function_exported?/3 returns false if the module is not loaded (i.e. it does not load the module). Code.ensure_loaded?/1 should be preferred but it is a very expensive operation to be allowed in guard.
The is_atom check is the way to go. *José Valimwww.plataformatec.com.br <http://www.plataformatec.com.br/>Founder and Director of R&D* On Mon, Oct 16, 2017 at 9:34 PM, Allen Madsen <[email protected]> wrote: > This is the best way I know how to determine if it's a module vs an atom. > > function_exported?(X, :__info__, 1) > > You won't be able to use it in a guard though. > > Allen Madsen > http://www.allenmadsen.com > > On Mon, Oct 16, 2017 at 3:10 PM, Martin Svalin <[email protected]> > wrote: > >> The closest thing we have is `Code.ensure_loaded/1`. If you don't check >> that the module exists, you're basically just checking that the input is an >> atom. And if you use ensure_loaded, you'll have a predicate function with >> side effects. You'd also break the expectation of guard safety with the >> `is_` prefix. >> >> Would your `is_module/1` have different behaviour than `is_atom/1`? Would >> it be true only of atoms of the form `:"Elixir.SomeModule"`? I'm not sure >> it should, since `defmodule :random_atom` is valid. >> >> Which is a long way of saying, I think you should use `is_atom`. Perhaps >> with a line comment `# for modules`. >> >> >> mån 16 okt. 2017 kl 20:02 skrev Devon Estes <[email protected]>: >> >>> We just encountered something that seemed kind of odd, so I wanted to >>> pass it by the list to see if it could be a possible feature. >>> >>> In Benchee we want to accept either a module or a function as an >>> argument to a function. We'll have different behavior depending on the type >>> there (since we're expecting any module passed in to implement a certain >>> behaviour). However, there's no check for `is_module`. We were thinking of >>> using `is_atom` (see here: https://github.com/PragTob/ben >>> chee/pull/148/files#diff-e8ef07ff6be58cfaaaf6f03420fc53e7R75), but that >>> seems sort of confusing to me. I know technically modules are atoms, but >>> would it be possible to have an `is_module` function that can be used in >>> guard clauses and elsewhere that would more accurately convey the sort of >>> thing we're trying to do? >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elixir-lang-core" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit https://groups.google.com/d/ms >>> gid/elixir-lang-core/8a823a05-3da0-4de8-b96c-273bd12297b8% >>> 40googlegroups.com >>> <https://groups.google.com/d/msgid/elixir-lang-core/8a823a05-3da0-4de8-b96c-273bd12297b8%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "elixir-lang-core" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit https://groups.google.com/d/ms >> gid/elixir-lang-core/CAAHw6CKCXb0Q67YMXFF0_fdcUaLvXWnAz5mLHE >> GFCZB%2BrU_J_Q%40mail.gmail.com >> <https://groups.google.com/d/msgid/elixir-lang-core/CAAHw6CKCXb0Q67YMXFF0_fdcUaLvXWnAz5mLHEGFCZB%2BrU_J_Q%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/elixir-lang-core/CAK-y3Ctff5hfTWP7kQ8skvuoONNrCZ7Vj > 1eW0ZtibAzdEhOBHg%40mail.gmail.com > <https://groups.google.com/d/msgid/elixir-lang-core/CAK-y3Ctff5hfTWP7kQ8skvuoONNrCZ7Vj1eW0ZtibAzdEhOBHg%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4%2BJ67Pas_-zsR4%2BfFJ6fvaixjv7%2BmfNVPMN6MRzPT2-Rw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
