On Feb 10, 2019, at 8:30 AM, James Laskey <james.las...@oracle.com> wrote: > > I should know better than format e-mails. Many a backslash eaten. The summary > should be; > >>> For instance; if we got up from the table with the ", """, \", \""" set of >>> delimiters, we could still introduce structured delimiters in the future; >>> either with repeated \ (see Swift) or repeated ". We could also follow a >>> suggestion John made to use a pseudo nonce like \5" for \\\\\" or \""""".
Heh, I wondered about that. I'd like to propose a term, *for the dessert menu*, to better capture this idea of a "pseudo-nonce". I call it a "strong quote". A "strong quote" is a quote drawn from an infinite non-periodic set of candidates, all of which are reserved as options for introducing a quoted string. (Minor point #1: Really I should have said "scheme for strong quoting and unquoting". But "strong quote" sounds better and is unambiguous in context.) (Minor point #2: Strong quotes need strong unquotes. The set of unquotes needs to be correspondingly infinite, and each strong unquote needs to be derived from a corresponding quote. Unquotes could be the same strings as quotes, reversed strings, etc. They should to be distinct from something that might occur in naturally in a string body, like an escape sequence. The infinite choice of quotes is the major point.) Two important things to notice about strong quotes: 1. The infinite set is what makes the quotes strong. Any finite set can be embarrassed by asking it to quote a string which contains *all* the corresponding unquotes in the finite repertoire. Any finite choice takes us into those arguments that say, "surely we don't care about users who care to quote *that*". 2. The infinite set doesn't need to allow users to exercise some tasteless creativity, by picking nonces which (say) encode misleading intentions or irritating sentiments. The infinite set can be quite simple and regular. Two more less important things to notice: 3. The infinite set should not be just the cyclic repetition of some seed string, like a single quote character. This is why the word "non-periodic" appears above In the periodic case (alone) there are some strings which just barely miss being quotable, because you can't tell when the strong open quote ends and the string body begins. So the scheme of repeating a quote character "enough times" just barely misses being a proper strong quote scheme. 4. User creativity can be excluded even more by positing a normal form for a strongly-quoted string. In other words, although there is an infinite choice of strong quotes, the choice for a specific quote can be made mandatory, based on the context of the string to be quoted. An obvious choice is the shortest (or first) strong quote from the infinite set whose corresponding strong unquote does *not* occur in the string to be quoted. Whether a mis-quoted string is reported by an error or a warning is a further choice in user experience. The example scheme Jim noted of '\' Numeral '"' is an example of a strong quoting scheme, with the corresponding unquotes left as an exercise, including the task of avoiding collision with existing string body syntaxes. HTH — John
