[doc] cleanup & refactorings
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docs/extension/index.rst
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docs/extension/index.rst
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Extensions
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==========
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Extensions contains all things needed to work with a few popular third party tools.
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Most of them are available as optional extra dependencies, and the maturity stage of each may vary.
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.. toctree::
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:maxdepth: 2
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docker
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jupyter
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selenium
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sqlalchemy
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11
docs/guide/graphs.rst
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docs/guide/graphs.rst
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Graphs
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======
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Writing graphs
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::::::::::::::
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Debugging graphs
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::::::::::::::::
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Executing graphs
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::::::::::::::::
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@ -6,18 +6,9 @@ Here are a few guides and best practices to work with bonobo.
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.. toctree::
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:maxdepth: 2
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purity
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graphs
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transformations
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services
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environment
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purity
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There is a also few extensions that ease the use of the library with third party tools. Each integration is
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available as an optional extra dependency, and the maturity stage of each extension vary.
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.. toctree::
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:maxdepth: 2
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ext/docker
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ext/jupyter
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ext/selenium
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ext/sqlalchemy
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@ -1,34 +1,39 @@
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Pure transformations
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====================
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Best Practices
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==============
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The nature of components, and how the data flow from one to another, can be a bit tricky.
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Hopefully, they should be very easy to write with a few hints.
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The major problem we have is that one message (underlying implementation: :class:`bonobo.structs.bags.Bag`) can go
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through more than one component, and at the same time. If you wanna be safe, you tend to :func:`copy.copy()` everything
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between two calls to two different components, but that's very expensive.
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Pure transformations
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::::::::::::::::::::
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Instead, we chose the opposite: copies are never made, and you should not modify in place the inputs of your
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component before yielding them, and that mostly means that you want to recreate dicts and lists before yielding (or
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returning) them. Numeric values, strings and tuples being immutable in python, modifying a variable of one of those
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type will already return a different instance.
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One “message” (a.k.a :class:`bonobo.Bag` instance) may go through more than one component, and at the same time.
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To ensure your code is safe, one could :func:`copy.copy()` each message on each transformation input but that's quite
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expensive, especially because it may not be needed.
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Instead, we chose the opposite: copies are never made, instead you should not modify in place the inputs of your
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component before yielding them, which that mostly means that you want to recreate dicts and lists before yielding if
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their values changed.
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Numeric values, strings and tuples being immutable in python, modifying a variable of one of those type will already
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return a different instance.
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Examples will be shown with `return` statements, of course you can do the same with `yield` statements in generators.
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Numbers
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:::::::
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-------
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In python, numbers are immutable. So you can't be wrong with numbers. All of the following are correct.
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.. code-block:: python
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def do_your_number_thing(n: int) -> int:
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def do_your_number_thing(n):
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return n
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def do_your_number_thing(n: int) -> int:
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def do_your_number_thing(n):
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return n + 1
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def do_your_number_thing(n: int) -> int:
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def do_your_number_thing(n):
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# correct, but bad style
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n += 1
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return n
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@ -37,37 +42,37 @@ The same is true with other numeric types, so don't be shy.
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Tuples
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::::::
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------
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Tuples are immutable, so you risk nothing.
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.. code-block:: python
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def do_your_tuple_thing(t: tuple) -> tuple:
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def do_your_tuple_thing(t):
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return ('foo', ) + t
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def do_your_tuple_thing(t: tuple) -> tuple:
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def do_your_tuple_thing(t):
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return t + ('bar', )
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def do_your_tuple_thing(t: tuple) -> tuple:
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def do_your_tuple_thing(t):
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# correct, but bad style
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t += ('baaaz', )
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return t
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Strings
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:::::::
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-------
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You know the drill, strings are immutable.
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You know the drill, strings are immutable, too.
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.. code-block:: python
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def do_your_str_thing(t: str) -> str:
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def do_your_str_thing(t):
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return 'foo ' + t + ' bar'
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def do_your_str_thing(t: str) -> str:
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def do_your_str_thing(t):
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return ' '.join(('foo', t, 'bar', ))
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def do_your_str_thing(t: str) -> str:
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def do_your_str_thing(t):
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return 'foo {} bar'.format(t)
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You can, if you're using python 3.6+, use `f-strings <https://docs.python.org/3/reference/lexical_analysis.html#f-strings>`_,
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@ -75,15 +80,15 @@ but the core bonobo libraries won't use it to stay 3.5 compatible.
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Dicts
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:::::
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-----
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So, now it gets interesting. Dicts are mutable. It means that you can mess things up if you're not cautious.
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For example, doing the following may cause unexpected problems:
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For example, doing the following may (will) cause unexpected problems:
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.. code-block:: python
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def mutate_my_dict_like_crazy(d: dict) -> dict:
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def mutate_my_dict_like_crazy(d):
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# Bad! Don't do that!
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d.update({
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'foo': compute_something()
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@ -112,7 +117,7 @@ Now let's see how to do it correctly:
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.. code-block:: python
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def new_dicts_like_crazy(d: dict) -> dict:
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def new_dicts_like_crazy(d):
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# Creating a new dict is correct.
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return {
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**d,
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@ -120,7 +125,7 @@ Now let's see how to do it correctly:
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'bar': compute_anotherthing(),
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}
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def new_dict_and_yield() -> dict:
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def new_dict_and_yield():
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d = {}
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for i in range(100):
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# Different dict each time.
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@ -133,8 +138,8 @@ I bet you think «Yeah, but if I create like millions of dicts ...».
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Let's say we chose the opposite way and copied the dict outside the transformation (in fact, `it's what we did in bonobo's
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ancestor <https://github.com/rdcli/rdc.etl/blob/dev/rdc/etl/io/__init__.py#L187>`_). This means you will also create the
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same number of dicts, the difference is that you won't even notice it. Also, it means that if you want to yield the same
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dict 1 million times , going "pure" makes it efficient (you'll just yield the same object 1 million times) while going "copy
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crazy" will create 1 million objects.
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dict 1 million times, going "pure" makes it efficient (you'll just yield the same object 1 million times) while going
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"copy crazy" would create 1 million identical objects.
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Using dicts like this will create a lot of dicts, but also free them as soon as all the future components that take this dict
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as input are done. Also, one important thing to note is that most primitive data structures in python are immutable, so creating
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@ -7,6 +7,7 @@ Bonobo
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install
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tutorial/index
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guide/index
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extension/index
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reference/index
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faq
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contribute/index
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@ -1,6 +1,7 @@
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Installation
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============
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Create an ETL project
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:::::::::::::::::::::
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@ -15,6 +16,7 @@ Creating a project and starting to write code should take less than a minute:
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Once you bootstrapped a project, you can start editing the default example transformation by editing
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`my-etl-project/main.py`. Now, you can head to :doc:`tutorial/index`.
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Other installation options
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::::::::::::::::::::::::::
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@ -27,6 +29,7 @@ You can install it directly from the `Python Package Index <https://pypi.python.
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$ pip install bonobo
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Install from source
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-------------------
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@ -39,6 +42,13 @@ below).
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$ pip install git+https://github.com/python-bonobo/bonobo.git@develop#egg=bonobo
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.. note::
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Here, we use the `develop` branch, which is the incoming unreleased minor version. It's the way to "live on the
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edge", either to test your codebase with a future release, or to test unreleased features. You can use this
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technique to install any branch you want, and even a branch in your own repository.
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Editable install
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----------------
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@ -48,9 +58,11 @@ of your python interpreter.
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.. code-block:: shell-session
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$ pip install --editable git+https://github.com/python-bonobo/bonobo.git@master#egg=bonobo
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$ pip install --editable git+https://github.com/python-bonobo/bonobo.git@develop#egg=bonobo
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.. note:: You can also use the `-e` flag instead of the long version.
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.. note:: You can also use `-e`, the shorthand version of `--editable`.
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.. note:: Once again, we use `develop` here. New features should go to `develop`, while bugfixes can go to `master`.
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If you can't find the "source" directory, try trunning this:
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@ -58,6 +70,9 @@ If you can't find the "source" directory, try trunning this:
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$ python -c "import bonobo; print(bonobo.__path__)"
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Local clone
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-----------
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Another option is to have a "local" editable install, which means you create the clone by yourself and make an editable install
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from the local clone.
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@ -78,10 +93,25 @@ I usually name the git remote for the main bonobo repository "upstream", and my
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Of course, replace my github username by the one you used to fork bonobo. You should be good to go!
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Windows support
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:::::::::::::::
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Supported platforms
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:::::::::::::::::::
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There are minor issues on the windows platform, mostly due to the fact bonobo was not developed by experienced windows
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Linux, OSX and other Unixes
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---------------------------
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Bonobo test suite runs continuously on Linux, and core developpers use both OSX and Linux machines. Also, there are jobs
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running on production linux machines everyday, so the support for those platforms should be quite excellent.
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If you're using some esotheric UNIX machine, there can be surprises (although we're not aware, yet). We do not support
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officially those platforms, but if you can actually fix the problems on those systems, we'll be glad to integrate
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your patches (as long as it is tested, for both existing linux environments and your strange systems).
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Windows
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-------
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Windows support is correct, as a few contributors helped us to test and fix the quirks.
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There may still be minor issues on the windows platform, mostly due to the fact bonobo was not developed by windows
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users.
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We're trying to look into that but energy available to provide serious support on windows is very limited.
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