<!--
title: Prefer guard clauses
domain: cloud-infra
topic: Null Handling
language: Ruby
source: chef/chef
updated: 2025-01-06
url: https://awesomereviewers.com/reviewers/chef-prefer-guard-clauses/
-->

Use guard clauses with early returns for null checking instead of wrapping code in conditional blocks. This improves readability by reducing nesting and making the code's "happy path" more evident.

```ruby
# Instead of this:
unless current_record.nil?
  current_record.status = :skipped
  current_record.conditional = conditional
end

# Do this:
return if current_record.nil?
current_record.status = :skipped
current_record.conditional = conditional
```

For method chains with potential null values, use the safe navigation operator (`&.`) instead of explicit conditional blocks:

```ruby
# Instead of:
if license_keys.nil?
  nil
else
  license_keys.empty?
end

# Do this:
license_keys&.empty?
```

When checking for truthiness, use Ruby's idiomatic style which treats only `nil` and `false` as falsey:

```ruby
# Instead of:
unless new_resource.download_url.nil?
  # code
end

# Do this:
if new_resource.download_url
  # code
end
```

Remember to use `.compact` to remove nil values from arrays when needed:

```ruby
array_with_nils.compact  # Returns a new array with all nil elements removed
```

Only use safe navigation when the object might actually be nil. Don't use it on objects that will never be nil, such as class constants:

```ruby
# Unnecessary:
::File&.dirname(path)

# Better:
::File.dirname(path)  # Since ::File will never be nil
```