I certainly use environment variables in my code beyond just config files. So even though the idea of macros in runtime.exs is certainly nice, I still want to be able to access those environment variables values independently in my code as needed. This is why a separately initialized module where I can see/configure all the environment variables used by my app in one glance, makes more sense to me from flexibility and ease of use standpoint.
emadalam
0
D4no0
Well, the point of configuration is to use them in your code later, just as libraries use them and you can do that easily by calling get_env/3 or fetch_env/2, however taking in consideration the limitation of the configuration/compilation it seems that the only way to enforce something at compile-time is to make a custom module.
It would be great if such a functionality were to be introduced somewhere in the elixir internals so it could be used in all configurations.
1
stevensonmt
Thanks for clarifying as I had indeed misunderstood.
I’m still not sure I follow here though. This seems like with pattern matching you could hard code the strings for the env variables of interest and have the same sort of confidence. I can see that mahaul provides a single interface with the system env where you handle checking for the variables and providing defaults or handling errors rather than needing to do so everywhere you use the env variable in the application. Mahaul also seems to make it a lot easier to use different variables for different environments and to update them easily when the names of variables change between versions or something.
This sounds like a true win for me.
0
emadalam
Can you give some brief example of how such a dynamic pattern matching can work at compile time? Form what I can think of, the following will give you runtime errors without any compile time warnings.
defmodule Env do
def get_env("VAR_1"), do: "..."
def get_env("VAR_2"), do: "..."
end
defmodule SomeModule do
def something() do
Env.get_env("VAR_1") # works
Env.get_env("VAR_2") # works
Env.get_env("VAR_3") # runtime error with no compile time warnings
end
end
vs
defmodule Env do
use Mahaul,
VAR_1: [type: :str],
VAR_2: [type: :num]
end
defmodule SomeModule do
def something() do
Env.var_1() # works
Env.var_2() # works
Env.var_3() # compile time warnings for non-existing method call
end
end
2