'Flash cards' implementation, old and possibly buggy in some rarely used code paths, but it works. fileformat is 'answer $ question # comment'

kysija.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

from __future__ import division, print_function

import os
import codecs
from sys import argv, hexversion
from random import randint
from time import sleep

__NAME__ = 'Kysija'
__VERSION__ = 0.5
configfile = '.kysija.py'

helpmessage = u"""Runtime hotkeys:
  h,help        - Shows this text
  3,õ,a,add     - Duplicates last question
  d,.,',del,delete
                - Removes last question (but not it's duplicates)
  ANYNUMBER     - Shows question with number. Hint: enable "shownum" first
  EMPTY         - Continues
  *             - Anything else exits

Command line arguments:
 -v, --version  - Displays version information
 -h, --help     - You probably already have a good idea, what it does
 -d, --delimiter=STRING
                - Manually sets delimiter between question and answer
     --nosplit  - Does not try to guess a delimiter, shows full lines
                      instead of "questions" and "answers"
 -w, --wait=FORMULA
                - Sets, how long to wait before displaying answer
                 "0.5+0.1l" - 0.5 seconds plus 0.1 seconds for letter in answer
 --(no)shownum  - (don't) Show number for every question
 --(no)welcome  - Do (not) display a welcome message at startup
 --(no)forceclear
                - Try (not) to clear screen even when it seems impossible
 --(no)confirmexit
                - Do (not) confirm exit
 --configfile=FILE
                - Specify configuration file
 --mkconfig     - Creates or edits configuration file
 -i, --allow-interrupts
                - allows to interrupt questions before answer is diplayed.
                Default Linux, unstable on Windows.
 --disallow-interrupts
                - disables this feature on Linux too

Tips:
* Make the Terminal font BIG
* Name all input files .qa and set this program to open these by default
"""

# Python version specific
if hexversion > 0x03000000:
        raw_input = input

# OS specific functions
if os.name == "posix": # Unix/Linux/MacOS/BSD/etc
    clearcommand = 'clear'
    allow_timed_input = True

    def inconfigdir(s):
        return os.path.expanduser(os.path.join('~',s))

    from sys import stdin
    from select import select
    def timed_input(caption, default=False, timeout=1e308):
        print(caption,end='')
        i, o, e = select( [stdin], [], [], timeout )
        if i:
            return stdin.readline().strip()
        else:
            return default

elif os.name in ("nt", "dos", "ce"):
    clearcommand = 'CLS' # DOS/Windows
    allow_timed_input = False

    def inconfigdir(s):
        return os.path.expanduser(os.path.join('~',s)).replace(s,os.path.join('Local Settings','Application Data',s))

    from threading import Thread
    import msvcrt

    class KeyboardThread(Thread):
        def run(self):
            self.hasinput = False
            self.timedout = False
            self.input = ''
            while True:
                if msvcrt.kbhit():
                    self.hasinput = True
                    chr = msvcrt.getche()
                    if ord(chr) == 13:
                        break
                    elif ord(chr) >= 32:
                        self.input += chr
                if len(self.input) == 0 and self.timedout:
                    break

    def timed_input(caption, default=False, timeout=1e308):
        print(caption,end='');
        it = KeyboardThread()
        it.start()
        it.join(timeout)
        it.timedout = True
        if it.hasinput:
            print()
            return it.input
        else:
            return default
else:
    clearcommand = False
    allow_timed_input = False
    timed_input = False
    def inconfigdir(s):
        return s

junkstring = '40a2394bdd29dbb2e37264aac2ddd1c1'

# Configuration management
config = {}
configfile = inconfigdir(configfile)
try:
    from configobj import ConfigObj
    CO = True
except:
    CO = False

def unquote(s):
    if len(s) < 2:
        return s
    quotes = ['"',"'",'"""','`']
    if s[0] in quotes and s[-1] == s[0]:
        s = s[1:-1]
        return unquote(s)
    return s

def sbool(s):
    if s == 'False': return False
    return bool(s)

def readconfig(configfile):
    global config, delimiter, waitmod, waitmult, shownum, forceclear, confirmexit, welcome, swap, allow_timed_input
    if CO and configfile:
        config = ConfigObj(configfile)
    delimiter = config.get('delimiter', False)
    if delimiter == 'False':
        delimiter = False
    waitmod, waitmult = float(config.get('waitmod', 0.6)), float(config.get('waitmult',0.02)) # in seconds, equivelent to "--wait=0.07l+0.5"
    shownum = sbool(config.get('shownum', False)) # tekitab segadust, kuna kustutamisel numbrid nihkuvad
    forceclear = sbool(config.get('forceclear', False))
    confirmexit = sbool(config.get('confirmexit', True))
    welcome = sbool(config.get('welcome', True))
    swap = sbool(config.get('swap', False))
    allow_timed_input = sbool(config.get('allow_timed_input', False))

readconfig(configfile)

# exit() that asks for confirmation when needed
def doexit():
    global confirmexit
    if confirmexit:
        if raw_input('Exit(Y/n):') in ['n','no']: return
    exit()

def clear():
    global forceclear, clearcommand
    if clearcommand:
        os.system(clearcommand)
    elif forceclear:
        print('\n' * 100)

lastindex = 0

def ask(n=0,cl=True):
    global shownum, lastindex, tasks, delimiter
    if cl:
        clear()
    if tasks:
        if not n: n = randint(1,len(tasks))
        if shownum: print(str(n)+':',end=' ')
        lastindex = n-1
        a,q = tasks[n-1][0], tasks[n-1][1]
        if len(q) > 1:
            print(q)
            t = len(a)*waitmult+waitmod
            if timed_input:
                c = timed_input('',None,t)
                if c != None:
                    return c
            else:
                sleep(t)
        elif delimiter != junkstring:
            print('    >    ')
        print(a)
    else:
        print("THAT'S ALL!")
        exit()
    return False

def guessdelimiter(lss):
    nonprintables = [' ','\t','\n']
    counts = {}
    for line in lss:
        for char in set(line):
            if char not in nonprintables:
                counts[char] = counts.get(char,0) + 1
    counttuples = [ (c,counts[c]) for c in counts ]
    return max(counttuples,key=lambda t: t[-1])[0]

# Command line arguments, getting input file name
fname = ''

if '-v' in argv or '--version' in argv:
    clear()
    print(__NAME__, 'v'+str(__VERSION__))
    exit()
if '-h' in argv or '--help' in argv:
    clear()
    print(__NAME__, 'v'+str(__VERSION__)+'\n\n'+helpmessage)
    exit()

for arg in argv[1:]:
    if arg.startswith('--configfile='):
        configfile = arg.replace('--configfile=','')
        configfile = unquote(configfile)
        configfile = os.path.expanduser(configfile)
        readconfig(configfile)
    elif arg.startswith('--delimiter=') or arg.startswith('-d'):
        delimiter = arg.replace('--delimiter=','').replace('-d','')
        delimiter = unquote(delimiter)
    elif arg in ['--nosplit', '--nodelimiter']:
        delimiter = junkstring
    elif arg.startswith('--wait=') or arg.startswith('-w'):
        s = arg.replace('--wait=','').replace('-w','')
        s = unquote(s)
        waitmult = waitmod = 0
        for g in s.split('+'):
            if 'l' in g:
                waitmult += float(''.join([c for c in g if c in '.0123456789']))
            else:
                waitmod  += float(''.join([c for c in g if c in '.0123456789']))
    elif arg == '--welcome':
        welcome = True
    elif arg == '--nowelcome':
        welcome = False
    elif arg == '--shownum':
        shownum = True
    elif arg == '--noshownum':
        shownum = False
    elif arg == '--forceclear':
        forceclear = True
    elif arg == '--noforceclear':
        forceclear = False
    elif arg == '--confirmexit':
        confirmexit = True
    elif arg == '--noconfirmexit':
        confirmexit = False
    elif arg == '-s' or arg == '--swap':
        swap = True
    elif arg == '--noswap':
        swap = False
    elif arg in ['-i', '--allow-interrupts']:
        allow_timed_input = True
    elif arg == '--disallow-interrupts':
        allow_timed_input = False
    elif arg == '--mkconfig':
        if CO:
            config.filename = configfile
            config['delimiter'] = delimiter
            config['waitmod'], config['waitmult'] = waitmod, waitmult
            config['shownum'] = shownum
            config['forceclear'] = forceclear
            config['confirmexit'] = confirmexit
            config['welcome'] = welcome
            config['swap'] = swap
            config['allow_timed_input'] = allow_timed_input
            config.write()
            exit()
        else:
            print("Cannot create configuration file, ConfigObj is missing.")
    elif not ( fname or arg.startswith('-') ):
        fname = arg
    else:
        print('Unrecognised command line argument "'+arg+'"')
        exit()

if not allow_timed_input:
    timed_input = False

while not fname:
    fname = unquote(raw_input("Enter path to input file or drag and drop: ").strip())

# Open file
try:
    f = codecs.open(fname,'r',encoding='utf-8')
except:
    print('Error opening file "'+str(fname)+'", please check that it exists and is readable by you', file=sys.stderr)
    exit()

# Prepare for action
text = f.read()
lines = text.split('\n')

# Parse options embedded in qa file. TODO: what options should be allowed to be set this way?
while lines[0].startswith('# -*- ') and '-*-' in lines[0][6:]:
    line = lines[0].replace('# -*- ','')
    line = line.split('-*-')[0]
    key, value = line.split(':')[0], ':'.join(line.split(':')[1:])
    key = key.strip()
    value = value.strip()
    if key in ['delimiter']: # string options
        vars()[key] = value
        del lines[0]
    elif key in ['waitmod','waitmult']: # float options
        vars()[key] = float(value)
        del lines[0]
    elif key in ['swap']: # boolean options
        vars()[key] = sbool(value)
        del lines[0]
    else:
        print('ERROR: unrecognised option', key )

if not delimiter:
    delimiter = guessdelimiter(lines)

tasks = [] #list of tuples: ('answer','question')

for line in lines:
    if line.startswith('#'):
        continue # Ignore comment lines
    line = line.split('#')[0] # Remove inline comments
    if line.startswith(r'\#'):
        line = line.replace(r'\#','#') # TODO: is there a better way to allow lines starting with #?
    t = line.split(delimiter)
    a = t[0].strip()
    q = ''.join(t[1:]).strip()
    if swap == True:
        a, q = q, a
    if a:
        tasks.append((a,q))

# The visible part
if welcome:
    print('[ENTER] to continue, for other options see help (enter "h").')
else:
    ask(False)

c = False
while True:
    n = 0
    if not c and c != '':
        c = raw_input()
    if c == '': pass
    elif c.lower() in ['h','help']:
        clear()
        print(helpmessage)
        continue
    elif c.lower() in ["'",'.',',','delete','del','d']:
        del(tasks[lastindex]) # deletes last question, but not its duplicates
    elif c.lower() in ['3',u'õ','õ',b'õ','add','z']:
        tasks.append(tasks[lastindex]) # Makes last question occur more (duplicates)
    elif c.isdigit():
        n = (int(c)-1)%len(tasks) + 1
    else: doexit()
    c = ask(n)