I understand what runtime and compile dependencies between modules are and when they happen. But I have a problem understanding one particular situation in which a recompilation of some files is required after changes in others. Here’s what xref graph shows: ~/dev/elixir/dep-example $ elixir --ver…

A concrete example of A that would showcase this issue like this might look like this: defmodule A @the_answer B.search() def get_the_answer, do: @the_answer end So when C changes, A needs to be recompiled because B.search/0 might call a function in C

As far as I understand it the compiler doesn’t know if any code B holds for changing A at compile time is provided by calling into C. Therefore if C changes A needs to change as well.

Right, if A has compile-time dependency on B, and B has runtime dependency on C, when C changes, A has to be re-compiled even though B does not have to! See https://milhouse.dev/2016/08/11/understanding-elixir-recompilation/ , https://telnyx.com/resources/renan-ranelli-understanding-elixirs-re-comp…

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Implicit compile-time dependencies

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szajbus February 10, 2020, 8:47pm 5

Thanks, it makes perfect sense now!