casa6

import contextlib

import os

import sys

​

​

def immediate_exit_with_handlers(exit_status=0):

    """

    Exits using os._exit(exit_status), to terminate when running in

    IPython.start_ipython() (which captures SystemExit and all exceptions).

    But before that abrupt exit it ensures that all the exit handlers

    registerd with atexit are run.

    """

    def run_atexit_handlers():

        # Note: the drawback of this approach is that atexit._exithandlers is

        # NOT available in Python 3

        import atexit

        # This could be done with atexit._run_exitfuncs(), but let's avoid

        # using one more protected function:

        for handler_tuple in reversed(atexit._exithandlers):

            # Try/except is to avoid application process hanging when the 

            # background process (tcl in particular)

            # is already destroyed

            try:

                handler_tuple[0]()

            except:

                pass

​

    run_atexit_handlers()

    import os

    os._exit(exit_status)

​

​

###

### redirect_argv(...) is used to present a consistent, clean sys.argv to

### the file being executed (via "-c somescript.py arg1, arg2..."). The

### redirect_exit(...) is used to substitue in the hard exit that comes

### with "os._exit(status)". Otherwise, ipython prevents "sys.exit(...)"

### exit and dumps us back to the ipython command line.

###

def redirect_exit(msg=None):

    if isinstance(msg, int):

        immediate_exit_with_handlers(msg)

    elif msg is not None:

        sys.stderr.write(str(msg))

    immediate_exit_with_handlers(0)

​

​

@contextlib.contextmanager

def redirect_argv(args):

    sys._argv = sys.argv[:]

    ###

    ### this could be cleaned up to be just:

    ###

    ###    sys.argv = ['somescript.py', arg1, arg2...]

    ###

    ### but casa scripts seem to have been

    ### expecting the 'casa' arg as well as the '-c' arg

    sys.argv = ['casa', '-c'] + args

    sys._save_exit = sys.exit

    sys.exit = redirect_exit

    yield

    sys.argv = sys._argv

    sys.exit = sys._save_exit