Win Tickets To Detroit.Code

I am very excited to be helping with the inaugural Detroit.Code conference here in July 2017.  In fact all of us that work on the DetroitDevDay conference are very excited about this new conference.  We all support growing the metro Detroit software development community and this is another great step in growing that community. (Full disclosure: I am speaking at Detroit.Code.)

As such we want to help make sure as many folks get to the conference as possible. So we’re going to give away a couple of tickets to the event. However, we want to have a little fun at the same time.  So we’re also going to run a little coding contest; everyone who gets the right answer on the coding contest will be entered into a drawing for the two tickets we’re giving away.

I have no interest in spamming folks with the details of the coding contest so if you’re reading this and you’d be interested in getting into the contest, please send me an e-mail at (gad I’m sure to have more spam soon) and I will add you to the list of folks who get the coding challenge.

Code And Coffee

I’ve always admired something that my friend @CarinMeier mentioned that they do down in Cincinnati (or at least they used to do it anyway).  That’s  a once-monthly “Code And Coffee” where people would get together at a local coffee shop to drink coffee and learn about some interesting topic.

I’m going to be at the Biggby Coffee in Clawson (on 14 Mile) on Wednesday May 3, 2017 at 7 am.  If you’re reading this blog post consider yourself invited to join me for some coffee, some shop talk, and likely some coding.  If you want to join, feel free. People who know me will probably guess that I’m likely to talk about functional programming but honestly I’m willing to talk about almost anything technology related.  If you do decide to join, bring a laptop.

Left Side vs. Right Side Agile

We were discussing agile today and I came up with something that I thought might be worth sharing with others.

Individuals and interactions over processes and tools
Working software over comprehensive documentation
Customer collaboration over contract negotiation
Responding to change over following a plan

And I was saying to some of the folks on my team that it seems as if we’re getting right side agile and not left side.  While lots of firms these days are calling themselves agile they’re still very much on the right side of that list. As someone put it to me, lots of places are doing waterfall with daily stand ups and two week sprints.

So maybe we need to start calling out our managers and our VP’s on right side agile and tell them that we favor the left side and we want them to favor it too.

Premature Generalization

I’m sure most developers reading this post will be familiar with the term “premature optimization”. For those who may not be familiar, this refers to the tendency that some developers have to worrying about the performance of their code, usually but not always in terms of execution time, before their code is proven to work correctly in terms of customer requirements. It’s like saying, “Hmm, this function call may take 3 clock cycles to execute but if I inline the code it won’t take any extra clock cycles” before the developer has correctly defined the function to be called. It’s generally considered a poor way to write software. I believe it was probably Joe Armstrong, one of the co-creators of Erlang, who said “Make it right, make it fast, then make it pretty.” Getting the code right always comes before any sort of optimization should be attempted.

Risking the perils that may befall anyone who coins a neologism, I propose another premature condition which developers should try to avoid: premature generalization. I would define premature generalization as being the tendency to assume that what you see or what you want is what every other developer sees and/or wants. It’s the tendency of the novice developer to post messages like “Hey function x isn’t working. What’s wrong?” assuming that the rest of us also have the problem they have and we therefore don’t need any more detail to know what he or she is talking about. It’s also the tendency to assume that because they need to address some particular use case that most developers working in the language will need to address the same use case: “Hey I need library function x to return an error status when I pass it a bad argument but throw an exception when I pass it a good but out of range argument. Can we modify the standard library to do this?” In both cases, I believe they’re prematurely assuming their question is generic and therefore they don’t need to provide details to others.

Although I feel I’m flogging a dead equine I hasten to point out that as software developers we should usually proceed from the assumption that the error we’re seeing is due to something specific to us. We should also proceed from the assumption that any use case we have is likely to be a use case specific to us until we see evidence otherwise. Yes, I am aware of the irony of making generic statements here—but given what I’ve seen over 25+ years of software development I don’t believe that I’m indulging myself in premature generalization.

Making Exrm Work On Windows

So as many of you will know I’m very interested in Elixir.  I also want to see it work better on Windows.  There are a few of us that have been working on it.

I’ve also been very interested in how one can deploy an Elixir app on a machine which doesn’t have Erlang and Elixir already installed.  While most of us don’t mind having to have Erlang and Elixir around because we are doing development work, it would be much more secure to only have to deploy the binaries that need to be deployed for an app.

Since I started on Elixir one of the nicest folks in the community (and that’s saying something) has been Paul Schoenfelder. When I was first struggling to learn Elixir, Paul very patiently helped me to get started.  So I became aware of one of the utilities that Paul built: EXRM.  Exrm is a tool to automate the production of a package of the needed Elixir and Erlang binaries to deploy an app. It allows a developer to deploy his or her Elixir app with only the needed runtime files so that the target machine doesn’t have to have Elixir or Erlang installed.

So I asked Paul what I could do to sort of return the favor for the help he gave me when I started and he mentioned that he wasn’t as pleased as he might be with the support for Windows in EXRM.  So I started digging into EXRM to see what I might do to get it working on Windows.

A few instructive things I spotted right away. I noticed that the way the Windows batch files were constructed they will not work correctly if they’re not run from the correct directory. I mention this for others who may try to use EXRM on Windows.

Spaces In Directory Names

I noted also that there were several places where directories containing spaces and too many characters were also a problem. The original developers of the batch files wrapped double quotes around all the directory names. If you decide to build Windows batch files, please note that wrapping double quotes around directory names is a bit error prone and tough to get right.  Hence I opted to modify all the various places where they had double quoted directory names to using 8.3 versions of the names.  That fixed up all the references to directories so that everything was found correctly.

Getting Services Working

Next there was the question of getting Windows Services working for Erlang. While digging into the batch files I discovered that basically the issue hinged on the installation of the service.  Once the service was installed correctly, it looked as if the rest of the operations on the services (starting, stopping, restarting etc.) would work correctly.

I had to hunt around for a while to figure out what I needed to do to get the service to install correctly.  I finally figured out that what was happening was the wrong parameter was getting passed as the binary to be started when the service gets started.  And so I repaired it.

A Few More Details

You’ll also need to unblock the erl.exe and epmd.exe files for the Windows Firewall.  You can wait for Windows to prompt you or you can proactively unblock them via this escript.

You may also need to deploy msvcr100.dll to your deployment machine as well.  If it’s a Windows 10 machine you may need to do this.

So we’re almost ready to roll the changes into EXRM so we can get people to be able to deploy Elixir apps on Windows.

I will continue to work with Paul on improving support for EXRM on Windows.  Keep watching this space; we’ve got some interesting ideas we’ll be trying to roll out in the next few months or so.