.. _tutorial:

Tutorial
--------

There are two important classes in ``pyte``: :class:`~pyte.screens.Screen`
and :class:`~pyte.streams.Stream`. The `Screen` is the terminal screen
emulator. It maintains an in-memory buffer of text and text-attributes
to display. The `Stream` is the stream processor. It processes the input
and dispatches events. Events are things like ``LINEFEED``, ``DRAW "a"``,
or ``CURSOR_POSITION 10 10``. See the :ref:`API reference <api>` for more
details.

In general, if you just want to know what's being displayed on screen you
can do something like the following:

    >>> from __future__ import unicode_literals
    >>> import pyte
    >>> screen = pyte.Screen(80, 24)
    >>> stream = pyte.Stream(screen)
    >>> stream.feed(b"Hello World!")
    >>> screen.display
        ['Hello World!                                                                    ',
         '                                                                                ',
         '                                                                                ',
         '                                                                                ',
         '                                                                                ',
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         '                                                                                ']


**Note**: ``Screen`` has no idea what is the source of bytes fed into ``Stream``,
so, obviously, it **can't read** or **change** environment variables, which implies
that:

* it doesn't adjust `LINES` and `COLUMNS` on ``"resize"`` event;
* it doesn't use locale settings (`LC_*` and `LANG`);
* it doesn't use `TERM` value and expects it to be `"linux"` and only `"linux"`.

And that's it for Hello World! Head over to the `examples
<https://github.com/selectel/pyte/examples>`_ for  more.
