CODEWITHSUNDEEP
elixir
Chen Yu
Chen Yu

Reputation: 4077

when function name end with `!`

Consider Application.fetch_env!/2. What’s the special meaning for ending with ! for a function name?

defp db_host do
  Application.fetch_env!(:my_app, :db_host)
end

Upvotes: 0

Views: 215

Answers (1)

UnholySheep
UnholySheep

Reputation: 4096

As explained in the Naming Convention section "Trailing Bang": https://hexdocs.pm/elixir/1.13.4/naming-conventions.html#trailing-bang-foo

A trailing bang (exclamation mark) signifies a function or macro where failure cases raise an exception.

So the function Application.fetch_env! will raise an ArgumentError when the configuration parameter does not exist (as stated in the documentation) while Application.fetch_env (without exclamation mark) will return an :error in case of a non-existing parameter

Upvotes: 5

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