> On 26 Apr 2017, at 01:01, PBKResearch <pe...@pbkresearch.co.uk> wrote:
>
> Browsing in Pharo, I found that Dictionary has a subclass KeyedTree, which is
> in effect a set of nested dictionaries. Retrieval is by quoting a path, which
> is simply an array of keys. So in your case it would read:
> dict1 atPath: #(’key1’ ‘key2’ ‘key3’).
> This might be more efficient than repeated use of the DNU mechanism. It is
> not clear (to me, at least) how to construct the nested dictionaries as a
> KeyedTree in the first place, but this might be an alternative approach.
I saw this too and I thought it was interesting, hence I added it to
NeoJSONObject.
Name: Neo-JSON-Core-SvenVanCaekenberghe.40
Author: SvenVanCaekenberghe
Time: 26 April 2017, 4:35:49.433269 pm
UUID: c336587e-740a-0d00-b51a-dacd0088e41c
Ancestors: Neo-JSON-Core-SvenVanCaekenberghe.39
Name: Neo-JSON-Tests-SvenVanCaekenberghe.38
Author: SvenVanCaekenberghe
Time: 26 April 2017, 4:36:04.583272 pm
UUID: 73623f7f-740a-0d00-b51b-f4000088e41c
Ancestors: Neo-JSON-Tests-SvenVanCaekenberghe.37
From the class comment:
Additionally, I support path access for nested instances of me, using #atPath:
and #atPath:put:
The first is special because it returns nil as soon as a key is missing. The
second is special because it creates extra levels (instances of me) as needed
to follow the path of keys.
NeoJSONObject new atPath: #(one two three) put: 42; yourself.
NeoJSONObject new atPath: #(one two three) put: 42; atPath: #(one two
three).
For the examples given above, the actual JSON looks like this:
{"one":{"two":{"three":42}}}
Sven
> Hope this helps
>
> Peter Kenny
>
> From: Pharo-users [mailto:pharo-users-boun...@lists.pharo.org] On Behalf Of
> Markus Böhm
> Sent: 24 April 2017 18:42
> To: pharo-users@lists.pharo.org
> Subject: [Pharo-users] Hot to retrieve values from Nested Dictionaries
>
> May I ask:
> What's the idiomatic way to retrieve values from nested dictionaries?
>
> (((dict1 at: 'key1') at: 'key2') at: 'key3')
>
> Are all the brackets really necessary?
>
> BR Mike
