import subprocess
from subprocess import CalledProcessError
import sys

class Shell(object):
    """An advanced shell, with the ability to do dry-run and log commands"""
    def __init__(self, verbose = False, dry = False):
        """ `verbose`   Whether or not to print the command and outputs
            `dry`       Whether or not to not run any commands, and just print"""
        self.verbose = verbose
        self.dry = dry
    def call(self, *args):
        if self.dry or self.verbose:
            print "$ " + ' '.join(args)
        if self.dry: return
        proc = None
        if self.verbose:
            proc = subprocess.Popen(args, stdout=sys.stdout, stderr=sys.stderr)
        else:
            proc = subprocess.Popen(args)
        proc.communicate()
        if proc.returncode:
            raise CalledProcessError(proc.returncode, args)