Add support for TA-Lib binary installed in virtualenv.

[gw0]

Workaround to add support for using TA-Lib binary libraries installed inside the virtualenv directory (eg ./venv/lib).

[mrjbq7]

I assume this should check for exists first?

activate = os.getenv('VIRTUAL_ENV', './venv') + '/bin/activate'
if os.path.exists(activate):
    with open(activate) as f:
        f.write("\nexport LD_LIBRARY_PATH=$VIRTUAL_ENV/lib:$LD_LIBRARY_PATH\n")

I have not used virtual env much, but is $VIRTUAL_ENV/lib a standard location for loading libraries, or a workaround for talib? Also, is $VIRTUAL_ENV/bin/activate a standard script that is run?

[mrjbq7]

Is there a way to detect that we are in a virtual env?

[gw0]

Yes, you are correct. Such a check is necessary.

When you create a virtualenv the following standard directory structure appears (bin, include, lib, local, src) and Python binaries and packages get installed into it thereafter. There is no standard location where you create a $VIRTUAL_ENV, some put it in a subdirectory of their project project/venv others directly in project project. Nevertheless this works great for all Python-related things, you just run . venv/bin/activate and use pip install and other things as usual, knowing it will install everything inside the virtualenv. As far as I know the best way to detect a virtualenv is using $VIRTUAL_ENV environment variable.

Unfortunately non-Python libraries are not handled by virtualenv at all. Nevertheless in my setups I usually install them inside the virtualenv directory (./configure --prefix=$VIRTUAL_ENV). This way binaries get installed into ./venv/bin and work automatically (because $PATH is configured correctly by ./venv/bin/activate) and libraries into./venv/lib. After adding a line such asexport LD_LIBRARY_PATH=$VIRTUAL_ENV/lib:$LD_LIBRARY_PATH` they also work as expected.

In case this seems to you as an ugly workaround, you may want to add an option to specify a custom includes and lib folder to search for the TA-Lib (eg. through an environment variable).

[mrjbq7]

I found a page that talks about using LD_RUN_PATH for this:

https://groups.google.com/forum/#!topic/python-virtualenv/-U4epR1YWFk

Also, not something I expect you to have to work on, but would be nice if it worked on Mac, Linux, and Windows like the talib library does.

[gw0]

Hm, maybe it would be great if the Python package would also include (or download) and compile the ta-lib library if it is not installed system-wide? Like some packages do?