Python sys.displayhook() Examples

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec(code, globals, locals)
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            exc_info = sys.exc_info()[:2]
            self.error(traceback.format_exception_only(*exc_info)[-1].strip()) 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec code in globals, locals
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            t, v = sys.exc_info()[:2]
            if type(t) == type(''):
                exc_type_name = t
            else: exc_type_name = t.__name__
            print >>self.stdout, '***', exc_type_name + ':', v 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec code in globals, locals
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            t, v = sys.exc_info()[:2]
            if type(t) == type(''):
                exc_type_name = t
            else: exc_type_name = t.__name__
            print >>self.stdout, '***', exc_type_name + ':', v 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec code in globals, locals
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            t, v = sys.exc_info()[:2]
            if type(t) == type(''):
                exc_type_name = t
            else: exc_type_name = t.__name__
            print >>self.stdout, '***', exc_type_name + ':', v 

def system(cmd):
    """Win32 version of os.system() that works with network shares.

    Note that this implementation returns None, as meant for use in IPython.

    Parameters
    ----------
    cmd : str
      A command to be executed in the system shell.

    Returns
    -------
    None : we explicitly do NOT return the subprocess status code, as this
    utility is meant to be used extensively in IPython, where any return value
    would trigger :func:`sys.displayhook` calls.
    """
    with AvoidUNCPath() as path:
        if path is not None:
            cmd = '"pushd %s &&"%s' % (path, cmd)
        with Win32ShellCommandController(cmd) as scc:
            scc.run() 

def system(cmd):
    """Win32 version of os.system() that works with network shares.

    Note that this implementation returns None, as meant for use in IPython.

    Parameters
    ----------
    cmd : str
      A command to be executed in the system shell.

    Returns
    -------
    None : we explicitly do NOT return the subprocess status code, as this
    utility is meant to be used extensively in IPython, where any return value
    would trigger :func:`sys.displayhook` calls.
    """
    # The controller provides interactivity with both
    # stdin and stdout
    #import _process_win32_controller
    #_process_win32_controller.system(cmd)

    with AvoidUNCPath() as path:
        if path is not None:
            cmd = '"pushd %s &&"%s' % (path, cmd)
        return process_handler(cmd, _system_body) 

def dhook_wrap(func,*a,**k):
    """Wrap a function call in a sys.displayhook controller.

    Returns a wrapper around func which calls func, with all its arguments and
    keywords unmodified, using the default sys.displayhook.  Since IPython
    modifies sys.displayhook, it breaks the behavior of certain systems that
    rely on the default behavior, notably doctest.
    """

    def f(*a,**k):

        dhook_s = sys.displayhook
        sys.displayhook = sys.__displayhook__
        try:
            out = func(*a,**k)
        finally:
            sys.displayhook = dhook_s

        return out

    f.__doc__ = func.__doc__
    return f 

def system_piped(self, cmd):
        """Call the given cmd in a subprocess, piping stdout/err

        Parameters
        ----------
        cmd : str
          Command to execute (can not end in '&', as background processes are
          not supported.  Should not be a command that expects input
          other than simple text.
        """
        if cmd.rstrip().endswith('&'):
            # this is *far* from a rigorous test
            # We do not support backgrounding processes because we either use
            # pexpect or pipes to read from.  Users can always just call
            # os.system() or use ip.system=ip.system_raw
            # if they really want a background process.
            raise OSError("Background processes not supported.")

        # we explicitly do NOT return the subprocess status code, because
        # a non-None value would trigger :func:`sys.displayhook` calls.
        # Instead, we store the exit_code in user_ns.
        self.user_ns['_exit_code'] = system(self.var_expand(cmd, depth=1)) 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec code in globals, locals
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            t, v = sys.exc_info()[:2]
            if type(t) == type(''):
                exc_type_name = t
            else: exc_type_name = t.__name__
            print >>self.stdout, '***', exc_type_name + ':', v 

def displayhook(self, obj):
        self.locals['_'] = obj
        if isinstance(obj, defer.Deferred):
            # XXX Ick, where is my "hasFired()" interface?
            if hasattr(obj, "result"):
                self.write(repr(obj))
            elif id(obj) in self._pendingDeferreds:
                self.write("<Deferred #%d>" % (self._pendingDeferreds[id(obj)][0],))
            else:
                d = self._pendingDeferreds
                k = self.numDeferreds
                d[id(obj)] = (k, obj)
                self.numDeferreds += 1
                obj.addCallbacks(self._cbDisplayDeferred, self._ebDisplayDeferred,
                                 callbackArgs=(k, obj), errbackArgs=(k, obj))
                self.write("<Deferred #%d>" % (k,))
        elif obj is not None:
            self.write(repr(obj)) 

def test_pprint_compact(self):
        with patch('sys.stdout', new_callable=StringIO) as mock_stdout:

            # - test compact pprint-ing with 80x25 terminal
            with patch.object(pythonrc.subprocess, 'check_output',
                              return_value='25 80'):
                sys.displayhook(list(range(22)))
                self.assertIn('20, 21]', sys.stdout.getvalue())
                sys.displayhook(list(range(23)))
                self.assertIn('21,\n 22]', sys.stdout.getvalue())

            # - test compact pprint-ing with resized 100x25 terminal
            with patch.object(pythonrc.subprocess, 'check_output',
                              return_value=('25 100')):
                sys.displayhook(list(range(23)))
                self.assertIn('21, 22]', sys.stdout.getvalue()) 

def _reset_py_display() -> None:
        """
        Resets the dynamic objects in the sys module that the py and ipy consoles fight over.
        When a Python console starts it adopts certain display settings if they've already been set.
        If an ipy console has previously been run, then py uses its settings and ends up looking
        like an ipy console in terms of prompt and exception text. This method forces the Python
        console to create its own display settings since they won't exist.

        IPython does not have this problem since it always overwrites the display settings when it
        is run. Therefore this method only needs to be called before creating a Python console.
        """
        # Delete any prompts that have been set
        attributes = ['ps1', 'ps2', 'ps3']
        for cur_attr in attributes:
            try:
                del sys.__dict__[cur_attr]
            except KeyError:
                pass

        # Reset functions
        sys.displayhook = sys.__displayhook__
        sys.excepthook = sys.__excepthook__ 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec(code, globals, locals)
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            exc_info = sys.exc_info()[:2]
            self.error(traceback.format_exception_only(*exc_info)[-1].strip()) 

def handle(self):
        """Override base method"""
        executive = Executive(self)
        self.register("exec", executive)
        self.console = self.get_remote_proxy("console")
        sys.stdin = PyShell.PseudoInputFile(self.console, "stdin",
                IOBinding.encoding)
        sys.stdout = PyShell.PseudoOutputFile(self.console, "stdout",
                IOBinding.encoding)
        sys.stderr = PyShell.PseudoOutputFile(self.console, "stderr",
                IOBinding.encoding)

        sys.displayhook = rpc.displayhook
        # page help() text to shell.
        import pydoc # import must be done here to capture i/o binding
        pydoc.pager = pydoc.plainpager

        # Keep a reference to stdin so that it won't try to exit IDLE if
        # sys.stdin gets changed from within IDLE's shell. See issue17838.
        self._keep_stdin = sys.stdin

        self.interp = self.get_remote_proxy("interp")
        rpc.RPCHandler.getresponse(self, myseq=None, wait=0.05) 

def begin(self):
        self.text.mark_set("iomark", "insert")
        self.resetoutput()
        if use_subprocess:
            nosub = ''
            client = self.interp.start_subprocess()
            if not client:
                self.close()
                return False
        else:
            nosub = ("==== No Subprocess ====\n\n" +
                    "WARNING: Running IDLE without a Subprocess is deprecated\n" +
                    "and will be removed in a later version. See Help/IDLE Help\n" +
                    "for details.\n\n")
            sys.displayhook = rpc.displayhook

        self.write("Python %s on %s\n%s\n%s" %
                   (sys.version, sys.platform, self.COPYRIGHT, nosub))
        self.text.focus_force()
        self.showprompt()
        import tkinter
        tkinter._default_root = None # 03Jan04 KBK What's this?
        return True 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec(code, globals, locals)
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            exc_info = sys.exc_info()[:2]
            self.error(traceback.format_exception_only(*exc_info)[-1].strip()) 

def init_pprint(self):
        """Activates pretty-printing of output values.
        """
        keys_re = re.compile(r'([\'\("]+(.*?[\'\)"]: ))+?')
        color_dict = partial(keys_re.sub, lambda m: purple(m.group()))
        format_func = pprint.pformat
        if sys.version_info.major >= 3 and sys.version_info.minor > 3:
            format_func = partial(pprint.pformat, compact=True)

        def pprint_callback(value):
            if value is not None:
                try:
                    rows, cols = os.get_teminal_size()
                except AttributeError:
                    try:
                        rows, cols = map(int, subprocess.check_output(['stty', 'size']).split())
                    except:
                        cols = 80
                formatted = format_func(value, width=cols)
                print(color_dict(formatted) if issubclass(type(value), dict) else blue(formatted))
            self.locals['_'] = value

        sys.displayhook = pprint_callback 

def displayhook(self, obj):
        self.locals['_'] = obj
        if isinstance(obj, defer.Deferred):
            # XXX Ick, where is my "hasFired()" interface?
            if hasattr(obj, "result"):
                self.write(repr(obj))
            elif id(obj) in self._pendingDeferreds:
                self.write("<Deferred #%d>" % (self._pendingDeferreds[id(obj)][0],))
            else:
                d = self._pendingDeferreds
                k = self.numDeferreds
                d[id(obj)] = (k, obj)
                self.numDeferreds += 1
                obj.addCallbacks(self._cbDisplayDeferred, self._ebDisplayDeferred,
                                 callbackArgs=(k, obj), errbackArgs=(k, obj))
                self.write("<Deferred #%d>" % (k,))
        elif obj is not None:
            self.write(repr(obj)) 

def default(self, line):
        if line[:1] == '!': line = line[1:]
        locals = self.curframe_locals
        globals = self.curframe.f_globals
        try:
            code = compile(line + '\n', '<stdin>', 'single')
            save_stdout = sys.stdout
            save_stdin = sys.stdin
            save_displayhook = sys.displayhook
            try:
                sys.stdin = self.stdin
                sys.stdout = self.stdout
                sys.displayhook = self.displayhook
                exec code in globals, locals
            finally:
                sys.stdout = save_stdout
                sys.stdin = save_stdin
                sys.displayhook = save_displayhook
        except:
            t, v = sys.exc_info()[:2]
            if type(t) == type(''):
                exc_type_name = t
            else: exc_type_name = t.__name__
            print >>self.stdout, '***', exc_type_name + ':', v 

def runcode(self, *a, **kw):
        orighook, sys.displayhook = sys.displayhook, self.displayhook
        try:
            origout, sys.stdout = sys.stdout, FileWrapper(self.handler)
            try:
                code.InteractiveInterpreter.runcode(self, *a, **kw)
            finally:
                sys.stdout = origout
        finally:
            sys.displayhook = orighook 

def test_init_pprint(self):
        self.assertEqual(sys.displayhook.__name__, 'pprint_callback')
        with patch('sys.stdout', new_callable=StringIO) as mock_stdout:
            sys.displayhook(42)
            sys.displayhook({'spam': 42})
            self.assertEqual(
                sys.stdout.getvalue(),
                ("%s\n" "{%s42}\n") % (pythonrc.blue('42'),
                                       pythonrc.purple("'spam': "))
            ) 

def test_lost_displayhook(self):
        olddisplayhook = sys.displayhook
        del sys.displayhook
        code = compile("42", "<string>", "single")
        self.assertRaises(RuntimeError, eval, code)
        sys.displayhook = olddisplayhook 

def test_custom_displayhook(self):
        olddisplayhook = sys.displayhook
        def baddisplayhook(obj):
            raise ValueError
        sys.displayhook = baddisplayhook
        code = compile("42", "<string>", "single")
        self.assertRaises(ValueError, eval, code)
        sys.displayhook = olddisplayhook 

def uninstall_repl_displayhook():
    """
    Uninstall the matplotlib display hook.

    .. warning

       Need IPython >= 2 for this to work.  For IPython < 2 will raise a
       ``NotImplementedError``

    .. warning

       If you are using vanilla python and have installed another
       display hook this will reset ``sys.displayhook`` to what ever
       function was there when matplotlib installed it's displayhook,
       possibly discarding your changes.
    """
    global _IP_REGISTERED
    global _INSTALL_FIG_OBSERVER
    if _IP_REGISTERED:
        from IPython import get_ipython
        ip = get_ipython()
        try:
            ip.events.unregister('post_execute', _IP_REGISTERED)
        except AttributeError:
            raise NotImplementedError("Can not unregister events "
                                      "in IPython < 2.0")
        _IP_REGISTERED = None

    if _INSTALL_FIG_OBSERVER:
        _INSTALL_FIG_OBSERVER = False 

def uninstall_repl_displayhook():
    """
    Uninstall the matplotlib display hook.

    .. warning

       Need IPython >= 2 for this to work.  For IPython < 2 will raise a
       ``NotImplementedError``

    .. warning

       If you are using vanilla python and have installed another
       display hook this will reset ``sys.displayhook`` to what ever
       function was there when matplotlib installed it's displayhook,
       possibly discarding your changes.
    """
    global _IP_REGISTERED
    global _INSTALL_FIG_OBSERVER
    if _IP_REGISTERED:
        from IPython import get_ipython
        ip = get_ipython()
        try:
            ip.events.unregister('post_execute', _IP_REGISTERED)
        except AttributeError:
            raise NotImplementedError("Can not unregister events "
                                      "in IPython < 2.0")
        _IP_REGISTERED = None

    if _INSTALL_FIG_OBSERVER:
        _INSTALL_FIG_OBSERVER = False 

def displayhook(self, obj):
        """Custom displayhook for the exec in default(), which prevents
        assignment of the _ variable in the builtins.
        """
        # reproduce the behavior of the standard displayhook, not printing None
        if obj is not None:
            self.message(repr(obj)) 

def displayhook(self, obj):
        """Custom displayhook for the exec in default(), which prevents
        assignment of the _ variable in the builtins.
        """
        # reproduce the behavior of the standard displayhook, not printing None
        if obj is not None:
            print repr(obj) 

def displayhook(): r"""
Test that changing sys.displayhook doesn't matter for doctest.

    >>> import sys
    >>> orig_displayhook = sys.displayhook
    >>> def my_displayhook(x):
    ...     print('hi!')
    >>> sys.displayhook = my_displayhook
    >>> def f():
    ...     '''
    ...     >>> 3
    ...     3
    ...     '''
    >>> test = doctest.DocTestFinder().find(f)[0]
    >>> r = doctest.DocTestRunner(verbose=False).run(test)
    >>> post_displayhook = sys.displayhook

    We need to restore sys.displayhook now, so that we'll be able to test
    results.

    >>> sys.displayhook = orig_displayhook

    Ok, now we can check that everything is ok.

    >>> r
    TestResults(failed=0, attempted=1)
    >>> post_displayhook is my_displayhook
    True
""" 

def displayhook(obj):
        try:
            stream = _local.stream
        except AttributeError:
            return _displayhook(obj)
        # stream._write bypasses escaping as debug_repr is
        # already generating HTML for us.
        if obj is not None:
            _local._current_ipy.locals['_'] = obj
            stream._write(debug_repr(obj)) 

def tearDown(self):
        sys.stdout = self.orig_stdout
        sys.stderr = self.orig_stderr
        sys.displayhook = self.orig_displayhook
        test.support.reap_children()