lang/python-packages/README.md

   1 This package allows users to package python modules without creating package
   2 Makefiles for each individual module and their dependencies.  It provides a
   3 way making packaging python packages faster and may also facilitate the process
   4 of developing Makefiles for new python packages
   5
   6 This is a raw DEVEL only package.  Using it may entail a lot of implementation
   7 details and you may need to resolve target dependencies and package details on
   8 your own
   9
  10 - Third party python packages may depend on features not included in e.g.
  11   python-light
  12 - Some python modules may require host install of another module to progress,
  13   e.g. target cryptography requires host cffi
  14 - Some python modules have external C library dependencies, e.g. pyOpenSSL
  15   requires openssl libs
  16 - Some packages may have an autoconf configure script whose arguments we
  17   cannot control with pip and has to be passed on (hacked) by overriding some
  18   environment variables
  19
  20 ## How it works
  21
  22 1. Install host modules required for building target modules
  23 2. Install each target module to separate directories
  24 3. Install another copy of modules for cleanup purposes to make list of
  25    installed files to be removed from target modules installed in step 2
  26
  27 Why should it be so
  28
  29 1. Installing target cryptography requires host installation of cffi module
  30 2. cryptography requires setuptools and pip will install its own copy with
  31    --ignore-installed.  When PACKAGE_python-setuptools is also selected, opkg
  32    will complain of data file clashes if it was not removed here.
  33
  34 Pip will handle dependency requirements of python modules, but external
  35 dependencies like c libraries has to be prepared by the build system.  The
  36 issue is that there is currently no way to express such dependencies, thus may
  37 cause build failure, e.g. pycrypto requires the presence of libgmp to build
  38 successfully.
  39
  40 ## Tips
  41
  42 If something goes wrong, we can add additional arguments to pip command
  43 line to check the detailed build process.  Some useful arguments may be
  44
  45 - -v, for verbose output.  Repeat this option if the current level of
  46   verbosity is not enough
  47 - --no-clean, for preserving pip build dir on build failure
  48
  49 ## Examples
  50
  51 tornado (python-only module)
  52
  53         CONFIG_PACKAGE_python-packages=y
  54         CONFIG_PACKAGE_python-packages-list="tornado==4.4.2"
  55
  56 cryptography (requires installation of host modules and cleanup on target modules)
  57
  58         CONFIG_PACKAGE_python-packages=y
  59         CONFIG_PACKAGE_python-packages-list-host="cffi"
  60         CONFIG_PACKAGE_python-packages-list="cryptography"
  61         CONFIG_PACKAGE_python-packages-list-cleanup="setuptools"
  62
  63 pycrypto 2.7a1 (python module with autoconf configure script; depends on
  64 libgmp; broken wmmintrin.h).  2.6.1 does not work because of a flaw in
  65 the setup.py hardcoding host include directory
  66
  67         CONFIG_PACKAGE_libgmp=y
  68         CONFIG_PACKAGE_python-packages=y
  69         CONFIG_PACKAGE_python-packages-list="https://github.com/dlitz/pycrypto/archive/v2.7a1.tar.gz"
  70         CONFIG_PACKAGE_python-packages-envs="ac_cv_header_wmmintrin_h=no build_alias=$(GNU_HOST_NAME) host_alias=$(GNU_TARGET_NAME) target_alias=$(GNU_TARGET_NAME)"
  71         CONFIG_PACKAGE_python-packages-extra-deps="libgmp.so.10"
  72