[Scons-dev] Distinguishing Debian and Fedora

[Jason Kenny]

I think this is a great idea.

However a word of warning. How this applied could break existing code people have.

Changing the env[“PLATFORM”] from posix to something like “linux” or “Linux_debian” is not backward compatible.

The reality is that a string was used for good or bad. 

I would suggest that we defined something new so we don’t break existing build code. I know I have suggested something from parts, but I seem to have to make it a 100% independent package on pypi for it to be used by SCons.

I think we need to look at Greg’s Noel IAPAT idea. I been calling it settings and have a great start of it going on Parts. I don’t think we want do this kind of change without some thought.

I personally think we should deprecate PLATFORM and replace it with a HOST_XXX and TARGET_XXX value. Where XXX would be values like:

1) OS ( this is abstract)
2) OS-VARIANT/ Vender ( this is detailed)
3) Architecture ( this is abstract)
4) CPU-Type( this is detailed)

I have found over and over again people need, as you get more low level, more detail. But to much detail can be a problem if one does not provide a good abstraction to replace it.

People need detail something like this is fedora or redhat, or the only need details such as this is windows or posix.

I know one item I would fix in the Parts Api for SystemPlatform would have been to move to use of functions for the abstract layers vs string or enums. Functions such as isX86() or isx86_64(), or isPosix or isLinux() I think will work better long term as it provides way to say useful stuff without knowing details that might change in unexpected ways. I have learned what seems good today probably will not make as much sense tomorrow, normally for reason we cannot foresee. 

I should also note maintaining more detail will  have a higher maintainer cost.

Jason


From: Russel Winder
Sent: Tuesday, January 19, 2016 5:42 AM
To: SCons_Developers
Subject: Re: [Scons-dev] Distinguishing Debian and Fedora

The following is a "doodle" for the direction I think the whole
platform detection thing should go. It is all about removing strings as
selectors, which has to be a bad thing given the propensity of many to
mis-spell things. 


from enum import Enum, unique

@unique
class OS_Type(Enum):
    posix = 0
    linux_debian = 1
    linux_fedora = 2
    darwin = 3
    windows_win32 = 4
    windows_cygwin = 5
    windows_mingw = 6

def which_posix():
    with open('/etc/os-release') as f:
        for line in f:
            if 'ID' in line:
                return {
                    'debian': OS_Type.linux_debian,
                    'fedora': OS_Type.linux_fedora,
                    }[line.split('=')[1].strip()]
        return OS_Type.posix

environment = Environment(
    tools=('g++', 'gnulink'),
)

platform = {
    'posix': which_posix(),
    'darwin': OS_Type.darwin,
}[environment['PLATFORM']]

environment.MergeFlags('!pkg-config --cflags --libs gtkmm-3.0')

if platform == OS_Type.linux_fedora:
    environment.MergeFlags('!pkg-config --cflags --libs gstreamermm-
0.10')
elif platform == OS_Type.linux_debian:
    environment.MergeFlags('!pkg-config --cflags --libs gstreamermm-
1.0')
else:
    print('Platform not understood.')
    Exit(1)

environment.Program('stuff.cpp', CXXFLAGS=['-std=c++14', '-W', '-
Wall'])




-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at winder.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder

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