From 266c2c9a072bf3289fd7f2d75278b7d59528378c Mon Sep 17 00:00:00 2001
From: Matthias Baumgartner <dev@igsor.net>
Date: Sat, 24 Dec 2022 10:27:09 +0100
Subject: package restructuring: base

* Reader and Extractor to respective reader/extractor modules
* ReaderBuilder to reader module
* ExtractorBuilder to extractor module
* Loading module in utils (safe_load, unpack_name)
* Pipeline and PipelineBuilder to lib module
* errors to utils
* documentation: "standard import" and "external import"
---
 bsie/utils/loading.py | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 bsie/utils/loading.py

(limited to 'bsie/utils/loading.py')

diff --git a/bsie/utils/loading.py b/bsie/utils/loading.py
new file mode 100644
index 0000000..eb05c35
--- /dev/null
+++ b/bsie/utils/loading.py
@@ -0,0 +1,54 @@
+"""
+
+Part of the bsie module.
+A copy of the license is provided with the project.
+Author: Matthias Baumgartner, 2022
+"""
+# standard imports
+import importlib
+import typing
+
+# inner-module imports
+from . import errors
+
+# exports
+__all__: typing.Sequence[str] = (
+    'safe_load',
+    'unpack_qualified_name',
+    )
+
+
+## code ##
+
+def safe_load(module_name: str, class_name: str):
+    """Get a class from a module. Raise BuilderError if anything goes wrong."""
+    try:
+        # load the module
+        module = importlib.import_module(module_name)
+    except Exception as err:
+        # cannot import module
+        raise errors.LoaderError(f'cannot load module {module_name}') from err
+
+    try:
+        # get the class from the module
+        cls = getattr(module, class_name)
+    except Exception as err:
+        # cannot find the class
+        raise errors.LoaderError(f'cannot load class {class_name} from module {module_name}') from err
+
+    return cls
+
+
+def unpack_qualified_name(name):
+    """Split a name into its module and class component (dot-separated)."""
+    if not isinstance(name, str):
+        raise TypeError(name)
+    if '.' not in name:
+        raise ValueError('name must be a qualified class name.')
+    module_name, class_name = name[:name.rfind('.')], name[name.rfind('.')+1:]
+    if module_name == '':
+        raise ValueError('name must be a qualified class name.')
+    return module_name, class_name
+
+
+## EOF ##
-- 
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