Source code for bokeh.core.property.instance

#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2019, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
#
# The full license is in the file LICENSE.txt, distributed with this software.
#-----------------------------------------------------------------------------
''' Provide the Instance property.

The Instance property is used to construct object graphs of Bokeh models,
where one Bokeh model refers to another.

'''

#-----------------------------------------------------------------------------
# Boilerplate
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from __future__ import absolute_import, division, print_function, unicode_literals

import logging
log = logging.getLogger(__name__)

#-----------------------------------------------------------------------------
# Imports
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# Standard library imports
from importlib import import_module

# External imports
from six import iteritems, string_types

# Bokeh imports
from .bases import DeserializationError, Property

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# Globals and constants
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__all__ = (
    'Instance',
)

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# General API
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[docs]class Instance(Property): ''' Accept values that are instances of |HasProps|. ''' def __init__(self, instance_type, default=None, help=None): if not isinstance(instance_type, (type,) + string_types): raise ValueError("expected a type or string, got %s" % instance_type) from ..has_props import HasProps if isinstance(instance_type, type) and not issubclass(instance_type, HasProps): raise ValueError("expected a subclass of HasProps, got %s" % instance_type) self._instance_type = instance_type super(Instance, self).__init__(default=default, help=help) def __str__(self): return "%s(%s)" % (self.__class__.__name__, self.instance_type.__name__) @property def has_ref(self): return True @property def instance_type(self): if isinstance(self._instance_type, string_types): module, name = self._instance_type.rsplit(".", 1) self._instance_type = getattr(import_module(module, "bokeh"), name) return self._instance_type def from_json(self, json, models=None): if json is None: return None elif isinstance(json, dict): from ...model import Model if issubclass(self.instance_type, Model): if models is None: raise DeserializationError("%s can't deserialize without models" % self) else: model = models.get(json["id"]) if model is not None: return model else: raise DeserializationError("%s failed to deserialize reference to %s" % (self, json)) else: attrs = {} for name, value in iteritems(json): prop_descriptor = self.instance_type.lookup(name).property attrs[name] = prop_descriptor.from_json(value, models) # XXX: this doesn't work when Instance(Superclass) := Subclass() # Serialization dict must carry type information to resolve this. return self.instance_type(**attrs) else: raise DeserializationError("%s expected a dict or None, got %s" % (self, json)) def validate(self, value, detail=True): super(Instance, self).validate(value, detail) if value is not None: if not isinstance(value, self.instance_type): msg = "" if not detail else "expected an instance of type %s, got %s of type %s" % (self.instance_type.__name__, value, type(value).__name__) raise ValueError(msg) def _may_have_unstable_default(self): # because the instance value is mutable return True def _sphinx_type(self): fullname = "%s.%s" % (self.instance_type.__module__, self.instance_type.__name__) return self._sphinx_prop_link() + "( %s )" % self._sphinx_model_link(fullname)
#----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------