External access to matrix objects about canmatrix

[ebroecker]

Hi Christian,

While technical it is possible to access the '_'-variables from outside it's definitively a very good idea to strive to a stable API.

I don't like the idea to rename the attributes.

I'd prefer property-functions.

@altendky : what Do you think?
@christiansandberg : what would be your favorite?

[christiansandberg]

I also think property functions is the most elegant and backwards-compatible way to do it.

Maybe also add iteration support to the list type classes (FrameList, BoardUnitListe, SignalGroup, and Frame).

for frame in matrix.frames:
    print(frame.name)
    for signal in frame:
        print(signal.name)

[altendky]

Unlike other languages you don't have to make every last setter and getter function ahead of time in Python.

class MyClass():
    def __init__(self):
        self.my_property = 42

can be refactored without user knowledge to:

class MyClass():
    def __init__(self):
        self._my_property = 42

    @property
    def my_property(self):
        # do something more here like count how many accesses if you want
        return self._my_property

    @my_property.setter
    def my_property(self, value):
        # check the new value to confirm validity or notify another class or whatever
        self._my_property = value

In both cases you can interact with my_property such as:

mc = MyClass()
mc.my_property = 10
a = mc.my_property

So, for the members that are just _ prefixed but do not presently need to have any extra in the accessors than just the assignment and return, just remove the _. They can be refactored to have accessors later using @property.

All that said, I have not read up on the PEP's related to this. PEP8 doesn't even mention properties. Google's Python style says to "Use properties for accessing or setting data where you would normally have used simple, lightweight accessor or setter methods."

For iteration? Maybe those classes should just inherit from list and add their custom functions? This would avoid creating a bunch of pass through functions like:

def __len__(self):
    return self._fl.__len__()

def __getitem__(self):
    return self._fl.__getitem__()

[ebroecker]

started with this issue in branch "stableApi"

[ebroecker]

any comments/wishes to branch stableApi?

all attributes have their properties now.

if no futher wishes, I'll close this issue the next days and merge stableApi to master.

[christiansandberg]

To me it looks good!