Pipeless

A simple library for building a data pipeline.

It's an advanced version of this: function4(function3(function2(function1(0))))

It looks like this:

from pipeless import pipeline

error_handler = lambda item, exception: None
function, run, _ = pipeline(error_handler)


@function
def add_one(_):
    return _ + 1

list(run([1, 2, 3]))  # [2, 3, 4]


@function
def doubler(_):
    yield _
    yield _ * 2

list(run([1, 2, 3]))  # [2, 4, 3, 6, 4, 8]

• Pipelines operate over a source iterator (like a generator or a list).

• Functions can return 1 Item, None to drop the item, or a generator. If a generator is given, the items all continue along the pipeline, creating a fork.

  +-----------------------------------+
  |                                   |
  |    add_one   doubler              |
  |    [1]--|-2----\-----2            |
  |    Input        -----4            |
  |                    Output [2,4]   |
  |                                   |
  +-----------------------------------+

• All exception are caught and handled by the optional error_handler input argument to prevent one broken item from stopping the flow. If the handler returns something, that something continues on down the pipeline.
• Functions can be grouped with an optional argument on the annotator i.e. @function('my_group'). Set up your functions this way and you can skip groups with the function_groups_to_skip argument on the pipeline runner.

See the docstrings in pipeline.py for more information!

Versions:

• 2.0 Removed cli generator and optional tuples
• 1.1 Function builders optional.
• 1.0.1 Fixed ordering problem.

Installation

Supports Python 2.6, 2.7, 3.x, pypy.

pip install pipeless

or copy pipeless.py into your project.

Support

Need some help? Send me an email at theandychase@gmail.com and I'll do my best to help you.

Contribution

Send me suggestions, issues, and pull requests on Github and I'll gladly review them!

Licence

The MIT License (MIT)

Copyright (c) 2013 Andrew Chase

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.