Credo
Credo v1.6.4

View Source Credo.Check.Warning.UnusedFileOperation (Credo v1.6.4)

This check has a base priority of high and works with any version of Elixir.

Explanation

The result of a call to the File module's functions has to be used.

While this is correct ...

def read_from_cwd(filename) do
  # TODO: use Path.join/2
  filename = File.cwd!() <> "/" <> filename

  File.read(filename)
end

... we forgot to save the result in this example:

def read_from_cwd(filename) do
  File.cwd!() <> "/" <> filename

  File.read(filename)
end

Since Elixir variables are immutable, many File operations don't work on the variable you pass in, but return a new variable which has to be used somehow.

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.