Making The Bad Impossible
Don’t Generate Compiler Warnings
I was doing some work this morning when I received a general email to a group of developers for a large project that sort of pleaded with and sort of demanded that members of the group not check in code that generated compiler warnings. And, I agree with that. Although, with the way that particular project is structured, this is easier said than done in some cases. There are dozens and dozens of assemblies in it, not all of which are re-compiled with a build, so someone may generate a warning, not notice it, and then not see it in subsequent runs if that assembly isn’t recompiled. Doing a rebuild instead of a build as habit is impractical here.
Something bothered me about this request and I couldn’t put my finger on it. I mean, the request is reasonable and correct. But, the email seemed sort of inappropriate in the way that talking about one’s salary or personal politics seems sort of inappropriate. It made me uncomfortable. The “why” of this kicked in after a few minutes. The email made me uncomfortable because it should have no need to exist. No email like that should ever be sent.
Don’t Do X
Some time back, I blogged about tribal knowledge, and why I view it as a bad thing. Tribal knowledge is a series of things that accrue over time in a project or group that are not manifest and can only be learned and memorized by experienced team members:
You ask for a code review, and a department hero takes one look at your code and freaks out at you. “You can never call MakeABar before MakeABaz!!! If you do that, the application will crash, the computer will probably turn off, and you might just flood the Eastern Seaboard!”
Dully alarmed, you make a note of this and underline it, vowing never to create Bars before Bazes. You’ve been humbled, and you don’t know why. Thank goodness the Keeper of The Tribal Knowledge was there to prevent a disaster. Maybe someday you’ll be the Keeper of The Tribal Knowledge.
We’ve all experienced things like this when it comes to code. Sometimes, they’re particulars of the application in question, such as in the tribal knowledge examples. Sometimes, they’re matters of organizational or other aesthetics, such as alphabetizing variable declarations, or maybe some other scheme. Sometimes, they’re coding conventions or standards in general. But, they’re always things that a person or group decide upon and then enforce by asking, telling, demanding, cajoling, threatening, begging, shaming, etc.
As a project or collaborative effort in general proceeds, the number of these items tends to increase, and the attendant maintenance effort increases along with it. One rule is simple and easy to remember. When the number gets up to five, people sometimes start to forget. As it balloons from there, team members become increasingly incapable of using a mental checklist and the checklist finds its way to a spreadsheet, or, perhaps a wall:
When this happens, the time spent conforming to it starts to add up. There is the development time, and then the post-development checklist validation time. Now, theoretically, a few times through the checklist and developers start tending to write code that conforms to it, so the lost time is, perhaps, somewhat mitigated, but the check itself is still more or less required. If someone gets very good at compliance, but makes one typo or careless error, a public shaming will occur and re-up the amount of time being spent on The List.
And, The List probably grows and changes over time, so no one is ever really comfortable with it. The List isn’t just tribal knowledge – it’s “meta-tribal knowledge”.
Stop the Madness
Is The List really necessary? People who enjoy dealing with the DMV or other bureaucracies may think so, and most developers may resign themselves to this sort of thing as an occupational hazard, but why are we doing this? Why do we have to remember to do a whole bunch of things and not do a whole bunch of other things. We’re programmers – can’t we automate this?!?
I believe that the answer to that question is “absolutely, and you should.” To circle back to my introductory example, rather than send out emails about checking for compiler warnings, why not set the build to treat warnings as errors? Then, nobody has to remember anything – generating a compiler warning will impede immediate progress and thus immediately be rectified. No emails, no post-it, and no entry in The List.
Alphabetized variables? Write a script on the build machine that parses your checked in files. Casing conventions? Write another parsing script or use something like DevExpress to automate it. Dependency management? Organize code into assemblies/libraries that make it impossible for developers to include the wrong namespaces or use the wrong classes.
And that’s the meat of the issue. Don’t tell people not to do bad things – make it impossible via immediate feedback. If I’m expected not to generate compiler warnings, make it so that I get the feedback of not being able to run my tests or application until I clean up my mess. That sort of scheme retains the learning and feedback paradigm, but without being a drain on productivity or the need for others to be involved. Constructor injection is based on this principle, when you really think about it. Using that injection scheme, I don’t need to wonder what I have to do before instantiating a Foo – the compiler tells me by not building if I don’t give Foo what it wants. I don’t have to go ask anyone. I don’t have to find out at a code review. I can just see it for myself and learn on my own.
Obviously, it’s not possible to make all bad things impossible. If you can do that, you probably have better things to do than code, like running the world. But, I would advocate that we go after the low-hanging fruit. This is really just an incarnation of the fail early concept, but that doesn’t just describe code behavior at runtime. It also can describe the feedback loop for development standards and preferences. Static analysis tools, auto-checkers, rules engines, etc are our friends. They automate code checking so that it need not be done by asking, telling, demanding, cajoling, threatening, begging, shaming, etc.