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Re: std::format and json objects

From: Federico Kircheis <federico_at_[hidden]>
Date: Tue, 18 Apr 2023 14:58:25 +0200
On Tue, Apr 18, 2023 at 08:32:32AM -0400, Jason McKesson via Std-Discussion wrote:
>On Tue, Apr 18, 2023 at 7:53 AM Federico Kircheis via Std-Discussion
><std-discussion_at_[hidden]> wrote:
>> Hello, I have a question regarding std::format.
>> The API works generally very well, but it is problematic to escape every
>> { and }, especially when there are a lot of those, like in json objects.
>> Suppose I have for example the literal
>> R"json({
>> "data": {
>> "data 1": [
>> {"id":1,"name":"foo"},
>> {"id":2,"name":"bar"}
>> ],
>> "data 2": {"id":2,"name":"____"}
>> },
>> "otherstuff": {
>> "void": [[1,42],[-1,____]]
>> }
>> })json"
>> And I would like to use std::format for replacing ____ with some values.
>> As far as I know, it is not possible to instruct std::format to use
>> another pair of delimiters for a single call.
>> Falling back to std::printf or std::cout does not seem to be the right
>> solution, and escaping every { and } has drawbacks too.
>> Was this issue ever discussed or acknowledged?
>> Are there some obvious workarounds I'm missing?
>No tool is going to be perfect for every application, and for basic
>tools like `format`, you have to pick *something* for your delimiter.
>Find/replace is not `format`'s job. That's the job of a regex tool.

I suppose my choice of words was not ideal.
I did not want to say I want to replace ____ with a given value, ____ is
in this example the placeholder for the value one is going to format.

I could obviously not use {} for describing the issue, maybe it would
have been better if I've used the std::printf syntax: %s and %d


Received on 2023-04-18 12:58:31