class method
ENV.keep_if
ENV.keep_if { |name, value| block } → ENV
ENV.keep_if → an_enumerator
hash.c
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static VALUE
env_keep_if(VALUE ehash)
{
RETURN_SIZED_ENUMERATOR(ehash, 0, 0, rb_env_size);
env_select_bang(ehash);
return envtbl;
}
Yields each environment variable name and its value as a 2-element Array, deleting each environment variable for which the block returns false or nil, and returning ENV:
Example
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') ENV.keep_if { |name, value| name.start_with?('b') } # => ENV ENV # => {"bar"=>"1", "baz"=>"2"}
Returns an Enumerator if no block given:
Example
ENV.replace('foo' => '0', 'bar' => '1', 'baz' => '2') e = ENV.keep_if # => #<Enumerator: {"bar"=>"1", "baz"=>"2", "foo"=>"0"}:keep_if> e.each { |name, value| name.start_with?('b') } # => ENV ENV # => {"bar"=>"1", "baz"=>"2"}