somelib, go will look for a src/somelib folder in all of the folders in the $GOPATH environment variable. This works nicely for globally installed packages, but it makes encapsulating a project with a specific version, or modified version, rather tedious. Whenever you go to work on this project you'll have to add its path to your $GOPATH, or add the path permanently, which could break other projects which may use a different version of somelib.

My solution is in the form of a simple script I'm calling go+. go+ will search in currrent directory and all of its parents for a file called GOPROJROOT. If it finds that file in a directory, it prepends that directory's absolute path to your $GOPATH and stops the search. Regardless of whether or not GOPROJROOT was found go+ will passthrough all arguments to the actual go call. The modification to $GOPATH will only last the duration of the call.

As an example, consider the following: /tmp /hello GOPROJROOT /src /somelib/somelib.go /hello.go

If hello.go depends on somelib, as long as you run go+ from /tmp/hello or one of its children your project will still compile

Here is the source code for go+:

#!/bin/sh

SEARCHING_FOR=GOPROJROOT
ORIG_DIR=$(pwd)

STOPSEARCH=0
SEARCH_DIR=$ORIG_DIR
while [ $STOPSEARCH = 0 ]; do

    RES=$( find $SEARCH_DIR -maxdepth 1 -type f -name $SEARCHING_FOR | \
           grep -P "$SEARCHING_FOR$" | \
           head -n1 )

    if [ "$RES" = "" ]; then
        if [ "$SEARCH_DIR" = "/" ]; then
            STOPSEARCH=1
        fi
        cd ..
        SEARCH_DIR=$(pwd)
    else
        export GOPATH=$SEARCH_DIR:$GOPATH
        STOPSEARCH=1
    fi
done

cd "$ORIG_DIR"
exec go $@

UPDATE: Goat

I'm leaving this post for posterity, but go+ has some serious flaws in it. For one, it doesn't allow for specifying the version of a dependency you want to use. To this end, I wrote goat which does all the things go+ does, plus real dependency management, PLUS it is built in a way that if you've been following go's best-practices for code organization you shouldn't have to change any of your existing code AT ALL. It's cool, check it out.