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# itypes
[Build Status]
Basic immutable container types for Python.
A simple implementation that's designed for simplicity over performance.
Use these in circumstances where it may result in more comprehensible code,
or when you want to create custom types with restricted, immutable
interfaces.
For an alternative implementation designed for performance,
please see [pyrsistent].
### Installation
Install using `pip`:
pip install itypes
### Instantiating dictionaries and lists.
>>> import itypes
>>> d = itypes.Dict({'a': 1, 'b': 2, 'c': 3})
>>> l = itypes.List(['a', 'b', 'c'])
### On instantiation, nested types are coerced to immutables.
>>> d = itypes.Dict({'a': 123, 'b': ['a', 'b', 'c']})
>>> d['b']
List(['a', 'b', 'c'])
### Assignments and deletions return new copies.
Methods: `set(key, value)`, `delete(key)`
>>> d2 = d.set('c', 456)
>>> d2
Dict({'a': 123, 'b': ['a', 'b', 'c'], 'c': 456})
>>> d3 = d2.delete('a')
>>> d3
Dict({'b': ['a', 'b', 'c'], 'c': 456})
### Standard assignments and deletions fail.
>>> d['z'] = 123
TypeError: 'Dict' object doesn't support item assignment
>>> del(d['c'])
TypeError: 'Dict' object doesn't support item deletion
### Nested lookups.
Method: `get_in(keys, default=None)`
>>> d['b'][-1]
'c'
>>> d['b'][5]
IndexError: list index out of range
>>> d.get_in(['b', -1])
'c'
>>> d.get_in(['b', 5])
None
### Nested assignments and deletions.
Methods: `set_in(keys, value)`, `delete_in(keys)`
>>> d2 = d.set_in(['b', 1], 'xxx')
>>> d2
Dict({'a': 123, 'b': ['a', 'xxx', 'c']})
>>> d3 = d2.delete_in(['b', 0])
>>> d3
Dict({'a': 123, 'b': ['xxx', 'c']})
### Equality works against standard types.
>>> d = itypes.Dict({'a': 1, 'b': 2, 'c': 3})
>>> d == {'a': 1, 'b': 2, 'c': 3}
True
### Objects are hashable.
>>> hash(d)
277752239
### Shortcuts for switching between mutable and immutable types.
Functions: `to_mutable(instance)`, `to_immutable(value)`
>>> value = itypes.to_mutable(d)
>>> value
{'a': 123, 'b': ['a', 'b', 'c']}
>>> itypes.to_immutable(value)
Dict({'a': 123, 'b': ['a', 'b', 'c']})
### Subclassing.
Only private attribute names may be set on instances. Use `@property` for
attribute access.
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