Prevent !cmd to try to run backgrounded (cmd &) processes.

IPython/zmq/zmqshell.py

@@ -1,418 +1,427 b''
 """A ZMQ-based subclass of InteractiveShell.
 
 This code is meant to ease the refactoring of the base InteractiveShell into
 something with a cleaner architecture for 2-process use, without actually
 breaking InteractiveShell itself.  So we're doing something a bit ugly, where
 we subclass and override what we want to fix.  Once this is working well, we
 can go back to the base class and refactor the code for a cleaner inheritance
 implementation that doesn't rely on so much monkeypatching.
 
 But this lets us maintain a fully working IPython as we develop the new
 machinery.  This should thus be thought of as scaffolding.
 """
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
+from __future__ import print_function
+
 # Stdlib
 import inspect
 import os
 import re
 import sys
 
 from subprocess import Popen, PIPE
 
 # Our own
 from IPython.core.interactiveshell import (
     InteractiveShell, InteractiveShellABC
 )
 from IPython.core.displayhook import DisplayHook
 from IPython.core.macro import Macro
 from IPython.utils.path import get_py_filename
 from IPython.utils.text import StringTypes
 from IPython.utils.traitlets import Instance, Type, Dict
 from IPython.utils.warn import warn
 from IPython.zmq.session import extract_header
 from IPython.core.payloadpage import install_payload_page
 from session import Session
 
 #-----------------------------------------------------------------------------
 # Globals and side-effects
 #-----------------------------------------------------------------------------
 
 # Install the payload version of page.
 install_payload_page()
 
 #-----------------------------------------------------------------------------
 # Functions and classes
 #-----------------------------------------------------------------------------
 
 class ZMQDisplayHook(DisplayHook):
 
     session = Instance(Session)
     pub_socket = Instance('zmq.Socket')
     parent_header = Dict({})
 
     def set_parent(self, parent):
         """Set the parent for outbound messages."""
         self.parent_header = extract_header(parent)
 
     def start_displayhook(self):
         self.msg = self.session.msg(u'pyout', {}, parent=self.parent_header)
 
     def write_output_prompt(self):
         """Write the output prompt."""
         if self.do_full_cache:
             self.msg['content']['output_sep'] = self.output_sep
             self.msg['content']['prompt_string'] = str(self.prompt_out)
             self.msg['content']['prompt_number'] = self.prompt_count
             self.msg['content']['output_sep2'] = self.output_sep2
 
     def write_result_repr(self, result_repr):
         self.msg['content']['data'] = result_repr
 
     def finish_displayhook(self):
         """Finish up all displayhook activities."""
         self.pub_socket.send_json(self.msg)
         self.msg = None
 
 
 class ZMQInteractiveShell(InteractiveShell):
     """A subclass of InteractiveShell for ZMQ."""
 
     displayhook_class = Type(ZMQDisplayHook)
 
     def system(self, cmd):
-        cmd = self.var_expand(cmd, depth=2)
+        cmd = self.var_expand(cmd, depth=2).strip()
+        
+        # Runnning a bacgkrounded process from within the gui isn't supported
+        # because we do p.wait() at the end.  So instead of silently blocking
+        # we simply refuse to run in this mode, to avoid surprising the user.
+        if cmd.endswith('&'):
+            raise OSError("Background processes not supported.")
+        
         sys.stdout.flush()
         sys.stderr.flush()
         p = Popen(cmd, shell=True, stdout=PIPE, stderr=PIPE)
         for line in p.stdout.read().split('\n'):
             if len(line) > 0:
-                print line
+                print(line)
         for line in p.stderr.read().split('\n'):
             if len(line) > 0:
-                print line
+                print(line, file=sys.stderr)
         p.wait()
 
     def init_io(self):
         # This will just use sys.stdout and sys.stderr. If you want to
         # override sys.stdout and sys.stderr themselves, you need to do that
         # *before* instantiating this class, because Term holds onto 
         # references to the underlying streams.
         import IPython.utils.io
         Term = IPython.utils.io.IOTerm()
         IPython.utils.io.Term = Term
 
     def magic_edit(self,parameter_s='',last_call=['','']):
         """Bring up an editor and execute the resulting code.
 
         Usage:
           %edit [options] [args]
 
         %edit runs IPython's editor hook.  The default version of this hook is
         set to call the __IPYTHON__.rc.editor command.  This is read from your
         environment variable $EDITOR.  If this isn't found, it will default to
         vi under Linux/Unix and to notepad under Windows.  See the end of this
         docstring for how to change the editor hook.
 
         You can also set the value of this editor via the command line option
         '-editor' or in your ipythonrc file. This is useful if you wish to use
         specifically for IPython an editor different from your typical default
         (and for Windows users who typically don't set environment variables).
 
         This command allows you to conveniently edit multi-line code right in
         your IPython session.
         
         If called without arguments, %edit opens up an empty editor with a
         temporary file and will execute the contents of this file when you
         close it (don't forget to save it!).
 
 
         Options:
 
         -n <number>: open the editor at a specified line number.  By default,
         the IPython editor hook uses the unix syntax 'editor +N filename', but
         you can configure this by providing your own modified hook if your
         favorite editor supports line-number specifications with a different
         syntax.
         
         -p: this will call the editor with the same data as the previous time
         it was used, regardless of how long ago (in your current session) it
         was.
 
         -r: use 'raw' input.  This option only applies to input taken from the
         user's history.  By default, the 'processed' history is used, so that
         magics are loaded in their transformed version to valid Python.  If
         this option is given, the raw input as typed as the command line is
         used instead.  When you exit the editor, it will be executed by
         IPython's own processor.
         
         -x: do not execute the edited code immediately upon exit. This is
         mainly useful if you are editing programs which need to be called with
         command line arguments, which you can then do using %run.
 
 
         Arguments:
 
         If arguments are given, the following possibilites exist:
 
         - The arguments are numbers or pairs of colon-separated numbers (like
         1 4:8 9). These are interpreted as lines of previous input to be
         loaded into the editor. The syntax is the same of the %macro command.
 
         - If the argument doesn't start with a number, it is evaluated as a
         variable and its contents loaded into the editor. You can thus edit
         any string which contains python code (including the result of
         previous edits).
 
         - If the argument is the name of an object (other than a string),
         IPython will try to locate the file where it was defined and open the
         editor at the point where it is defined. You can use `%edit function`
         to load an editor exactly at the point where 'function' is defined,
         edit it and have the file be executed automatically.
 
         If the object is a macro (see %macro for details), this opens up your
         specified editor with a temporary file containing the macro's data.
         Upon exit, the macro is reloaded with the contents of the file.
 
         Note: opening at an exact line is only supported under Unix, and some
         editors (like kedit and gedit up to Gnome 2.8) do not understand the
         '+NUMBER' parameter necessary for this feature. Good editors like
         (X)Emacs, vi, jed, pico and joe all do.
 
         - If the argument is not found as a variable, IPython will look for a
         file with that name (adding .py if necessary) and load it into the
         editor. It will execute its contents with execfile() when you exit,
         loading any code in the file into your interactive namespace.
 
         After executing your code, %edit will return as output the code you
         typed in the editor (except when it was an existing file). This way
         you can reload the code in further invocations of %edit as a variable,
         via _<NUMBER> or Out[<NUMBER>], where <NUMBER> is the prompt number of
         the output.
 
         Note that %edit is also available through the alias %ed.
 
         This is an example of creating a simple function inside the editor and
         then modifying it. First, start up the editor:
 
         In [1]: ed
         Editing... done. Executing edited code...
         Out[1]: 'def foo():n    print "foo() was defined in an editing session"n'
 
         We can then call the function foo():
         
         In [2]: foo()
         foo() was defined in an editing session
 
         Now we edit foo.  IPython automatically loads the editor with the
         (temporary) file where foo() was previously defined:
         
         In [3]: ed foo
         Editing... done. Executing edited code...
 
         And if we call foo() again we get the modified version:
         
         In [4]: foo()
         foo() has now been changed!
 
         Here is an example of how to edit a code snippet successive
         times. First we call the editor:
 
         In [5]: ed
         Editing... done. Executing edited code...
         hello
         Out[5]: "print 'hello'n"
 
         Now we call it again with the previous output (stored in _):
 
         In [6]: ed _
         Editing... done. Executing edited code...
         hello world
         Out[6]: "print 'hello world'n"
 
         Now we call it with the output #8 (stored in _8, also as Out[8]):
 
         In [7]: ed _8
         Editing... done. Executing edited code...
         hello again
         Out[7]: "print 'hello again'n"
 
 
         Changing the default editor hook:
 
         If you wish to write your own editor hook, you can put it in a
         configuration file which you load at startup time.  The default hook
         is defined in the IPython.core.hooks module, and you can use that as a
         starting example for further modifications.  That file also has
         general instructions on how to set a new hook for use once you've
         defined it."""
         
         # FIXME: This function has become a convoluted mess.  It needs a
         # ground-up rewrite with clean, simple logic.
 
         def make_filename(arg):
             "Make a filename from the given args"
             try:
                 filename = get_py_filename(arg)
             except IOError:
                 if args.endswith('.py'):
                     filename = arg
                 else:
                     filename = None
             return filename
 
         # custom exceptions
         class DataIsObject(Exception): pass
 
         opts,args = self.parse_options(parameter_s,'prn:')
         # Set a few locals from the options for convenience:
         opts_p = opts.has_key('p')
         opts_r = opts.has_key('r')
         
         # Default line number value
         lineno = opts.get('n',None)
         if lineno is not None:
             try:
                 lineno = int(lineno)
             except:
                 warn("The -n argument must be an integer.")
                 return
 
         if opts_p:
             args = '_%s' % last_call[0]
             if not self.shell.user_ns.has_key(args):
                 args = last_call[1]
             
         # use last_call to remember the state of the previous call, but don't
         # let it be clobbered by successive '-p' calls.
         try:
             last_call[0] = self.shell.displayhook.prompt_count
             if not opts_p:
                 last_call[1] = parameter_s
         except:
             pass
 
         # by default this is done with temp files, except when the given
         # arg is a filename
         use_temp = 1
 
         if re.match(r'\d',args):
             # Mode where user specifies ranges of lines, like in %macro.
             # This means that you can't edit files whose names begin with
             # numbers this way. Tough.
             ranges = args.split()
             data = ''.join(self.extract_input_slices(ranges,opts_r))
         elif args.endswith('.py'):
             filename = make_filename(args)
             data = ''
             use_temp = 0
         elif args:
             try:
                 # Load the parameter given as a variable. If not a string,
                 # process it as an object instead (below)
 
                 #print '*** args',args,'type',type(args)  # dbg
                 data = eval(args,self.shell.user_ns)
                 if not type(data) in StringTypes:
                     raise DataIsObject
 
             except (NameError,SyntaxError):
                 # given argument is not a variable, try as a filename
                 filename = make_filename(args)
                 if filename is None:
                     warn("Argument given (%s) can't be found as a variable "
                          "or as a filename." % args)
                     return
 
                 data = ''
                 use_temp = 0
             except DataIsObject:
 
                 # macros have a special edit function
                 if isinstance(data,Macro):
                     self._edit_macro(args,data)
                     return
                                 
                 # For objects, try to edit the file where they are defined
                 try:
                     filename = inspect.getabsfile(data)
                     if 'fakemodule' in filename.lower() and inspect.isclass(data):                     
                         # class created by %edit? Try to find source
                         # by looking for method definitions instead, the
                         # __module__ in those classes is FakeModule.
                         attrs = [getattr(data, aname) for aname in dir(data)]
                         for attr in attrs:
                             if not inspect.ismethod(attr):
                                 continue
                             filename = inspect.getabsfile(attr)
                             if filename and 'fakemodule' not in filename.lower():
                                 # change the attribute to be the edit target instead
                                 data = attr 
                                 break
                     
                     datafile = 1
                 except TypeError:
                     filename = make_filename(args)
                     datafile = 1
                     warn('Could not find file where `%s` is defined.\n'
                          'Opening a file named `%s`' % (args,filename))
                 # Now, make sure we can actually read the source (if it was in
                 # a temp file it's gone by now).
                 if datafile:
                     try:
                         if lineno is None:
                             lineno = inspect.getsourcelines(data)[1]
                     except IOError:
                         filename = make_filename(args)
                         if filename is None:
                             warn('The file `%s` where `%s` was defined cannot '
                                  'be read.' % (filename,data))
                             return
                 use_temp = 0
         else:
             data = ''
 
         if use_temp:
             filename = self.shell.mktempfile(data)
-            print 'IPython will make a temporary file named:',filename
+            print('IPython will make a temporary file named:', filename)
 
         # Make sure we send to the client an absolute path, in case the working
         # directory of client and kernel don't match
         filename = os.path.abspath(filename)
 
         payload = {
             'source' : 'IPython.zmq.zmqshell.ZMQInteractiveShell.edit_magic',
             'filename' : filename,
             'line_number' : lineno
         }
         self.payload_manager.write_payload(payload)
 
 
     def _showtraceback(self, etype, evalue, stb):
 
         exc_content = {
             u'status' : u'error',
             u'traceback' : stb,
             u'ename' : unicode(etype.__name__),
             u'evalue' : unicode(evalue)
         }
 
         dh = self.displayhook
         exc_msg = dh.session.msg(u'pyerr', exc_content, dh.parent_header)
         # Send exception info over pub socket for other clients than the caller
         # to pick up
         dh.pub_socket.send_json(exc_msg)
 
         # FIXME - Hack: store exception info in shell object.  Right now, the
         # caller is reading this info after the fact, we need to fix this logic
         # to remove this hack.
         self._reply_content = exc_content
         # /FIXME
         
         return exc_content
 
     def runlines(self, lines, clean=False):
         return InteractiveShell.runlines(self, lines, clean)
 
 InteractiveShellABC.register(ZMQInteractiveShell)