Hello! I want to “save function” (module, name, arity) to the database to be able to call it later, potentially after BEAM was restarted. My plan is to use Functions.capture(module, function_name, arity) to be able to call the function after “loading” from the database. How can I obtain module, fu…

[image] stjefim: What are the reasons it is debug only? What are the alternatives? The underlying Erlang function docs says it’s “mainly” for debugging: This BIF is mainly intended for debugging, but it can sometimes be useful in library functions that need to verify, for example, the arity…

Not sure I follow. You have the module, the function name and the arity beforehand, why use the result of Function.capture result at all? Why not cut out the middleman and just store those 3 pieces in the DB? :thinking:

Not sure if I understood you correctly, but here is the clarification. I plan to use Functions.capture to “load function” from the database. My problem is how to “store function” to the database from the Elixir code, i.e. I want to write a function function_to_string(f) which can be called like this…

[image] stjefim: So to answer your question - I agree I just need to store these 3 pieces in the DB, however, how to obtain them from a function capture. I don’t think there is a general solution as function can be anonymous. Also, storing function in a db may not be the best idea. Code will …

Thank you, it will be useful after “loading function” - no need to do Functions.capture.

You want to store the function’s bytecode itself in the DB? :thinking: I still don’t get your requirement.

I agree with all your points: I will not support anonymous functions. Haven’t thought about versioning yet, but not a big problem for me. Agreed - but can do some validation to allow only certain functions to be called.

No, I will not store byte code in DB. My requirement is to convert function capture, e.g. &MyModule.my_function/0 into module name as string, function name as string and function arity as integer.

[image] stjefim: convert function capture, e.g. &MyModule.my_function/0 into module name as string, function name as string and function arity as integer. That’s not possible. Because you can’t turn a function value back to MFA, just like you can’t turn a value back to the variable name. You…

[image] stjefim: How can I obtain module, function name and arity from a function capture (e.g. &MyModule.my_function/0) to “save function”? The specific thing you’re looking for is :erlang.fun_info: iex(1)> f = &String.capitalize/1 &String.capitalize/1 iex(2)> :erlang.fun_info(f) [module: …

Elixir Programming Language Forum

Get function name, module and arity from function capture

Questions & Help Questions

bartblast March 14, 2025, 9:41pm 4

Hey @stjefim, are you aware of Kernel.apply/3?