Look up control sequences at init time

2 files changed, 25 insertions, 7 deletions

diff --git a/NEWS b/NEWS
index 0dee0b4..fec99cd 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,12 @@
 NEWS file for ttystatus
 =======================
 
+Version 0.26, released 2015-10-06
+---------------------------------
+
+* Fix looking up of capabilities when there is not terminal. Reported
+  by Sharon Kimble.
+
 Version 0.25, released 2015-10-05
 ---------------------------------
 
diff --git a/ttystatus/tty.py b/ttystatus/tty.py
index 21e75cc..580401b 100644
--- a/ttystatus/tty.py
+++ b/ttystatus/tty.py
@@ -26,25 +26,37 @@ class PhysicalTerminal(object):
 
     def __init__(self):
         self._terminal = None
+        self._cuu = None
+        self._cud = None
+        self._cr = None
+        self._el = None
 
     def open_tty(self):
         self._terminal = open('/dev/tty', 'wb')
         curses.setupterm(None, self._terminal.fileno())
+        self._cuu = curses.tparm(curses.tigetstr('cuu'), 1)
+        self._cud = curses.tparm(curses.tigetstr('cud'), 1)
+        self._cr = curses.tigetstr('cr')
+        self._el = curses.tigetstr('el')
 
     def has_capabilities(self):
-        return all(curses.tigetstr(x) is not None
-                   for x in ['cuu', 'cud', 'cr', 'el'])
+        return (self._cuu is not None and
+                self._cud is not None and
+                self._cr is not None and
+                self._el is not None)
 
     def get_up_sequence(self):
-        return curses.tparm(curses.tigetstr('cuu'), 1)
+        assert self._cuu is not None
+        return self._cuu
 
     def get_down_sequence(self):
-        return curses.tparm(curses.tigetstr('cud'), 1)
+        assert self._cud is not None
+        return self._cud
 
     def get_erase_line_sequence(self):
-        cr = curses.tigetstr('cr')
-        el = curses.tigetstr('el')
-        return cr + el
+        assert self._cr is not None
+        assert self._el is not None
+        return self._cr + self._el
 
     def get_width(self):
         '''Return width of terminal in characters.