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Re: Strings

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  • Atif Aziz
    ... It is up to the coder to define best practices not the format to impose or restrict them.
    Message 1 of 12 , Jan 5, 2006
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      >>
      It is up to the coder to define 'best practices' not the format to
      impose or restrict them.
      <<

      Agreed. The problem lies in some of the inconsistencies surrounding
      the goals, purpose and application of JSON and which I am interested
      in seeing disambiguated. As it stands, right now, the contents of
      the specification are, without a doubt, really good enough for a
      machine encoder. There is little information in there to guide the
      decoders. A human encoder is only at the mercy of the decoder's
      flexibility and there's even more trouble if the implementation
      swaps from underneath his or her feet. Why are humans such a big
      issue? Well, it's right there as the second claim in the
      specification: "It is easy for humans to read and write." The rules
      about strings and unquotable member names is less of a concern for
      humans because allowing a smaller subset means remembering fewer
      rules. However, the resistance to mention comments whatsoever is
      just incomprehensible and beyond me.

      >>
      Then again, it is a 'subset' of JavaScript Object Literals, lowest
      common denominator to be compatible with other languages.
      <<

      Incidentally, what is a data format doing concerning itself with
      lanugages and bindings? I can understand leveraging familiarity with
      existing syntax across the C-family of languages, but that can only
      be used with grain of salt in the design of the data format. The
      lowest common denominator argument is only good enough while things
      remain simple.

      --- In json@yahoogroups.com, "George" <georgenava@y...> wrote:
      >
      > I agree 100% with you.
      > Do as I do and use Javascript Object Literals as they are
      specified in
      > the Javascript or ECMAScript Reference.
      >
      > Anything the JS parser allows is considered valid:
      > - Comments
      > - Quoted/Unquoted keys
      > - Numbered Keys
      > - Single/Double Quotes
      > - Scientific Notation
      > - Unicode
      >
      > It is up to the coder to define 'best practices' not the format to
      > impose or restrict them.
      >
      > Then again, it is a 'subset' of JavaScript Object Literals, lowest
      > common denominator to be compatible with other languages.
      >
      > If your target are web apps, HTML and JS, just go and use the whole
      > set and more.
      >
      > Crockford knows I always opposed his stubbornness ;-)
      >
      > George
      >
      > --- In json@yahoogroups.com, Martin Cooper <mfncooper@g...> wrote:
      > >
      > > On 1/3/06, Douglas Crockford <douglas@c...> wrote:
      > > >
      > > > JSON has a string notation which is similar to that used in
      the C
      > > > family languages. Strings are bounded by double quote
      characters.
      > > > Escapement is provided by the backslash. The spec specifically
      allows
      > > > the slash to be escaped so that JSON can be delivered in HTML
      > documents.
      > >
      > >
      > > These statements have me really wondering about what JSON is
      > supposed to be.
      > > The reasoning behind removing comments was that it would "more
      > closely align
      > > JSON with YAML and Python". Now we have double quoted strings
      only,
      > which is
      > > "similar to that used in the C family language", and so that
      it "can be
      > > delivered in HTML documents".
      > >
      > > And here was me blithely thinking JSON was supposed to be
      a "JavaScript
      > > Object Notation". What happened to the JavaScript focus? With
      all due
      > > respect, it's beginning to seem like JSON is supposed to be a
      minimalist
      > > object notation that's compatible with JavaScript and as many
      other
      > > languages as possible. Perhaps it should be renamed "MON" for
      > Minimal Object
      > > Notation? ;-) The "JSON" moniker is seeming less and less
      appropriate.
      > >
      > > The single quote convention is not included in JSON because it
      is not
      > > > needed.
      > >
      > >
      > > It wasn't "needed" in JavaScript / ECMAScript either, but they
      still
      > > included it. It's convenient because it frequently allows you to
      avoid
      > > backslashes / escapes in string literals.
      > >
      > > All strings can be represented with the double quote notation.
      > > > C itself does not have single quote strings. Many PHP
      programmers are
      > > > confused by JavaScript's single quote strings.
      > >
      > >
      > > Add PHP to the list of non-JavaScript languages JSON is trying
      to cater
      > > to... (... and add PHP programmers to my list of not-so-smart-
      folks
      > if they
      > > can't understand string quoting... ;)
      > >
      > > JSON requires that keys be quoted because of an error in the
      > > > ECMAScript spec that disallows the use of unquoted reserved
      words as
      > > > keys. The list of reserved words is surprisingly long and
      difficult to
      > > > remember. The best practice is to always quote keys.
      > >
      > >
      > > That is a good reason to document a "best practice". It is in no
      way a
      > > reason to ban people from using unquoted key names.
      > >
      > > As an historical note, the very first JSON message contained as
      one of
      > > > its keys the word "do". It was not quoted, and it caused a
      syntax
      > error.
      > >
      > >
      > > Not a good start, huh? ;-)
      > >
      > > --
      > > Martin Cooper
      > >
      > >
      > > Yahoo! Groups Links
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > > >
      > >
      > >
      > > [Non-text portions of this message have been removed]
      > >
      >
    • Atif Aziz
      ... And who took away single quoted strings and unquoted member names?! Hell yes, I d like to see the reasoning for changes like that, too.
      Message 2 of 12 , Jan 5, 2006
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        Dave said [1]:

        >>
        And who took away single quoted strings and unquoted member names?!
        Hell yes, I'd like to see the reasoning for changes like that, too.<<
        <<

        I'd like apologize for this misconception and correct where I have
        been wrong. It appears that the spec never actually endorsed
        unquoted keys or single-quote strings. I went back and looked at the
        earliest version of the spec [2] I could find (dated Apr 17, 2003)
        and there's no mention of it in there. So technically speaking, it
        was never removed (unlike comments, which were). Whether they should
        be added is another story altogether. Right now, I'd just like to
        stick to clarification.

        The confusion came from two sources. First of all, the JSON spec
        seemed small enough to keep in the head. In fact, the easiest rule
        to remember was that, aside from expressions, JSON is really just a
        formalization of JavaScript's literal notation for dictionaries,
        arrays and primitives like strings, numbers, booleans and null. It
        turns out that it's a little less than that, but this detail fades
        away as you spend time in the various implementations; therein lies
        the second problem. Most implementations seem to be exercising (and
        rightly so) a good axiom of the web, "Be liberal in what you require
        but conservative in what you do." So the spec is clear and thorough
        from the encoding perspective (conservative) and no one has
        questioned that (some have been calling it "best practices"). The
        decoding end, however, varies a lot and leads to confusion
        (including my own rearding quotes). I originally started my C#
        implementation as a re-factoring of the Java version 0.1 [3]. At the
        time, this is what was said about the parser's level of tolerance:

        ========================================
        The texts produced by the toString() methods are very strict. The
        constructors are more forgiving in the texts they will accept.

        - An extra comma may appear just before the closing brace.
        - Strings may be quoted with single quotes.
        - Strings do not need to be quoted at all if they do not contain
        leading or trailing spaces, and if they do not contain any of these
        characters: { } [ ] / \ : ,
        - Numbers may have the 0- (octal) or 0x- (hex) prefix.
        ========================================

        The second and third point had somehow ruined my memory of the spec
        as I started spending more time in unit-testing and bootstrapping
        the parser with hand-coded JSON samples. The original JavaScript
        implementation [4] was on par with the above level of acceptance. In
        fact, both allowed more JavaScript literals to be expressed than
        JSON permits (which you could argue was reasonable). Today, version
        2.0 of the Java implementation [4] has gone considerably more
        liberal:

        ========================================
        The constructors are more forgiving in the texts they will accept:

        - An extra , (comma) may appear just before the closing brace.
        - Strings may be quoted with ' (single quote).
        - Strings do not need to be quoted at all if they do not begin with
        a quote or single quote, and if they do not contain leading or
        trailing spaces, and if they do not contain any of these characters:
        { } [ ] / \ : , = ; # and if they do not look like numbers and if
        they are not the reserved words true, false, or null.
        - Keys can be followed by = or => as well as by :.
        - Values can be followed by ; (semicolon) as well as by , (comma).
        - Numbers may have the 0- (octal) or 0x- (hex) prefix.
        - Comments written in the slashshlash, slashstar, and hash
        conventions will be ignored.
        ========================================

        Fine, so these are the decisions of merely one implementation. What
        is disturbing, however, is that the JavaScript version has gone
        completely in the opposite direction in favor of speed; so as to be
        able to benefit from native parsing provided strict adherence to the
        JSON token space. Consequently, it's gone intolerant and sticks to
        the encoding specification, bit-by-bit. So much so, that a JSON
        sample (incidentally with comments) on the site [6] won't pass it.
        Again, if this was done in a compatible manner then it would be less
        of a problem, but I consider these to be *reference* implementations
        of the standard!

        My comments on comments (pun intended), however, still stand in face
        of weak and subjective arguments that they are not needed. It is
        precisely in the light of such concerns that I was hoping that
        comments warrant a mention!

        -Atif

        ----------

        [1] http://shrinkster.com/ahp ;
        http://groups.yahoo.com/group/json/message/186
        [2] http://shrinkster.com/ahq ;
        http://web.archive.org/web/*/http://www.crockford.com/JSON/
        [3] http://shrinkster.com/ahr ;
        http://web.archive.org/web/20050306024809/http://www.crockford.com/JS
        ON/javadoc/org/json/JSONObject.html
        [4] http://shrinkster.com/ahs ;
        http://www.raboof.com/Projects/Jayrock/json.js
        [5] http://shrinkster.com/aht ;
        http://www.crockford.com/JSON/javadoc/org/json/JSONObject.html
        [6] http://shrinkster.com/ahu ;
        http://www.crockford.com/JSON/example.html

        --- In json@yahoogroups.com, "Douglas Crockford" <douglas@c...>
        wrote:
        >
        > JSON has a string notation which is similar to that used in the C
        > family languages. Strings are bounded by double quote characters.
        > Escapement is provided by the backslash. The spec specifically
        allows
        > the slash to be escaped so that JSON can be delivered in HTML
        documents.
        >
        > The single quote convention is not included in JSON because it is
        not
        > needed. All strings can be represented with the double quote
        notation.
        > C itself does not have single quote strings. Many PHP programmers
        are
        > confused by JavaScript's single quote strings.
        >
        > JSON requires that keys be quoted because of an error in the
        > ECMAScript spec that disallows the use of unquoted reserved words
        as
        > keys. The list of reserved words is surprisingly long and
        difficult to
        > remember. The best practice is to always quote keys.
        >
        > As an historical note, the very first JSON message contained as
        one of
        > its keys the word "do". It was not quoted, and it caused a syntax
        error.
        >
      • Douglas Crockford
        ... I used to agree what comments would be useful. But since I started using JSON, I never discovered what that use was. I have seen them used very badly. I
        Message 3 of 12 , Jan 5, 2006
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          > My comments on comments (pun intended), however, still stand in face
          > of weak and subjective arguments that they are not needed. It is
          > precisely in the light of such concerns that I was hoping that
          > comments warrant a mention!

          I used to agree what comments would be useful. But since I started
          using JSON, I never discovered what that use was. I have seen them
          used very badly. I have asked several times what the value is that
          requires that support be added to every implementation. I am still
          listening.
        • Martin Cooper
          ... You re not convinced that saving developers time is valuable? OK, then, how about compatibility? There are lots of JSON implementations out there already,
          Message 4 of 12 , Jan 5, 2006
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            On 1/5/06, Douglas Crockford <douglas@...> wrote:
            >
            > > My comments on comments (pun intended), however, still stand in face
            > > of weak and subjective arguments that they are not needed. It is
            > > precisely in the light of such concerns that I was hoping that
            > > comments warrant a mention!
            >
            > I used to agree what comments would be useful. But since I started
            > using JSON, I never discovered what that use was. I have seen them
            > used very badly. I have asked several times what the value is that
            > requires that support be added to every implementation. I am still
            > listening.


            You're not convinced that saving developers' time is valuable?

            OK, then, how about compatibility? There are lots of JSON implementations
            out there already, and I'm sure most of them already support comments, my
            own included. Interoperability between those and new ones would be reduced
            by eliminating comments from the spec now. The cat is already out of the
            bag.

            --
            Martin Cooper


            Yahoo! Groups Links
            >
            >
            >
            >
            >
            >
            >
            >


            [Non-text portions of this message have been removed]
          • jemptymethod
            ... I don t think this is an error in the ... spec .... I can think of at least one other language that disallows unquoted reserved words as keys (Lua), and
            Message 5 of 12 , Jan 14, 2006
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              --- In json@yahoogroups.com, "Douglas Crockford" <douglas@c...> wrote:
              >
              > JSON requires that keys be quoted because of an error in the
              > ECMAScript spec that disallows the use of unquoted reserved words as
              > keys. The list of reserved words is surprisingly long and difficult to
              > remember. The best practice is to always quote keys.

              I don't think this is "an error in the ... spec" .... I can think of
              at least one other language that disallows unquoted reserved words as
              keys (Lua), and there are others I'm certain
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