comment on

> both a regex like /\A(\d+(?:\.\.\d+)?)(?:,(?1))*\z/

That's overkill in that case,...

> and checking eval for errors.

... checking eval for errors is enough, once the code fails.

Your all-covered approach reminds me of parents insisting to drive their kids to school while they keep their bike's helmet on.

Like this you are scaring them away from learning how to bike by themselves.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery}

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