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Re:Tips on adding JSON output to your CLI app by kbrazil on Monday December 06, 2021 @11:28AM (#29461747)
Maybe not, but more often than not you really have an array of objects, and that's where JSON helps.
Re:Tips on adding JSON output to your CLI app by IgorPartola on Monday December 06, 2021 @07:20PM (#29467621)
Look at my original example. The JSON punctuation just muddled the text format without adding any additional value. The point of JSON is the (very limited) type system, nested schema, and heterogeneous format (if array A has two elements B and C, they don’t need to be the same type). None of that seems applicable to what you want out of a UNIX utility.
Re:Tips on adding JSON output to your CLI app by kbrazil on Tuesday December 07, 2021 @12:36PM (#29475588)
What I was getting at is:

    cpu: 0.2
    kw_read_s: 0.12
is describing a single 'object'. How do you describe an array or list of these objects? Something like:

    cpu: 0.2
    kw_read_s: 0.12

    cpu: 1.3
    kw_read_s: 0.4
Do you use a blank line to denote a new 'object'? In JSON it would be done this way, and this conforms to how the vast majority of command output maps (as they tend to be rows of columnar data):

    [
      {
        "cpu": 0.2,
        "kw_read_s": 0.12
      },
      {
        "cpu": 1.3,
        "kw_read_s": 0.4
      }
    ]
The other benefit to JSON here is that the formatting doesn't matter. This could also be expressed as a block of text with no spaces or newlines between elements:

    [{"cpu": 0.2,"kw_read_s": 0.12},{"cpu": 1.3,"kw_read_s": 0.4}]
Finally, this can also be streamed, using JSON Lines:

    {"cpu": 0.2, "kw_read_s": 0.12}
    {"cpu": 1.3, "kw_read_s": 0.4}
Re:Tips on adding JSON output to your CLI app by IgorPartola on Tuesday December 07, 2021 @08:09PM (#29480241)
The OP specifically advocates against your proposed pattern and points out why nesting isn’t ideal. Also JSON doesn’t support fixed point numbers so JSON.encode(JSON.parse(input)) != input even if your equality assumes that formatting doesn’t matter.
Re:Tips on adding JSON output to your CLI app by zeroimpl on Monday December 06, 2021 @09:50PM (#29468642)
You're not wrong, but sometimes simple formats aren't as simple as they look. It sounds like what you want is basically a format like /etc/os-release:

    NAME="Rocky Linux"
    VERSION="8.5 (Green Obsidian)"
    ID="rocky"
    ID_LIKE="rhel centos fedora"
    VERSION_ID="8.5"
    PLATFORM_ID="platform:el8"
    PRETTY_NAME="Rocky Linux 8.5 (Green Obsidian)"
    ANSI_COLOR="0;32"
    CPE_NAME="cpe:/o:rocky:rocky:8.5:GA"
    HOME_URL="https://rockylinux.org/"
    BUG_REPORT_URL="https://bugs.rockylinux.org/"
    ROCKY_SUPPORT_PRODUCT="Rocky Linux"
    ROCKY_SUPPORT_PRODUCT_VERSION="8"
On the surface this seems great, but those quotation marks are kind of annoying. Is it possible there's an escape syntax that's used in case the name also includes quotes? eg VERSION="8.5 (Green \"Aqua\" Obsidian)"? Is it also possible you can embed newlines in between the quotes too? Who knows... Thankfully with JSON there is a simple spec.