# Exception handling

import atexit

import sys

import strings

import util

def add_msg(e, msg): e.args = (strings.ensure_newl(str(e))+msg,)

def repl_msg(e, **repls): e.args = (str(e) % repls,)

class ExceptionWithCause(Exception):

    def __init__(self, msg, cause=None):

        Exception.__init__(self, msg)

        if cause != None: add_msg(self, 'cause: '+str(cause))

def print_ex(e, with_name=True):

    msg = strings.ensure_newl(str(e))

    if with_name: msg = util.type_name(e)+': '+msg

    sys.stderr.write('! '+msg)

class ExTracker:

    def __init__(self):

        self.e_ct = 0

        def at_exit():

            if self.e_ct > 0:

                raise SystemExit('Encountered '+str(self.e_ct)+' error(s)')

        atexit.register(at_exit)

    def track(self, e, **format):

        self.e_ct += 1

        print_ex(e, **format)