I can't help with the getopt problem, but from a pure 'if I was going to have to use this' perspective:
How about: --list '4==100,8>1000,7<=15'. It's easier to type and clearer to read.
And leaves you the simple task of breaking up the parameter yourself rather than fighting with an undocumented and experimental feature.
With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
In reply to Re: getopt long, named argument with multiple values