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427 lines
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427 lines
18 KiB
Plaintext
Metadata-Version: 1.0
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Name: blessings
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Version: 1.3
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Summary: A thin, practical wrapper around terminal formatting, positioning, and more
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Home-page: https://github.com/erikrose/blessings
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Author: Erik Rose
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Author-email: erikrose@grinchcentral.com
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License: MIT
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Description: =========
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Blessings
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=========
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Coding with Blessings looks like this... ::
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from blessings import Terminal
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t = Terminal()
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print t.bold('Hi there!')
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print t.bold_red_on_bright_green('It hurts my eyes!')
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with t.location(0, t.height - 1):
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print 'This is at the bottom.'
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Or, for byte-level control, you can drop down and play with raw terminal
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capabilities::
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print '{t.bold}All your {t.red}bold and red base{t.normal}'.format(t=t)
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print t.wingo(2)
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The Pitch
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=========
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Blessings lifts several of curses_' limiting assumptions, and it makes your
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code pretty, too:
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* Use styles, color, and maybe a little positioning without clearing the whole
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screen first.
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* Leave more than one screenful of scrollback in the buffer after your program
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exits, like a well-behaved command-line app should.
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* Get rid of all those noisy, C-like calls to ``tigetstr`` and ``tparm``, so
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your code doesn't get crowded out by terminal bookkeeping.
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* Act intelligently when somebody redirects your output to a file, omitting the
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terminal control codes the user doesn't want to see (optional).
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.. _curses: http://docs.python.org/library/curses.html
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Before And After
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----------------
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Without Blessings, this is how you'd print some underlined text at the bottom
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of the screen::
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from curses import tigetstr, setupterm, tparm
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from fcntl import ioctl
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from os import isatty
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import struct
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import sys
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from termios import TIOCGWINSZ
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# If we want to tolerate having our output piped to other commands or
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# files without crashing, we need to do all this branching:
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if hasattr(sys.stdout, 'fileno') and isatty(sys.stdout.fileno()):
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setupterm()
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sc = tigetstr('sc')
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cup = tigetstr('cup')
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rc = tigetstr('rc')
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underline = tigetstr('smul')
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normal = tigetstr('sgr0')
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else:
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sc = cup = rc = underline = normal = ''
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print sc # Save cursor position.
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if cup:
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# tigetnum('lines') doesn't always update promptly, hence this:
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height = struct.unpack('hhhh', ioctl(0, TIOCGWINSZ, '\000' * 8))[0]
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print tparm(cup, height - 1, 0) # Move cursor to bottom.
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print 'This is {under}underlined{normal}!'.format(under=underline,
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normal=normal)
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print rc # Restore cursor position.
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Phew! That was long and full of incomprehensible trash! Let's try it again,
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this time with Blessings::
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from blessings import Terminal
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term = Terminal()
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with term.location(0, term.height - 1):
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print 'This is', term.underline('pretty!')
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Much better.
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What It Provides
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================
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Blessings provides just one top-level object: ``Terminal``. Instantiating a
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``Terminal`` figures out whether you're on a terminal at all and, if so, does
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any necessary terminal setup. After that, you can proceed to ask it all sorts
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of things about the terminal. Terminal terminal terminal.
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Simple Formatting
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-----------------
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Lots of handy formatting codes ("capabilities" in low-level parlance) are
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available as attributes on a ``Terminal``. For example::
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from blessings import Terminal
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term = Terminal()
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print 'I am ' + term.bold + 'bold' + term.normal + '!'
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You can also use them as wrappers so you don't have to say ``normal``
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afterward::
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print 'I am', term.bold('bold') + '!'
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Or, if you want fine-grained control while maintaining some semblance of
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brevity, you can combine it with Python's string formatting, which makes
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attributes easy to access::
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print 'All your {t.red}base {t.underline}are belong to us{t.normal}'.format(t=term)
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Simple capabilities of interest include...
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* ``bold``
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* ``reverse``
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* ``underline``
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* ``no_underline`` (which turns off underlining)
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* ``blink``
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* ``normal`` (which turns off everything, even colors)
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* ``clear_eol`` (clear to the end of the line)
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* ``clear_bol`` (clear to beginning of line)
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* ``clear_eos`` (clear to end of screen)
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Here are a few more which are less likely to work on all terminals:
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* ``dim``
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* ``italic`` and ``no_italic``
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* ``shadow`` and ``no_shadow``
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* ``standout`` and ``no_standout``
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* ``subscript`` and ``no_subscript``
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* ``superscript`` and ``no_superscript``
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* ``flash`` (which flashes the screen once)
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Note that, while the inverse of ``underline`` is ``no_underline``, the only way
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to turn off ``bold`` or ``reverse`` is ``normal``, which also cancels any
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custom colors. This is because there's no way to tell the terminal to undo
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certain pieces of formatting, even at the lowest level.
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You might notice that the above aren't the typical incomprehensible terminfo
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capability names; we alias a few of the harder-to-remember ones for
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readability. However, you aren't limited to these: you can reference any
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string-returning capability listed on the `terminfo man page`_ by the name
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under the "Cap-name" column: for example, ``term.rum``.
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.. _`terminfo man page`: http://www.manpagez.com/man/5/terminfo/
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Color
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-----
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16 colors, both foreground and background, are available as easy-to-remember
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attributes::
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from blessings import Terminal
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term = Terminal()
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print term.red + term.on_green + 'Red on green? Ick!' + term.normal
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print term.bright_red + term.on_bright_blue + 'This is even worse!' + term.normal
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You can also call them as wrappers, which sets everything back to normal at the
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end::
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print term.red_on_green('Red on green? Ick!')
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print term.yellow('I can barely see it.')
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The available colors are...
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* ``black``
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* ``red``
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* ``green``
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* ``yellow``
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* ``blue``
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* ``magenta``
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* ``cyan``
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* ``white``
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You can set the background color instead of the foreground by prepending
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``on_``, as in ``on_blue``. There is also a ``bright`` version of each color:
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for example, ``on_bright_blue``.
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There is also a numerical interface to colors, which takes an integer from
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0-15::
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term.color(5) + 'Hello' + term.normal
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term.on_color(3) + 'Hello' + term.normal
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term.color(5)('Hello')
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term.on_color(3)('Hello')
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If some color is unsupported (for instance, if only the normal colors are
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available, not the bright ones), trying to use it will, on most terminals, have
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no effect: the foreground and background colors will stay as they were. You can
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get fancy and do different things depending on the supported colors by checking
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`number_of_colors`_.
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.. _`number_of_colors`: http://packages.python.org/blessings/#blessings.Terminal.number_of_colors
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Compound Formatting
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-------------------
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If you want to do lots of crazy formatting all at once, you can just mash it
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all together::
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from blessings import Terminal
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term = Terminal()
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print term.bold_underline_green_on_yellow + 'Woo' + term.normal
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Or you can use your newly coined attribute as a wrapper, which implicitly sets
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everything back to normal afterward::
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print term.bold_underline_green_on_yellow('Woo')
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This compound notation comes in handy if you want to allow users to customize
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the formatting of your app: just have them pass in a format specifier like
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"bold_green" on the command line, and do a quick ``getattr(term,
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that_option)('Your text')`` when you do your formatting.
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I'd be remiss if I didn't credit couleur_, where I probably got the idea for
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all this mashing.
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.. _couleur: http://pypi.python.org/pypi/couleur
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Parametrized Capabilities
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-------------------------
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Some capabilities take parameters. Rather than making you dig up ``tparm()``
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all the time, we simply make such capabilities into callable strings. You can
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pass the parameters right in::
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from blessings import Terminal
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term = Terminal()
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print term.move(10, 1)
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Here are some of interest:
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``move``
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Position the cursor elsewhere. Parameters are y coordinate, then x
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coordinate.
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``move_x``
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Move the cursor to the given column.
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``move_y``
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Move the cursor to the given row.
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You can also reference any other string-returning capability listed on the
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`terminfo man page`_ by its name under the "Cap-name" column.
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.. _`terminfo man page`: http://www.manpagez.com/man/5/terminfo/
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Height and Width
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----------------
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It's simple to get the height and width of the terminal, in characters::
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from blessings import Terminal
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term = Terminal()
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height = term.height
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width = term.width
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These are newly updated each time you ask for them, so they're safe to use from
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SIGWINCH handlers.
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Temporary Repositioning
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-----------------------
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Sometimes you need to flit to a certain location, print something, and then
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return: for example, when updating a progress bar at the bottom of the screen.
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``Terminal`` provides a context manager for doing this concisely::
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from blessings import Terminal
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term = Terminal()
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with term.location(0, term.height - 1):
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print 'Here is the bottom.'
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print 'This is back where I came from.'
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Parameters to ``location()`` are ``x`` and then ``y``, but you can also pass
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just one of them, leaving the other alone. For example... ::
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with term.location(y=10):
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print 'We changed just the row.'
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If you want to reposition permanently, see ``move``, in an example above.
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Pipe Savvy
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----------
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If your program isn't attached to a terminal, like if it's being piped to
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another command or redirected to a file, all the capability attributes on
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``Terminal`` will return empty strings. You'll get a nice-looking file without
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any formatting codes gumming up the works.
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If you want to override this--like if you anticipate your program being piped
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through ``less -r``, which handles terminal escapes just fine--pass
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``force_styling=True`` to the ``Terminal`` constructor.
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In any case, there is an ``is_a_tty`` attribute on ``Terminal`` that lets you
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see whether the attached stream seems to be a terminal. If it's false, you
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might refrain from drawing progress bars and other frippery, since you're
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apparently headed into a pipe::
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from blessings import Terminal
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term = Terminal()
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if term.is_a_tty:
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with term.location(0, term.height - 1):
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print 'Progress: [=======> ]'
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print term.bold('Important stuff')
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Shopping List
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=============
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There are decades of legacy tied up in terminal interaction, so attention to
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detail and behavior in edge cases make a difference. Here are some ways
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Blessings has your back:
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* Uses the terminfo database so it works with any terminal type
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* Provides up-to-the-moment terminal height and width, so you can respond to
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terminal size changes (SIGWINCH signals). (Most other libraries query the
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``COLUMNS`` and ``LINES`` environment variables or the ``cols`` or ``lines``
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terminal capabilities, which don't update promptly, if at all.)
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* Avoids making a mess if the output gets piped to a non-terminal
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* Works great with standard Python string templating
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* Provides convenient access to all terminal capabilities, not just a sugared
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few
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* Outputs to any file-like object, not just stdout
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* Keeps a minimum of internal state, so you can feel free to mix and match with
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calls to curses or whatever other terminal libraries you like
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Blessings does not provide...
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* Native color support on the Windows command prompt. However, it should work
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when used in concert with colorama_.
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.. _colorama: http://pypi.python.org/pypi/colorama/0.2.4
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Bugs
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====
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Bugs or suggestions? Visit the `issue tracker`_.
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.. _`issue tracker`: https://github.com/erikrose/blessings/issues/new
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License
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=======
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Blessings is under the MIT License. See the LICENSE file.
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Version History
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===============
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1.3
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* Add ``number_of_colors``, which tells you how many colors the terminal
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supports.
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* Made ``color(n)`` and ``on_color(n)`` callable to wrap a string, like the
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named colors can. Also, make them both fall back to the ``setf`` and
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``setb`` capabilities (like the named colors do) if the ANSI ``setaf`` and
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``setab`` aren't available.
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* Allow ``color`` attr to act as an unparametrized string, not just a
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callable.
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* Make ``height`` and ``width`` examine any passed-in stream before falling
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back to stdout. (This rarely if ever affects actual behavior; it's mostly
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philosophical.)
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* Make caching simpler and slightly more efficient.
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* Get rid of a reference cycle between Terminals and FormattingStrings.
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* Update docs to reflect that terminal addressing (as in ``location()``) is
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0-based.
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1.2
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* Added support for Python 3! We need 3.2.3 or greater, because the curses
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library couldn't decide whether to accept strs or bytes before that
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(http://bugs.python.org/issue10570).
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* Everything that comes out of the library is now unicode. This lets us
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support Python 3 without making a mess of the code, and Python 2 should
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continue to work unless you were testing types (and badly). Please file a
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bug if this causes trouble for you.
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* Changed to the MIT License for better world domination.
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* Added Sphinx docs.
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1.1
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* Added nicely named attributes for colors.
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* Introduced compound formatting.
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* Added wrapper behavior for styling and colors.
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* Let you force capabilities to be non-empty, even if the output stream is
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not a terminal.
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* Added the ``is_a_tty`` attribute for telling whether the output stream is a
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terminal.
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* Sugared the remaining interesting string capabilities.
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* Let ``location()`` operate on just an x *or* y coordinate.
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1.0
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* Extracted Blessings from nose-progressive, my `progress-bar-having,
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traceback-shortcutting, rootin', tootin' testrunner`_. It provided the
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tootin' functionality.
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.. _`progress-bar-having, traceback-shortcutting, rootin', tootin' testrunner`: http://pypi.python.org/pypi/nose-progressive/
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Keywords: terminal,tty,curses,ncurses,formatting,style,color,console
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Platform: UNKNOWN
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Classifier: Intended Audience :: Developers
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Classifier: Natural Language :: English
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Classifier: Development Status :: 5 - Production/Stable
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Classifier: Environment :: Console
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Classifier: Environment :: Console :: Curses
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Classifier: License :: OSI Approved :: MIT License
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Classifier: Operating System :: POSIX
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Classifier: Programming Language :: Python :: 2
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Classifier: Programming Language :: Python :: 2.5
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Classifier: Programming Language :: Python :: 2.6
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Classifier: Programming Language :: Python :: 2.7
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Classifier: Programming Language :: Python :: 3
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Classifier: Programming Language :: Python :: 3.2
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Classifier: Topic :: Software Development :: Libraries
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Classifier: Topic :: Software Development :: User Interfaces
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Classifier: Topic :: Terminals
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