MultiLineReader

input() and the readline module support single-line input. I.e., each time the dude typing on the keyboard presses Enter, that ends the line of input, which is then added to the history maintained by readline. It would be nice to type a \ at the end of the line, and continue typing a command on the next line(as happens on bash), but that doesn't work.

input() and readline can, however, deal with history items that happen to be multi-line due to embedded \n characters. The MultiLineReader class takes advantage of this. If a line of input is terminated by a continuation string (e.g. ), then an additional line of input is requested. This continues until a line is provided that does not end with the continuation string. MultiLineReader.input reads lines until it detects one not terminated by a continuation string, and returns those lines concatenated into a string (removing the \ and \n terminating each non-terminal line).

History items are correctly maintained, replacing multiple continued lines, with the one joined-together line. When one of these multi-line history items is edited, it shows up to the keyboard dude as it was typed in originally: multiple lines, with all but the last ending in the continuation string.

Usage

Create a MultiLineReader using the constructor. Specify the location of your application's history file, if you want the history of input lines to survive process boundaries. E.g.

reader = MultiLineReader(history_file='/home/marcel/.app_history')

This creates a multi-line reader, using \ as the continuation string. If you want a different continuation string, specify a value for the continuation argument.

To read lines from the console use MultiLineReader.input() instead of Python's input() function. (MultiLineReader.input wraps input()). E.g.

line = reader.input('> ', '+ ')

This reads one or more lines from stdin. Lines that are to be continued must end with the continuation string (\ by default). > is the prompt for the first line of input. + is used for continuation lines.

Call MultiLineReader.close() when you are done with input. This will record the history file on disk.

Integration with the readline module

You can configure readline as you ordinarily do. But you should not call readline.read_history_file, readline.write_history_file, or any functions that modify history items, as these will interfere with the operation of MultiLineReader.

main()

The main() function included solicits input, and then when input is complete, prints the lines returned by input() and the history. The lines show multilines concatenated together, while the history lines show the line breaks and cotinuations.