Read only mac address rp2040

[dhalbert]

EDIT: Also fixes #7357.

https://forums.adafruit.com/viewtopic.php?p=952638: user found AttributeError message confusing when trying to set MAC address on Pico W. The attribute exists, despite the message, but is not settable (currently?) for CYW43.

• Used NotImplementedError instead, with a clarifying message.
• Share that message with another place.
• Merge "read-only` messages to reduce number of messages.

[dhalbert]

Will revise to fix #7357.

[jepler]

>>> class X:
...     @property
...     def p(self): return 1
... 
>>> x = X()
>>> x.p
1
>>> x.p = 7
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: can't set attribute

Python uses AttributeError for a non-settable property but it has a clearer error ("can't set" vs "has no attribute").

Maybe we should fix this by making the failure to set the attribute have a distinct message:

diff --git a/py/runtime.c b/py/runtime.c
index 6be5c22335..89d459648a 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -1247,7 +1247,7 @@ void mp_store_attr(mp_obj_t base, qstr attr, mp_obj_t value) {
     mp_raise_AttributeError(MP_ERROR_TEXT("no such attribute"));
     #else
     mp_raise_msg_varg(&mp_type_AttributeError,
-        MP_ERROR_TEXT("'%s' object has no attribute '%q'"),
+        MP_ERROR_TEXT("'%s' object can't set attribute '%q'"),
         mp_obj_get_type_str(base), attr);
     #endif
 }

It'd be up to you whether to have the sites you changed here use this style of message or the style of message that you already used.

[jepler]

(or save even more code space by making the property either a GET or a GETSET depending on #defines, which would let this site's error checking be reused)

[jepler]

@dhalbert let me know when you update this PR

[dhalbert]

@jepler on CYW43, is the fact you can't set the MAC address for station or AP mode inherent, or just not implemented yet? That affects my thinking about what error to raise.

I am changing the the AttributeError message in py/runtime.c to be "can't set attribute '%q'", which will match CPython.

[jepler]

As far as I can tell the mac address is not settable in cyw43.

[jepler]

Thank you!

[dhalbert]

Tested on Pico W and Metro ESP32-S2.