bug#21798: 25.0.50; [PATCH] Add support for retrieving paths to JSON elements

[Simen Heggestøyl]

Hello Dmitry, thanks for the feedback.

On Tue, Nov 3, 2015 at 3:00 AM, Dmitry Gutov <dgutov@yandex.ru> wrote:

I have to say, I'm still not very comfortable with mixing it sort of alien logic inside json-read-object and json-read-array (would anyone else like to chime in with their opinion?).

I understand your uneasiness, I feel the same way after you pointed it

out.

Here's an idea: both json-read-object-1 and json-read-array-2 will advise json-read to add the new logic around calls to it (there will have to be some guard in the advice, so that recursive calls are run unmodified).

I'm reluctant to use advises for it, not based on my own experience, but

based on advice from the Elisp manual:

[...] advice should be reserved for the cases where you cannot modify

a function’s behavior in any other way. [...] In particular, Emacs’s

own source files should not put advice on functions in Emacs. (There

are currently a few exceptions to this convention, but we aim to

correct them.)

Here we do have a chance to modify the functions' behavior.

How about a sort of compromise between our approaches: provide

'json-read-object' and 'json-read-array' with pre- and post-read

callback functions, that are only called when they're set. That would

make it possible to leverage the power of 'json-read-object' and

'json-read-array' by binding the callback functions, without mixing

alien logic into them.

That would also make it a lot cleaner when adding other extensions to

them in the future, compared to my original suggestion.

If that sounds good to you, I'll cook up a new patch!

-- Simen