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@philippjfr @xavArtley @xtaje @mattpap @jlstevens @ceball @a-recknagel
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"""
Defines the Viewable and Reactive baseclasses allow all panel objects
to display themselves, communicate with a Python process and react in
response to changes to parameters and the underlying bokeh models.
"""
from __future__ import absolute_import, division, unicode_literals
import difflib
import logging
import re
import sys
import threading
import traceback
import uuid
from collections import namedtuple
from functools import partial
import param
from bokeh.document.document import Document as _Document, _combine_document_events
from bokeh.document.events import ModelChangedEvent
from bokeh.io import curdoc as _curdoc
from bokeh.models import CustomJS
from pyviz_comms import JupyterCommManager
from .callbacks import PeriodicCallback
from .config import config, panel_extension
from .io.embed import embed_state
from .io.model import add_to_doc
from .io.notebook import (
get_comm_customjs, ipywidget, push, render_mimebundle,
render_model, show_embed, show_server
)
from .io.save import save
from .io.state import state
from .io.server import StoppableThread, get_server, unlocked
from .util import escape, param_reprs
LinkWatcher = namedtuple("Watcher","inst cls fn mode onlychanged parameter_names what queued target links transformed")
class Layoutable(param.Parameterized):
align = param.ObjectSelector(default='start',
objects=['start', 'end', 'center'], doc="""
Whether the object should be aligned with the start, end or
center of its container""")
aspect_ratio = param.Parameter(default=None, doc="""
Describes the proportional relationship between component's
width and height. This works if any of component's dimensions
are flexible in size. If set to a number, ``width / height =
aspect_ratio`` relationship will be maintained. Otherwise, if
set to ``"auto"``, component's preferred width and height will
be used to determine the aspect (if not set, no aspect will be
preserved).
""")
background = param.Parameter(default=None, doc="""
Background color of the component.""")
css_classes = param.List(default=None, doc="""
CSS classes to apply to the layout.""")
width = param.Integer(default=None, bounds=(0, None), doc="""
The width of the component (in pixels). This can be either
fixed or preferred width, depending on width sizing policy.""")
height = param.Integer(default=None, bounds=(0, None), doc="""
The height of the component (in pixels). This can be either
fixed or preferred height, depending on height sizing policy.""")
min_width = param.Integer(default=None, bounds=(0, None), doc="""
Minimal width of the component (in pixels) if width is adjustable.""")
min_height = param.Integer(default=None, bounds=(0, None), doc="""
Minimal height of the component (in pixels) if height is adjustable.""")
max_width = param.Integer(default=None, bounds=(0, None), doc="""
Minimal width of the component (in pixels) if width is adjustable.""")
max_height = param.Integer(default=None, bounds=(0, None), doc="""
Minimal height of the component (in pixels) if height is adjustable.""")
margin = param.Parameter(default=5, 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).""")
width_policy = param.ObjectSelector(
default="auto", objects=['auto', 'fixed', 'fit', 'min', 'max'], doc="""
Describes how the component should maintain its width.
* "auto"
Use component's preferred sizing policy.
* "fixed"
Use exactly ``width`` pixels. Component will overflow if it
can't fit in the available horizontal space.
* "fit"
Use component's preferred width (if set) and allow it to fit
into the available horizontal space within the minimum and
maximum width bounds (if set). Component's width neither
will be aggressively minimized nor maximized.
* "min"
Use as little horizontal space as possible, not less than
the minimum width (if set). The starting point is the
preferred width (if set). The width of the component may
shrink or grow depending on the parent layout, aspect
management and other factors.
* "max"
Use as much horizontal space as possible, not more than the
maximum width (if set). The starting point is the preferred
width (if set). The width of the component may shrink or
grow depending on the parent layout, aspect management and
other factors.
""")
height_policy = param.ObjectSelector(
default="auto", objects=['auto', 'fixed', 'fit', 'min', 'max'], doc="""
Describes how the component should maintain its height.
* "auto"
Use component's preferred sizing policy.
* "fixed"
Use exactly ``width`` pixels. Component will overflow if it
can't fit in the available horizontal space.
* "fit"
Use component's preferred width (if set) and allow it to fit
into the available horizontal space within the minimum and
maximum width bounds (if set). Component's width neither
will be aggressively minimized nor maximized.
* "min"
Use as little horizontal space as possible, not less than
the minimum width (if set). The starting point is the
preferred width (if set). The width of the component may
shrink or grow depending on the parent layout, aspect
management and other factors.
* "max"
Use as much horizontal space as possible, not more than the
maximum width (if set). The starting point is the preferred
width (if set). The width of the component may shrink or
grow depending on the parent layout, aspect management and
other factors.
""")
sizing_mode = param.ObjectSelector(default=None, objects=[
'fixed', 'stretch_width', 'stretch_height', 'stretch_both',
'scale_width', 'scale_height', 'scale_both', None], doc="""
How the component should size itself.
This is a high-level setting for maintaining width and height
of the component. To gain more fine grained control over
sizing, use ``width_policy``, ``height_policy`` and
``aspect_ratio`` instead (those take precedence over
``sizing_mode``).
* "fixed"
Component is not responsive. It will retain its original
width and height regardless of any subsequent browser window
resize events.
* "stretch_width"
Component will responsively resize to stretch to the
available width, without maintaining any aspect ratio. The
height of the component depends on the type of the component
and may be fixed or fit to component's contents.
* "stretch_height"
Component will responsively resize to stretch to the
available height, without maintaining any aspect ratio. The
width of the component depends on the type of the component
and may be fixed or fit to component's contents.
* "stretch_both"
Component is completely responsive, independently in width
and height, and will occupy all the available horizontal and
vertical space, even if this changes the aspect ratio of the
component.
* "scale_width"
Component will responsively resize to stretch to the
available width, while maintaining the original or provided
aspect ratio.
* "scale_height"
Component will responsively resize to stretch to the
available height, while maintaining the original or provided
aspect ratio.
* "scale_both"
Component will responsively resize to both the available
width and height, while maintaining the original or provided
aspect ratio.
""")
def __init__(self, **params):
if (params.get('width', None) is not None and
params.get('height', None) is not None and
params.get('width_policy') is None and
params.get('height_policy') is None and
'sizing_mode' not in params):
params['sizing_mode'] = 'fixed'
elif not self.param.sizing_mode.constant and not self.param.sizing_mode.readonly:
params['sizing_mode'] = params.get('sizing_mode', config.sizing_mode)
super(Layoutable, self).__init__(**params)
class ServableMixin(object):
def _modify_doc(self, server_id, title, doc):
"""
Callback to handle FunctionHandler document creation.
"""
if server_id:
state._servers[server_id][2].append(doc)
return self.server_doc(doc, title)
def _get_server(self, port=0, websocket_origin=None, loop=None,
show=False, start=False, title=None, verbose=False,
**kwargs):
return get_server(self, port, websocket_origin, loop, show,
start, title, verbose, **kwargs)
#----------------------------------------------------------------
# Public API
#----------------------------------------------------------------
def servable(self, title=None):
"""
Serves the object if in a `panel serve` context and returns
the Panel object to allow it to display itself in a notebook
context.
Arguments
---------
title : str
A string title to give the Document (if served as an app)
Returns
-------
The Panel object itself
"""
if _curdoc().session_context:
logger = logging.getLogger('bokeh')
for handler in logger.handlers:
if isinstance(handler, logging.StreamHandler):
handler.setLevel(logging.WARN)
self.server_doc(title=title)
return self
def show(self, port=0, websocket_origin=None, threaded=False,
title=None, verbose=True, **kwargs):
"""
Starts a Bokeh server and displays the Viewable in a new tab.
Arguments
---------
port: int (optional, default=0)
Allows specifying a specific port
websocket_origin: str or list(str) (optional)
A list of hosts that can connect to the websocket.
This is typically required when embedding a server app in
an external web site.
If None, "localhost" is used.
threaded: boolean (optional, default=False)
Whether to launch the Server on a separate thread, allowing
interactive use.
title : str
A string title to give the Document (if served as an app)
verbose: boolean (optional, default=True)
Whether to print the address and port
Returns
-------
server: bokeh.server.Server or threading.Thread
Returns the Bokeh server instance or the thread the server
was launched on (if threaded=True)
"""
if threaded:
from tornado.ioloop import IOLoop
loop = IOLoop()
server = StoppableThread(
target=self._get_server, io_loop=loop,
args=(port, websocket_origin, loop, True, True, title, verbose),
kwargs={'title': title})
server.start()
else:
server = self._get_server(
port, websocket_origin, show=True, start=True,
title=title, verbose=verbose, **kwargs
)
return server
class Viewable(Layoutable, ServableMixin):
"""
Viewable is the baseclass all objects in the panel library are
built on. It defines the interface for declaring any object that
displays itself by transforming the object(s) being wrapped into
models that can be served using bokeh's layout engine. The class
also defines various methods that allow Viewable objects to be
displayed in the notebook and on bokeh server.
"""
__abstract = True
_preprocessing_hooks = []
def __init__(self, **params):
super(Viewable, self).__init__(**params)
self._documents = {}
self._models = {}
self._found_links = set()
def __repr__(self, depth=0):
return '{cls}({params})'.format(cls=type(self).__name__,
params=', '.join(param_reprs(self)))
def __str__(self):
return self.__repr__()
def _get_model(self, doc, root=None, parent=None, comm=None):
"""
Converts the objects being wrapped by the viewable into a
bokeh model that can be composed in a bokeh layout.
Arguments
----------
doc: bokeh.Document
Bokeh document the bokeh model will be attached to.
root: bokeh.Model
The root layout the viewable will become part of.
parent: bokeh.Model
The parent layout the viewable will become part of.
comm: pyviz_comms.Comm
Optional pyviz_comms when working in notebook
Returns
-------
model: bokeh.Model
"""
raise NotImplementedError
def _cleanup(self, root):
"""
Clean up method which is called when a Viewable is destroyed.
Arguments
---------
root: bokeh.model.Model
Bokeh model for the view being cleaned up
"""
if root.ref['id'] in state._handles:
del state._handles[root.ref['id']]
def _preprocess(self, root):
"""
Applies preprocessing hooks to the model.
"""
for hook in self._preprocessing_hooks:
hook(self, root)
def _render_model(self, doc=None, comm=None):
if doc is None:
doc = _Document()
if comm is None:
comm = state._comm_manager.get_server_comm()
model = self.get_root(doc, comm)
if config.embed:
embed_state(self, model, doc,
json=config.embed_json,
json_prefix=config.embed_json_prefix,
save_path=config.embed_save_path,
load_path=config.embed_load_path,
progress=False)
else:
add_to_doc(model, doc)
return model
def _repr_mimebundle_(self, include=None, exclude=None):
loaded = panel_extension._loaded
if not loaded and 'holoviews' in sys.modules:
import holoviews as hv
loaded = hv.extension._loaded
if config.comms == 'ipywidgets':
widget = ipywidget(self)
data = {}
if widget._view_name is not None:
data['application/vnd.jupyter.widget-view+json'] = {
'version_major': 2,
'version_minor': 0,
'model_id': widget._model_id
}
if widget._view_name is not None:
widget._handle_displayed()
return data, {}
if not loaded:
self.param.warning('Displaying Panel objects in the notebook '
'requires the panel extension to be loaded. '
'Ensure you run pn.extension() before '
'displaying objects in the notebook.')
return None
try:
from IPython import get_ipython
assert get_ipython().kernel is not None
state._comm_manager = JupyterCommManager
except Exception:
pass
from IPython.display import display
comm = state._comm_manager.get_server_comm()
doc = _Document()
model = self._render_model(doc, comm)
if config.console_output != 'disable':
handle = display(display_id=uuid.uuid4().hex)
state._handles[model.ref['id']] = (handle, [])
if config.embed:
return render_model(model)
return render_mimebundle(model, doc, comm)
def _server_destroy(self, session_context):
"""
Server lifecycle hook triggered when session is destroyed.
"""
doc = session_context._document
self._cleanup(self._documents[doc])
del self._documents[doc]
#----------------------------------------------------------------
# Public API
#----------------------------------------------------------------
def clone(self, **params):
"""
Makes a copy of the object sharing the same parameters.
Arguments
---------
params: Keyword arguments override the parameters on the clone.
Returns
-------
Cloned Viewable object
"""
return type(self)(**dict(self.param.get_param_values(), **params))
def pprint(self):
"""
Prints a compositional repr of the class.
"""
print(self)
def select(self, selector=None):
"""
Iterates over the Viewable and any potential children in the
applying the Selector.
Arguments
---------
selector: type or callable or None
The selector allows selecting a subset of Viewables by
declaring a type or callable function to filter by.
Returns
-------
viewables: list(Viewable)
"""
if (selector is None or
(isinstance(selector, type) and isinstance(self, selector)) or
(callable(selector) and not isinstance(selector, type) and selector(self))):
return [self]
else:
return []
def app(self, notebook_url="localhost:8888", port=0):
"""
Displays a bokeh server app inline in the notebook.
Arguments
---------
notebook_url: str
URL to the notebook server
port: int (optional, default=0)
Allows specifying a specific port
"""
return show_server(self, notebook_url, port)
def embed(self, max_states=1000, max_opts=3, json=False,
save_path='./', load_path=None, progress=True):
"""
Renders a static version of a panel in a notebook by evaluating
the set of states defined by the widgets in the model. Note
this will only work well for simple apps with a relatively
small state space.
Arguments
---------
max_states: int
The maximum number of states to embed
max_opts: int
The maximum number of states for a single widget
json: boolean (default=True)
Whether to export the data to json files
save_path: str (default='./')
The path to save json files to
load_path: str (default=None)
The path or URL the json files will be loaded from.
progress: boolean (default=False)
Whether to report progress
"""
show_embed(
self, max_states, max_opts, json, save_path,
load_path, progress
)
def get_root(self, doc=None, comm=None):
"""
Returns the root model and applies pre-processing hooks
Arguments
---------
doc: bokeh.Document
Bokeh document the bokeh model will be attached to.
comm: pyviz_comms.Comm
Optional pyviz_comms when working in notebook
Returns
-------
Returns the bokeh model corresponding to this panel object
"""
doc = doc or _curdoc()
root = self._get_model(doc, comm=comm)
self._preprocess(root)
ref = root.ref['id']
state._views[ref] = (self, root, doc, comm)
return root
def save(self, filename, title=None, resources=None, template=None,
template_variables=None, embed=False, max_states=1000,
max_opts=3, embed_json=False, json_prefix='', save_path='./',
load_path=None):
"""
Saves Panel objects to file.
Arguments
---------
filename: string or file-like object
Filename to save the plot to
title: string
Optional title for the plot
resources: bokeh resources
One of the valid bokeh.resources (e.g. CDN or INLINE)
template:
passed to underlying io.save
template_variables:
passed to underlying io.save
embed: bool
Whether the state space should be embedded in the saved file.
max_states: int
The maximum number of states to embed
max_opts: int
The maximum number of states for a single widget
embed_json: boolean (default=True)
Whether to export the data to json files
json_prefix: str (default='')
Prefix for the auto-generated json directory
save_path: str (default='./')
The path to save json files to
load_path: str (default=None)
The path or URL the json files will be loaded from.
"""
return save(self, filename, title, resources, template,
template_variables, embed, max_states, max_opts,
embed_json, json_prefix, save_path, load_path)
def server_doc(self, doc=None, title=None):
"""
Returns a serveable bokeh Document with the panel attached
Arguments
---------
doc : bokeh.Document (optional)
The bokeh Document to attach the panel to as a root,
defaults to bokeh.io.curdoc()
title : str
A string title to give the Document
Returns
-------
doc : bokeh.Document
The bokeh document the panel was attached to
"""
doc = doc or _curdoc()
title = title or 'Panel Application'
doc.title = title
model = self.get_root(doc)
if hasattr(doc, 'on_session_destroyed'):
doc.on_session_destroyed(self._server_destroy)
self._documents[doc] = model
add_to_doc(model, doc)
return doc
class Reactive(Viewable):
"""
Reactive is a Viewable object that also supports syncing between
the objects parameters and the underlying bokeh model either via
the defined pyviz_comms.Comm type or when using bokeh server.
In order to bi-directionally link parameters with bokeh model
instances the _link_params and _link_props methods define
callbacks triggered when either the parameter or bokeh property
values change. Since there may not be a 1-to-1 mapping between
parameter and the model property the _process_property_change and
_process_param_change may be overridden to apply any necessary
transformations.
"""
# Timeout if a notebook comm message is swallowed
_timeout = 20000
# Timeout before the first event is processed
_debounce = 50
# Mapping from parameter name to bokeh model property name
_rename = {}
# Allows defining a mapping from model property name to a JS code
# snippet that transforms the object before serialization
_js_transforms = {}
# Transforms from input value to bokeh property value
_source_transforms = {}
_target_transforms = {}
def __init__(self, **params):
# temporary flag denotes panes created for temporary, internal
# use which should be garbage collected once they have been used
super(Reactive, self).__init__(**params)
self._processing = False
self._events = {}
self._changing = {}
self._callbacks = []
self._links = []
self._link_params()
#----------------------------------------------------------------
# Callback API
#----------------------------------------------------------------
def _update_model(self, events, msg, root, model, doc, comm=None):
if comm:
filtered = {}
for k, v in msg.items():
try:
change = (k not in self._changing or
self._changing[k] != v or
self._changing['id'] != model.ref['id'])
except Exception:
change = True
if change:
filtered[k] = v
for attr, new in filtered.items():
setattr(model, attr, new)
event = doc._held_events[-1] if doc._held_events else None
if (event and event.model is model and event.attr == attr and
event.new is new):
continue
# If change did not trigger event trigger it manually
old = getattr(model, attr)
serializable_new = model.lookup(attr).serializable_value(model)
event = ModelChangedEvent(doc, model, attr, old, new, serializable_new)
_combine_document_events(event, doc._held_events)
else:
model.update(**msg)
def _link_params(self):
def param_change(*events):
msgs = []
for event in events:
msg = self._process_param_change({event.name: event.new})
if msg:
msgs.append(msg)
events = {event.name: event for event in events}
msg = {k: v for msg in msgs for k, v in msg.items()}
if not msg:
return
for ref, (model, parent) in self._models.items():
if ref not in state._views:
continue
viewable, root, doc, comm = state._views[ref]
if comm or state._unblocked(doc):
with unlocked():
self._update_model(events, msg, root, model, doc, comm)
if comm and 'embedded' not in root.tags:
push(doc, comm)
else:
cb = partial(self._update_model, events, msg, root, model, doc, comm)
if doc.session_context:
doc.add_next_tick_callback(cb)
else:
cb()
params = self._synced_params()
if params:
watcher = self.param.watch(param_change, params)
self._callbacks.append(watcher)
def _on_error(self, ref, error):
if ref not in state._handles or config.console_output in [None, 'disable']:
return
handle, accumulator = state._handles[ref]
formatted = '\n<pre>'+escape(traceback.format_exc())+'</pre>\n'
if config.console_output == 'accumulate':
accumulator.append(formatted)
elif config.console_output == 'replace':
accumulator[:] = [formatted]
if accumulator:
handle.update({'text/html': '\n'.join(accumulator)}, raw=True)
def _on_stdout(self, ref, stdout):
if ref not in state._handles or config.console_output is [None, 'disable']:
return
handle, accumulator = state._handles[ref]
formatted = ["%s</br>" % o for o in stdout]
if config.console_output == 'accumulate':
accumulator.extend(formatted)
elif config.console_output == 'replace':
accumulator[:] = formatted
if accumulator:
handle.update({'text/html': '\n'.join(accumulator)}, raw=True)
def _link_props(self, model, properties, doc, root, comm=None):
ref = root.ref['id']
if comm is None:
for p in properties:
if isinstance(p, tuple):
_, p = p
model.on_change(p, partial(self._server_change, doc, ref))
elif config.embed:
pass
else:
on_msg = partial(self._comm_change, ref=ref)
client_comm = state._comm_manager.get_client_comm(
on_msg=on_msg, on_error=partial(self._on_error, ref),
on_stdout=partial(self._on_stdout, ref)
)
for p in properties:
if isinstance(p, tuple):
p, attr = p
else:
p, attr = p, p
customjs = self._get_customjs(attr, client_comm, ref)
model.js_on_change(p, customjs)
def _comm_change(self, msg, ref=None):
if not msg:
return
self._changing.update(msg)
msg.pop('id', None)
self._events.update(msg)
try:
self._change_event()
finally:
self._changing = {}
def _server_change(self, doc, ref, attr, old, new):
self._events.update({attr: new})
if not self._processing:
self._processing = True
if doc.session_context:
doc.add_timeout_callback(partial(self._change_event, doc), self._debounce)
else:
self._change_event(doc)
def _process_events(self, events):
self.param.set_param(**self._process_property_change(events))
def _change_event(self, doc=None):
try:
state.curdoc = doc
thread = threading.current_thread()
thread_id = thread.ident if thread else None
state._thread_id = thread_id
events = self._events
self._events = {}
self._process_events(events)
finally:
self._processing = False
state.curdoc = None
state._thread_id = None
def _get_customjs(self, change, client_comm, plot_id):
"""
Returns a CustomJS callback that can be attached to send the
model state across the notebook comms.
"""
transform = self._js_transforms.get(change)
return get_comm_customjs(
change, client_comm, plot_id, transform, self._timeout, self._debounce
)
#----------------------------------------------------------------
# Model API
#----------------------------------------------------------------
def _init_properties(self):
return {k: v for k, v in self.param.get_param_values()
if v is not None}
@property
def _linkable_params(self):
return [p for p in self._synced_params()
if self._source_transforms.get(p, False) is not None]
def _synced_params(self):
return list(self.param)
def _process_property_change(self, msg):
"""
Transform bokeh model property changes into parameter updates.
Should be overridden to provide appropriate mapping between
parameter value and bokeh model change. By default uses the
_rename class level attribute to map between parameter and
property names.
"""
inverted = {v: k for k, v in self._rename.items()}
return {inverted.get(k, k): v for k, v in msg.items()}
def _process_param_change(self, msg):
"""
Transform parameter changes into bokeh model property updates.
Should be overridden to provide appropriate mapping between
parameter value and bokeh model change. By default uses the
_rename class level attribute to map between parameter and
property names.
"""
properties = {self._rename.get(k, k): v for k, v in msg.items()
if self._rename.get(k, False) is not None}
if 'width' in properties and self.sizing_mode is None:
properties['min_width'] = properties['width']
if 'height' in properties and self.sizing_mode is None:
properties['min_height'] = properties['height']
return properties
def _cleanup(self, root):
super(Reactive, self)._cleanup(root)
# Clean up comms
model, _ = self._models.pop(root.ref['id'], (None, None))
if model is None:
return
customjs = model.select({'type': CustomJS})
pattern = r"data\['comm_id'\] = \"(.*)\""
for js in customjs:
comm_ids = list(re.findall(pattern, js.code))
if not comm_ids:
continue
comm_id = comm_ids[0]
comm = state._comm_manager._comms.pop(comm_id, None)
if comm:
try:
comm.close()
except Exception:
pass
#----------------------------------------------------------------
# Public API
#----------------------------------------------------------------
def controls(self, parameters=[], jslink=True):
"""
Creates a set of widgets which allow manipulating the parameters
on this instance. By default all parameters which support
linking are exposed, but an explicit list of parameters can
be provided.
Arguments
---------
parameters: list(str)
An explicit list of parameters to return controls for.
jslink: bool
Whether to use jslinks instead of Python based links.
This does not allow using all types of parameters.
Returns
-------
A layout of the controls
"""
from .param import Param
from .layout import Tabs, WidgetBox
from .widgets import LiteralInput
if parameters:
linkable = parameters
elif jslink:
linkable = self._linkable_params
else:
linkable = list(self.param)
params = [p for p in linkable if p not in Layoutable.param]
controls = Param(self.param, parameters=params, default_layout=WidgetBox,
name='Controls')
layout_params = [p for p in linkable if p in Layoutable.param]
if 'name' not in layout_params and self._rename.get('name', False) is not None and not parameters:
layout_params.insert(0, 'name')
style = Param(self.param, parameters=layout_params, default_layout=WidgetBox,
name='Layout')
if jslink:
for p in params:
widget = controls._widgets[p]
widget.jslink(self, value=p, bidirectional=True)
if isinstance(widget, LiteralInput):
widget.serializer = 'json'
for p in layout_params:
widget = style._widgets[p]
widget.jslink(self, value=p, bidirectional=True)
if isinstance(widget, LiteralInput):
widget.serializer = 'json'
if params and layout_params:
return Tabs(controls.layout[0], style.layout[0])
elif params:
return controls.layout[0]
return style.layout[0]
def link(self, target, callbacks=None, **links):
"""
Links the parameters on this object to attributes on another
object in Python. Supports two modes, either specify a mapping
between the source and target object parameters as keywords or
provide a dictionary of callbacks which maps from the source
parameter to a callback which is triggered when the parameter
changes.
Arguments
---------
target: object
The target object of the link.
callbacks: dict
Maps from a parameter in the source object to a callback.
**links: dict
Maps between parameters on this object to the parameters
on the supplied object.
"""
if links and callbacks:
raise ValueError('Either supply a set of parameters to '
'link as keywords or a set of callbacks, '
'not both.')
elif not links and not callbacks:
raise ValueError('Declare parameters to link or a set of '
'callbacks, neither was defined.')
_updating = []
def link(*events):
for event in events:
if event.name in _updating: continue
_updating.append(event.name)
try:
if callbacks:
callbacks[event.name](target, event)
else:
setattr(target, links[event.name], event.new)
except Exception:
raise
finally:
_updating.pop(_updating.index(event.name))
params = list(callbacks) if callbacks else list(links)
cb = self.param.watch(link, params)
link = LinkWatcher(*tuple(cb)+(target, links, callbacks is not None))
self._links.append(link)
return cb
def add_periodic_callback(self, callback, period=500, count=None,
timeout=None, start=True):
"""
Schedules a periodic callback to be run at an interval set by
the period. Returns a PeriodicCallback object with the option
to stop and start the callback.
Arguments
---------
callback: callable
Callable function to be executed at periodic interval.
period: int
Interval in milliseconds at which callback will be executed.
count: int
Maximum number of times callback will be invoked.
timeout: int
Timeout in seconds when the callback should be stopped.
start: boolean (default=True)
Whether to start callback immediately.
Returns
-------
Return a PeriodicCallback object with start and stop methods.
"""
cb = PeriodicCallback(callback=callback, period=period,
count=count, timeout=timeout)
if start:
cb.start()
return cb
def jscallback(self, args={}, **callbacks):
"""
Allows defining a JS callback to be triggered when a property
changes on the source object. The keyword arguments define the
properties that trigger a callback and the JS code that gets
executed.
Arguments
----------
args: dict
A mapping of objects to make available to the JS callback
**callbacks: dict
A mapping between properties on the source model and the code
to execute when that property changes
Returns
-------
callback: Callback
The Callback which can be used to disable the callback.
"""
from .links import Callback
for k, v in list(callbacks.items()):
callbacks[k] = self._rename.get(v, v)
return Callback(self, code=callbacks, args=args)
def jslink(self, target, code=None, args=None, bidirectional=False, **links):
"""
Links properties on the source object to those on the target
object in JS code. Supports two modes, either specify a
mapping between the source and target model properties as
keywords or provide a dictionary of JS code snippets which
maps from the source parameter to a JS code snippet which is
executed when the property changes.
Arguments
----------
target: HoloViews object or bokeh Model or panel Viewable
The target to link the value to.
code: dict
Custom code which will be executed when the widget value
changes.
bidirectional: boolean
Whether to link source and target bi-directionally
**links: dict
A mapping between properties on the source model and the
target model property to link it to.
Returns
-------
link: GenericLink
The GenericLink which can be used unlink the widget and
the target model.
"""
if links and code:
raise ValueError('Either supply a set of properties to '
'link as keywords or a set of JS code '
'callbacks, not both.')
elif not links and not code:
raise ValueError('Declare parameters to link or a set of '
'callbacks, neither was defined.')
if args is None:
args = {}
mapping = code or links
for k in mapping:
if k not in self.param and k not in list(self._rename.values()):
matches = difflib.get_close_matches(k, list(self.param))
if matches:
matches = ' Similar parameters include: %r' % matches
else:
matches = ''
raise ValueError("Could not jslink %r parameter (or property) "
"on %s object because it was not found.%s"
% (k, type(self).__name__, matches))
elif (self._source_transforms.get(k, False) is None or
self._rename.get(k, False) is None):
raise ValueError("Cannot jslink %r parameter on %s object, "
"the parameter requires a live Python kernel "
"to have an effect." % (k, type(self).__name__))
if isinstance(target, Reactive) and code is None:
for k, p in mapping.items():
if p not in target.param and p not in list(target._rename.values()):
matches = difflib.get_close_matches(p, list(target.param))
if matches:
matches = ' Similar parameters include: %r' % matches
else:
matches = ''
raise ValueError("Could not jslink %r parameter (or property) "
"on %s object because it was not found.%s"
% (p, type(self).__name__, matches))
elif (target._source_transforms.get(p, False) is None or
target._rename.get(p, False) is None):
raise ValueError("Cannot jslink %r parameter on %s object "
"to %r parameter on %s object. It requires "
"a live Python kernel to have an effect."
% (k, type(self).__name__, p, type(target).__name__))
from .links import Link
return Link(self, target, properties=links, code=code, args=args,
bidirectional=bidirectional)
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