The Tor Browser: comparison python/blessings/README.rst

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+=========
+Blessings
+=========
+Coding with Blessings looks like this... ::
+from blessings import Terminal
+t = Terminal()
+print t.bold('Hi there!')
+print t.bold_red_on_bright_green('It hurts my eyes!')
+with t.location(0, t.height - 1):
+print 'This is at the bottom.'
+Or, for byte-level control, you can drop down and play with raw terminal
+capabilities::
+print '{t.bold}All your {t.red}bold and red base{t.normal}'.format(t=t)
+print t.wingo(2)
+The Pitch
+=========
+Blessings lifts several of curses_' limiting assumptions, and it makes your
+code pretty, too:
+* Use styles, color, and maybe a little positioning without clearing the whole
+screen first.
+* Leave more than one screenful of scrollback in the buffer after your program
+exits, like a well-behaved command-line app should.
+* Get rid of all those noisy, C-like calls to ``tigetstr`` and ``tparm``, so
+your code doesn't get crowded out by terminal bookkeeping.
+* Act intelligently when somebody redirects your output to a file, omitting the
+terminal control codes the user doesn't want to see (optional).
+.. _curses: http://docs.python.org/library/curses.html
+Before And After
+----------------
+Without Blessings, this is how you'd print some underlined text at the bottom
+of the screen::
+from curses import tigetstr, setupterm, tparm
+from fcntl import ioctl
+from os import isatty
+import struct
+import sys
+from termios import TIOCGWINSZ
+# If we want to tolerate having our output piped to other commands or
+# files without crashing, we need to do all this branching:
+if hasattr(sys.stdout, 'fileno') and isatty(sys.stdout.fileno()):
+setupterm()
+sc = tigetstr('sc')
+cup = tigetstr('cup')
+rc = tigetstr('rc')
+underline = tigetstr('smul')
+normal = tigetstr('sgr0')
+else:
+sc = cup = rc = underline = normal = ''
+print sc  # Save cursor position.
+if cup:
+# tigetnum('lines') doesn't always update promptly, hence this:
+height = struct.unpack('hhhh', ioctl(0, TIOCGWINSZ, '\000' * 8))[0]
+print tparm(cup, height - 1, 0)  # Move cursor to bottom.
+print 'This is {under}underlined{normal}!'.format(under=underline,
+normal=normal)
+print rc  # Restore cursor position.
+Phew! That was long and full of incomprehensible trash! Let's try it again,
+this time with Blessings::
+from blessings import Terminal
+term = Terminal()
+with term.location(0, term.height - 1):
+print 'This is', term.underline('pretty!')
+Much better.
+What It Provides
+================
+Blessings provides just one top-level object: ``Terminal``. Instantiating a
+``Terminal`` figures out whether you're on a terminal at all and, if so, does
+any necessary terminal setup. After that, you can proceed to ask it all sorts
+of things about the terminal. Terminal terminal terminal.
+Simple Formatting
+-----------------
+Lots of handy formatting codes ("capabilities" in low-level parlance) are
+available as attributes on a ``Terminal``. For example::
+from blessings import Terminal
+term = Terminal()
+print 'I am ' + term.bold + 'bold' + term.normal + '!'
+You can also use them as wrappers so you don't have to say ``normal``
+afterward::
+print 'I am', term.bold('bold') + '!'
+Or, if you want fine-grained control while maintaining some semblance of
+brevity, you can combine it with Python's string formatting, which makes
+attributes easy to access::
+print 'All your {t.red}base {t.underline}are belong to us{t.normal}'.format(t=term)
+Simple capabilities of interest include...
+* ``bold``
+* ``reverse``
+* ``underline``
+* ``no_underline`` (which turns off underlining)
+* ``blink``
+* ``normal`` (which turns off everything, even colors)
+* ``clear_eol`` (clear to the end of the line)
+* ``clear_bol`` (clear to beginning of line)
+* ``clear_eos`` (clear to end of screen)
+Here are a few more which are less likely to work on all terminals:
+* ``dim``
+* ``italic`` and ``no_italic``
+* ``shadow`` and ``no_shadow``
+* ``standout`` and ``no_standout``
+* ``subscript`` and ``no_subscript``
+* ``superscript`` and ``no_superscript``
+* ``flash`` (which flashes the screen once)
+Note that, while the inverse of ``underline`` is ``no_underline``, the only way
+to turn off ``bold`` or ``reverse`` is ``normal``, which also cancels any
+custom colors. This is because there's no way to tell the terminal to undo
+certain pieces of formatting, even at the lowest level.
+You might notice that the above aren't the typical incomprehensible terminfo
+capability names; we alias a few of the harder-to-remember ones for
+readability. However, you aren't limited to these: you can reference any
+string-returning capability listed on the `terminfo man page`_ by the name
+under the "Cap-name" column: for example, ``term.rum``.
+.. _`terminfo man page`: http://www.manpagez.com/man/5/terminfo/
+Color
+-----
+16 colors, both foreground and background, are available as easy-to-remember
+attributes::
+from blessings import Terminal
+term = Terminal()
+print term.red + term.on_green + 'Red on green? Ick!' + term.normal
+print term.bright_red + term.on_bright_blue + 'This is even worse!' + term.normal
+You can also call them as wrappers, which sets everything back to normal at the
+end::
+print term.red_on_green('Red on green? Ick!')
+print term.yellow('I can barely see it.')
+The available colors are...
+* ``black``
+* ``red``
+* ``green``
+* ``yellow``
+* ``blue``
+* ``magenta``
+* ``cyan``
+* ``white``
+You can set the background color instead of the foreground by prepending
+``on_``, as in ``on_blue``. There is also a ``bright`` version of each color:
+for example, ``on_bright_blue``.
+There is also a numerical interface to colors, which takes an integer from
+0-15::
+term.color(5) + 'Hello' + term.normal
+term.on_color(3) + 'Hello' + term.normal
+term.color(5)('Hello')
+term.on_color(3)('Hello')
+If some color is unsupported (for instance, if only the normal colors are
+available, not the bright ones), trying to use it will, on most terminals, have
+no effect: the foreground and background colors will stay as they were. You can
+get fancy and do different things depending on the supported colors by checking
+`number_of_colors`_.
+.. _`number_of_colors`: http://packages.python.org/blessings/#blessings.Terminal.number_of_colors
+Compound Formatting
+-------------------
+If you want to do lots of crazy formatting all at once, you can just mash it
+all together::
+from blessings import Terminal
+term = Terminal()
+print term.bold_underline_green_on_yellow + 'Woo' + term.normal
+Or you can use your newly coined attribute as a wrapper, which implicitly sets
+everything back to normal afterward::
+print term.bold_underline_green_on_yellow('Woo')
+This compound notation comes in handy if you want to allow users to customize
+the formatting of your app: just have them pass in a format specifier like
+"bold_green" on the command line, and do a quick ``getattr(term,
+that_option)('Your text')`` when you do your formatting.
+I'd be remiss if I didn't credit couleur_, where I probably got the idea for
+all this mashing.
+.. _couleur: http://pypi.python.org/pypi/couleur
+Parametrized Capabilities
+-------------------------
+Some capabilities take parameters. Rather than making you dig up ``tparm()``
+all the time, we simply make such capabilities into callable strings. You can
+pass the parameters right in::
+from blessings import Terminal
+term = Terminal()
+print term.move(10, 1)
+Here are some of interest:
+``move``
+Position the cursor elsewhere. Parameters are y coordinate, then x
+coordinate.
+``move_x``
+Move the cursor to the given column.
+``move_y``
+Move the cursor to the given row.
+You can also reference any other string-returning capability listed on the
+`terminfo man page`_ by its name under the "Cap-name" column.
+.. _`terminfo man page`: http://www.manpagez.com/man/5/terminfo/
+Height and Width
+----------------
+It's simple to get the height and width of the terminal, in characters::
+from blessings import Terminal
+term = Terminal()
+height = term.height
+width = term.width
+These are newly updated each time you ask for them, so they're safe to use from
+SIGWINCH handlers.
+Temporary Repositioning
+-----------------------
+Sometimes you need to flit to a certain location, print something, and then
+return: for example, when updating a progress bar at the bottom of the screen.
+``Terminal`` provides a context manager for doing this concisely::
+from blessings import Terminal
+term = Terminal()
+with term.location(0, term.height - 1):
+print 'Here is the bottom.'
+print 'This is back where I came from.'
+Parameters to ``location()`` are ``x`` and then ``y``, but you can also pass
+just one of them, leaving the other alone. For example... ::
+with term.location(y=10):
+print 'We changed just the row.'
+If you want to reposition permanently, see ``move``, in an example above.
+Pipe Savvy
+----------
+If your program isn't attached to a terminal, like if it's being piped to
+another command or redirected to a file, all the capability attributes on
+``Terminal`` will return empty strings. You'll get a nice-looking file without
+any formatting codes gumming up the works.
+If you want to override this--like if you anticipate your program being piped
+through ``less -r``, which handles terminal escapes just fine--pass
+``force_styling=True`` to the ``Terminal`` constructor.
+In any case, there is an ``is_a_tty`` attribute on ``Terminal`` that lets you
+see whether the attached stream seems to be a terminal. If it's false, you
+might refrain from drawing progress bars and other frippery, since you're
+apparently headed into a pipe::
+from blessings import Terminal
+term = Terminal()
+if term.is_a_tty:
+with term.location(0, term.height - 1):
+print 'Progress: [=======>   ]'
+print term.bold('Important stuff')
+Shopping List
+=============
+There are decades of legacy tied up in terminal interaction, so attention to
+detail and behavior in edge cases make a difference. Here are some ways
+Blessings has your back:
+* Uses the terminfo database so it works with any terminal type
+* Provides up-to-the-moment terminal height and width, so you can respond to
+terminal size changes (SIGWINCH signals). (Most other libraries query the
+``COLUMNS`` and ``LINES`` environment variables or the ``cols`` or ``lines``
+terminal capabilities, which don't update promptly, if at all.)
+* Avoids making a mess if the output gets piped to a non-terminal
+* Works great with standard Python string templating
+* Provides convenient access to all terminal capabilities, not just a sugared
+few
+* Outputs to any file-like object, not just stdout
+* Keeps a minimum of internal state, so you can feel free to mix and match with
+calls to curses or whatever other terminal libraries you like
+Blessings does not provide...
+* Native color support on the Windows command prompt. However, it should work
+when used in concert with colorama_.
+.. _colorama: http://pypi.python.org/pypi/colorama/0.2.4
+Bugs
+====
+Bugs or suggestions? Visit the `issue tracker`_.
+.. _`issue tracker`: https://github.com/erikrose/blessings/issues/new
+License
+=======
+Blessings is under the MIT License. See the LICENSE file.
+Version History
+===============
+1.3
+* Add ``number_of_colors``, which tells you how many colors the terminal
+supports.
+* Made ``color(n)`` and ``on_color(n)`` callable to wrap a string, like the
+named colors can. Also, make them both fall back to the ``setf`` and
+``setb`` capabilities (like the named colors do) if the ANSI ``setaf`` and
+``setab`` aren't available.
+* Allow ``color`` attr to act as an unparametrized string, not just a
+callable.
+* Make ``height`` and ``width`` examine any passed-in stream before falling
+back to stdout. (This rarely if ever affects actual behavior; it's mostly
+philosophical.)
+* Make caching simpler and slightly more efficient.
+* Get rid of a reference cycle between Terminals and FormattingStrings.
+* Update docs to reflect that terminal addressing (as in ``location()``) is
+0-based.
+1.2
+* Added support for Python 3! We need 3.2.3 or greater, because the curses
+library couldn't decide whether to accept strs or bytes before that
+(http://bugs.python.org/issue10570).
+* Everything that comes out of the library is now unicode. This lets us
+support Python 3 without making a mess of the code, and Python 2 should
+continue to work unless you were testing types (and badly). Please file a
+bug if this causes trouble for you.
+* Changed to the MIT License for better world domination.
+* Added Sphinx docs.
+1.1
+* Added nicely named attributes for colors.
+* Introduced compound formatting.
+* Added wrapper behavior for styling and colors.
+* Let you force capabilities to be non-empty, even if the output stream is
+not a terminal.
+* Added the ``is_a_tty`` attribute for telling whether the output stream is a
+terminal.
+* Sugared the remaining interesting string capabilities.
+* Let ``location()`` operate on just an x *or* y coordinate.
+1.0
+* Extracted Blessings from nose-progressive, my `progress-bar-having,
+traceback-shortcutting, rootin', tootin' testrunner`_. It provided the
+tootin' functionality.
+.. _`progress-bar-having, traceback-shortcutting, rootin', tootin' testrunner`: http://pypi.python.org/pypi/nose-progressive/

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