Source code for astropy.utils.collections
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
A module containing specialized collection classes.
"""
[docs]
class HomogeneousList(list):
"""
A subclass of list that contains only elements of a given type or
types. If an item that is not of the specified type is added to
the list, a `TypeError` is raised.
"""
def __init__(self, types, values=[]):
"""
Parameters
----------
types : sequence of types
The types to accept.
values : sequence, optional
An initial set of values.
"""
self._types = types
super().__init__()
self.extend(values)
def _assert(self, x):
if not isinstance(x, self._types):
raise TypeError(
f"homogeneous list must contain only objects of type '{self._types}'"
)
def __iadd__(self, other):
self.extend(other)
return self
def __setitem__(self, idx, value):
if isinstance(idx, slice):
value = list(value)
for item in value:
self._assert(item)
else:
self._assert(value)
return super().__setitem__(idx, value)
[docs]
def append(self, x):
self._assert(x)
return super().append(x)
[docs]
def insert(self, i, x):
self._assert(x)
return super().insert(i, x)
[docs]
def extend(self, x):
for item in x:
self._assert(item)
super().append(item)