.. _features:

========
Features
========

.. meta::
   :description: Unicon features
   :keywords: unicon, features

.. Modified: 2018-10-23/05:37-0400 btiffin
.. Copyright 2016 Brian Tiffin
.. This file is part of the Unicon Programming document
.. GPL 3.0+ :ref:`license` 

.. image:: images/unicon.png
   :align: center

.. only:: html

    :ref:`genindex`
    :floatright:`<a href="http://unicon.sourceforge.net/">Unicon</a>`

.. index:: features

Unicon features
===============
Unicon is a feature rich environment.  This chapter deals with some of the
more *miscellaneous* components included in Unicon that are not detailed in
other sections. 

.. index:: keyboard

.. _keyboard:

Keyboard functions
..................

Unicon supports keyboard scanning outside normal standard IO operation
support.  This allows for pending key tests, unbuffered input (no Enter key
required) and other niceties.

:c:func:`kbhit` checks if there is a keyboard character waiting to be read.
:c:func:`getch` reads a key (and will wait if needed) without echo to screen.
:c:func:`getche` reads a key (and will wait if needed) with echo to screen.


.. literalinclude:: examples/keyboarding.icn
   :language: unicon
   :start-after: ##+

.. only:: html

    .. rst-class:: rightalign

        :download:`examples/keyboarding.icn`

Sample run:

.. command-output:: unicon -s keyboarding.icn -x
   :cwd: examples

--------


.. index:: pty, pseudo terminals

.. _pseudo terminal:

Pseudo terminals
................

Qutaiba Mahmoud added support for pseudo terminals in Unicon when attaining
his Master's Degree in Computer Science, outlined in a report hosted along
with the Unicon Technical Reports, at

http://www2.cs.uidaho.edu/~jeffery/unicon/reports/mahmoud.pdf

Basically, a file stream is opened with mode :unicon:`"prw"`, which gives a
Unicon master terminal program asynchronous read and write access to another
interactive process.

This feature is similar to the capabilities provided in the famous `Expect`
`Tcl/Tk` extension by Don Libes.

.. todo:: add pty sample

--------


.. index:: libz, compression

.. _libz:

libz compression
................

Compression can be used in Unicon file operations, and is also supported in
the compiler for compressed `icode` generation, if ``libz`` is available
during Unicon build.

:command:`unicon -Z program.icn` will produce a compressed ``icode`` file.  It
will be automatically uncompressed at runtime, *assuming support is included
in the current VM when invoked*.

Programmers can also use this feature with the :unicon:`"z"` mode modifier of
the `open` function.  Compressed data is not line oriented, so use `reads` and
`writes`.

.. literalinclude:: examples/gzio.icn
   :language: unicon
   :start-after: ##+

.. only:: html

    .. rst-class:: rightalign

        :download:`examples/gzio.icn`

Sample run:

.. command-output:: unicon -s gzio.icn -x
   :cwd: examples


.. only:: html
   
    ..

    --------

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