Added example solutions to several chapters. Feel free to create a pull request with your answers. Also for the chapters that have no solutions yet :)

CH_06_decorators/exercise_03/solution_00.py

@@ -0,0 +1,46 @@
+# Modify the memoization function to function with unhashable types.
+
+import functools
+
+
+cache = dict()
+
+def memoize(function):
+    def safe_hash(args):
+        '''
+        In the case of unhashable types use the `repr()` to be hashable.
+        '''
+        try:
+            return hash(args)
+        except TypeError:
+            return repr(args)
+
+    @functools.wraps(function)
+    def _memoize(*args):
+        # If the cache is not available, call the function
+        # Note that all args need to be hashable
+        # key = function, safe_hash(args)
+        key = function, args
+        if key not in cache:
+            cache[key] = function(*args)
+        return cache[key]
+
+    return _memoize
+
+
+@memoize
+def printer(*args):
+    print(args)
+
+
+def main():
+    # Should work as expected
+    printer('a', 'b', 'c')
+
+    # Would have issues with the original memoize function because the
+    # parameters are unhashable
+    printer(dict(a=1, b=2, c=3))
+
+
+if __name__ == '__main__':
+    main()