[Scons-users] Using Validators

[Florian Lindner]

Hello,

I have a Variable with an validator:

vars.Add("compiler", "desc", "g++", validator=compiler_validator)

def compiler_validator(key, value, environment):
    if value in ["g++", "icc", "clang++"] or value.startswith("mpic"):
        return True
    else:
        return False


When called
scons [...] compiler=clang 
the function above is called and returns False. Despite of that the 
compilation starts...

When called
scons [...] compiler=foobar
is returns False too and the scons quits with the completely unrelated 
error:

Checking for C++ header file boost/array.hpp... no
ERROR: Header 'boost/array.hpp' (needed for Boost) not found or does not 
compile!

When called
scons [...] compiler=clang++
everything works.

I suppose that return False on invalidate values is correctly, the validator 
is undocumented and the API states only the arguments, not the return type 
and semantics.

Thanks!
Florian