self.params should support name based access

[janchorowski]

Since all parametets have names, we can easily add name-based access to self.params:

class Parameters(AnnotatingList):
    """Adds the PARAMETER role to parameters automatically."""
    ...

    def __getattr__(self, name):
        for l in self:
            if getattr(object, 'name', None) == name:
                return l
        raise AttributeError

then we can write self.params.weights instead of declaring a property or remember the parameter's order.

Searching through a list shouldn't matter speed-wise for the small number of parameters bricks typically have.

[rizar]

@dwf, in the context of our recent discussion this might sounds interesting to you.

[rizar]

It seems to me that adding this to Blocks and getting read of all parameter getting properties is really simple and uncontroversial, and even does not require any documentation changes.

[dwf]

The implementation you propose should fall back on super(Parameters, self).__getattr__(name) after the loop rather than the raise statement. Otherwise SGTM.

[dwf]

Oh, one complication: names are not unique on nontrivial Bricks like MLP... so this functionality could be a source of hard-to-find bugs. We could maybe address this by adding a flag to the Parameters class that enforces this uniqueness and refusing to do attribute-style lookup if it is not set.

[rizar]

@dwf , I am confused, MLP does not have its own parameters at all, does it?

[dwf]

I guess I my be thinking of brick ownership in the variable filter...

[janchorowski]

I implemented a test version of this and with a fix for pickling it works. Checking for name uniqueness is a good idea, I guess other code such as Model assumes name uniqueness.

[rizar]

We definitely assume in many places of Blocks code that parameter names of all bricks are unique. That indeed could be explicitly checked by the Parameters object.