Merge pull request #315 from swarmer/separate-tty

Add ability to control pudb from a separate tty

README.rst

@@ -43,6 +43,8 @@ Features
 * PuDB places special emphasis on exception handling. A post-mortem mode makes
   it easy to retrace a crashing program's last steps.
 
+* Ability to control the debugger from a separate terminal.
+
 * IPython integration (see `wiki <http://wiki.tiker.net/PuDB>`_)
 
 * Should work with Python 2.6 and newer, including Python 3.

doc/starting.rst

@@ -29,6 +29,32 @@ This is equivalent to::
 which is useful if you want to run PuDB in a version of Python other than the
 one you most recently installed PuDB with.
 
+Debugging from a separate terminal
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+It's possible to control the debugger from a separate terminal. This is useful
+if there are several threads running that are printing to stdout while
+you're debugging and messing up the terminal, or if you want to keep the
+original terminal available for any other reason.
+
+Open a new terminal. First, you need to get the path of the tty of the
+terminal you want to debug from. To do that, use the standard unix
+command `tty`. It will print something like `/dev/pts/3`.
+
+Then you need to make sure that your terminal doesn't have a shell actively
+reading and possibly capturing some of the input that should go to pudb.
+To do that run a placeholder command that does nothing,
+such as `perl -MPOSIX -e pause`.
+
+Then set the PUDB_TTY environment variable to the path tty gave you,
+for example::
+
+    PUDB_TTY=/dev/pts/3 pudb my-script.py
+
+Now instead of using the current terminal, pudb will use this tty for its UI.
+You may want to use the internal shell in pudb, as others will still use the
+original terminal.
+
 Remote debugging
 ^^^^^^^^^^^^^^^^
 

pudb/__init__.py

@@ -70,8 +70,33 @@ else:
 CURRENT_DEBUGGER = []
 
 
+def _tty_override():
+    import os
+    return os.environ.get('PUDB_TTY')
+
+
+def _open_tty(tty_path):
+    import io, os, sys
+    if sys.version_info[0] == 2:
+        tty_file = open(tty_path, 'r+b', buffering=0)
+        term_size = None
+    else:
+        tty_file = io.TextIOWrapper(open(tty_path, 'r+b', buffering=0))
+        term_size = os.get_terminal_size(tty_file.fileno())
+
+    return tty_file, term_size
+
+
 def _get_debugger(**kwargs):
     if not CURRENT_DEBUGGER:
+        tty_path = _tty_override()
+        if tty_path and ('stdin' not in kwargs or 'stdout' not in kwargs):
+            tty_file, term_size = _open_tty(tty_path)
+
+            kwargs.setdefault('stdin', tty_file)
+            kwargs.setdefault('stdout', tty_file)
+            kwargs.setdefault('term_size', term_size)
+
         from pudb.debugger import Debugger
         dbg = Debugger(**kwargs)