Question: function_parameter_count rule behavior

[varunpm1]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Possible Bug

Swift Lint rule - function_parameter_count

func test(a: Int, b: Int, c: Int, d: Int, e: Int, f: Int = 0, g: Int = 0)

The total parameters count for the above function is 7 (i.e., 5 compulsory parameters and 2 optional parameters). So I would like to know if the rule function_parameter_count should throw a warning for this function or not. Currently, this rule doesn't throw a warning for such functions.

func test(a: Int, b: Int, c: Int, d: Int, e: Int, f: Int, g: Int)

However, making all parameters as compulsory throws warning as expected.

• Which Xcode version are you using (check xcode-select -p)? - XCode 9.3

As per my understanding, this should throw a warning in both the scenarios since total parameter count exceeds the limit. Any help/suggestions appreciated here.

Thanks, Varun

[marcelofabri]

That's the expected behavior: we currently don't count the default parameters. If you feel like this is important, this could be a configuration option and PRs would be welcome.

[varunpm1]

Understood. I think this could be added as a configuration option. Anyway, this is just my suggestion.

Thanks, Varun

[marcelofabri]

@varunpm1 would you want to implement it and contribute back?

[varunpm1]

Hi @marcelofabri

I could try but I'm not sure on the steps to contributing.

[jpsim]

@varunpm1 thanks for your interest in contributing! Please read our CONTRIBUTING.md document and let us know if you have any questions.

[varunpm1]

A small concern here -

When I tried to go through the steps as per CONTRIBUTING.md, I couldn't run the following command -
$ make docker_test

I'm receiving the following error -
/bin/sh: docker: command not found

Any help here would be appreciated.

Also, I'm assuming that this has to be a separate rule, correct?

[jpsim]

Are you sure you have docker installed? Instructions to do so here: https://docs.docker.com/install/

[jpsim]

And no, to configure the function_parameter_count rule to not ignore default parameters, I'd recommend you add an ignores_default_parameters configuration option to the rule, which would default to true but that you could get the behavior you want by setting it to false.

[varunpm1]

Got it. Thanks for the help. Trying to implement the configuration.

[varunpm1]

I have sent a PR to master branch with the required configuration. I have also added a test case for function_parameter_count rule. Let me know if anything else is needed here.

[jpsim]

Thanks for taking the initiative to do this! Myself or another contributor will hopefully have time to review your PR shortly.

[varunpm1]

Closing this issue as the PR has been merged.