Re: Ann: SWI-Prolog 7.1.13

2014-04-19 9:19 GMT+02:00 rlaanemets <[email protected]>:

> Does the sematic issue come from the need to support nondet mode when the
> Key
> is unbound? As this has the usual (for anything that involves exceptions?)
> order-dependent semantics:
>
> ?- D = _{ a: 1 }, X = b, get_dict_ex(X, D, 1).
> ERROR: get_dict_ex/3: key `b' does not exist in _G2711{a:1}
>
> ?- D = _{ a: 1 }, get_dict_ex(X, D, 1), X = b.
> false
>
> Anyway, I have never used get_dict_ex/3 with an unbound Key, never even
> thought about that :)
>
> Now the question is: will the dot (.) operator keep throwing exception on
> the missing key or is that going to be changed? The documentation for
> http://swi-prolog.org/pldoc/doc_for?object=get_dict/3 says:
>
> "This predicate is normally accessed using the functional notation
> Dict.Key"
>
> which hints that it might not.
>
> By the way, the comment on top of '.'/3 still looks wrong:
>
> http://www.swi-prolog.org/git/pl-devel.git/blob/dec32b691ac0ca322456a4734f7c01d908ce2d32:/boot/dicts.pl
>
> "fails if the first argument is not a dict or the second is not a valid key
> or unbound"
>
> Not sure how many here use Kate but I also attempted to fix their warnings
> for the Swi dict syntax:
> https://bugs.kde.org/show_bug.cgi?id=333608
>
>

Just a curiosity: I use  Kate' syntax highlighter in QtCreator, handy when
modifying scripts attached - possibily - to resource files.

bye Carlo


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