I can attach a command with a binding

requirements.txt

@@ -36,7 +36,7 @@ markdown-it-py==4.0.0
 mdurl==0.1.2
 more-itertools==10.8.0
 myauth==0.2.0
-myutils==0.1.0
+myutils==0.4.0
 nh3==0.3.1
 oauthlib==3.3.1
 packaging==25.0

src/myfasthtml/controls/helpers.py

@@ -30,8 +30,7 @@ class mk:
   @staticmethod
   def manage_command(ft, command: Command):
     if command:
-      htmx = command.get_htmx_params()
+      ft = command.bind_ft(ft)
-      ft.attrs |= htmx
     
     return ft
   

src/myfasthtml/core/commands.py

@@ -1,6 +1,8 @@
 import uuid
 from typing import Optional
 
+from myutils.observable import NotObservableError, ObservableEvent, add_event_listener, remove_event_listener
+
 from myfasthtml.core.constants import Routes, ROUTE_ROOT
 
 
@@ -25,13 +27,14 @@ class BaseCommand:
     self.id = uuid.uuid4()
     self.name = name
     self.description = description
-    self.htmx_extra = {}
+    self._htmx_extra = {}
+    self._bindings = []
     
     # register the command
     CommandsManager.register(self)
   
   def get_htmx_params(self):
-    return self.htmx_extra | {
+    return self._htmx_extra | {
         "hx-post": f"{ROUTE_ROOT}{Routes.Commands}",
         "hx-vals": f'{{"c_id": "{self.id}"}}',
     }
@@ -39,9 +42,46 @@ class BaseCommand:
   def execute(self):
     raise NotImplementedError
   
-  def htmx(self, target=None):
+  def htmx(self, target="this", swap="innerHTML"):
-    if target:
+    if target is None:
-      self.htmx_extra["hx-target"] = target
+      self._htmx_extra["hx-swap"] = "none"
+    elif target != "this":
+      self._htmx_extra["hx-target"] = target
+    
+    if swap is None:
+      self._htmx_extra["hx-swap"] = "none"
+    elif swap != "innerHTML":
+      self._htmx_extra["hx-swap"] = swap
+    return self
+  
+  def bind_ft(self, ft):
+    """
+    Update the FT with the command's HTMX parameters.
+
+    :param ft:
+    :return:
+    """
+    htmx = self.get_htmx_params()
+    ft.attrs |= htmx
+    return ft
+  
+  def bind(self, data):
+    """
+    Attach a binding to the command.
+    When done, if a binding is triggered during the execution of the command,
+    the results of the binding will be passed to the command's execute() method.
+    :param data:
+    :return:
+    """
+    if not hasattr(data, '_listeners'):
+      raise NotObservableError(
+        f"Object must be made observable with make_observable() before binding"
+      )
+    self._bindings.append(data)
+    
+    # by default, remove the swap on the attached element when binding is used
+    self._htmx_extra["hx-swap"] = "none"
+    
     return self
 
 
@@ -71,7 +111,26 @@ class Command(BaseCommand):
     self.kwargs = kwargs
   
   def execute(self):
-    return self.callback(*self.args, **self.kwargs)
+    ret_from_bindings = []
+    
+    def binding_result_callback(attr, old, new, results):
+      ret_from_bindings.extend(results)
+    
+    for data in self._bindings:
+      add_event_listener(ObservableEvent.AFTER_PROPERTY_CHANGE, data, "", binding_result_callback)
+    
+    ret = self.callback(*self.args, **self.kwargs)
+    
+    for data in self._bindings:
+      remove_event_listener(ObservableEvent.AFTER_PROPERTY_CHANGE, data, "", binding_result_callback)
+    
+    if not ret_from_bindings:
+      return ret
+    
+    if isinstance(ret, list):
+      return ret + ret_from_bindings
+    else:
+      return [ret] + ret_from_bindings
   
   def __str__(self):
     return f"Command({self.name})"

src/myfasthtml/examples/binding_datalist.py

@@ -27,12 +27,12 @@ class Data:
 
 def add_suggestion():
   nb = len(data.value)
-  data.value.append(f"suggestion{nb}")
+  data.value = data.value + [f"suggestion{nb}"]
 
 
 def remove_suggestion():
   if len(data.value) > 0:
-    data.value.pop()
+    data.value = data.value[:-1]
 
 
 data = Data(["suggestion1", "suggestion2", "suggestion3"])
@@ -49,8 +49,8 @@ def get():
   mk.manage_binding(input_elt, Binding(data))
   mk.manage_binding(label_elt, Binding(data))
   
-  add_button = mk.button("Add", command=Command("Add", "Add a suggestion", add_suggestion))
+  add_button = mk.button("Add", command=Command("Add", "Add a suggestion", add_suggestion).bind(data))
-  remove_button = mk.button("Remove", command=Command("Remove", "Remove a suggestion", remove_suggestion))
+  remove_button = mk.button("Remove", command=Command("Remove", "Remove a suggestion", remove_suggestion).bind(data))
   
   return Div(
     add_button,

tests/core/test_commands.py

@@ -1,6 +1,18 @@
+from dataclasses import dataclass
+from typing import Any
+
 import pytest
+from fasthtml.components import Button
+from myutils.observable import make_observable, bind
 
 from myfasthtml.core.commands import Command, CommandsManager
+from myfasthtml.core.constants import ROUTE_ROOT, Routes
+from myfasthtml.test.matcher import matches
+
+
+@dataclass
+class Data:
+  value: Any
 
 
 def callback():
@@ -23,3 +35,61 @@ def test_i_can_create_a_command_with_no_params():
 def test_command_are_registered():
   command = Command('test', 'Command description', callback)
   assert CommandsManager.commands.get(str(command.id)) is command
+
+
+def test_i_can_bind_a_command_to_an_element():
+  command = Command('test', 'Command description', callback)
+  elt = Button()
+  updated = command.bind_ft(elt)
+  
+  expected = Button(hx_post=f"{ROUTE_ROOT}{Routes.Commands}")
+  
+  assert matches(updated, expected)
+
+
+def test_i_can_suppress_swapping_with_target_attr():
+  command = Command('test', 'Command description', callback).htmx(target=None)
+  elt = Button()
+  updated = command.bind_ft(elt)
+  
+  expected = Button(hx_post=f"{ROUTE_ROOT}{Routes.Commands}", hx_swap="none")
+  
+  assert matches(updated, expected)
+
+
+def test_i_can_bind_a_command_to_an_observable():
+  data = Data("hello")
+  
+  def on_data_change(old, new):
+    return old, new
+  
+  def another_callback():
+    data.value = "new value"
+    return "another callback result"
+  
+  make_observable(data)
+  bind(data, "value", on_data_change)
+  command = Command('test', 'Command description', another_callback).bind(data)
+  
+  res = command.execute()
+  
+  assert res == ["another callback result", ("hello", "new value")]
+
+
+def test_i_can_bind_a_command_to_an_observable_2():
+  data = Data("hello")
+  
+  def on_data_change(old, new):
+    return old, new
+  
+  def another_callback():
+    data.value = "new value"
+    return ["another 1", "another 2"]
+  
+  make_observable(data)
+  bind(data, "value", on_data_change)
+  command = Command('test', 'Command description', another_callback).bind(data)
+  
+  res = command.execute()
+  
+  assert res == ["another 1", "another 2", ("hello", "new value")]