What is a pager?

A pager is a terminal program that can be used to view the content of a file, or the output stream from another application.

For instance, when we run man vim, the actual content is displayed in a pager, according to the $PAGER environment variable.

Important for a pager is that the input can be streamed. For instance when we execute find / | pypager; we don’t want to wait for the whole file system to be traversed, before displaying anything. Data is only read from the input pipe, when it needs to be displayed.

Popular pager applications are more, less and most.

Features

• Highlighting of text [0].

• Searching.

• Many key bindings from less are implemented.

[0] (It understands the output of man pages, ANSI escape codes and further, it can use Pygments to highlight about any file.)

Usage

# Install it.
pip install pypager

# Tell the environment to use this pager. Put the following line in
# ~/.bashrc if you like.
export PAGER=pypager

# Following commands, and many others should pick up the pager.
man vim
git diff

# View a file, using this pager.
pypager some_source_code.py

As a library

from pypager.source import GeneratorSource
from pypager.pager import Pager


def generate_a_lot_of_content():
    """
    This is a function that generates content on the fly.
    It's called when the pager needs to display more content.

    This should yield prompt_toolkit `(style_string, text)` tuples.
    """
    counter = 0
    while True:
        yield [("", 'line: %i\n' % counter)]
        counter += 1


if __name__ == '__main__':
    p = Pager()
    p.add_source(GeneratorSource(generate_a_lot_of_content())
    p.run()