[gentoo-dev] PYTHON_DEPEND - Suggested replacement for NEED_PYTHON

[Arfrever Frehtes Taifersar Arahesis]

I would like to suggest introduction of support for PYTHON_DEPEND variable, which
would be a better replacement for NEED_PYTHON variable. NEED_PYTHON variable
does not allow to specify that e.g. only versions of Python 2 are accepted.
(Eventually PYTHON_DEPEND variable will have to be set only in ebuilds of packages
not supporting installation for multiple versions of Python.)

Suggested syntax:
  PYTHON_DEPEND="[USE_flag?] <X[:[Y][:[Z]]]> [X[:[Y][:[Z]]]]"
    <required_component>, [optional_component]
    X - Major version of Python ('2' or '3') or '*'.
    Y - Minimal version of Python in the form of ${major_version}.${minor_version}.
    Z - Maximal version of Python in the form of ${major_version}.${minor_version}.
        It will be probably very rarely used.

Examples:
  PYTHON_DEPEND="2"
    Dependency on any version of Python 2.

  PYTHON_DEPEND="2:2.5"
    Dependency on Python 2.7, 2.6 or 2.5.

  PYTHON_DEPEND="*:2.6"
    Dependency on Python 3.2, 3.1, 3.0, 2.7 or 2.6.

  PYTHON_DEPEND="2:2.7 3:3.1"
    Dependency on Python 3.2, 3.1 or 2.7.

  PYTHON_DEPEND="2:2.5:2.6"
    Dependency on Python 2.6 or 2.5.

  PYTHON_DEPEND="2::2.6"
    Dependency on Python 2.6, 2.5 or 2.4.

  PYTHON_DEPEND="python? 2"
    Dependency on any version of Python 2 when "python" USE flag is enabled.

-- 
Arfrever Frehtes Taifersar Arahesis