Change Go comments from /* */ to //

It was quite late after I started learning Go that you should not really use /* */ comments but almost always use //, so I had a lot of files which use the "traditional C" style comments.

This Perl script reads in all files ending in .go in the current directory, and converts traditional C style comments before functions and methods into the C++ style comments which are the standard in Go.

It relies on three CPAN modules, File::Slurper to read and write the files, C::Tokenize for the regular expressions for comments, and File::Versions to make a backup of the old file, which it does using an Emacs-style numbered backup. This script by default just overwrites the files. I haven't had any catastrophes using it so far, but you use this at your own risk.

#!/usr/bin/env perl

# Change go comments from /* to // form.

use warnings;
use strict;
use File::Slurper qw/read_text write_text/;
use C::Tokenize ':all';
use File::Versions ':all';
my @files = <*.go>;
for my $file (@files) {
    my $text = read_text ($file);
    while ($text =~ m!(($trad_comment_re)\s*func\s+((?:\(\s*\w+\s*\*?\s*\w+\s*\))?\s*(?:[a-zA-Z]\S+)))!g) {
        my $a = $1;
        my $c = $2;
        my $f = $3;
        $c = decomment ($c);
        $c =~ s!^\s*!// !gms;
        $text =~ s!\Q$a\E!$c\nfunc $f!g;
    }
    make_backup ($file);
    write_text ($file, $text);
}

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