Implement ESCDELAY environment value

Closes #158

blessed/keyboard.py

@@ -1,6 +1,7 @@
 """Sub-module providing 'keyboard awareness'."""
 
 # std imports
+import os
 import re
 import time
 import platform
@@ -448,4 +449,18 @@ def _read_until(term, pattern, timeout):
     ('KEY_BEGIN', curses.KEY_BEG),
 )
 
+#: Default delay, in seconds, of Escape key detection in
+#: :meth:`Terminal.inkey`.` curses has a default delay of 1000ms (1 second) for
+#: escape sequences.  This is too long for modern applications, so we set it to
+#: 350ms, or 0.35 seconds. It is still a bit conservative but does well with
+#: for telnet or ssh servers.
+DEFAULT_ESCDELAY = 0.35
+if os.environ.get('ESCDELAY'):
+    try:
+        DEFAULT_ESCDELAY = int(os.environ['ESCDELAY']) / 1000.0
+    except ValueError:
+        # invalid values of 'ESCDELAY' are ignored
+        pass
+
+
 __all__ = ('Keystroke', 'get_keyboard_codes', 'get_keyboard_sequences',)

blessed/terminal.py

@@ -23,7 +23,8 @@
                        resolve_sequence,
                        get_keyboard_codes,
                        get_leading_prefixes,
-                       get_keyboard_sequences)
+                       get_keyboard_sequences,
+                       DEFAULT_ESCDELAY)
 from .sequences import Termcap, Sequence, SequenceTextWrapper
 from .colorspace import RGB_256TABLE
 from .formatters import (COLORS,
@@ -1425,7 +1426,7 @@ def keypad(self):
             self.stream.write(self.rmkx)
             self.stream.flush()
 
-    def inkey(self, timeout=None, esc_delay=0.35):
+    def inkey(self, timeout=None, esc_delay=DEFAULT_ESCDELAY):
         """
         Read and return the next keyboard event within given timeout.
 
@@ -1434,12 +1435,20 @@ def inkey(self, timeout=None, esc_delay=0.35):
         :arg float timeout: Number of seconds to wait for a keystroke before
             returning.  When ``None`` (default), this method may block
             indefinitely.
-        :arg float esc_delay: To distinguish between the keystroke of
-           ``KEY_ESCAPE``, and sequences beginning with escape, the parameter
-           ``esc_delay`` specifies the amount of time after receiving escape
-           (``chr(27)``) to seek for the completion of an application key
-           before returning a :class:`~.Keystroke` instance for
-           ``KEY_ESCAPE``.
+        :arg float esc_delay: Time in seconds to block after Escape key
+           is received to await another key sequence beginning with
+           escape such as *KEY_LEFT*, sequence ``'\x1b[D'``], before returning a
+           :class:`~.Keystroke` instance for ``KEY_ESCAPE``.
+
+           Users may also override this for all blessed and curses applications
+           with environment value of ESCDELAY_ as an integer in milliseconds.
+           You may also override user preference as an argument to this function,
+           as the delay value is in seconds.
+
+           It could be set to low value such as 10, modern pipelines typically
+           transmit a keyboard input sequence without framing and this can often
+           be safely set at very low values!
+
         :rtype: :class:`~.Keystroke`.
         :returns: :class:`~.Keystroke`, which may be empty (``u''``) if
            ``timeout`` is specified and keystroke is not received.
@@ -1458,7 +1467,6 @@ def inkey(self, timeout=None, esc_delay=0.35):
         resolve = functools.partial(resolve_sequence,
                                     mapper=self._keymap,
                                     codes=self._keycodes)
-
         stime = time.time()
 
         # re-buffer previously received keystrokes,

tests/test_core.py

@@ -91,9 +91,13 @@ def child():
     child()
 
 
+@pytest.fixture(scope="session", autouse=True)
 @pytest.mark.skipif(IS_WINDOWS, reason="requires more than 1 tty")
 def test_number_of_colors_without_tty():
     """``number_of_colors`` should return 0 when there's no tty."""
+    if 'COLORTERM' in os.environ:
+        del os.environ['COLORTERM']
+
     @as_subprocess
     def child_256_nostyle():
         t = TestTerminal(stream=six.StringIO())
@@ -118,6 +122,15 @@ def child_0_forcestyle():
                          force_styling=True)
         assert (t.number_of_colors == 0)
 
+    @as_subprocess
+    def child_24bit_forcestyle_with_colorterm():
+        os.environ['COLORTERM'] = 'truecolor'
+        t = TestTerminal(kind='vt220', stream=six.StringIO(),
+                         force_styling=True)
+        assert (t.number_of_colors == 1 << 24)
+
+
+
     child_0_forcestyle()
     child_8_forcestyle()
     child_256_forcestyle()

tests/test_keyboard.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 """Tests for keyboard support."""
 # std imports
+import os
 import sys
 import platform
 import tempfile
@@ -363,3 +364,31 @@ def child(kind):  # pylint: disable=too-many-statements
         assert resolve(u"\x1bOS").name == "KEY_F4"
 
     child('xterm')
+
+UNDER_PY34 = sys.version_info[0:2] < (3, 4)
+
+@pytest.fixture(scope="session", autouse=True)
+@pytest.mark.skipif(UNDER_PY34, reason="importlib was renamed in py34")
+def test_ESCDELAY_unset():
+    if 'ESCDELAY' in os.environ:
+        del os.environ['ESCDELAY']
+    import importlib, blessed.keyboard
+    importlib.reload(blessed.keyboard)
+    assert blessed.keyboard.DEFAULT_ESCDELAY == 0.35
+
+@pytest.fixture(scope="session", autouse=True)
+@pytest.mark.skipif(UNDER_PY34, reason="importlib was renamed in py34")
+def test_ESCDELAY_bad_value():
+    os.environ['ESCDELAY'] = 'XYZ123!'
+    import importlib, blessed.keyboard
+    importlib.reload(blessed.keyboard)
+    assert blessed.keyboard.DEFAULT_ESCDELAY == 0.35
+
+@pytest.fixture(scope="session", autouse=True)
+@pytest.mark.skipif(UNDER_PY34, reason="importlib was renamed in py34")
+def test_ESCDELAY_bad_value():
+    os.environ['ESCDELAY'] = '10'
+    import importlib, blessed.keyboard
+    importlib.reload(blessed.keyboard)
+    assert blessed.keyboard.DEFAULT_ESCDELAY == 0.01
+