Merge pull request #1145 from pranavbabu/main

Add Money.with_bank for Dynamic Currency Stores

Author: yukideluxe

CHANGELOG.md

@@ -22,6 +22,7 @@
 - Add `Currency#cents_based?` to check if currency is cents-based
 - Add ability to nest `Money.with_rounding_mode` blocks
 - Allow `nil` to be used as a default_currency
+- Add ability to nest `Money.with_bank` blocks
 
 ## 6.19.0
 

lib/money/money.rb

@@ -154,14 +154,37 @@ def self.default_currency=(currency)
     @default_currency = currency
   end
 
+  # Modified to support thread-local bank override
   def self.default_bank
+    # Check for thread-local bank first, then fall back to global default
+    return Thread.current[:money_bank] if Thread.current[:money_bank]
+
     if @default_bank.respond_to?(:call)
       @default_bank.call
     else
       @default_bank
     end
   end
 
+  # Thread-safe bank switching method
+  # Temporarily changes the default bank in the current thread only
+  #
+  # @param [Money::Bank::Base] bank The bank to use within the block
+  # @yield The block within which the bank will be changed
+  # @return [Object] block results
+  #
+  # @example
+  #   Money.with_bank(european_bank) do
+  #     Money.new(100, "USD").exchange_to("EUR")
+  #   end
+  def self.with_bank(bank)
+    original_bank = Thread.current[:money_bank]
+    Thread.current[:money_bank] = bank
+    yield
+  ensure
+    Thread.current[:money_bank] = original_bank
+  end
+
   def self.locale_backend=(value)
     @locale_backend = value ? LocaleBackend.find(value) : nil
   end

sig/lib/money/money.rbs

@@ -233,6 +233,18 @@ class Money
   #   end
   def self.with_rounding_mode: (untyped mode) { () -> untyped } -> untyped
 
+  # Temporarily changes the default bank in the current thread only
+  #
+  # @param [Money::Bank::Base] bank The bank to use within the block
+  # @yield The block within which the bank will be changed
+  # @return [Object] block results
+  #
+  # @example
+  #   Money.with_bank(european_bank) do
+  #     Money.new(100, "USD").exchange_to("EUR")
+  #   end
+  def self.with_bank: (Money::Bank::Base bank) { () -> untyped } -> untyped
+
   # Adds a new exchange rate to the default bank and return the rate.
   #
   # @param [Currency, String, Symbol] from_currency Currency to exchange from.

spec/money_spec.rb

@@ -310,6 +310,65 @@
     end
   end
 
+  describe '.with_bank' do
+    it 'fallbacks to old bank after block' do
+      old_bank = Money.default_bank
+
+      bank = Money::Bank::VariableExchange.new
+
+      Money.with_bank(bank) {}
+      expect(Money.default_bank).to eq(old_bank)
+    end
+
+    it "uses the correct bank inside block" do
+      old_bank = Money.default_bank
+      custom_store = double
+      bank = Money::Bank::VariableExchange.new(custom_store)
+      Money.with_bank(bank) do
+        expect(custom_store).to receive(:add_rate).with("USD", "EUR", 0.5)
+        Money.add_rate("USD", "EUR", 0.5)
+      end
+
+      expect(old_bank).to receive(:add_rate).with("UAH", "NOK", 0.8)
+      Money.add_rate("UAH", "NOK", 0.8)
+    end
+
+    it 'safely handles concurrent usage in different threads' do
+      results = []
+      results_mutex = Mutex.new
+      threads = []
+
+      custom_store = double
+      custom_bank = Money::Bank::VariableExchange.new(custom_store)
+
+      2.times do |i|
+        threads << Thread.new do
+          bank_to_use = custom_bank
+          expected_bank = custom_bank
+
+          Money.with_bank(bank_to_use) do
+            sleep(0.01)
+
+            actual_bank = ::Money.default_bank
+            result = {
+              thread_id: Thread.current.object_id,
+              expected: expected_bank,
+              actual: actual_bank,
+              match: expected_bank == actual_bank
+            }
+            results_mutex.synchronize do
+              results << result
+            end
+          end
+        end
+      end
+
+      threads.each(&:join)
+      mismatches = results.reject { |r| r[:match] }
+      expect(mismatches.length).to be_zero
+    end
+  end
+
   %w[cents pence].each do |units|
     describe "##{units}" do
       it "is a synonym of #fractional" do