Avoid array and hash constructor when empty


ID: ruby-best-practices/literal-hash-array

Language: Ruby

Severity: Notice

Category: Best Practices


The rule “Avoid array and hash constructor when empty” is an important practice in Ruby for creating empty arrays and hashes. It dictates that developers should use literal constructors [] for arrays and {} for hashes rather than Array.new and Hash.new when the array or hash being created is empty.

This rule is important because it promotes code readability and simplicity. The literal constructors [] and {} are concise, straightforward, and are commonly used in the Ruby community. Using these instead of Array.new and Hash.new makes the code easier to read and understand.

To adhere to this rule, always use [] to initialize an empty array and {} to initialize an empty hash. However, it is acceptable to use Array.new and Hash.new when you are initializing an array or hash with default values, as demonstrated in the compliant code example.

Non-Compliant Code Examples

foo = Array.new
bar = Hash.new

Compliant Code Examples

foo = []
bar = {}
# Okay since they contain values
baz = Array.new(42) 
qux = Hash.new(99)
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