Python More or Less

This library makes it easy to add more paginating to your application.

This means that it will print a full page of output, after which it will prompt the user on how to continue.

It supports multiple continue actions, and full control over where the input comes from, and where the output is printed to.

Available continue actions

This library supports all the usual continue actions, like space for another page, enter for a single more line, and many more.

To see all the available operations, press h at the --More-- prompt:

-------------------------------------------------------------------------------
Most commands can optionally be preceded by an integer argument k.
The default values are printed in brackets.
A star (*) indicates the value of k becomes the new default.
-------------------------------------------------------------------------------
<space>                Display next k lines of text [current screen size]
<return>               Display next k lines of text [1]*
q or Q or <interrupt>  Exit from more
=                      Display current line number
l                      Toggle printing line number on every line [currently disabled]
/<regular expression>  Search for kth occurrence of the regular expression [1]
n                      Search for kth occurrence of the last regular expression [1]
.                      Repeat previous command
h or ?                 Display this help text
-------------------------------------------------------------------------------

How to use this library

All you need to do is call paginate and pass in your input lines:

import more_or_less

more_or_less.paginate(input=iterator_or_queue)

This uses your terminal's screen height, and prints the text to stdout.

Do you want to use something other than stdout? Just pass in what output to use

more_or_less.paginate(input=iterator, output=stderr)

This can be any object that has a write and flush method

class MyCustomOutput(object):
    def write(self, text):
        pass

    def flush(self):
        pass

def paginate(iterator):
    more_or_less.paginate(input=iterator,  output=myCustomOutput())

To use another screen height than your terminal session, pass in a ScreenDimensions object, like the built-in FixedSizeScreen:

import more_or_less

more_or_less.paginate(
    input=iterator,
    screen_dimensions=more_or_less.FixedSizeScreen(height=25)
)

Finally, to run the paginator asynchronously, simply pass in asynchronous=True

more_or_less.paginate(
    input=iterator,
    asynchronous=True
)

This is especially useful if you use a queue.Queue as input. In this case, use more_or_less.END_OF_INPUT to let our paginator know it should stop, and join the returned object to wait for the paginator to end:

my_queue = queue.Queue()
controller = more_or_less.paginate(input=my_queue, asynchronous=True)

my_queue.put('first line\n')
my_queue.put('second line\n')
# Signal we're done
my_queue.put(more_or_less.END_OF_INPUT)
# Wait for the pagination to complete
controller.join()

Advanced topics

Adding plugins

All actions you take at the more prompt (space for one more page, enter for one more line, and so on) are installed using plugins.

This makes it easy to extend the functionality, by creating your own MorePlugin and installing it through more_or_less.add_plugin.

For examples, see our rainbow plugin and our rainbow toggle.

Changing prompt reader

When the output is paused waiting for a continue action, we read this action from stdin.

This can be changed by passing in a custom Input object. For example, any time we hit a more prompt the following code will automatically search for "the search pattern":

class MyCustomInput(more_or_less.Input):

        def prompt(self, message):
            # Return a full line of input.
            # Used for example after typing a '/'
            return "the search pattern"

        def get_character(self, message):
            # Returns a single input character
            return '/'

more_or_less.paginate(input=iterator, prompt=MyCustomInput())

Running unittests

Checkout this code, go to the root directory and execute

python -m unittest discover tests -v