13conio Module

13.1Overview

The conio module provides following measures to work on a console screen:

  • Moves the cursor where texts are printed.
  • Changes text colors.
  • Retrieves console size.
  • Waits for keyboard input.

To utilize it, import the conio module using import function.

Below is an example to print a frame around a console: 

import(conio)

conio.clear()
[w, h] = conio.getwinsize()
conio.moveto(0, 0) {
    print('*' * w)
}
conio.moveto(0, 1 .. (h - 2)) {
    print('*', ' ' * (w - 2), '*')
}
conio.moveto(0, h - 1) {
    print('*' * w)
}
conio.waitkey():raise

13.2Module Function

The conio module provides following functions:

conio.clear(region?:symbol):void

Clears the screen.

In default, it clears whole the screen. Argument region that takes one of the symbols below would specify the region to be cleared.

  • `line .. clears characters in the line where the cursor exists.
  • `left .. clears characters on the left side of the cursor.
  • `right .. clears characters on the right side of the cursor.
  • `top .. clears characters on the above side of the cursor.
  • `bottom .. clears characters on the below side of the cursor.
conio.getwinsize()
Returns the screen size as a list [width, height].
conio.setcolor(fg:symbol:nil, bg?:symbol):map:void {block?}

Sets foreground and background color of text by specifying a color symbol. Available color symbols are listed below:

  • `black
  • `blue
  • `green
  • `aqua
  • `cyan
  • `red
  • `purple
  • `magenta
  • `yellow
  • `white
  • `gray
  • `bright_blue
  • `bright_green
  • `bright_aqua
  • `bright_cyan
  • `bright_red
  • `bright_purple
  • `bright_magenta
  • `bright_yellow
  • `bright_white

If fg is set to nil, the foreground color remains unchanged. If bg is omitted or set to nil, the background color remains unchanged.

If block is specified, the color is changed before evaluating the block, and then gets back to what has been set when done.

conio.moveto(x:number, y:number):map:void {block?}

Moves cursor to the specified position. The most top-left position on the screen is represented as 0, 0.

If block is specified, the cursor is moved before evaluating the block, and then gets back to where it has been when done.

conio.waitkey():[raise]

Waits for a keyboard input and returns a character code number associated with the key.

If :raise attribute is specified, hitting Ctrl-C issues a terminating signal that causes the program done.

Character code numbers of some of the special keys are defined as below:

  • conio.K_BACKSPACE
  • conio.K_TAB
  • conio.K_RETURN
  • conio.K_ESCAPE
  • conio.K_SPACE
  • conio.K_UP
  • conio.K_DOWN
  • conio.K_RIGHT
  • conio.K_LEFT
  • conio.K_INSERT
  • conio.K_HOME
  • conio.K_END
  • conio.K_PAGEUP
  • conio.K_PAGEDOWN
  • conio.K_DELETE