Added behavior subject

src/cpl_reactive_extensions/behavior_subject.py

@@ -0,0 +1,23 @@
+from cpl_core.type import T
+from cpl_reactive_extensions.observable import Observable
+
+
+class BehaviorSubject(Observable):
+    def __init__(self, _t: type, value: T):
+        Observable.__init__(self, lambda x: x)
+
+        if not isinstance(value, _t):
+            raise TypeError(f"Expected {_t.__name__} not {type(value).__name__}")
+
+        self._t = _t
+        self._value = value
+
+    @property
+    def value(self) -> T:
+        return self._value
+
+    def next(self, value: T):
+        if not isinstance(value, self._t):
+            raise TypeError(f"Expected {self._t.__name__} not {type(value).__name__}")
+
+        self._value = value

src/cpl_reactive_extensions/subject.py

@@ -7,14 +7,3 @@ class Subject(Observable):
         Observable.__init__(self)
 
         self._t = _t
-        self._value: T = None
-
-    @property
-    def value(self) -> T:
-        return self._value
-
-    def next(self, value: T):
-        if not isinstance(value, self._t):
-            raise TypeError(f"Expected {self._t.__name__} not {type(value).__name__}")
-
-        self._value = value

unittests/unittests_reactive_extenstions/reactive_test_case.py

@@ -4,6 +4,7 @@ import unittest
 from threading import Timer
 
 from cpl_core.console import Console
+from cpl_reactive_extensions.behavior_subject import BehaviorSubject
 from cpl_reactive_extensions.observable import Observable
 from cpl_reactive_extensions.observer import Observer
 from cpl_reactive_extensions.subject import Subject
@@ -114,3 +115,14 @@ class ReactiveTestCase(unittest.TestCase):
         observable.subscribe(subject, self._on_error)
 
         self.assertFalse(self._error)
+
+    def test_behavior_subject(self):
+        subject = BehaviorSubject(int, 0)
+
+        subject.subscribe(lambda x: Console.write_line("a", x))
+
+        subject.next(1)
+        subject.next(2)
+
+        subject.subscribe(lambda x: Console.write_line("b", x))
+        subject.next(3)