I have six chunks of 52 lines of very similar code that I need to isolate all the differences in.

I've been tackling it by eye, and have it mostly working, but there remains some small difference that I'm not seeing; and I'm going bug-eyed for looking.

Anyone any thoughts how to do a six-way diff?

Everything below is update.

I settled for a low tech solution that worked surprisingly well.

First, I put the six chunks of code into separate files. Then I wrote the following simple Perl script that loaded the lines of those files in to an AoAs: all the line 1s in to one array, all line 2s in to another; and so on; and then printed them to standard out:

#! perl -slw
use strict;
use Data::Dump qw[ pp ];

my @lines;

for my $file ( qw[ x1.js x2.js y1.js y2.js z1.js z2.js ] ){
    open FH, '<', $file or die $!;
    push @{ $lines[ $. ] }, $_ while <FH>;
    close FH;
}

for my $l ( @lines ) {
    next unless defined $l;
    print @$l;
}
[download]

What I got after normalising the files and lines -- which was surprisingly quick by referencing the output -- was stuff that looked like this:

E:\Chart>diff6 | more
gg = _GetGrid( this.Min.y / this.Parent.Zoom.y, this.Max.y / this.Pare
+nt.Zoom.y, this.Scale.y );
gg = _GetGrid( this.Min.z / this.Parent.Zoom.z, this.Max.z / this.Pare
+nt.Zoom.z, this.Scale.z );
gg = _GetGrid( this.Min.x / this.Parent.Zoom.x, this.Max.x / this.Pare
+nt.Zoom.x, this.Scale.x );
gg = _GetGrid( this.Min.z / this.Parent.Zoom.z, this.Max.z / this.Pare
+nt.Zoom.z, this.Scale.z );
gg = _GetGrid( this.Min.x / this.Parent.Zoom.x, this.Max.x / this.Pare
+nt.Zoom.x, this.Scale.x );
gg = _GetGrid( this.Min.y / this.Parent.Zoom.y, this.Max.y / this.Pare
+nt.Zoom.y, this.Scale.y );

if( this.GridDelta.y != 0 ) gg[1] = this.GridDelta.y;
if( this.GridDelta.z != 0 ) gg[1] = this.GridDelta.z;
if( this.GridDelta.x != 0 ) gg[1] = this.GridDelta.x;
if( this.GridDelta.z != 0 ) gg[1] = this.GridDelta.z;
if( this.GridDelta.x != 0 ) gg[1] = this.GridDelta.x;
if( this.GridDelta.y != 0 ) gg[1] = this.GridDelta.y;

var ii = 0;
var ii = 0;
var ii = 0;
var ii = 0;
var ii = 0;
var ii = 0;

for( var jj = gg[2]; jj >= gg[0]; jj -= gg[1] ) {
for( var jj = gg[2]; jj >= gg[0]; jj -= gg[1] ) {
for( var jj = gg[2]; jj >= gg[0]; jj -= gg[1] ) {
for( var jj = gg[2]; jj >= gg[0]; jj -= gg[1] ) {
for( var jj = gg[2]; jj >= gg[0]; jj -= gg[1] ) {
for( var jj = gg[2]; jj >= gg[0]; jj -= gg[1] ) {

    pp.y = jj * this.Parent.Zoom.y;
    pp.z = jj * this.Parent.Zoom.z;
    pp.x = jj * this.Parent.Zoom.x;
    pp.z = jj * this.Parent.Zoom.z;
    pp.x = jj * this.Parent.Zoom.x;
    pp.y = jj * this.Parent.Zoom.y;

    pp.z = this.Min.z;
    pp.y = this.Min.y;
    pp.z = this.Min.z;
    pp.x = this.Min.x;
    pp.y = this.Min.y;
    pp.x = this.Min.x;

    var vv = this.Parent.ScreenPos( pp );
    var vv = this.Parent.ScreenPos( pp );
    var vv = this.Parent.ScreenPos( pp );
    var vv = this.Parent.ScreenPos( pp );
    var vv = this.Parent.ScreenPos( pp );
    var vv = this.Parent.ScreenPos( pp );

    fromOV( this.Line[4][ii], vv.x, vv.y );
    fromOV( this.Line[5][ii], vv.x, vv.y );
    fromOV( this.Line[2][ii], vv.x, vv.y );
    fromOV( this.Line[3][ii], vv.x, vv.y );
    fromOV( this.Line[0][ii], vv.x, vv.y );
    fromOV( this.Line[1][ii], vv.x, vv.y );
    ...
[download]

I piped that into a file, wrapped it into a subroutine and eliminated the duplicates, then went through the sets of lines with differences and parameterised them one at a time. The result is:

Where first six lines are the call sites and the rest the fully parameterised function.

And the best bit: IT WORKS!

The names need work, but that's true for all the names in the library. And a job for tomorrow.