[Scons-users] Handling user supplied CPPPATH with Variables?

[Andrew C. Morrow]

How should list-y variables like CPPPATH be handled with Variables? I'd
like users of my SConstruct to be able to say one of:

scons CPPPATH=/my/first/path CPPPATH=/my/second/path
scons CPPPATH=/my/first/path,my/second/path

Where I have declared a CPPPATH variable with AddVariables:

cmdLineVars = Variables(None, ARGUMENTS)
cmdLineVars.AddVariables(
    ('CPPPATH', 'Preprocessor search path')
)

env = Environment(
    variables=cmdLineVars,
)

In the first case, it doesn't work because the multiple CPPPATH values are
lost during conversion to the ARGUMENTS dict, so I end up with env['CPPPATH']
= 'my/second/path', where the value is a string, and I've lost the first
argument.

In the second case, it doesn't work because the entire argument is treated
like a string, so env['CPPPATH']='my/first/path,my/second/path'. I'd need
some sort of hook to parse the delimiter, and return a list, but the
converter arg doesn't seem appropriate because it is required to return a
string.

What I would like is a way to let the invoker list as many paths as
required for their environment, and end up with:

env['CPPATH']=['/my/first/path', '/my/second/path', ... '/my/nth/path']

Ideally I'd like to do this for many separate Variables that are best
handled as lists, like LIBPATH, CFLAGS, etc.

Any ideas? Otherwise I will need to use the Options mechanism instead, I
think.

Thanks,
Andrew
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