rebar3_hank

The Erlang Dead Code Cleaner

Kill it with Fire

Mr. Scorpio says productivity is up 2%, and it's all because of my motivational techniques, like donuts and the possibility of more donuts to come.
(Homer Simpsons)

Build

$ rebar3 compile

Test

$ rebar3 test

Use

Add the plugin to your rebar config:

{project_plugins, [rebar3_hank]}

Then just call the plugin directly in an existing application:

$ rebar3 hank # or…
$ rebar3 kiwf # (Kill It With Fire)

This will review your project, analyzing every *.[he]rl file in it (optionally skipping some folders/files if you want to - see below). It will then apply its rules and produce a list of all the dead code that you can effectively delete and/or refactor.

Certainty

In principle, Hank should have Dialyzer levels of certainty. That is: if Hank points at some code, you can be 100% sure it's dead.

That means that if you find some false positives (i.e. Hank pointed at some code that was not really dead / should not be deleted), please report it as a bug and we'll take care of fixing it.

Configuration

The plugin supports the following configuration options in the hank section of rebar.config:

rules ([hank_rule:t()]):
- This is the list of rules to apply to the analyzed code. Each rule is a module that should apply the hank_rule behavior.
- If this option is not defined, Hank will apply all the default rules.
ignore ([file:filename_all() | {file:filename_all(), hank_rule:t()} | {file:filename_all(), hank_rule:t(), list()}]):
- List of wildcard patterns representing the files and rules that Hank will ignore when formatting. Tuple format is used to ignore only a specific rule in those files.
```
{hank,
[{ignore, [
"rel/**/*",
"lib/some_module.erl",
{"test/**/*.erl", unnecessary_function_arguments}
]}]}
```
- For ignoring options for unused_configuration_options rule, set a list of keys from the .config files you want to ignore.
```
{hank,
[{ignore, [
{"sys.config", unused_configuration_options, [not_used_but_ignored]}
]}]}
```
- You can also ignore a specific file adding the attribute -hank ignore. to it.
- And you can ignore specific rules adding the attribute -hank [hank_rule:t()]. with the list of rules you want to ignore.

Ignore specific rule items

You can even ignore specific rule items with the -hank attribute by giving extra ignore specifications for each rule, example:

-hank([unused_macros,  %% Will ignore the whole rule within the module
       {unused_callbacks, cb_func_name_to_ignore}  %% Will ignore the given callback funcion name within the module
       {unnecessary_function_arguments,  %% You can give a list of multiple specs (or a single one like above)
           [{ignore_me, 2},  %% Will ignore any unused argument from `ignore_me/2` within the module
            {ignore_me_too, 3, 2},  %% Will ignore the 2nd argument from `ignore_me_too/3` within the module
            ignore_me_again]}]). %% Will ignore any unused argument from any `ignore_me_again/x` within the module (no matter the arity)

Refer to each rule documentation for further details.

Rules

Find detailed information about the rules provided by Hank in hex docs.