From ea3a298aba95ce38b6fe7744ff570193d3ffc752 Mon Sep 17 00:00:00 2001
From: nick evans <nick@rubinick.dev>
Date: Thu, 20 Jun 2024 07:29:40 -0400
Subject: [PATCH] =?UTF-8?q?=F0=9F=94=A7=20Add=20Config#with(**attrs)=20to?=
 =?UTF-8?q?=20make=20child=20configs?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 lib/net/imap/config.rb       | 18 ++++++++++++++++++
 test/net/imap/test_config.rb | 25 +++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/lib/net/imap/config.rb b/lib/net/imap/config.rb
index 9f1540bc0..10740ffb9 100644
--- a/lib/net/imap/config.rb
+++ b/lib/net/imap/config.rb
@@ -165,6 +165,24 @@ def update(**attrs)
         self
       end
 
+      # :call-seq:
+      #   with(**attrs) -> config
+      #   with(**attrs) {|config| } -> result
+      #
+      # Without a block, returns a new config which inherits from self.  With a
+      # block, yields the new config and returns the block's result.
+      #
+      # If no keyword arguments are given, an ArgumentError will be raised.
+      #
+      # If +self+ is frozen, the copy will also be frozen.
+      def with(**attrs)
+        attrs.empty? and
+          raise ArgumentError, "expected keyword arguments, none given"
+        copy = new(**attrs)
+        copy.freeze if frozen?
+        block_given? ? yield(copy) : copy
+      end
+
       # :call-seq: to_h -> hash
       #
       # Returns all config attributes in a hash.
diff --git a/test/net/imap/test_config.rb b/test/net/imap/test_config.rb
index 2e90e3ef0..d8d2ef6eb 100644
--- a/test/net/imap/test_config.rb
+++ b/test/net/imap/test_config.rb
@@ -212,4 +212,29 @@ class ConfigTest < Test::Unit::TestCase
     assert_same false, config.sasl_ir?     # unchanged
   end
 
+  test "#with" do
+    orig = Config.new(open_timeout: 123, sasl_ir: false)
+    assert_raise(ArgumentError) do
+      orig.with
+    end
+    copy = orig.with(open_timeout: 456, idle_response_timeout: 789)
+    refute copy.frozen?
+    assert_same orig, copy.parent
+    assert_equal 123, orig.open_timeout # unchanged
+    assert_equal 456, copy.open_timeout
+    assert_equal 789, copy.idle_response_timeout
+    vals = nil
+    result = orig.with(open_timeout: 99, idle_response_timeout: 88) do |c|
+      vals = [c.open_timeout, c.idle_response_timeout, c.frozen?]
+      :result
+    end
+    assert_equal :result, result
+    assert_equal [99, 88, false], vals
+    orig.freeze
+    result = orig.with(open_timeout: 11) do |c|
+      vals = [c.open_timeout, c.idle_response_timeout, c.frozen?]
+    end
+    assert_equal [11, 5, true], vals
+  end
+
 end