Automatically materialize USB and CAN mixins for compatibility

electronics_abstract_parts/IoController.py

@@ -1,5 +1,5 @@
 from itertools import chain
-from typing import List, Dict, Tuple, Type
+from typing import List, Dict, Tuple, Type, Optional
 
 from deprecated import deprecated
 
@@ -25,6 +25,14 @@ def __init__(self, *args, **kwargs) -> None:
     self.i2c = self.Port(Vector(I2cController.empty()), optional=True)
     self.uart = self.Port(Vector(UartPort.empty()), optional=True)
 
+    # USB and CAN are now mixins, but automatically materialized for compatibility and simplicity
+    # In new code, explicit mixin syntax should be used.
+    self.usb: Vector[UsbDevicePort]
+    self.can: Vector[CanControllerPort]
+    from electronics_abstract_parts import IoControllerUsb, IoControllerCan
+    self._usb_mixin: Optional[IoControllerUsb] = None
+    self._can_mixin: Optional[IoControllerCan] = None
+
     self.spi_peripheral = self.Port(Vector(SpiPeripheral.empty()), optional=True)
     self.i2c_target = self.Port(Vector(I2cTarget.empty()), optional=True)
 
@@ -33,6 +41,22 @@ def __init__(self, *args, **kwargs) -> None:
     self._io_ports: List[BasePort] = [  # ordered by assignment order, most restrictive should be first
       self.adc, self.spi, self.i2c, self.uart, self.spi_peripheral, self.i2c_target, self.gpio]
 
+  def __getattr__(self, item):
+    # automatically materialize USB and CAN mixins on abstract classes, only if this is IoController
+    # note, getattr ONLY called when the field does not exist, and hasattr is implemented via getattr
+    if self.__class__ is IoController and item == 'usb':
+      if self._usb_mixin is None:
+        from electronics_abstract_parts import IoControllerUsb
+        self._usb_mixin = self.with_mixin(IoControllerUsb())
+      return self._usb_mixin.usb
+    elif self.__class__ is IoController and item == 'can':
+      if self._can_mixin is None:
+        from electronics_abstract_parts import IoControllerCan
+        self._can_mixin = self.with_mixin(IoControllerCan())
+      return self._can_mixin.can
+    else:
+      raise AttributeError(item)  # ideally we'd use super().__getattr__(...), but that's not defined in base classes
+
   def _type_of_io(self, io_port: BasePort) -> Type[Port]:
     if isinstance(io_port, Vector):
       return io_port.elt_type()

examples/test_can_adapter.py

@@ -30,10 +30,9 @@ def contents(self) -> None:
     ) as imp:
       self.mcu = imp.Block(IoController())
 
-      (self.usb_esd, ), _ = self.chain(self.usb.usb, imp.Block(UsbEsdDiode()),
-                                       self.mcu.with_mixin(IoControllerUsb()).usb.request())
-      (self.xcvr, ), self.can_chain = self.chain(self.mcu.with_mixin(IoControllerCan()).can.request('can'),
-                                                 imp.Block(Iso1050dub()))
+      # this uses the legacy / simple (non-mixin) USB and CAN IO style
+      (self.usb_esd, ), _ = self.chain(self.usb.usb, imp.Block(UsbEsdDiode()), self.mcu.usb.request())
+      (self.xcvr, ), self.can_chain = self.chain(self.mcu.can.request('can'), imp.Block(Iso1050dub()))
 
       (self.sw_usb, ), _ = self.chain(imp.Block(DigitalSwitch()), self.mcu.gpio.request('sw_usb'))
       (self.sw_can, ), _ = self.chain(imp.Block(DigitalSwitch()), self.mcu.gpio.request('sw_can'))

examples/test_datalogger.py

@@ -51,10 +51,10 @@ def contents(self) -> None:
     ) as imp:
       self.mcu = imp.Block(IoController())
 
-      self.connect(self.mcu.with_mixin(IoControllerUsb()).usb.request(), self.usb_conn.usb)
+      # this uses the legacy / simple (non-mixin) USB and CAN IO style
+      self.connect(self.mcu.usb.request(), self.usb_conn.usb)
 
-      (self.can, ), _ = self.chain(self.mcu.with_mixin(IoControllerCan()).can.request('can'),
-                                   imp.Block(CalSolCanBlock()))
+      (self.can, ), _ = self.chain(self.mcu.can.request('can'), imp.Block(CalSolCanBlock()))
 
       # TODO need proper support for exported unconnected ports
       self.can_gnd_load = self.Block(DummyVoltageSink())