Style-HashSlice.md

Pattern: Missing use of Hash#slice

Issue: -

Description

Checks for usages of Hash#reject, Hash#select, and Hash#filter methods that can be replaced with Hash#slice method.

Examples

# bad
{foo: 1, bar: 2, baz: 3}.select {|k, v| k == :bar }
{foo: 1, bar: 2, baz: 3}.reject {|k, v| k != :bar }
{foo: 1, bar: 2, baz: 3}.filter {|k, v| k == :bar }
{foo: 1, bar: 2, baz: 3}.select {|k, v| k.eql?(:bar) }

# bad
{foo: 1, bar: 2, baz: 3}.select {|k, v| %i[bar].include?(k) }
{foo: 1, bar: 2, baz: 3}.reject {|k, v| !%i[bar].include?(k) }
{foo: 1, bar: 2, baz: 3}.filter {|k, v| %i[bar].include?(k) }

# bad
{foo: 1, bar: 2, baz: 3}.select {|k, v| !%i[bar].exclude?(k) }
{foo: 1, bar: 2, baz: 3}.reject {|k, v| %i[bar].exclude?(k) }

# bad
{foo: 1, bar: 2, baz: 3}.select {|k, v| k.in?(%i[bar]) }
{foo: 1, bar: 2, baz: 3}.reject {|k, v| !k.in?(%i[bar]) }

# good
{foo: 1, bar: 2, baz: 3}.slice(:bar)

Further Reading

• RuboCop - Style/HashSlice