View Source Credo.Check.Refactor.LongQuoteBlocks (Credo v1.7.8)
Basics
This check is enabled by default.
Learn how to disable it via
.credo.exs
.
This check has a base priority of high
and works with any version of Elixir.
Explanation
Long quote
blocks are generally an indication that too much is done inside
them.
Let's look at why this is problematic:
defmodule MetaCommand do
def __using__(opts \\ []) do
modes = opts[:modes]
command_name = opts[:command_name]
quote do
def run(filename) do
contents =
if File.exists?(filename) do
{:ok, file} = File.open(filename, unquote(modes))
{:ok, contents} = IO.read(file, :line)
File.close(file)
contents
else
""
end
case contents do
"" ->
# ...
unquote(command_name) <> rest ->
# ...
end
end
# ...
end
end
end
A cleaner solution would be to call "regular" functions outside the
quote
block to perform the actual work.
defmodule MyMetaCommand do
def __using__(opts \\ []) do
modes = opts[:modes]
command_name = opts[:command_name]
quote do
def run(filename) do
MyMetaCommand.run_on_file(filename, unquote(modes), unquote(command_name))
end
# ...
end
end
def run_on_file(filename, modes, command_name) do
contents =
# actual implementation
end
end
This way it is easier to reason about what is actually happening. And to debug it.
Check-Specific Parameters
Use the following parameters to configure this check:
:max_line_count
The maximum number of lines a quote block should be allowed to have.
This parameter defaults to 150
.
:ignore_comments
Ignores comments when counting the lines of a quote
block.
This parameter defaults to false
.
General Parameters
Like with all checks, general params can be applied.
Parameters can be configured via the .credo.exs
config file.