At the Bank we have a home-grown ETL framework that we've been using for quite some time. We recently completed a total rewrite, but unfortunately we left out a few changes. Had I gotten those changes in 5 months ago, I would have only had to break the API of about 10 modules. Today, in order to make those changes, I have to break the API of 122 modules.

What follows is an account of this ordeal, provided for entertainment value only. There will be a future post that explains some of the things I did to make this task surmountable.

Day 1

• 3:45pm - 122 modules left
• 4:31pm - 112 modules left - And then I remember there's another feature to add that will require another migration of all these modules I will have to do.
• 4:52pm - 106 modules left - Test::Continuous removes 3 steps for each module. Total time saved: HOLY FUCK THAT'S AWESOME
• 5:35pm - 97 modules left - Every commit message during this ordeal is another love note to those who put off this migration five months ago, when there were only 10 modules to migrate.
• 6:09pm - 94 modules left - New API to change: Create a role to do it for me! +100 experience points!
• 6:15pm - 93 modules left - Why unpack the hash of args passed-in to the method if the method you're calling takes exactly the same arguments? my $arg_name = $args{arg_name}; return $self->method( arg_name => $arg_name ) should never happen!
• 6:37pm - 87 modules left - A thought: If the other team using this project ultimately rejects this API change, I get to write my own brand-new ETL framework from scratch! Temptation, thy name is Zoidberg.
• 6:51pm - 84 modules left - Found a bug in the new API! Finally something interesting to do!
• 7:00pm - 80 modules left - Every time you copy/paste code in tests, God inflicts another programmer with carpal tunnel. Please think of the programmers.

Day 2

• 3:02pm - 80 modules left - Let's see if I remember all the macros I left in vim over the weekend... Test::Continuous is still running, which is nice
• 3:18pm - 71 modules left - The end is in sight!
• 4:30pm - 52 modules left - Perhaps I was premature...
• 6:30pm - 41 modules left - Caught up putting out fires in other places. Derail.

Day 3

• 1:35pm - 41 modules left - Another bug in the new API. Doing it this way is certainly shaking out the bugs.
• 2:21pm - 20 modules left - Smooth sailing at last...
• 3:47pm - 0 modules left - AND THE CROWD GOES WILD!

Total time elapsed: 3.25+3.5+2.25 = 9 hours. Not bad for 130 commits to migrate 122 modules.