[Python-ideas] iterator/stream-based JSON API

[Daniel Holth]

On Mon, Jun 3, 2013 at 5:12 AM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> On Sun, 2 Jun 2013 22:11:23 -0400
> Daniel Holth <dholth at gmail.com> wrote:
>> When will the stdlib get a decent iterator/stream-based JSON API? For
>> example automated packaging tools may be parsing a lot of JSON but
>> ignoring most of it, and it would be lovely to say "if key not in
>> interesting: skip_without_parsing()".

No offense meant. The existing JSON API is quite good.

> Do you think that would make a significant difference? I'm not sure
> what "parsing a lot of JSON" means, but I suppose packaging metadata is
> usually quite small.

I don't know whether it would matter for packaging but it would be
very useful sometimes.

The jsonpull API looks like:
http://code.google.com/p/jsonpull/source/browse/trunk/Example.java

A bit like:

parser = Json(text)
parser.eat('{') # expect an object
for element in parser.objectElements():
    parser.eat(Json.KEY)
    key = parser.getString()
    if key == "name":
        name = parser.getStringValue()
    elif key == "contact":


You can ask it what the next token is, seek ahead (never behind) to a
named key in an object, or iterate over all the keys in an object
without necessarily iterating over child objects. Once you get to an
interesting sub-object you can get an iterator for that sub-object and
perhaps pass it to a child constructor.