Create wrapper function for common class functionality (orest-d#15)

* Implement wrapper functions for plot and read
* Implement wrapper for conversion routines

src/py4vasp/data/__init__.py

@@ -26,6 +26,7 @@
 from .trajectory import Trajectory
 from .viewer3d import Viewer3d
 from .structure import Structure
+from py4vasp.exceptions import NotImplementException
 
 import plotly.io as pio
 import cufflinks as cf
@@ -37,4 +38,33 @@
 cf.set_config_file(theme="ggplot")
 
 _this_mod = sys.modules[__name__]
-__all__ = [name for name, _ in inspect.getmembers(_this_mod, inspect.isclass)]
+_class_names = [name for name, _ in inspect.getmembers(_this_mod, inspect.isclass)]
+_classes = [value for _, value in inspect.getmembers(_this_mod, inspect.isclass)]
+_functions = set(("read", "plot"))
+for c in _classes:
+    for name, _ in inspect.getmembers(c, inspect.isfunction):
+        if "to_" in name:
+            _functions.add(name)
+__all__ = _class_names + list(_functions)
+
+
+def get_function_if_possible(obj, name):
+    try:
+        return getattr(obj, name)
+    except AttributeError as err:
+        class_ = obj.__class__.__name__
+        msg = "For the {} no {} function is implemented.".format(class_, name)
+        raise NotImplementException(msg) from err
+
+
+def _wrapper_factory(module, name):
+    def wrapper(cls, *args, **kwargs):
+        with cls.from_file() as obj:
+            function = get_function_if_possible(obj, name)
+            return function(*args, **kwargs)
+
+    setattr(module, name, wrapper)
+
+
+for function in _functions:
+    _wrapper_factory(_this_mod, function)

src/py4vasp/exceptions/exceptions.py

@@ -9,3 +9,7 @@ class RefinementException(Py4VaspException):
 
 class UsageException(Py4VaspException):
     """The user provided input is not suitable for processing"""
+
+
+class NotImplementException(Py4VaspException):
+    """Exception raised when a function is called that is not implemented."""

tests/data/test_wrapper.py

@@ -0,0 +1,60 @@
+from py4vasp.data import plot, read, to_dict
+from py4vasp.exceptions import NotImplementException
+from unittest.mock import MagicMock
+from contextlib import contextmanager
+import pytest
+
+
+def test_plot():
+    plotable = MagicMock()
+    context = plotable.from_file.return_value
+    obj = context.__enter__.return_value
+    # without arguments
+    res = plot(plotable)
+    plotable.from_file.assert_called_once()
+    context.__enter__.assert_called_once()
+    obj.plot.assert_called_once()
+    assert res == obj.plot.return_value
+    # with arguments
+    res = plot(plotable, "arguments")
+    obj.plot.assert_called_with("arguments")
+
+
+def test_plot():
+    readable = MagicMock()
+    context = readable.from_file.return_value
+    obj = context.__enter__.return_value
+    # without arguments
+    res = read(readable)
+    readable.from_file.assert_called_once()
+    context.__enter__.assert_called_once()
+    obj.read.assert_called_once()
+    assert res == obj.read.return_value
+    # with arguments
+    res = read(readable, "arguments")
+    obj.read.assert_called_with("arguments")
+
+
+def test_conversion():
+    convertible = MagicMock()
+    context = convertible.from_file.return_value
+    obj = context.__enter__.return_value
+    # without arguments
+    res = to_dict(convertible)  # we test to_dict as generic for conversion
+    convertible.from_file.assert_called_once()
+    context.__enter__.assert_called_once()
+    obj.to_dict.assert_called_once()
+    assert res == obj.to_dict.return_value
+    # with arguments
+    res = to_dict(convertible, "arguments")
+    obj.to_dict.assert_called_with("arguments")
+
+
+def test_exception():
+    class NoReadDefined:
+        @contextmanager
+        def from_file():
+            yield NoReadDefined()
+
+    with pytest.raises(NotImplementException):
+        read(NoReadDefined)