Deprecate constructor as a block

docsite/source/index.html.md

@@ -28,7 +28,7 @@ class App
   end
   # Defaults to nil if no default value is given
   setting :adapter
-  # Pre-process values
+  # Construct values
   setting(:path, 'test') { |value| Pathname(value) }
   # Passing the reader option as true will create attr_reader method for the class
   setting :pool, 5, reader: true

lib/dry/configurable/dsl.rb

@@ -5,6 +5,7 @@
 require 'dry/configurable/settings'
 require 'dry/configurable/compiler'
 require 'dry/configurable/dsl/args'
+require 'dry/core/deprecations'
 
 module Dry
   module Configurable
@@ -49,6 +50,11 @@ def setting(name, *args, &block)
           if block.arity.zero?
             ast << [:nested, [node, DSL.new(&block).ast]]
           else
+            Dry::Core::Deprecations.announce(
+              'passing a constructor as a block',
+              'Provide a `constructor:` keyword argument instead',
+              tag: 'dry-configurable'
+            )
             ast << [:constructor, [node, block]]
           end
         else

spec/integration/dry/configurable/setting_spec.rb

@@ -97,9 +97,9 @@
       end
     end
 
-    context 'with a value pre-processor' do
-      it 'pre-processes the value with nil default' do
-        klass.setting(:path, nil) { |value| "test:#{value || "fallback"}" }
+    context 'with a value constructor' do
+      it 'constructs the value with nil default' do
+        klass.setting(:path, nil, constructor: ->(value) { "test:#{value || "fallback"}" })
 
         expect(object.config.path).to eql("test:fallback")
 
@@ -110,22 +110,20 @@
         expect(object.config.path).to eql('test:foo')
       end
 
-      it 'pre-processes the value with undefined default' do
-        klass.setting(:path) { |value| "test:#{value || "fallback"}" }
+      it 'constructs the value with undefined default' do
+        klass.setting(:path, constructor: ->(value) { "test:#{value || "fallback"}" })
 
         expect(object.config.path).to eql('test:fallback')
       end
 
-      it 'pre-processes the value with non-nil default' do
-        klass.setting(:path, 'test') { |value| Pathname(value) }
+      it 'constructs the value with non-nil default' do
+        klass.setting(:path, 'test', constructor: ->(value) { Pathname(value) })
 
         expect(object.config.path).to eql(Pathname('test'))
       end
 
-      it 'raises pre-processor errors immediately' do
-        klass.setting :failable do |value|
-          value.to_sym unless value.nil?
-        end
+      it 'raises constructor errors immediately' do
+        klass.setting(:failable, constructor: ->(value) { value.to_sym unless value.nil? })
 
         expect {
           object.config.failable = 12
@@ -316,7 +314,7 @@
     end
 
     it 'creates distinct setting values across instances' do
-      klass.setting(:path, 'test') { |m| Pathname(m) }
+      klass.setting(:path, 'test', constructor: ->(m) { Pathname(m) })
 
       new_object = klass.new
 

spec/unit/dry/configurable/dsl_spec.rb

@@ -43,6 +43,15 @@
   end
 
   it 'compiles a setting with a constructor' do
+    setting = dsl.setting(:dsn, 'sqlite', constructor: ->(value) { "jdbc:#{value}" })
+
+    expect(setting.name).to be(:dsn)
+    expect(setting.value).to eql('jdbc:sqlite')
+  end
+
+  it 'supports but deprecates giving a constructor as a block' do
+    expect(Dry::Core::Deprecations).to receive(:announce)
+
     setting = dsl.setting(:dsn, 'sqlite') { |value| "jdbc:#{value}" }
 
     expect(setting.name).to be(:dsn)