From e177e2feed1bfbe29f32c3378978313d19ce1c26 Mon Sep 17 00:00:00 2001
From: ptmcg <ptmcg@austin.rr.com>
Date: Mon, 31 Dec 2018 13:10:59 -0600
Subject: Add document signoff and library book state examples;

---
 examples/statemachine/libraryBookDemo.py | 78 ++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 examples/statemachine/libraryBookDemo.py

(limited to 'examples/statemachine/libraryBookDemo.py')

diff --git a/examples/statemachine/libraryBookDemo.py b/examples/statemachine/libraryBookDemo.py
new file mode 100644
index 0000000..84108e5
--- /dev/null
+++ b/examples/statemachine/libraryBookDemo.py
@@ -0,0 +1,78 @@
+import statemachine
+import librarybookstate
+
+
+class Book:
+    def __init__(self):
+        self._state = librarybookstate.New()
+
+    @property
+    def state(self):
+        return self._state
+
+    # get behavior/properties from current state
+    def __getattr__(self, attrname):
+        attr = getattr(self._state, attrname)
+        if isinstance(getattr(librarybookstate, attrname, None),
+                      librarybookstate.BookStateTransition):
+            return lambda: setattr(self, '_state', attr())
+        return attr
+
+    def __str__(self):
+        return "{}: {}".format(self.__class__.__name__, self._state)
+
+
+class RestrictedBook(Book):
+    def __init__(self):
+        super(RestrictedBook, self).__init__()
+        self._authorized_users = []
+
+    def authorize(self, name):
+        self._authorized_users.append(name)
+
+    # specialized checkout to check permission of user first
+    def checkout(self, user=None):
+        if user in self._authorized_users:
+            self._state = self._state.checkout()
+        else:
+            raise Exception("{} could not check out restricted book".format((user, "anonymous")[user is None]))
+
+
+def run_demo():
+    book = Book()
+    book.shelve()
+    print(book)
+    book.checkout()
+    print(book)
+    book.checkin()
+    print(book)
+    book.reserve()
+    print(book)
+    try:
+        book.checkout()
+    except statemachine.InvalidTransitionException:
+        print('..cannot check out reserved book')
+    book.release()
+    print(book)
+    book.checkout()
+    print(book)
+    print()
+
+    restricted_book = RestrictedBook()
+    restricted_book.authorize("BOB")
+    restricted_book.restrict()
+    print(restricted_book)
+    for name in [None, "BILL", "BOB"]:
+        try:
+            restricted_book.checkout(name)
+        except Exception as e:
+            print('..' + str(e))
+        else:
+            print('checkout to', name)
+    print(restricted_book)
+    restricted_book.checkin()
+    print(restricted_book)
+
+
+if __name__ == '__main__':
+    run_demo()
-- 
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