And let's be honest here... We don't like working on other people's code. It's not something to be ashamed of. After all software development is in many ways a creative endeavor, an ill-defined Venn intersection between creativity, engineering, salesmanship, sarcasm, and caffeine. And who wants to create on top of something that's already been created? A painter prefers a canvas to be blank. A sculptor prefers an unbroken stone. But these analogies extend only so far in our craft, and clinging too tightly to them detracts from the team.
So how do we approach existing ("legacy") code? Hopefully not with judgements and preconceptions.
Over the years I've heard lots of good advice from my manager. Recently he made a suggestion which particularly resonated with me, "Don't pass judgement on their code for at least a month." My initial internal reaction was to remind myself that "I know these code smells all too well" and that "I've had enough conversations with these guys to know that they have no idea what they're doing." The sheer arrogance of these thoughts quickly became apparent. Clearly I needed to do a little less deciding and a little more observing.
What can be observed is the history of the codebase. Why certain things were done certain ways, what other factors have been in place (including the factors which have long-since vanished after having left their discernible mark in the code). What becomes clear during this period is the subtle reminder that our clients and counterparts are not unintelligent, neither malicious nor insane, and that as reasonable people with reasonable goals they have time and again enacted reasonable decisions with the information they had. Maybe that information was incorrect or incomplete, or maybe that information has changed over time.
"This legacy code is a mess" is in every way a cop-out. It's how we throw in the towel, declaring to the world that we are not in a position to help. Even if it's correct, it's not productive. (This reminds me of another nugget of management wisdom I've heard, "Being right isn't good enough.") The productive approach is to understand the decisions of yesterday so that we can better advise on the decisions of today.
A significant reason why this advice resonates with me is because, during this "month of observation," a curious turning of the tables has occurred. While at this client, I've written some of the best code in my life. It's a small project, and one in which I was explicitly given freedom to demonstrate some technologies, patterns, and practices which could be applied elsewhere in the company's software. It was both a solution to a simple problem as well as a proof of concept for solution patterns in general. And almost immediately after I completed development of this codebase the client hired a new Solution Architect who took one look at it and didn't like it.
It wasn't what he expected. Or, rather, it wasn't what he would have written. And because it didn't fit his mold, it was to him in every way a "legacy mess." How could this be? Patterns are documented, concerns are separated, test coverage is high, each individual fully-encapsulated component is elegant in its simplicity. (At least, I think so.) And it was everything he didn't want in an architecture.
Who is he to tell me that my baby is ugly? Well, who am I to tell any client that their baby is ugly?
What he hasn't been able to tell me is any meaningful reason why my code is "bad." If he could, I'd be happy to listen to his points. Any opportunity to learn and improve is welcome. But "I don't like it" isn't such an opportunity. So, following that same reasoning, what meaningful points can I provide the client about their code? Why don't I like it?
Those points can be productive and helpful, as long as they're backed by meaningful information. And that information starts with understanding the existing codebase and why each component is what it is. Despite years of experience, that understanding doesn't come from a cursory look at the code but rather from time spent "in the trenches" working, studying, observing. Doing so "for at least a month" sounds like as good a rule of thumb as any.