From 789e7f626e40d20cea7f1b526d798bec941344cf Mon Sep 17 00:00:00 2001
From: Joseph Weston <joseph@weston.cloud>
Date: Fri, 23 Feb 2018 19:25:31 +0100
Subject: [PATCH] add lazy module importer
We will need to issue deprecation warnings when using this with
'kwant.continuum', so we have to roll our own so we can hook into
the attribute access. When we no longer need this feature we
can replace this with a simpler implementation using
'importlib.util.LazyLoader'.
---
kwant/_common.py | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/kwant/_common.py b/kwant/_common.py
index 76e952cf..48c45eaa 100644
--- a/kwant/_common.py
+++ b/kwant/_common.py
@@ -6,10 +6,12 @@
# the file AUTHORS.rst at the top-level directory of this distribution and at
# http://kwant-project.org/authors.
+import sys
import numpy as np
import numbers
import inspect
import warnings
+import importlib
from contextlib import contextmanager
__all__ = ['KwantDeprecationWarning', 'UserCodeError']
@@ -123,3 +125,26 @@ def get_parameters(func):
takes_kwargs = any(i.kind is inspect.Parameter.VAR_KEYWORD
for i in pars.values())
return required_params, default_params, takes_kwargs
+
+
+class lazy_import:
+ def __init__(self, module, package='kwant', deprecation_warning=False):
+ if module.startswith('.') and not package:
+ raise ValueError('Cannot import a relative module without a package.')
+ self.__module = module
+ self.__package = package
+ self.__deprecation_warning = deprecation_warning
+
+ def __getattr__(self, name):
+ if self.__deprecation_warning:
+ absolute_module = '.'.join((self.__package, self.__module))
+ msg = ("Accessing {0} without an explicit import is deprecated. "
+ "Instead, explicitly 'import {0}'."
+ ).format('.'.join((self.__package, self.__module)))
+ warnings.warn(msg, KwantDeprecationWarning, stacklevel=2)
+ relative_module = '.' + self.__module
+ mod = importlib.import_module(relative_module, self.__package)
+ # Replace this _LazyModuleProxy with an actual module
+ package = sys.modules[self.__package]
+ setattr(package, self.__module, mod)
+ return getattr(mod, name)
--
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