Why would we use def table do [{?a..?m, :"foo@computer-name"}, {?n..?z, :"bar@computer-name"}] end Rather than table = [{?a..?m, :"foo@computer-name"}, {?n..?z, :"bar@computer-name"}] In this example defmodule KV.Router do @doc """ Dispatch the given `mod`, `fun`, `args` request to the …

I use functions in these situations to allow myself the liberty to replace a hard-coded constant with a value fetched from a configuration provider – be it plain normal OS environment variables, various secret managers like those found in the Kubernetes ecosystem, AWS-specific secret key-value store…

Awesome reply, thanks [image] dimitarvp: Putting constant values inside your code is a bad idea no matter the programming language. More often than not, you’ll find yourself needing to modify it down the line and then you’ll have trouble finding where did you put it exactly (trust me, we forget…

Well, look at your route function above. The table() call blends in perfectly with everything else. Now turn that into an inline variable. Imagine you work actively on something else for 3 months and then come back to this code with the requirement to make that table configurable. Would you immediat…

Wonderful, no yeah I get it. So in this particular case module attributes would be equivalent to what I was asking

[image] dimitarvp: Putting constant values inside your code is a bad idea no matter the programming language. To clarify what I think you mean, inline inside the code with no name to them, such as c = 6.28318530718 * r. As opposed to putting up top @PI 3.14159265359 (dunno offhand if Elixir …

[image] davearonson: @PI 3.14159265359 (dunno offhand if Elixir provides this but anyway There’s :math.pi() in erlang.

Yes, that’s what I am saying. Lack of description of what the inline value is supposed to be is a very common problem in most codebases I ever reviewed and participated in.

Ah, yup. “Magic Numbers”, some folks call it.

Something that noone has mentioned yet, is that module attributes are only available in the module they are defined in. So if I have defmodule A do @pi 3.14159 end And I have defmodule B do def pi, do: 3.14159 end Then I can do this: B.pi() # 3.14159 But I cannot get the constant value I…

It’s not mentioned because module attributes are usually used as module-scope (private) constants. :man_shrugging: [image] John-Goff: defmodule Example do @constant "..." def constant, do: @constant end That’s what I do most of the time, for future-proofing. But it was rarely needed.