# Python Substrate Interface Library
#
# Copyright 2018-2023 Stichting Polkascan (Polkascan Foundation).
#
# 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,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from typing import Callable
from .extensions import Extension
from .exceptions import ExtensionCallNotFound
__all__ = ['ExtensionInterface']
[docs]
class ExtensionInterface:
"""
Keeps tracks of active extensions and which calls can be made
"""
def __init__(self, substrate):
self.substrate = substrate
self.extensions = []
def __len__(self):
return len(self.extensions)
def __iter__(self):
for item in self.extensions:
yield item
def __add__(self, other):
self.register(other)
return self
[docs]
def register(self, extension: Extension):
"""
Register an extension instance to the registry and calls initialization
Parameters
----------
extension: Extension
Returns
-------
"""
if not isinstance(extension, Extension):
raise ValueError("Provided extension is not a subclass of Extension")
extension.init(self.substrate)
self.extensions.append(extension)
[docs]
def unregister_all(self):
"""
Unregister all extensions and free used resources and connections
Returns
-------
"""
for extension in self.extensions:
extension.close()
[docs]
def call(self, name: str, *args, **kwargs):
"""
Tries to call extension function with `name` and provided args and kwargs
Will raise a `ExtensionCallNotFound` when no method is found in current extensions
Parameters
----------
name
args
kwargs
Returns
-------
"""
return self.get_extension_callable(name)(*args, **kwargs)
[docs]
def get_extension_callable(self, name: str) -> Callable:
for extension in self.extensions:
if isinstance(extension, Extension):
if hasattr(extension, name):
try:
# Call extension that implements functionality
self.substrate.debug_message(f"Call '{name}' using extension {extension.__class__.__name__} ...")
return getattr(extension, name)
except NotImplementedError:
pass
raise ExtensionCallNotFound(f"No extension registered that implements call '{name}'")
def __getattr__(self, name):
return self.get_extension_callable(name)