Hello everyone. I’m pretty new to Elixir. I have question about alias and import usage. Does using import makes impact on app performance because of importing all of the code into module? When should I use import and when alias? I didn’t find any good answer for this question. Thanks in advance.

import does not “import” the code into the module’s .beam. All calls are resolved at compile time and both alias qualified calls and imported calls count as remote calls. It’s mostly a convenience for the human reader of your code.

After reading this about upgrading to Phoenix 1.4 : A Routes alias has been added to app_web.ex for view and controller blocks in favor over the previously imported AppWeb.Router.Helpers . The new Routes alias makes it clearer where page_path/page_url and friends exist and removes com…

There absolutely is a cost to using import, because it needs to require the selected module as part of its functionality. require does cause a compile time dependency, which means both modules can no longer be compiled in parallel, but need to be compiled one after the other. The upside is that you …

Thank you for this clarification. ^^

[image] LostKobrakai: There absolutely is a cost to using import , because it needs to require the selected module as part of its functionality. require does cause a compile time dependency, which means both modules can no longer be compiled in parallel, but need to be compiled one after the oth…

[image] christhekeele: In this case there is no impact. I am not so sure. IIRC imported functions aren’t remotely called, which mean that if you overwrite imported module in the runtime then the module will still use old implementations. alias will make calls remote, so there will be negligib…

That’s a good point, I forget that local vs remote calls have slightly different hot-code-reloading characteristics, and import vs alias determines if they are local or remote. I’d be curious to see what the performance diff between the two is, even though it’s totally negligible to every applicati…

[image] hauleth: import ed functions aren’t remotely called Is that true? I always thought import just did a compile time check for the functions’ existence, but still generated the remote call AST.

[image] christhekeele: and import vs alias determines if they are local or remote. import and alias do not change if a function call is remote or local… alias Foo.Bar Bar.baz() import Foo.Bar baz() Will both result in BEAM bytecode roughly equivalent to the following and therefore be remot…

[image] NobbZ: import and alias do not change if a function call is remote or local… This is correct. Both imported and aliased calls are remote calls.

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hauleth October 17, 2019, 9:23pm 12

Ok, TIL. My bad