[Proposal] @dependency_of
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Brian Cardarella
Feb 28, 2017, 3:55:47 AM2/28/17
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I am doing some meta programming that has one module depending upon the state of another. However it isn't being picked up by the compiler that these two modules are related. And when the parent changes the child should be marked for recompilation. It would be really nice if we had a simple module attribute like: `@dependency_of` that took a list of modules. This could be incorporated into the manifest write out for determining dependencies. I assume at that point the compiler could work as normal.
José Valim
Feb 28, 2017, 3:58:01 AM2/28/17
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"require OtherModule" should do it. If not, it is a bug in Mix or Elixir, so please provide a mechanism to reproduce it so we can fix it. :)
On Tue, Feb 28, 2017 at 9:55 AM, Brian Cardarella <br...@dockyard.com> wrote:
I am doing some meta programming that has one module depending upon the state of another. However it isn't being picked up by the compiler that these two modules are related. And when the parent changes the child should be marked for recompilation. It would be really nice if we had a simple module attribute like: `@dependency_of` that took a list of modules. This could be incorporated into the manifest write out for determining dependencies. I assume at that point the compiler could work as normal.
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José Valim
Feb 28, 2017, 3:59:09 AM2/28/17
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Actually, if you invoke the other module explicitly, it should also be enough to list it as a dependency and for Elixir/Mix to track it. Unless you are somehow generating those module names dynamically. Here is a good article on the topic: http://milhouseonsoftware.com/2016/08/11/understanding-elixir-recompilation/
Brian Cardarella
Feb 28, 2017, 4:04:13 AM2/28/17
to elixir-lang-core, jose....@plataformatec.com.br
The problem is the compilation order. The relationship between mod A & B is being written in __before_compile__ for each module. mod A is using Module.put_attribute(B, :requires, A) in its __before_compile__ then B would do something like:
quote do
for mod <- @requires, do: require mod
end
However B gets compiled before A and its @requires is always empty.
On Tuesday, February 28, 2017 at 3:59:09 AM UTC-5, José Valim wrote:
Actually, if you invoke the other module explicitly, it should also be enough to list it as a dependency and for Elixir/Mix to track it. Unless you are somehow generating those module names dynamically. Here is a good article on the topic: http://milhouseonsoftware.com/2016/08/11/understanding-elixir-recompilation/
On Tue, Feb 28, 2017 at 9:57 AM, José Valim <jose....@plataformatec.com.br> wrote:
"require OtherModule" should do it. If not, it is a bug in Mix or Elixir, so please provide a mechanism to reproduce it so we can fix it. :)
On Tue, Feb 28, 2017 at 9:55 AM, Brian Cardarella <br...@dockyard.com> wrote:
I am doing some meta programming that has one module depending upon the state of another. However it isn't being picked up by the compiler that these two modules are related. And when the parent changes the child should be marked for recompilation. It would be really nice if we had a simple module attribute like: `@dependency_of` that took a list of modules. This could be incorporated into the manifest write out for determining dependencies. I assume at that point the compiler could work as normal.
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Brian Cardarella
Feb 28, 2017, 4:13:38 AM2/28/17
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Actually, I may have solve my problem by reversing everything. :p
José Valim
Feb 28, 2017, 4:15:02 AM2/28/17
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I would recommend taking a step back. Injecting attributes from one module into the other is almost never going to work because the compiler happens in parallel. There is no guaranteed order of execution. B may not even be available unless you require it, which, as you said, means it will be compiled before A.
I would recommend reversing it if possible and have B explicitly require A.
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