Source code for pennylane.templates.decorator

# Copyright 2018-2021 Xanadu Quantum Technologies Inc.

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
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"""
This module contains the template decorator.
"""
from functools import wraps


[docs]def template(func): """Register a quantum template with PennyLane. This decorator wraps the given function and makes it return a list of all queued Operations. **Example:** When defining a :doc:`template </introduction/templates>`, simply decorate the template function with this decorator. .. code-block:: python3 @qml.template def bell_state_preparation(wires): qml.Hadamard(wires=wires[0]) qml.CNOT(wires=wires) This registers the template with PennyLane, making it compatible with functions that act on templates, such as :func:`pennylane.inv`: .. code-block:: python3 dev = qml.device('default.qubit', wires=2) @qml.qnode(dev) def circuit(): qml.inv(bell_state_preparation(wires=[0, 1])) return qml.expval(qml.PauliZ(0) @ qml.PauliZ(1)) Args: func (callable): A template function Returns: callable: The wrapper function """ import pennylane as qml # pylint: disable=import-outside-toplevel @wraps(func) def wrapper(*args, **kwargs): with qml.tape.OperationRecorder() as rec: func(*args, **kwargs) return rec.queue return wrapper