destructure

Easy declarative schema validation with optional name-binding.

>>> from destructure import Binding, match
>>>
>>> o = Binding()
>>> schema = {
...     'string': str,
...     'any': ...,
...     'binding': o.name,
...     'sequence': [1, 2, ...],
...     'mapping': {'a': int, ...: ...},
... }
>>> data = {
...     'string': 'a',
...     'any': 5j,
...     'binding': 42,
...     'sequence': [1, 2, 3, 4],
...     'mapping': {'a': 1, 'b': 2, 'c': 3},
... }
>>> guard = lambda : o.name > 10
>>> data == match(schema, data, guard)
True
>>> o.name
42

Pick between several schemas with a handy Switch.case.

>>> from destructure import Binding, Switch
>>>
>>> o = Binding()
>>> schema1 = [1, o.x, 3]
>>> schema2 = [2, 4, o.x]
>>>
>>> s = Switch([2, 4, 6])
>>> if s.case(schema1):
...     print(o.x)
... elif s.case(schema2):
...     print(o.x)
... else:
...     print('otherwise')
6

Schemas may include many kinds of objects, though to make use of Ellipses or Binding, the class must support keyword arguments and cannot be too strict with parameter type-checking.

>>> class Foo:
...     def __init__(self, bar):
...         self.bar = bar
>>> bind = Binding()
>>> schema = Foo(bar=bind.x)
>>> result = match(schema, Foo(bar=1))
>>> bind.x
1

See some example scripts for a practical usage, in context.