not as bad as I was thinking it would be

esphome/components/template/select/__init__.py

@@ -17,6 +17,9 @@ from .. import template_ns
 TemplateSelect = template_ns.class_(
     "TemplateSelect", select.Select, cg.PollingComponent
 )
+TemplateSelectWithSetAction = template_ns.class_(
+    "TemplateSelectWithSetAction", TemplateSelect
+)
 
 
 def validate(config):
@@ -62,7 +65,9 @@ CONFIG_SCHEMA = cv.All(
 
 
 async def to_code(config):
-    var = cg.new_Pvariable(config[CONF_ID])
+    # Use subclass with trigger only when set_action is configured
+    cls = TemplateSelectWithSetAction if CONF_SET_ACTION in config else TemplateSelect
+    var = cg.new_Pvariable(config[CONF_ID], cls)
     await cg.register_component(var, config)
     await select.register_select(var, config, options=config[CONF_OPTIONS])
 
@@ -87,7 +92,6 @@ async def to_code(config):
             cg.add(var.set_restore_value(True))
 
     if CONF_SET_ACTION in config:
-        cg.add_define("USE_TEMPLATE_SELECT_SET_TRIGGER")
         await automation.build_automation(
             var.get_set_trigger(), [(cg.StringRef, "x")], config[CONF_SET_ACTION]
         )

esphome/components/template/select/template_select.cpp

@@ -41,10 +41,6 @@ void TemplateSelect::update() {
 }
 
 void TemplateSelect::control(size_t index) {
-#ifdef USE_TEMPLATE_SELECT_SET_TRIGGER
-  this->set_trigger_->trigger(StringRef(this->option_at(index)));
-#endif
-
   if (this->optimistic_)
     this->publish_state(index);
 
@@ -52,6 +48,11 @@ void TemplateSelect::control(size_t index) {
     this->pref_.save(&index);
 }
 
+void TemplateSelectWithSetAction::control(size_t index) {
+  this->set_trigger_.trigger(StringRef(this->option_at(index)));
+  TemplateSelect::control(index);
+}
+
 void TemplateSelect::dump_config() {
   LOG_SELECT("", "Template Select", this);
   LOG_UPDATE_INTERVAL(this);

esphome/components/template/select/template_select.h

@@ -9,7 +9,8 @@
 
 namespace esphome::template_ {
 
-class TemplateSelect final : public select::Select, public PollingComponent {
+/// Base template select class - used when no set_action is configured
+class TemplateSelect : public select::Select, public PollingComponent {
  public:
   template<typename F> void set_template(F &&f) { this->f_.set(std::forward<F>(f)); }
 
@@ -18,9 +19,6 @@ class TemplateSelect final : public select::Select, public PollingComponent {
   void dump_config() override;
   float get_setup_priority() const override { return setup_priority::HARDWARE; }
 
-#ifdef USE_TEMPLATE_SELECT_SET_TRIGGER
-  Trigger<StringRef> *get_set_trigger() const { return this->set_trigger_; }
-#endif
   void set_optimistic(bool optimistic) { this->optimistic_ = optimistic; }
   void set_initial_option_index(size_t initial_option_index) { this->initial_option_index_ = initial_option_index; }
   void set_restore_value(bool restore_value) { this->restore_value_ = restore_value; }
@@ -30,12 +28,19 @@ class TemplateSelect final : public select::Select, public PollingComponent {
   bool optimistic_ = false;
   size_t initial_option_index_{0};
   bool restore_value_ = false;
-#ifdef USE_TEMPLATE_SELECT_SET_TRIGGER
-  Trigger<StringRef> *set_trigger_ = new Trigger<StringRef>();
-#endif
   TemplateLambda<std::string> f_;
 
   ESPPreferenceObject pref_;
 };
 
+/// Template select with set_action trigger - only instantiated when set_action is configured
+class TemplateSelectWithSetAction final : public TemplateSelect {
+ public:
+  Trigger<StringRef> *get_set_trigger() { return &this->set_trigger_; }
+
+ protected:
+  void control(size_t index) override;
+  Trigger<StringRef> set_trigger_;
+};
+
 }  // namespace esphome::template_