Remove fallback to 24x80, and fix docstring formatting.

There are some advantages to falling back to 24x80: for example, the ability to easily render output based on height and width when being piped through `less`. However, that's a backward incompatible change--we explicitly documented the None return values in earlier versions--so I don't want to make it lightly. Reverting it for now because I want to get the unquestionable parts of this merged in.

1 files changed, 11 insertions, 7 deletions

diff --git a/blessings/__init__.py b/blessings/__init__.py
index 8183265..4506869 100644
--- a/blessings/__init__.py
+++ b/blessings/__init__.py
@@ -217,10 +217,13 @@ class Terminal(object):
         return self._height_and_width()[1]
 
     def _height_and_width(self):
-        """Return a tuple of (terminal height, terminal width),
-           using TIOCGWINSZ (Terminal I/O-Control: Get Window Size),
-           falling back to environment variables (LINES, COLUMNS),
-           and 24 x 80 when otherwise unavailable."""
+        """Return a tuple of (terminal height, terminal width).
+
+        Start by trying TIOCGWINSZ (Terminal I/O-Control: Get Window Size),
+        falling back to environment variables (LINES, COLUMNS), and returning
+        (None, None) if those are unavailable or invalid.
+
+        """
         # tigetnum('lines') and tigetnum('cols') update only if we call
         # setupterm() again.
         for descriptor in self._init_descriptor, sys.__stdout__:
@@ -232,9 +235,10 @@ class Terminal(object):
                 # as when when stdout is piped to another program, fe. tee(1),
                 # these ioctls will raise IOError
                 pass
-        lines, cols = (int(environ.get('LINES', '24')),
-                       int(environ.get('COLUMNS', '80')))
-        return lines, cols
+        try:
+            return int(environ.get('LINES')), int(environ.get('COLUMNS'))
+        except TypeError:
+            return None, None
 
     @contextmanager
     def location(self, x=None, y=None):