Added Yay backend for updates script (#758)

i3pystatus/updates/yay.py

@@ -0,0 +1,44 @@
+from i3pystatus.core.command import run_through_shell
+from i3pystatus.updates import Backend
+
+
+class Yay(Backend):
+    """
+    This module counts the available updates using yay.
+    By default it will only count aur packages. Thus it can be used with the
+    pacman backend like this:
+
+    .. code-block:: python
+
+        from i3pystatus.updates import pacman, yay
+        status.register("updates", backends = \
+[pacman.Pacman(), yay.Yay()])
+
+    To count both pacman and aur packages, pass False in the constructor:
+
+    .. code-block:: python
+
+        from i3pystatus.updates import yay
+        status.register("updates", backends = [yay.Yay(False)])
+    """
+
+    def __init__(self, aur_only=True):
+        self.aur_only = aur_only
+
+    @property
+    def updates(self):
+        if(self.aur_only):
+            command = ["yay", "-Qua"]
+        else:
+            command = ["yay", "-Qu"]
+        checkupdates = run_through_shell(command)
+        out = checkupdates.out
+        return out.count("\n"), out
+
+Backend = Yay
+
+if __name__ == "__main__":
+    """
+    Call this module directly; Print the update count and notification body.
+    """
+    print("Updates: {}\n\n{}".format(*Backend().updates))