Lib/_sitebuiltins.py

"""
The objects used by the site module to add custom builtins.
"""

# Those objects are almost immortal and they keep a reference to their module
# globals.  Defining them in the site module would keep too many references
# alive.
# Note this means this module should also avoid keep things alive in its
# globals.

import sys

class Quitter(object):
    def __init__(self, name, eof):
        self.name = name
        self.eof = eof
    def __repr__(self):
        return 'Use %s() or %s to exit' % (self.name, self.eof)
    def __call__(self, code=None):
        # Shells like IDLE catch the SystemExit, but listen when their
        # stdin wrapper is closed.
        try:
            sys.stdin.close()
        except:
            pass
        raise SystemExit(code)


class _Printer(object):
    """interactive prompt objects for printing the license text, a list of
    contributors and the copyright notice."""

    MAXLINES = 23

    def __init__(self, name, data, files=(), dirs=()):
        import os
        self.__name = name
        self.__data = data
        self.__lines = None
        self.__filenames = [os.path.join(dir, filename)
                            for dir in dirs
                            for filename in files]

    def __setup(self):
        if self.__lines:
            return
        data = None
        for filename in self.__filenames:
            try:
                with open(filename, "r") as fp:
                    data = fp.read()
                break
            except OSError:
                pass
        if not data:
            data = self.__data
        self.__lines = data.split('\n')
        self.__linecnt = len(self.__lines)

    def __repr__(self):
        self.__setup()
        if len(self.__lines) <= self.MAXLINES:
            return "\n".join(self.__lines)
        else:
            return "Type %s() to see the full %s text" % ((self.__name,)*2)

    def __call__(self):
        self.__setup()
        prompt = 'Hit Return for more, or q (and Return) to quit: '
        lineno = 0
        while 1:
            try:
                for i in range(lineno, lineno + self.MAXLINES):
                    print(self.__lines[i])
            except IndexError:
                break
            else:
                lineno += self.MAXLINES
                key = None
                while key is None:
                    key = input(prompt)
                    if key not in ('', 'q'):
                        key = None
                if key == 'q':
                    break


class _Helper(object):
    """Define the builtin 'help'.
    This is a wrapper around pydoc.help (with a twist).

    """

    def __repr__(self):
        return "Type help() for interactive help, " \
               "or help(object) for help about object."
    def __call__(self, *args, **kwds):
        import pydoc
        return pydoc.help(*args, **kwds)