curses.setupterm(), TypeError: argument must be an int, or have a fileno() method about pudb

[inducer]

What is sys.stdout/stdin when you run that?

[aconrad]

So I've added to the file pudb/debugger.py, line 1187:

        if curses:
            print sys.stdout
            print sys.stderr
            curses.setupterm()

... which prints out:

<nose.plugins.xunit.Tee object at 0x1fa4cd0>
<nose.plugins.xunit.Tee object at 0x1fa4d10>

This happens when using pudb called from nosetests. I believe this used to work before I recently re-installed my system.

[inducer]

Can you try current git? If it works, I'll push out a new version.

[aconrad]

Yup, I just tested it and it works like a charm! Thanks @inducer!

[inducer]

2013.3.4 released.

[timblaktu]

@inducer I am encountering this problem when trying to pudb.set_trace() in a unittest-based test runner process. I suspect the problem is caused by the framework or my code changing stdout/err in an unexpected way, but have not been able to determine root cause and could use your help.

I am using python 2.7.13 on debian 9.3, and using the following relevant packages:

Name: pudb
Version: 2018.1
Name: Pygments
Version: 2.2.0
Name: urwid
Version: 2.0.1

When I put pudb.set_trace in one of my tests and run, I see this stack trace:

.
.
. (entry point from my code)
  File "/usr/lib/python2.7/bdb.py", line 49, in trace_dispatch
    return self.dispatch_line(frame)
  File "/usr/local/lib/python2.7/dist-packages/pudb/debugger.py", line 187, in dispatch_line
    self.user_line(frame)
  File "/usr/local/lib/python2.7/dist-packages/pudb/debugger.py", line 408, in user_line
    self.interaction(frame)
  File "/usr/local/lib/python2.7/dist-packages/pudb/debugger.py", line 376, in interaction
    show_exc_dialog=show_exc_dialog)
  File "/usr/local/lib/python2.7/dist-packages/pudb/debugger.py", line 2118, in call_with_ui
    return f(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pudb/debugger.py", line 2362, in interaction
    self.event_loop()
  File "/usr/local/lib/python2.7/dist-packages/pudb/debugger.py", line 2315, in event_loop
    self.size = self.screen.get_cols_rows()
  File "/usr/local/lib/python2.7/dist-packages/urwid/raw_display.py", line 655, in get_cols_rows
    termios.TIOCGWINSZ, ' '*4)
TypeError: argument must be an int, or have a fileno() method.

The main process above is setting sys.stdout and sys.stderr to custom "Tee" objects that "fans out" these streams to a file in addition to the original streams. This tee object indeed implements fileno() so I'm not sure what it's complaining about:

  class Tee(object):
      '''Implements functionality similar to tee program on linux.

      At construction, overwrites sys.stdout (or sys.stderr) with itself, and opens file.
      Subsequently, When sys.stdout (or sys.stderr) is written to by this process, the string
      is written to both the original sys.stdout (or sys.stderr) and the specified file.
      At destruction, the original sys.stdout (or sys.stderr) is restored and the file closed.

      The default file mode 'a' enables the same file to be written to multiple
      times within the same process, by creating and destroying Tee objects
      with the same filename. It is also required mode when using 2 Tee objects pointing
      at the same file (e.g. one for stdout and one for stderr).
      '''

      def __init__(self, filename, what_to_redirect=sys.stdout, mode='a'):
          self.file = open(filename, mode)
          self.what_to_redirect = what_to_redirect
          if self.what_to_redirect is sys.stdout:
              sys.stdout = self
          elif self.what_to_redirect is sys.stderr:
              sys.stderr = self

      def __del__(self):
          if self.what_to_redirect is sys.stdout:
              sys.stdout = self.what_to_redirect
          elif self.what_to_redirect is sys.stderr:
              sys.stderr = self.what_to_redirect
          self.flush()
          self.file.close()

      def write(self, data):
          self.file.write(data)
          self.what_to_redirect.write(data)

      def flush(self):
          self.file.flush()

      def fileno(self):
          '''Pudb was barfing when hitting a breakpoint bc this method wasn't defined.
          I believe the right thing to do is to return the file descriptor of what is
          being redirected, i.e. stderr/out.'''
          self.what_to_redirect.fileno()

When I insert:

            print sys.stdout
            print sys.stderr

in either the pudb/debugger.py or the urwid/raw_display.py lines, I get a mysterious syntax error.

I have confirmed pudb.set_trace():

• works in a simple script in same environment
• does not work in some other scripts of mine that run outside/independent of unittest, but only in cases where the set_trace() call is made in another process.

Any clues on how to fix the unittest/Tee case above? Thanks!

[inducer]

@timblaktu That sounds like an issue with urwid/termios not accepting an object it claims to accept. Could you raise an issue there?

[timblaktu]

Done. urwid/urwid#316 (comment)

Thanks, @inducer.