Bylaw.Credo.Check.Elixir.NoLowLevelProcessPrimitives (bylaw_credo v0.1.0-alpha.1)

Basics

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

Explanation

Disallows direct usage of Process, GenServer, and :ets.

Examples

Avoid:

  Process.put(:current_tenant, tenant_id)
  GenServer.call(MyApp.Registry, {:lookup, key})
  :ets.lookup(:cache, key)

Prefer:

  fetch_tenant(conn)
  MyApp.Registry.lookup(key)
  Cache.fetch(key)

Notes

Stateful and process-based primitives are exceptions, not defaults. They exist for very specific use cases and should only be introduced after gaining explicit approval.

Most of the time the right answer is simpler than you think - plain functions, passing values through arguments, or returning data from the caller is almost always preferable to reaching for Process, GenServer, :ets, or any other stateful primitive.

Note: Agent is not flagged because it cannot be reliably distinguished from aliased application modules (e.g. MyApp.Agents.Agent) at the AST level. Task is also not flagged - it is a reasonable concurrency tool that does not introduce hidden state.

Before adding process-level machinery, ask yourself:

1. Can I solve this with a plain function and its arguments?
2. Am I introducing state/concurrency where none is needed?
3. Have I gotten explicit approval to use process primitives here?

If the answer to all three is "yes, I really need this", disable the check for the call site:

  # credo:disable-for-next-line Bylaw.Credo.Check.Elixir.NoLowLevelProcessPrimitives
  Process.put(:key, value)

Path exclusions are matched against the source filename and are intended for generated files or temporary migration areas.

The check uses static AST analysis, so dynamic code generation and macro-expanded code may fall outside its signal.

Options

Configure options in .credo.exs with the check tuple:

%{
  configs: [
    %{
      name: "default",
      checks: [
        {Bylaw.Credo.Check.Elixir.NoLowLevelProcessPrimitives,
         [
           excluded_paths: ["test/support/"]
         ]}
      ]
    }
  ]
}

• :excluded_paths - List of path prefixes or regexes to exclude from this check.

Usage

Add this check to Credo's checks: list in .credo.exs:

%{
  configs: [
    %{
      name: "default",
      checks: [
        {Bylaw.Credo.Check.Elixir.NoLowLevelProcessPrimitives, []}
      ]
    }
  ]
}

Check-Specific Parameters

Use the following parameters to configure this check:

:excluded_paths

List of path prefixes or regexes to exclude from this check.

This parameter defaults to [].

General Parameters

Like with all checks, general params can be applied.

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