Source code for panel.pane.base

Defines base classes for Pane components which allow wrapping a Python
object transforming it into a Bokeh model that can be rendered.
from __future__ import annotations

from functools import partial
from typing import (
    TYPE_CHECKING, Any, Callable, ClassVar, Dict, List, Mapping, Optional,
    Tuple, Type, TypeVar,

import numpy as np
import param

from bokeh.models import ImportedStyleSheet
from bokeh.models.layouts import (
    GridBox as _BkGridBox, TabPanel as _BkTabPanel, Tabs as _BkTabs,

from .._param import Margin
from import _generate_hash
from import create_doc_if_none_exists, unlocked
from import push
from import state
from ..layout.base import (
    Column, ListPanel, NamedListPanel, Panel, Row,
from ..links import Link
from ..models import ReactiveHTML as _BkReactiveHTML
from ..reactive import Reactive
from ..util import param_reprs, param_watchers
from ..util.checks import is_dataframe, is_series
from ..util.parameters import get_params_to_inherit
from ..viewable import (
    Layoutable, ServableMixin, Viewable, Viewer,

    from bokeh.document import Document
    from bokeh.model import Model
    from pyviz_comms import Comm

[docs]def panel(obj: Any, **kwargs) -> Viewable: """ Creates a displayable Panel object given any valid Python object. The appropriate Pane to render a specific object is determined by iterating over all defined Pane types and querying it's `.applies` method for a priority value. Any keyword arguments are passed down to the applicable Pane. Setting `loading_indicator=True` will display a loading indicator while the function is being evaluated. To lazily render components when the application loads, you may also provide a Python function, with or without bound parameter dependencies and set `defer_load=True`. Reference: >>> pn.panel(some_python_object, width=500) Arguments --------- obj: object Any object to be turned into a Panel **kwargs: dict Any keyword arguments to be passed to the applicable Pane Returns ------- layout: Viewable A Viewable representation of the input object """ if isinstance(obj, (Viewable, ServableMixin)): return obj elif hasattr(obj, '__panel__'): if isinstance(obj, Viewer): return obj._create_view() if isinstance(obj, type) and issubclass(obj, Viewer): return panel(obj().__panel__()) return panel(obj.__panel__()) if kwargs.get('name', False) is None: kwargs.pop('name') pane = PaneBase.get_pane_type(obj, **kwargs)(obj, **kwargs) if len(pane.layout) == 1 and pane._unpack: return pane.layout[0] return pane.layout
[docs]class RerenderError(RuntimeError): """ Error raised when a pane requests re-rendering during initial render. """ def __init__(self, *args, layout=None, **kwargs): super().__init__(*args, **kwargs) self.layout = layout
T = TypeVar('T', bound='PaneBase')
[docs]class PaneBase(Reactive): """ PaneBase is the abstract baseclass for all atomic displayable units in the Panel library. We call any child class of `PaneBase` a `Pane`. Panes defines an extensible interface for wrapping arbitrary objects and transforming them into Bokeh models. Panes are reactive in the sense that when the object they are wrapping is replaced or modified the `bokeh.model.Model` that is rendered should reflect these changes. """ default_layout = param.ClassSelector(default=Row, class_=(Panel), is_instance=False, doc=""" Defines the layout the model(s) returned by the pane will be placed in.""") margin = Margin(default=(5, 10), doc=""" Allows to create additional space around the component. May be specified as a two-tuple of the form (vertical, horizontal) or a four-tuple (top, right, bottom, left).""") object = param.Parameter(default=None, allow_refs=True, doc=""" The object being wrapped, which will be converted to a Bokeh model.""") # When multiple Panes apply to an object, the one with the highest # numerical priority is selected. The default is an intermediate value. # If set to None, applies method will be called to get a priority # value for a specific object type. priority: ClassVar[float | bool | None] = 0.5 # Whether applies requires full set of keywords _applies_kw: ClassVar[bool] = False # Whether the Pane layout can be safely unpacked _unpack: ClassVar[bool] = True # Declares whether Pane supports updates to the Bokeh model _updates: ClassVar[bool] = False # Mapping from parameter name to bokeh model property name _rename: ClassVar[Mapping[str, str | None]] = { 'default_layout': None, 'loading': None } # List of parameters that trigger a rerender of the Bokeh model _rerender_params: ClassVar[List[str]] = ['object'] _skip_layoutable = ('background', 'css_classes', 'margin', 'name') __abstract = True def __init__(self, object=None, **params): self._object_changing = False super().__init__(object=object, **params) applies = self.applies(self.object, **(params if self._applies_kw else {})) if (isinstance(applies, bool) and not applies) and self.object is not None: self._type_error(self.object) kwargs = { k: v for k, v in params.items() if k in Layoutable.param and k not in self._skip_layoutable } self.layout = self.default_layout(self, **kwargs) self._internal_callbacks.extend([, list(Layoutable.param)),, self._rerender_params) ]) self._sync_layoutable() def _validate_ref(self, pname, value): super()._validate_ref(pname, value) if pname == 'object' and not self._applies_kw: applies = self.applies(value) if isinstance(applies, bool) and not applies: raise RuntimeError('Value is not valid.') def _sync_layoutable(self, *events: param.parameterized.Event): included = set(Layoutable.param) - set(self._skip_layoutable) if events: kwargs = { for event in events if in included } else: kwargs = { k: v for k, v in self.param.values().items() if k in included } if self.margin: margin = self.margin if isinstance(margin, tuple): if len(margin) == 2: t = b = margin[0] r = l = margin[1] else: t, r, b, l = margin else: t = r = b = l = margin if kwargs.get('width') is not None: kwargs['width'] = kwargs['width'] + l + r if kwargs.get('height') is not None: kwargs['height'] = kwargs['height'] + t + b old_values = self.layout.param.values() self.layout.param.update({k: v for k, v in kwargs.items() if v != old_values[k]}) def _type_error(self, object): raise ValueError("%s pane does not support objects of type '%s'." % (type(self).__name__, type(object).__name__)) def __repr__(self, depth: int = 0) -> str: cls = type(self).__name__ params = param_reprs(self, ['object']) obj = 'None' if self.object is None else type(self.object).__name__ template = '{cls}({obj}, {params})' if params else '{cls}({obj})' return template.format(cls=cls, params=', '.join(params), obj=obj) def __getitem__(self, index: int | str) -> Viewable: """ Allows pane objects to behave like the underlying layout """ return self.layout[index] #---------------------------------------------------------------- # Callback API #---------------------------------------------------------------- @property def _linked_properties(self) -> Tuple[str]: return tuple( self._property_mapping.get(p, p) for p in self.param if p not in PaneBase.param and self._property_mapping.get(p, p) is not None ) @property def _linkable_params(self) -> List[str]: return [p for p in self._synced_params if self._property_mapping.get(p, False) is not None] @property def _synced_params(self) -> List[str]: ignored_params = ['name', 'default_layout', 'loading', 'background', 'stylesheets']+self._rerender_params return [p for p in self.param if p not in ignored_params and not p.startswith('_')] def _param_change(self, *events: param.parameterized.Event) -> None: if self._object_changing: return super()._param_change(*events) def _update_object( self, ref: str, doc: 'Document', root: Model, parent: Model, comm: Comm | None ) -> None: old_model = self._models[ref][0] if self._updates: self._update(ref, old_model) return new_model = self._get_model(doc, root, parent, comm) try: if isinstance(parent, _BkGridBox): indexes = [ i for i, child in enumerate(parent.children) if child[0] is old_model ] if indexes: index = indexes[0] else: raise ValueError new_model = (new_model,) + parent.children[index][1:] elif isinstance(parent, _BkReactiveHTML): for node, children in parent.children.items(): if old_model in children: index = children.index(old_model) new_models = list(children) new_models[index] = new_model break elif isinstance(parent, _BkTabs): index = [tab.child for tab in parent.tabs].index(old_model) else: index = parent.children.index(old_model) except ValueError: self.param.warning( f'{type(self).__name__} pane model {old_model!r} could not be ' f'replaced with new model {new_model!r}, ensure that the parent ' 'is not modified at the same time the panel is being updated.' ) else: if isinstance(parent, _BkReactiveHTML): parent.children[node] = new_models elif isinstance(parent, _BkTabs): old_tab = parent.tabs[index] props = dict(old_tab.properties_with_values(), child=new_model) parent.tabs[index] = _BkTabPanel(**props) else: parent.children[index] = new_model layout_parent = self.layout._models.get(ref, [None])[0] if parent is layout_parent: parent.update(**self.layout._compute_sizing_mode( parent.children, dict( sizing_mode=self.layout.sizing_mode, styles=self.layout.styles, width=self.layout.width, min_width=self.layout.min_width, margin=self.layout.margin ) )) from import state ref = root.ref['id'] if ref in state._views: state._views[ref][0]._preprocess(root) def _update_pane(self, *events) -> None: for ref, (_, parent) in self._models.items(): if ref not in state._views or ref in state._fake_roots: continue viewable, root, doc, comm = state._views[ref] if comm or state._unblocked(doc): with unlocked(): self._update_object(ref, doc, root, parent, comm) if comm and 'embedded' not in root.tags: push(doc, comm) else: cb = partial(self._update_object, ref, doc, root, parent, comm) if doc.session_context: doc.add_next_tick_callback(cb) else: cb() def _update(self, ref: str, model: Model) -> None: """ If _updates=True this method is used to update an existing Bokeh model instead of replacing the model entirely. The supplied model should be updated with the current state. """ raise NotImplementedError def _get_root_model( self, doc: Optional[Document] = None, comm: Comm | None = None, preprocess: bool = True ) -> Tuple[Viewable, Model]: if self._updates: root = self._get_model(doc, comm=comm) root_view = self else: root = self.layout._get_model(doc, comm=comm) root_view = self.layout if preprocess: self._preprocess(root) return root_view, root #---------------------------------------------------------------- # Public API #----------------------------------------------------------------
[docs] @classmethod def applies(cls, obj: Any) -> float | bool | None: """ Returns boolean or float indicating whether the Pane can render the object. If the priority of the pane is set to `None`, this method may also be used to define a float priority depending on the object being rendered. """ return None
[docs] def clone(self: T, object: Optional[Any] = None, **params) -> T: """ Makes a copy of the Pane sharing the same parameters. Arguments --------- object: Optional new object to render params: Keyword arguments override the parameters on the clone. Returns ------- Cloned Pane object """ inherited = get_params_to_inherit(self) params = dict(inherited, **params) old_object = params.pop('object', None) if object is None: object = old_object return type(self)(object, **params)
[docs] def get_root( self, doc: Optional[Document] = None, comm: Comm | None = None, preprocess: bool = True ) -> Model: """ Returns the root model and applies pre-processing hooks Arguments --------- doc: bokeh.document.Document Optional Bokeh document the bokeh model will be attached to. comm: pyviz_comms.Comm Optional pyviz_comms when working in notebook preprocess: bool (default=True) Whether to run preprocessing hooks Returns ------- Returns the bokeh model corresponding to this panel object """ doc = create_doc_if_none_exists(doc) if self._design and comm: wrapper = self._design._wrapper(self) if wrapper is self: root_view, root = self._get_root_model(doc, comm, preprocess) else: root_view = wrapper root = wrapper.get_root(doc, comm, preprocess) else: root_view, root = self._get_root_model(doc, comm, preprocess) ref = root.ref['id'] state._views[ref] = (root_view, root, doc, comm) return root
[docs] @classmethod def get_pane_type(cls, obj: Any, **kwargs) -> Type['PaneBase']: """ Returns the applicable Pane type given an object by resolving the precedence of all types whose applies method declares that the object is supported. Arguments --------- obj (object): The object type to return a Pane type for Returns ------- The applicable Pane type with the highest precedence. """ if isinstance(obj, Viewable): return type(obj) descendents = [] for p in param.concrete_descendents(PaneBase).values(): if p.priority is None: applies = True try: priority = p.applies(obj, **(kwargs if p._applies_kw else {})) except Exception: priority = False else: applies = None priority = p.priority if isinstance(priority, bool) and priority: raise ValueError('If a Pane declares no priority ' 'the applies method should return a ' 'priority value specific to the ' 'object type or False, but the %s pane ' 'declares no priority.' % p.__name__) elif priority is None or priority is False: continue descendents.append((priority, applies, p)) pane_types = reversed(sorted(descendents, key=lambda x: x[0])) for _, applies, pane_type in pane_types: if applies is None: try: applies = pane_type.applies(obj, **(kwargs if pane_type._applies_kw else {})) except Exception: applies = False if not applies: continue return pane_type raise TypeError('%s type could not be rendered.' % type(obj).__name__)
[docs]class ModelPane(PaneBase): """ ModelPane provides a baseclass that allows quickly wrapping a Bokeh model and translating parameters defined on the class with properties defined on the model. In simple cases subclasses only have to define the Bokeh model to render to and the `_transform_object` method which transforms the Python object being wrapped into properties that the `bokeh.model.Model` can consume. """ _bokeh_model: ClassVar[Model] __abstract = True def _get_model( self, doc: Document, root: Model | None = None, parent: Model | None = None, comm: Comm | None = None ) -> Model: model = self._bokeh_model(**self._get_properties(doc)) if root is None: root = model self._models[root.ref['id']] = (model, parent) self._link_props(model, self._linked_properties, doc, root, comm) return model def _update(self, ref: str, model: Model) -> None: model.update(**self._get_properties(model.document)) def _init_params(self): params = { p: v for p, v in self.param.values().items() if v is not None and p not in ('name', 'default_layout') } params['object'] = self.object return params def _transform_object(self, obj: Any) -> Dict[str, Any]: return dict(object=obj) def _process_param_change(self, params): if 'object' in params: params.update(self._transform_object(params.pop('object'))) if self._bokeh_model is not None and 'stylesheets' in params: css = getattr(self._bokeh_model, '__css__', []) params['stylesheets'] = [ ImportedStyleSheet(url=ss) for ss in css ] + params['stylesheets'] return super()._process_param_change(params)
[docs]class ReplacementPane(PaneBase): """ ReplacementPane provides a baseclass for dynamic components that may have to dynamically update or switch out their contents, e.g. a dynamic callback that may return different objects to be rendered. When the pane updates it either entirely replaces the underlying `bokeh.model.Model`, by creating an internal layout to replace the children on, or updates the existing model in place. """ inplace = param.Boolean(default=False, doc=""" Whether to update the object inplace.""") object = param.Parameter(default=None, allow_refs=False, doc=""" The object being wrapped, which will be converted to a Bokeh model.""") _pane = param.ClassSelector(class_=Viewable, allow_refs=False) _ignored_refs: ClassVar[Tuple[str,...]] = ('object',) _linked_properties: ClassVar[Tuple[str,...]] = () _rename: ClassVar[Mapping[str, str | None]] = {'_pane': None, 'inplace': None} _updates: bool = True __abstract = True def __init__(self, object: Any=None, **params): self._kwargs = {p: params.pop(p) for p in list(params) if p not in self.param} super().__init__(object, **params) self._pane = panel(None) self._internal = True self._inner_layout = Column(self._pane, **{k: v for k, v in params.items() if k in Column.param}) self._internal_callbacks.append(, list(Layoutable.param)) ) self._sync_layout() def _get_model( self, doc: Document, root: Model | None = None, parent: Model | None = None, comm: Comm | None = None ) -> Model: if root: ref = root.ref['id'] if ref in self._models: self._cleanup(root) model = self._inner_layout._get_model(doc, root, parent, comm) root = root or model self._models[root.ref['id']] = (model, parent) return model @param.depends('_pane', '_pane.sizing_mode', '_pane.width_policy', '_pane.height_policy', watch=True) def _sync_layout(self): if not hasattr(self, '_inner_layout') or (self._pane is not None and getattr(self._pane, '_object_changing', False)): return self._inner_layout.param.update({ k: v for k, v in self._pane.param.values().items() if k in ('sizing_mode', 'width_policy', 'height_policy') }) def _update_inner_layout(self, *events): self._pane.param.update({ for event in events}) @classmethod def _recursive_update(cls, old: Reactive, new: Reactive): """ Recursively descends through Panel layouts and diffs their contents updating only changed parameters ensuring we don't have to trigger a full re-render of the entire component. Arguments --------- old: Reactive The Reactive component being updated or replaced. new: Reactive The new Reactive component that the old one is being updated or replaced with. """ ignored = ('name',) if isinstance(new, ListPanel): if len(old) == len(new): for i, (sub_old, sub_new) in enumerate(zip(old, new)): if type(sub_old) is not type(sub_new): old[i] = new continue if isinstance(new, NamedListPanel): old._names[i] = new._names[i] cls._recursive_update(sub_old, sub_new) ignored += ('objects',) pvals = dict(old.param.values()) new_params = {} for p, p_new in new.param.values().items(): p_old = pvals[p] if p in ignored or p_new is p_old: continue try: equal = p_new == p_old if is_dataframe(equal) or is_series(equal) or isinstance(equal, np.ndarray): equal = equal.all() equal = bool(equal) except Exception: try: equal = _generate_hash(p_new) == _generate_hash(p_old) except Exception: equal = False if not equal: new_params[p] = p_new if isinstance(old, PaneBase): changing = any(p in old._rerender_params for p in new_params) old._object_changing = changing try: with param.edit_constant(old): old.param.update(**new_params) finally: old._object_changing = False else: with param.edit_constant(old): old.param.update(**new_params) @classmethod def _update_from_object(cls, object: Any, old_object: Any, was_internal: bool, inplace: bool=False, **kwargs): pane_type = cls.get_pane_type(object) try: links = Link.registry.get(object) except TypeError: links = [] custom_watchers = [] if isinstance(object, Reactive): watchers = [ w for pwatchers in param_watchers(object).values() for awatchers in pwatchers.values() for w in awatchers ] custom_watchers = [ wfn for wfn in watchers if wfn not in object._internal_callbacks and not hasattr(wfn.fn, '_watcher_name') ] pane, internal = None, was_internal # If the object has no external referrers we can update # it inplace instead of replacing it if type(old_object) is pane_type and ((not links and not custom_watchers and was_internal) or inplace): if isinstance(object, Panel) and len(old_object) == len(object): for i, (old, new) in enumerate(zip(old_object, object)): if type(old) is not type(new): old_object[i] = new continue cls._recursive_update(old, new) elif isinstance(object, Reactive): cls._recursive_update(old_object, object) else: old_object.object = object else: # Replace pane entirely pane = panel(object, **{k: v for k, v in kwargs.items() if k in pane_type.param}) if pane is object: # If all watchers on the object are internal watchers # we can make a clone of the object and update this # clone going forward, otherwise we have replace the # model entirely which is more expensive. if not (custom_watchers or links): pane = object.clone() internal = True else: internal = False else: internal = object is not old_object return pane, internal def _update_inner(self, new_object: Any) -> None: kwargs = dict(self.param.values(), **self._kwargs) del kwargs['object'] new_pane, internal = self._update_from_object( new_object, self._pane, self._internal, **kwargs ) if new_pane is None: return self._pane = new_pane self._inner_layout[:] = [self._pane] self._internal = internal def _cleanup(self, root: Model | None = None) -> None: self._inner_layout._cleanup(root) super()._cleanup(root) #---------------------------------------------------------------- # Developer API #---------------------------------------------------------------- def _update_pane(self, *events) -> None: """ Updating of the object should be handled manually. """ #---------------------------------------------------------------- # Public API #----------------------------------------------------------------
[docs] def select(self, selector: type | Callable | None = None) -> List[Viewable]: """ Iterates over the Viewable and any potential children in the applying the Selector. Arguments --------- selector: (type | callable | None) The selector allows selecting a subset of Viewables by declaring a type or callable function to filter by. Returns ------- viewables: list(Viewable) """ selected = super().select(selector) selected += return selected