Remove instance_eval from InspectionTree (#210)

The InspectionTree class defines methods that create nodes in the tree.
Some of these methods take a block which is `instance_eval`'ed inside of
a new subtree. This use of `instance_eval` may seem to create a very
clean and easy to use API on the surface, but it quickly breaks down if,
as you are defining your InspectionTree, you need to extract methods
inside of your InspectionTreeBuilder and then reference them. _Not_
`instance_eval`'ing creates footguns, but it also removes the magic and
mystery around how InspectionTree works.

Author: mcmire

lib/super_diff/active_record/object_inspection/inspection_tree_builders/active_record_model.rb

@@ -8,27 +8,39 @@ def self.applies_to?(value)
           end
 
           def call
-            SuperDiff::ObjectInspection::InspectionTree.new do
-              as_lines_when_rendering_to_lines(collection_bookend: :open) do
-                add_text { |object| "#<#{object.class} " }
+            SuperDiff::ObjectInspection::InspectionTree.new do |t1|
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :open
+              ) do |t2|
+                t2.add_text "#<#{object.class} "
 
-                when_rendering_to_lines { add_text "{" }
+                # stree-ignore
+                t2.when_rendering_to_lines do |t3|
+                  t3.add_text "{"
+                end
               end
 
-              nested do |object|
-                insert_separated_list(
+              t1.nested do |t2|
+                t2.insert_separated_list(
                   ["id"] + (object.attributes.keys.sort - ["id"])
-                ) do |name|
-                  as_prefix_when_rendering_to_lines { add_text "#{name}: " }
+                ) do |t3, name|
+                  t3.as_prefix_when_rendering_to_lines do |t4|
+                    t4.add_text "#{name}: "
+                  end
 
-                  add_inspection_of object.read_attribute(name)
+                  t3.add_inspection_of object.read_attribute(name)
                 end
               end
 
-              as_lines_when_rendering_to_lines(collection_bookend: :close) do
-                when_rendering_to_lines { add_text "}" }
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :close
+              ) do |t2|
+                # stree-ignore
+                t2.when_rendering_to_lines do |t3|
+                  t3.add_text "}"
+                end
 
-                add_text ">"
+                t2.add_text ">"
               end
             end
           end

lib/super_diff/active_record/object_inspection/inspection_tree_builders/active_record_relation.rb

@@ -8,15 +8,24 @@ def self.applies_to?(value)
           end
 
           def call
-            SuperDiff::ObjectInspection::InspectionTree.new do
-              as_lines_when_rendering_to_lines(collection_bookend: :open) do
-                add_text "#<ActiveRecord::Relation ["
+            SuperDiff::ObjectInspection::InspectionTree.new do |t1|
+              # stree-ignore
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :open
+              ) do |t2|
+                t2.add_text "#<ActiveRecord::Relation ["
               end
 
-              nested { |array| insert_array_inspection_of(array) }
+              # stree-ignore
+              t1.nested do |t2|
+                t2.insert_array_inspection_of(object)
+              end
 
-              as_lines_when_rendering_to_lines(collection_bookend: :close) do
-                add_text "]>"
+              # stree-ignore
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :close
+              ) do |t2|
+                t2.add_text "]>"
               end
             end
           end

lib/super_diff/active_support/object_inspection/inspection_tree_builders/hash_with_indifferent_access.rb

@@ -8,19 +8,34 @@ def self.applies_to?(value)
           end
 
           def call
-            SuperDiff::ObjectInspection::InspectionTree.new do
-              as_lines_when_rendering_to_lines(collection_bookend: :open) do
-                add_text "#<HashWithIndifferentAccess {"
+            SuperDiff::ObjectInspection::InspectionTree.new do |t1|
+              # stree-ignore
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :open
+              ) do |t2|
+                t2.add_text "#<HashWithIndifferentAccess {"
               end
 
-              when_rendering_to_string { add_text " " }
+              # stree-ignore
+              t1.when_rendering_to_string do |t2|
+                t2.add_text " "
+              end
 
-              nested { |hash| insert_hash_inspection_of(hash) }
+              # stree-ignore
+              t1.nested do |t2|
+                t2.insert_hash_inspection_of(object)
+              end
 
-              when_rendering_to_string { add_text " " }
+              # stree-ignore
+              t1.when_rendering_to_string do |t2|
+                t2.add_text " "
+              end
 
-              as_lines_when_rendering_to_lines(collection_bookend: :close) do
-                add_text "}>"
+              # stree-ignore
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :close
+              ) do |t2|
+                t2.add_text "}>"
               end
             end
           end

lib/super_diff/active_support/object_inspection/inspection_tree_builders/ordered_options.rb

@@ -8,21 +8,34 @@ def self.applies_to?(value)
           end
 
           def call
-            SuperDiff::ObjectInspection::InspectionTree.new do
-              as_lines_when_rendering_to_lines(collection_bookend: :open) do
-                add_text "#<OrderedOptions {"
+            SuperDiff::ObjectInspection::InspectionTree.new do |t1|
+              # stree-ignore
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :open
+              ) do |t2|
+                t2.add_text "#<OrderedOptions {"
               end
 
-              when_rendering_to_string { add_text " " }
+              # stree-ignore
+              t1.when_rendering_to_string do |t2|
+                t2.add_text " "
+              end
 
-              nested do |ordered_options|
-                insert_hash_inspection_of(ordered_options.to_hash)
+              # stree-ignore
+              t1.nested do |t2|
+                t2.insert_hash_inspection_of(object.to_hash)
               end
 
-              when_rendering_to_string { add_text " " }
+              # stree-ignore
+              t1.when_rendering_to_string do |t2|
+                t2.add_text " "
+              end
 
-              as_lines_when_rendering_to_lines(collection_bookend: :close) do
-                add_text "}>"
+              # stree-ignore
+              t1.as_lines_when_rendering_to_lines(
+                collection_bookend: :close
+              ) do |t2|
+                t2.add_text "}>"
               end
             end
           end

lib/super_diff/object_inspection/inspection_tree.rb

@@ -7,7 +7,7 @@ def initialize(disallowed_node_names: [], &block)
         @disallowed_node_names = disallowed_node_names
         @nodes = []
 
-        instance_eval(&block) if block
+        evaluate_block(&block) if block
       end
 
       Nodes.registry.each do |node_class|
@@ -26,8 +26,7 @@ def before_each_callbacks
 
       def render_to_string(object)
         nodes.reduce("") do |string, node|
-          result = node.render_to_string(object)
-          string + result
+          string + node.render_to_string(object)
         end
       end
 
@@ -52,43 +51,45 @@ def render_to_lines(object, type:, indentation_level:)
           .first
       end
 
-      def evaluate_block(object, &block)
-        instance_exec(object, &block)
+      def evaluate_block(*args, &block)
+        block.call(self, *args)
       end
 
       def insert_array_inspection_of(array)
-        insert_separated_list(array) do |value|
+        insert_separated_list(array) do |t, value|
           # Have to do these shenanigans so that if value is a hash, Ruby
           # doesn't try to interpret it as keyword args
           if SuperDiff::Helpers.ruby_version_matches?(">= 2.7.1")
-            add_inspection_of(value, **{})
+            t.add_inspection_of(value, **{})
           else
-            add_inspection_of(*[value, {}])
+            t.add_inspection_of(*[value, {}])
           end
         end
       end
 
       def insert_hash_inspection_of(hash)
         keys = hash.keys
-
         format_keys_as_kwargs = keys.all? { |key| key.is_a?(Symbol) }
 
-        insert_separated_list(keys) do |key|
+        insert_separated_list(keys) do |t1, key|
           if format_keys_as_kwargs
-            as_prefix_when_rendering_to_lines { add_text "#{key}: " }
+            # stree-ignore
+            t1.as_prefix_when_rendering_to_lines do |t2|
+              t2.add_text "#{key}: "
+            end
           else
-            as_prefix_when_rendering_to_lines do
-              add_inspection_of key, as_lines: false
-              add_text " => "
+            t1.as_prefix_when_rendering_to_lines do |t2|
+              t2.add_inspection_of key, as_lines: false
+              t2.add_text " => "
             end
           end
 
           # Have to do these shenanigans so that if hash[key] is a hash, Ruby
           # doesn't try to interpret it as keyword args
           if SuperDiff::Helpers.ruby_version_matches?(">= 2.7.1")
-            add_inspection_of(hash[key], **{})
+            t1.add_inspection_of(hash[key], **{})
           else
-            add_inspection_of(*[hash[key], {}])
+            t1.add_inspection_of(*[hash[key], {}])
           end
         end
       end
@@ -97,10 +98,14 @@ def insert_separated_list(enumerable, &block)
         enumerable.each_with_index do |value, index|
           as_lines_when_rendering_to_lines(
             add_comma: index < enumerable.size - 1
-          ) do
-            when_rendering_to_string { add_text " " } if index > 0
-
-            evaluate_block(value, &block)
+          ) do |t1|
+            if index > 0
+              # stree-ignore
+              t1.when_rendering_to_string do |t2|
+                t2.add_text " "
+              end
+            end
+            t1.evaluate_block(value, &block)
           end
         end
       end

lib/super_diff/object_inspection/inspection_tree_builders/array.rb

@@ -7,27 +7,46 @@ def self.applies_to?(value)
         end
 
         def call
-          empty = -> { object.empty? }
-          nonempty = -> { !object.empty? }
-
-          InspectionTree.new do
-            only_when empty do
-              as_lines_when_rendering_to_lines { add_text "[]" }
+          InspectionTree.new do |t1|
+            t1.only_when empty do |t2|
+              # stree-ignore
+              t2.as_lines_when_rendering_to_lines do |t3|
+                t3.add_text "[]"
+              end
             end
 
-            only_when nonempty do
-              as_lines_when_rendering_to_lines(collection_bookend: :open) do
-                add_text "["
+            t1.only_when nonempty do |t2|
+              # stree-ignore
+              t2.as_lines_when_rendering_to_lines(
+                collection_bookend: :open
+              ) do |t3|
+                t3.add_text "["
               end
 
-              nested { |array| insert_array_inspection_of(array) }
+              # stree-ignore
+              t2.nested do |t3|
+                t3.insert_array_inspection_of(object)
+              end
 
-              as_lines_when_rendering_to_lines(collection_bookend: :close) do
-                add_text "]"
+              # stree-ignore
+              t2.as_lines_when_rendering_to_lines(
+                collection_bookend: :close
+              ) do |t3|
+                t3.add_text "]"
               end
             end
           end
         end
+
+        private
+
+        def empty
+          -> { object.empty? }
+        end
+
+        def nonempty
+          -> { !object.empty? }
+        end
       end
     end
   end

lib/super_diff/object_inspection/inspection_tree_builders/custom_object.rb

@@ -7,21 +7,31 @@ def self.applies_to?(value)
         end
 
         def call
-          InspectionTree.new do
-            as_lines_when_rendering_to_lines(collection_bookend: :open) do
-              add_text { |object| "#<#{object.class} " }
+          InspectionTree.new do |t1|
+            t1.as_lines_when_rendering_to_lines(
+              collection_bookend: :open
+            ) do |t2|
+              t2.add_text "#<#{object.class} "
 
-              when_rendering_to_lines { add_text "{" }
+              # stree-ignore
+              t2.when_rendering_to_lines do |t3|
+                t3.add_text "{"
+              end
             end
 
-            nested do |object|
-              insert_hash_inspection_of(object.attributes_for_super_diff)
+            t1.nested do |t2|
+              t2.insert_hash_inspection_of(object.attributes_for_super_diff)
             end
 
-            as_lines_when_rendering_to_lines(collection_bookend: :close) do
-              when_rendering_to_lines { add_text "}" }
+            t1.as_lines_when_rendering_to_lines(
+              collection_bookend: :close
+            ) do |t2|
+              # stree-ignore
+              t2.when_rendering_to_lines do |t3|
+                t3.add_text "}"
+              end
 
-              add_text ">"
+              t2.add_text ">"
             end
           end
         end