Is there a way to have a conditional requirements.txt file for my Python application based on platform?

Question

I have a python application that I wrote to be compatible with both, Linux and Windows platforms. However there is one problem... One of the python packages I need for Windows is not compatible with Linux. Fortunately there is another package that provides the same functionality on Linux. All other dependencies are compatible in both platforms.

I know I could have 2 separate requirement files to address both platform dependencies separately. Something like win_requirements.txt and linux_requirements.txt, however this approach doesn't feel like the best way to do it.

I wonder if there is a way I can have only one requirements.txt file so any user can use pip install -r requirements.txt to install all the dependencies regardless of what platform they are?

Maybe something like??:

SOAPpy>=0.12.22 pycrypto>=2.6.1 suds>=0.4 Python-ldap>=2.4.19 paramiko>=1.15.2 nose>=1.3.4 selenium>=2.44.0 bottle>=0.12.8 CherryPy>=3.6.0 pika>=0.9.14 if platform.system() == 'Linux':     wmi-client-wrapper>=0.0.12 else if platform.system() == 'Windows':     WMI>=1.4.9 

Answer 1

You can add certain conditional requirements after a semi-colon. Particularly useful for sys_platform and python_version.

Examples:

atomac==1.1.0; sys_platform == 'darwin' futures>=3.0.5; python_version < '3.0' futures>=3.0.5; python_version == '2.6' or python_version=='2.7' 

Apparently you can also exclude particular versions of a library:

futures>=3.0,!=3.0.5 

They are defined in PEP 508 and PEP 0345 (Environment Markers) but the syntax appears to follow the draft PEP 0496.