Pragmatic Book Club: Chapter 4

Chapter four, pragmatic paranoia. Now we’re getting into some more abstract and academic topics. Things we could think about introducing into our own codebases, even.

Section 23: Design by contract

• A completely unnecessary quote from the problematic Woody Allen. Great.
• Has anyone ever written clojure or elixir? Can you share a bit about how contracts form part of the language?
• What would it take for us to introduce design by contract to Customer Products?
• How do engineers at the FT reach a consensus on anything?
• Would we need to change all of our existing code?
• Would it be worth the effort?
• Type is a form of c
• [From the book] If DBC is so powerful, why isn’t it more widely used?

Section 24: Dead programs tell no lies

• Is this mantra something you consider when writing code or reviewing other people’s?
• Do you agree or disagree that with what the authors are saying about catching/re-raising exceptions on page 113?
• The authors only give the reasons why not re-raising is better, what are the reasons you might want to catch and re-raise?

Section 25: Assertive programming

• Do we use console.assert()?
• When I read around this topic it seems like in a lot of places people are missing what is pointed out by the book assertive programming should not be used to validate user input.
• Why should asserts not be used for handling user input? Because the program shouldn’t terminate when a user inputs something incorrectly, as they will do often(?)

Section 26: Balancing Resources

• This topic was pretty interesting to me, but it divided the book group. Some people felt it was not relevant to their day-to-day work. We predominantly write Node, and we use a lot of libraries. So the kinds of resource allocation issues this section talks about are often abstracted away and dealt with in those libraries.
• Good MDN article about memory
• Good Katie Fenn talk about garbage collection in Node
• Blog post from me from 2015 about a CPU usage bug I encountered and fixed in a mustache gem (Just to demonstrate that, rarely, we do encounter resource issues, even when writing front end code…)
• Anybody got any fun horror stories about resource allocation going wrong?