Re: [Pharo-project] Yet another Notation format: Object literals

Oct. 19, 2012

      On 19 October 2012 18:10, Igor Stasenko <siguctua@gmail.com> wrote:
...
On 19 October 2012 16:55, Dale Henrichs <dhenrich@vmware.com> wrote:
...
Igor,
I'm afraid that your notation is not very friendly to humans ... a computer can keep track of the key value pairs in the literal dictionary, but a human will fail very quickly...
The appeal of JSON (and STON) is that the output is readable by mere mortals:
(JavaScript Object Notation) is a lightweight
  data-interchange format. It is easy for humans to
  read and write.
What we're missing from Smalltalk is a literal dictionary or literal map syntax ... without that I'm afraid that for human friendly, lightweight notations we have to step away from the Smalltalk syntax - STON does this very nicely BTW...
no problem, Dale.
What symbol you want to have to separate keys from values?
is '->' ok?
Dictionary>>asObjectLiteral
"convert a receiver into an object literal "
^ Array streamContents: [:stream |
                stream nextPut: self class name.
                self keysAndValuesDo: [:key :value |
                        stream
                                nextPut: key asObjectLiteral;
                                nextPut: #->;
                                nextPut: value asObjectLiteral ] ]
(Dictionary newFromPairs: #( a b c d)) asObjectLiteral
#(#Dictionary
#a #'->' #b
#c #'->' #d)
which if you pretty-print will look like:
#(
Dictionary
a -> b
c -> d
)
is it better?
and, of course you can even put a delimiter(s):

 #(
 Dictionary
 a -> b.
 c -> d.
 )

or

 #(
 Dictionary
 a -> b;
 c -> d;
 )

or:

 #(
 Dictionary
{ a -> b };
{ c -> d };
 )
->> #(#Dictionary #'{' #a #'->' #b #'}' #';' #'{' #c #'->' #d #'}' #';')

this is completely arbitrary... because smalltalk literal syntax is
highly permissive :)

it only a little more work to extract keys and values from already
parsed literal array.
...
or you prefer this one:
#(
Dictionary
(a -> b)
(c -> d)
)
you can do anything you like, by implementing the conversion methods
in a way you like :)
...
Dale
----- Original Message -----
| From: "Igor Stasenko" <siguctua@gmail.com>
| To: "Pharo Development" <Pharo-project@lists.gforge.inria.fr>
| Sent: Friday, October 19, 2012 4:09:22 AM
| Subject: [Pharo-project] Yet another Notation format: Object literals
|
| Hi,
| as i promised before, here the simple smalltalk-based literal format.
| It based on smalltalk syntax, and so, unlike JSON, it doesn't needs
| to
| have separate parser (a normal smalltalk parser used for that).
|
| The idea is quite simple:
| you can tell any object to represent itself as an 'object literal' ,
| for example:
|
| (1@3) asObjectLiteral
| -->  #(#Point 1 3)
|
| { 1@2.  3@4. true. false . nil  } asObjectLiteral
|
| -> #(#Array #(#Point 1 2) #(#Point 3 4) true false nil)
|
| (Dictionary newFromPairs: { 1->#(1 2 3) . 'foo' -> 'bar' })
| asObjectLiteral
| ->
|  #(#Dictionary 1 #(#Array 1 2 3) 'foo' 'bar')
|
| Next thing, you can 'pretty-print' it (kinda):
|
| #(#Dictionary 1 #(#Array 1 2 3) 'foo' 'bar') printObjectLiteral
|
|  '#(#Dictionary
|       1
|       (#Array 1 2 3)
|       ''foo'' ''bar'')'
|
|
| and sure thing, you can do reverse conversion:
|
|  '#(#Dictionary
|       1
|       (#Array 1 2 3)
|       ''foo'' ''bar'')'  parseAsObjectLiteral
|
|  a Dictionary('foo'->'bar' 1->#(1 2 3) )
|
| Initially, i thought that it could be generic (by implementing
| default
| Object>>#asObjectLiteral),
| but then after discussing it with others, we decided to leave
|
| Object>>#asObjectLiteral to be a subclass responsibility.
| So, potentially the format allows to represent any object(s) as
| literals, except from circular referencing objects, of course.
|
| The implementation is fairly simple, as you may guess and contains no
| new classes, but just extension methods here and there.
|
| Take it with grain and salt, since it is just a small proof of
| concept. (And if doing it for real it may need some changes etc).
| Since i am far from areas right now, where it can be used, i don't
| want to pursue it further or advocate if this is the right way to do
| things.
| Neither i having a public repository for this project..
|
| So, if there anyone who willing to pick it up and pursue the idea
| further, please feel free to do so and make a public repository for
| project.
|
|
| --
| Best regards,
| Igor Stasenko.
|
--
Best regards,
Igor Stasenko.
-- 
Best regards,
Igor Stasenko.