front.scrap.binder_proposal

Naive stash of VF proposals for binding

class front.scrap.binder_proposal.Binder(state: <function NewType.<locals>.new_type at 0x7f581fd819d0>, factory: Callable, container: type)

class front.scrap.binder_proposal.HasState(*args, **kwargs)

front.scrap.binder_proposal.mk_binder(*identifiers: Union[Iterable[NewType.<locals>.new_type], str], state: NewType.<locals>.new_type, bound_val_factory=<class 'front.scrap.binder_proposal.BoundVal'>)

Parameters

• identifiers –

• bound_val_factory –

Returns

>>> Binder = mk_binder('foo bar')
>>> d = dict()
>>> b = Binder(d)

We b.foo exists, but is not set.

>>> b.foo
ValueNotSet

So let’s set it:

>>> b.foo = 42
>>> b.foo
42

So b.foo is now set, but the real point is that this assignment was “registered” in the state we give the Binder:

>>> d
{'foo': 42}

Wanna see that again?

>>> b.foo = "I'm bound"
>>> b.foo
"I'm bound"
>>> d
{'foo': "I'm bound"}

And same with b.bar:

>>> b.bar
ValueNotSet
>>> b.bar = "me too"
>>> b.bar
'me too'
>>> d
{'foo': "I'm bound", 'bar': 'me too'}

A Binder will also have some useful mapping methods that are linked to the underlying state.

>>> Binder = mk_binder('the', 'variables', 'I', 'want')
>>> state = dict()
>>> b = Binder(state)
>>> list(b)
[]
>>> b.want  # I see a want, but no value is set
ValueNotSet
>>> list(b)  # list still gives me nothing
[]
>>> b.want = 42  # but if I set a value for want
>>> list(b)  # I see want in the list
['want']
>>> 'want' in b  # I can do this too
True
>>> 'not_in_there' in b
False
>>> 'variables' in b  # 'variables' not "there" because not set
False