work with singletons without new_entity

README.md

@@ -259,6 +259,9 @@ class InitConfigSystem < ECS::System
   def init
     config = ...some config initializatio
     @world.new_entity.add(Config.new(config))
+
+    # another way
+    @world.add(Config.new(config)) unless @world.component_exists?(Config)
   end
 end
 

spec/myecs_spec.cr

@@ -463,6 +463,17 @@ describe ECS::Singleton do
     world.getConfig.value.should eq 100
     world.getConfig_ptr.value.value.should eq 100
   end
+
+  it "can be added and deleted from a world" do
+    world = ECS::World.new
+    expect_raises(Exception) { world.getConfig }
+    world.getConfig?.should be_nil
+    world.add(Config.new(100))
+    world.getConfig?.should be_truthy
+    world.getConfig.value.should eq 100
+    world.remove(Config)
+    world.getConfig?.should be_nil
+  end
 end
 
 class SystemGenerateEvent(Event) < ECS::System

src/myecs.cr

@@ -635,16 +635,33 @@ module ECS
         {% if obj.annotation(ECS::Singleton) %}
           {% obj_name = obj.id.split("::").last.id %}
           def get{{obj_name}}
-          @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).get_component?(Entity.new(self, NO_ENTITY)) || raise "{{obj}} was not created"
+          @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).get_component?(NO_ENTITY) || raise "{{obj}} was not created"
           end
 
           def get{{obj_name}}?
-            @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).get_component?(Entity.new(self, NO_ENTITY))
+            @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).get_component?(NO_ENTITY)
           end
 
           def get{{obj_name}}_ptr
-            @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).get_component_ptr(Entity.new(self, NO_ENTITY))
+            @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).get_component_ptr(NO_ENTITY)
           end
+
+          def add(comp : {{obj}})
+            @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).add_component(NO_ENTITY, comp)
+          end
+
+          def set(comp : {{obj}})
+            @pools[{{COMP_INDICES[obj]}}].as(Pool({{obj}})).add_or_update_component(NO_ENTITY, comp)
+          end
+
+          def remove(typ : {{obj}}.class)
+            @pools[{{COMP_INDICES[obj]}}].remove_component(NO_ENTITY)
+          end
+
+          def remove_if_present(typ : {{obj}}.class)
+            @pools[{{COMP_INDICES[obj]}}].try_remove_component(NO_ENTITY)
+          end
+
         {% end %}
 
       {% end %}