zf

unused_string_operation.ex (1155B)

---

 defmodule Credo.Check.Warning.UnusedStringOperation do
   use Credo.Check,
     base_priority: :high,
     explanations: [
       check: """
       The result of a call to the String module's functions has to be used.
 
       While this is correct ...
 
           def salutation(username) do
             username = String.downcase(username)
 
             "Hi #\{username}"
           end
 
       ... we forgot to save the downcased username in this example:
 
           # This is bad because it does not modify the username variable!
 
           def salutation(username) do
             String.downcase(username)
 
             "Hi #\{username}"
           end
 
       Since Elixir variables are immutable, String operations never work on the
       variable you pass in, but return a new variable which has to be used somehow.
       """
     ]
 
   alias Credo.Check.Warning.UnusedOperation
 
   @checked_module :String
   @funs_with_return_value nil
 
   @doc false
   @impl true
   def run(%SourceFile{} = source_file, params) do
     UnusedOperation.run(
       source_file,
       params,
       @checked_module,
       @funs_with_return_value,
       &format_issue/2
     )
   end
 end