Merge pull request #16 from st0012/add-and_print-method

Add TappingDevice#and_print method

README.md

@@ -30,9 +30,7 @@ class PostsController < ApplicationController
 
   def show
     @post = Post.find(params[:id])
-    tap_on!(@post) do |payload|
-      puts(payload.method_name_and_location)
-    end
+    tap_on!(@post).and_print(:method_name_and_location)
   end
 end
 ```
@@ -51,9 +49,7 @@ to_param FROM /RUBY_PATH/gems/2.6.0/gems/actionpack-5.2.0/lib/action_dispatch/ro
 Or you can use `tap_assoc!`. This is very useful for tracking potential n+1 query calls, here’s a sample from my work
 
 ```ruby
-tap_assoc!(order) do |payload|
-  puts(payload.method_name_and_location)
-end
+tap_assoc!(order).and_print(:method_name_and_location)
 ```
 
 ```
@@ -193,9 +189,7 @@ initialize @ Student
 - `filter_by_paths: [/path/]` - only contain calls from the specified paths
 
 ```ruby
-tap_on!(@post, exclude_by_paths: [/active_record/]) do |payload|
-  puts(payload.method_name_and_location)
-end
+tap_on!(@post, exclude_by_paths: [/active_record/]).and_print(:method_name_and_location)
 ```
 
 ```
@@ -236,9 +230,7 @@ class PostsController < ApplicationController
   before_action :set_post, only: [:show, :edit, :update, :destroy]
 
   def show
-    tap_on!(@post) do |payload|
-      puts(payload.method_name_and_location)
-    end
+    tap_on!(@post).and_print(:method_name_and_location)
   end
 end
 ```
@@ -287,9 +279,7 @@ Passed as 'record_or_hash_or_array' in method ':polymorphic_method'
 ### `tap_assoc!`
 
 ```ruby
-tap_assoc!(order) do |payload|
-  puts(payload.method_name_and_location)
-end
+tap_assoc!(order).and_print(:method_name_and_location)
 ```
 
 ```

lib/tapping_device.rb

@@ -21,6 +21,7 @@ class TappingDevice
 
   def initialize(options = {}, &block)
     @block = block
+    @output_block = nil
     @options = process_options(options)
     @calls = []
     @disabled = false
@@ -45,6 +46,10 @@ def tap_assoc!(record)
     track(record, condition: :tap_associations?)
   end
 
+  def and_print(payload_method)
+    @output_block = -> (payload) { puts(payload.send(payload_method)) }
+  end
+
   def set_block(&block)
     @block = block
   end
@@ -208,6 +213,8 @@ def is_from_target?(object, tp)
   def record_call!(payload)
     return if @disabled
 
+    @output_block.call(payload) if @output_block
+
     if @block
       root_device.calls << @block.call(payload)
     else

spec/tapping_device_spec.rb

@@ -283,6 +283,19 @@ def foo(obj)
     end
   end
 
+  describe "#and_print" do
+    let(:device) { described_class.new }
+
+    it "outputs payload with given payload method" do
+      stan = Student.new("Stan", 18)
+      device.tap_on!(stan).and_print(:method_name_and_arguments)
+
+      expect do
+        stan.name
+      end.to output("name <= {}\n").to_stdout
+    end
+  end
+
   describe ".devices" do
     it "stores all initialized devices" do
       device_1 = described_class.new