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#------------------------------------------------------------------------------
# Copyright (c) 2014-2024,, Nucleic Development Team.
#
# Distributed under the terms of the Modified BSD License.
#
# The full license is in the file LICENSE, distributed with this software.
#------------------------------------------------------------------------------
from atom.api import Callable, Tuple, Dict
from .constraint_helper import ConstraintHelper
class FactoryHelper(ConstraintHelper):
""" A constraint helper which delegates to a factory callable.
"""
#: The callable object which will generate the list of constraints.
#: It will be passed the constraints widget owner as the first
#: argument, and should return the list of generated constraints.
factory = Callable()
#: Additional positional arguments to pass to the callable.
args = Tuple()
#: Additional keyword arguments to pass to the callable.
kwargs = Dict()
def __init__(self, factory, *args, **kwargs):
""" Initialize a FactoryHelper.
Parameters
----------
factory : callable
The callable object which generates the constraints.
*args
Additional positional arguments to pass to the factory.
**kwargs
Additional keyword arguments to pass to the factory.
"""
self.factory = factory
self.args = args
self.kwargs = kwargs
def constraints(self, component):
""" Generate the constraints using the underlying factory.
This method will automatically expand ConstraintHelper objects
which are generated by the factory.
"""
factory = self.factory
if factory is None:
return []
cns = [] # inline `expand_constraints`
for cn in factory(component, *self.args, **self.kwargs):
if isinstance(cn, ConstraintHelper):
cns.extend(cn.create_constraints(component))
elif cn is not None:
cns.append(cn)
return cns
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