The JSON spec does (of course) not deal with cycles nor structure sharing, STON does (by design). The class comment clearly states: ... - referencePolicy <#normal|#ignore|#error> default is #normal if #normal, track and count object references and use references to implement sharing and break cycles if #error, track object references and signal STONWriterError when a shared reference is encountered if #ignore, don't track object references which might loop forever on cycles ... For JSON production (not a main goes of STON), it was set to #error, but like I showed, it you could prefer #ignore. You have to know what to feed it. Cycle/shared structure checking is expensive, i.e. slow(er) and uses more memory. I am not sure it is easy to make a difference between a cycle and a shared structure, I would have to think about that. And yes, NeoJSON will go happily in cycles.
On 27 Mar 2018, at 18:52, Peter Uhnák <i.uhnak@gmail.com> wrote:
Ah sorry, I'm blind.
Yes, ideally it should throw up an error in case of recursive. And I see that NeoJSON runs into infinite cycle, so I guess this should be addressed there too.
On Tue, Mar 27, 2018 at 6:41 PM, Herbert VojÄÃk <herby@mailbox.sk> wrote:
Peter Uhnák wrote: Hi Sven,
shouldn't it be set to #ignore by default for JSON then? Or is there a use case where it makes sense to have something else for JSON?
To keep STON practices / assumptions while using JSON to hold the data where STON is not supported yet, maybe? IIRC STON is positioning itself as JSON superset; but maybe only syntactic superset, while semantically it can be a bit different (so STONize to more low-level, JSON, syntax via STON; JSONize faithfully to JSON semantics using NeoJSON; but maybe I am just making things up).
Herbert: I am not talking about (infinitely) recursive references, but
I know; Sven explicitly asked what to do with cycles in that case, though.
referencing the same object, e.g.
Peter
On Tue, Mar 27, 2018 at 6:08 PM, Herbert VojÄÃk <herby@mailbox.sk <mailto:herby@mailbox.sk>> wrote:
Sven Van Caekenberghe wrote:
Hi Peter,
Both cases will pass using this expression:
String streamContents: [ :out | STON jsonWriter referencePolicy: #ignore; on: out; nextPut: d ].
The problem is what to do with cycles.
Be faithful to what JSON.stringify does in JS. See attachment. :-)
Herby
Sven
On 27 Mar 2018, at 17:43, Peter Uhnák<i.uhnak@gmail.com <mailto:i.uhnak@gmail.com>> wrote:
Hi,
I don't think this should throw an error when I am producing JSON.
``` d := { 'a' -> #(). 'b' -> #(). } asDictionary.
STON toJsonString: d. ```
dtto this
``` a := {'hm'}.
d := { 'a' -> a. 'b' -> a. } asDictionary.
STON toJsonString: d. ```
Maybe I should forgo using STON>>toJson* out of laziness (it is preinstalled) and always go for NeoJSON?
Peter