pythondialog 3.5.3

A Python interface to the UNIX dialog utility and mostly-compatible programs

Easy writing of graphical interfaces for terminal-based applications

Overview

pythondialog is a Python wrapper for the UNIX dialog utility originally written by Savio Lam and later rewritten by Thomas E. Dickey. Its purpose is to provide an easy to use, pythonic and as complete as possible interface to dialog from Python code.

pythondialog is free software, licensed under the GNU LGPL (GNU Lesser General Public License). Its home page is located at:

https://pythondialog.sourceforge.io/

and contains a short example, screenshots, a summary of the recent changes, links to the documentation, the Git repository, the mailing list, the issue tracker, etc.

If you want to get a quick idea of what this module allows one to do, you can download a release tarball and run demo.py:

PYTHONPATH=. python3 examples/demo.py

What is pythondialog good for? What are its limitations?

As you might infer from the name, dialog is a high-level program that generates dialog boxes. So is pythondialog. They allow you to build nice interfaces quickly and easily, but you don’t have full control over the widgets, nor can you create new widgets without modifying dialog itself. If you need to do low-level stuff, you should have a look at ncurses (cf. the curses module in the Python standard library), blessings or slang instead. For sophisticated text-mode interfaces, the Urwid Python library looks rather interesting, too.

Requirements

• As of version 2.12, pythondialog requires Python 3.0 or later in the 3.x series. pythondialog 3.5.3 has been tested with Python 3.9.

• dialog version 1.3-20201126-1 (the version shipped in Debian stable and unstable in November 2021) is broken; don’t waste your time with that version. dialog 1.3-20210621 works fine.

• Versions of pythondialog up to and including 3.5.1 had a backport to Python 2, however this outdated Python dialect isn’t supported anymore. You may find pointers to the old packages with Python 2 support on the pythondialog home page.

• Apart from that, pythondialog requires the dialog program (or a drop-in replacement for dialog). You can download dialog from:

  https://invisible-island.net/dialog/dialog.html

  Note that some features of pythondialog may require recent versions of dialog.

Quick installation instructions

If you have a working pip setup, you should be able to install pythondialog with:

pip install pythondialog

When doing so, make sure that your pip executable runs with the Python 3 installation you want to install pythondialog for.

For more detailed instructions, you can read the INSTALL file from a release tarball. You may also want to consult the pip documentation.

Documentation

The pythondialog Manual

The pythondialog Manual is written in reStructuredText format for the Sphinx documentation generator. The HTML documentation for the latest version of pythondialog as rendered by Sphinx should be available at:

https://pythondialog.sourceforge.io/doc/

The sources for the pythondialog Manual are located in the doc top-level directory of the pythondialog distribution, but the documentation build process pulls many parts from dialog.py (mainly docstrings).

To generate the documentation yourself from dialog.py and the sources in the doc directory, first make sure you have Sphinx and Make installed. Then, you can go to the doc directory and type, for instance:

make html

You will then find the output in the _build/html subdirectory of doc. Sphinx can build the documentation in many other formats. For instance, if you have LaTeX installed, you can generate the pythondialog Manual in PDF format using:

make latexpdf

You can run make from the doc directory to see a list of the available formats. Run make clean to clean up after the documentation build process.

For those who have installed Sphinx but not Make, it is still possible to build the documentation with a command such as:

sphinx-build -b html . _build/html

run from the doc directory. Please refer to sphinx-build for more details.

Reading the docstrings from an interactive Python interpreter

If you have already installed pythondialog, you may consult its docstrings in an interactive Python interpreter this way:

>>> import dialog; help(dialog)

but only parts of the documentation are available using this method, and the result is much less convenient to use than the pythondialog Manual as generated by Sphinx.

Enabling Deprecation Warnings

There are a few places in dialog.py that send a DeprecationWarning to warn developers about obsolete features. However, because of:

• the dialog output to the terminal;

• the fact that such warnings are silenced by default since Python 2.7 and 3.2;

you have to do two things in order to see them:

• redirect the standard error stream to a file;

• enable the warnings for the Python interpreter.

For instance, to see the warnings produced when running the demo, you can do:

PYTHONPATH=. python3 -Wd examples/demo.py 2>/path/to/file

and examine /path/to/file. This can also help you to find files that are still open when your program exits.

Note:

If your program is terminated by an unhandled exception while stderr is redirected as in the preceding command, you won’t see the traceback until you examine the file stderr was redirected to. This can be disturbing, as your program may exit with no apparent reason in such conditions.

For more explanations and other methods to enable deprecation warnings, please refer to:

https://docs.python.org/3/whatsnew/2.7.html

Troubleshooting

If you have a problem with a pythondialog call, you should read its documentation and the dialog(1) manual page. If this is not enough, you can enable logging of shell command-line equivalents of all dialog calls made by your program with a simple call to Dialog.setup_debug(), first available in pythondialog 2.12 (the expand_file_opt parameter may be useful in versions 3.3 and later). An example of this can be found in demo.py from the examples directory.

As of version 2.12, you can also enable this debugging facility for demo.py by calling it with the --debug flag (possibly combined with --debug-expand-file-opt in pythondialog 3.3 and later, cf. demo.py --help).

Using Xdialog instead of dialog

As far as I can tell, Xdialog has not been ported to GTK+ version 2 or later. It is not in Debian stable nor unstable (November 30, 2019). It is not installed on my system (because of the GTK+ 1.2 dependency), and according to the Xdialog-specific patches I received from Peter Åstrand in 2004, was not a drop-in replacement for dialog (in particular, Xdialog seemed to want to talk to the caller through stdout instead of stderr, grrrrr!).

All this to say that, even though I didn’t remove the options to use another backend than dialog, nor did I remove the handful of little, non-invasive modifications that help pythondialog work better with Xdialog, I don’t really support the latter. I test everything with dialog, and nothing with Xdialog.

That being said, here is the old text of this section (from 2004), in case you are still interested:

Starting with 2.06, there is an “Xdialog” compatibility mode that you can use if you want pythondialog to run the graphical Xdialog program (which should be found under http://xdialog.free.fr/) instead of dialog (text-mode, based on the ncurses library).

The primary supported platform is still dialog, but as long as only small modifications are enough to make pythondialog work with Xdialog, I am willing to support Xdialog if people are interested in it (which turned out to be the case for Xdialog).

The demo.py from pythondialog 2.06 has been tested with Xdialog 2.0.6 and found to work well (barring Xdialog’s annoying behaviour with the file selection dialog box).

Whiptail, anyone?

Well, pythondialog seems not to work very well with whiptail. The reason is that whiptail is not compatible with dialog anymore. Although you can tell pythondialog the program you want it to invoke, only programs that are mostly dialog-compatible are supported.

History

pythondialog was originally written by Robb Shecter. Sultanbek Tezadov added some features to it (mainly the first gauge implementation, I guess). Florent Rougon rewrote most parts of the program to make it more robust and flexible so that it can give access to most features of the dialog program. Peter Åstrand took over maintainership between 2004 and 2009, with particular care for the Xdialog support. Florent Rougon took over maintainership again starting from 2009…