[Qt-interest] serialize QScriptValue to json?

[Nathan Carter]

On Apr 8, 2009, at 4:50 PM, Liam Staskawicz wrote:

> Hi - I've just been getting my feet wet with QtScript and I've
> successfully been parsing JSON into QScriptValues via
> QScriptEngine::evaluate().  I haven't found yet if there's a built-in
> or recommended way to serialize a QScriptValue back to JSON.
>
> Is the idea to just create a routine that iterates over all the
> properties of a QScriptValue and builds up a JSON string?  Any other
> tips?  Thanks a bunch.

You have to be very careful with this.  Consider:

a = [];
a.push( a );

Now your iteration goes forever.

This, incidentally, also puts the built-in print() function into an  
infinite loop, so if your standards are not that high, you can just  
assume the caller has to avoid passing your routines these annoying  
structures.

But this is a tiny example that may seem unrealistic, while in  
reality, such structures can certainly arise.  Consider a tree  
structure where pointers to children and parents are kept; then maybe  
( a.firstChild == b ) && ( b.parent == a ).  Forever again.

Just something to keep in mind.  I've found this problem tricky, but  
not unsolvable.  Although I wasn't doing JSON, but traversing object  
trees for another reason.

Nathan