Richinput

Richinput is a library to read one character at a time from standard input in a nonblocking way.

As a key is pressed a callback is invoked, without waiting for .

Encodings are respected (the read char is unicode) and there are functions to deal with terminal escape sequences.

It is possible to read input one character at a time maintaining arrows keys, home key, end key, backspace and word wrap working normally.

API

get_char(prompt=u'')

Iterator that reads one character at a time, nonblocking, encoding aware. Yield a unicode character.

It is a low-level function, unless you want to decode terminal escape sequences yourself, use get_rich_char instead.

get_rich_char(prompt=u'', term=None)

Iterator that reads one "meaningful value" at a time, nonblocking, encoding aware. prompt is a label displayed before reading the input. term is an instance of terminfo.Term, needed to understand what the escape sequences means. If set to None it will be automatically detected.

The yielded value will be one of

• PrintableChar, if the character was not in a unicode General_Category starting with C.
• ControlKey, if the character was in a unicode General_Category starting with C
• EscapeSequence, if a terminal escape sequence was detected (e.g. a colour formatting request or the home key).

Note that only PrintableChar has a non-empty string representation, so something like the following code may come in handy

>>> print(''.join(get_rich_char(term)))

Richline

Use this class if you want the user to be able to have richline like capabilities (cursor movements, home/end keys, backspace, etc.) and still be notified at each key press.

def my_callback(cb, key_event, *args):
    if isinstance(key_event, PrintableChar):
        # do something, e.g. log the current letter
        log(key_event.value)

    return cb(None, key_event, *args)

richline = Richline()
text = richline.read(cb=my_callback)

You may modify the input, but either modify one readable character at a time or be in for a lot of pain.

This example colour the input and automatically change to uppercase the readable characters:

color_idx = 1
def colorful_string(cb, *args):
    global color_idx
    sys.stdout.write('\033[1;%dm' % ((color_idx % 8) + 30))
    color_idx += 1

    res = cb(None, *args)
    sys.stdout.write('\033[0m')
    return res

def up(cb, key_event, term, vterm, iline, previous, current, prev_idx, next_idx):
    if isinstance(key_event, PrintableChar):
        key_event.value = key_event.value.upper()
        current = current[:-1] + key_event.value
        iline.text = current
        log(current, previous)

    return colorful_string(cb, key_event, term, vterm, iline, previous, current, prev_idx, next_idx)

richline = RichLine()
text = richline.read(cb=up, prompt='Write what you want, try home key, arrows, canc, word-wrap,...: ')
print('\nYou wrote: ' + text)

RichPassword

Read a password displaying asterisks each time a key is pressed, showing for a second the latest typed character and letting the user move with arrows. If you press F1 you can toggle the asterisks on/off.

pw = RichPassword().read(prompt='Password: ')

License

Copyright 2014 Riccardo Attilio Galli riccardo@sideralis.org [http://www.sideralis.org]

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.