Add getpermission.py.

voussoirkit/getpermission.py

@@ -0,0 +1,36 @@
+YES_STRINGS = ['yes', 'y']
+NO_STRINGS = ['no', 'n']
+
+def getpermission(
+        prompt=None,
+        *,
+        yes_strings=YES_STRINGS,
+        no_strings=NO_STRINGS,
+        must_pick=False,
+    ):
+    '''
+    Prompt the user with a yes or no question.
+
+    Return True for yes, False for no, and None if undecided.
+
+    You can customize the strings that mean yes or no. For example, you could
+    create a "type the name of the thing you're about to delete" prompt.
+
+    If `must_pick`, then undecided is not allowed and the input will repeat
+    until they choose an acceptable answer. Either way, the intended usage of
+    `if getpermission():` will always only accept in case of explicit yes.
+    '''
+    if prompt is not None:
+        print(prompt)
+    while True:
+        answer = input(f'{yes_strings[0]}/{no_strings[0]}> ').strip()
+        yes = answer.lower() in (option.lower() for option in yes_strings)
+        no = answer.lower() in (option.lower() for option in no_strings)
+        if yes or no or not must_pick:
+            break
+
+    if yes:
+        return True
+    if no:
+        return False
+    return None