initial commit with barebones project structure

core/correctness/validation.py

@@ -0,0 +1,51 @@
+
+def check_input(variable, expected_type, or_none=False):
+    """
+    Checks if a given variable is of the expected type. Raises TypeError or
+    ValueError as appropriate if any issues are encountered.
+
+    :param variable: (any) variable to check type of
+
+    :param expected_type: (type) expected type of the provided variable
+
+    :param or_none: (optional) boolean of if the variable can be unset.
+    Default value is False.
+
+    :return: No return.
+    """
+
+    if not or_none:
+        if not isinstance(variable, expected_type):
+            raise TypeError(
+                'Expected type was %s, got %s'
+                % (expected_type, type(variable))
+            )
+    else:
+        if not isinstance(variable, expected_type) \
+                and not isinstance(variable, type(None)):
+            raise TypeError(
+                'Expected type was %s or None, got %s'
+                % (expected_type, type(variable))
+            )
+
+def valid_string(variable, valid_chars):
+    """
+    Checks that all characters in a given string are present in a provided
+    list of characters. Will raise an ValueError if unexpected character is
+    encountered.
+
+    :param variable: (str) variable to check.
+
+    :param valid_chars: (str) collection of valid characters.
+
+    :return: No return.
+    """
+    check_input(variable, str)
+    check_input(valid_chars, str)
+
+    for char in variable:
+        if char not in valid_chars:
+            raise ValueError(
+                "Invalid character '%s'. Only valid characters are: "
+                "%s" % (char, valid_chars)
+            )