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class method

ENV.reject!

ENV.reject! { |name, value| block } → ENV or nil
ENV.reject! → an_enumerator

Similar to ENV.delete_if, but returns nil if no changes were made.

Yields each environment variable name and its value as a 2-element Array, deleting each environment variable for which the block returns a truthy value, and returning ENV (if any deletions) or nil (if not):

Example
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2')
ENV.reject! { |name, value| name.start_with?('b') } # => ENV
ENV # => {"foo"=>"0"}
ENV.reject! { |name, value| name.start_with?('b') } # => nil

Returns an Enumerator if no block given:

Example
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2')
e = ENV.reject! # => #<Enumerator: {"bar"=>"1", "baz"=>"2", "foo"=>"0"}:reject!>
e.each { |name, value| name.start_with?('b') } # => ENV
ENV # => {"foo"=>"0"}
e.each { |name, value| name.start_with?('b') } # => nil
See also .reject .replace .rehash .select also in 4.1 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0