bionic (3) md_src_plugins_mathcheck_README.3elektra.gz

NAME

       md_src_plugins_mathcheck_READMEREADME
        -

       • infos = Information about the mathcheck plugin is in keys below

       • infos/author = Thomas Waser thomas.waser@libelektra.org

       • infos/licence = BSD

       • infos/needs =

       • infos/provides = check

       • infos/placements = presetstorage

       • infos/description =

       Compares a key value to a mathematical expression using polish prefix notation defined in the check/math
       metakey. Operations are + - / * . Operants are keys with names relative to the parent key. How the values
       are compared is specified at the beginning of the metakey using the conditions <, <=, ==, !=, =>, >, :=
       := is used to set key values. All values are interpreted as double floating point values.

   Examples
       check/math = '== + testval1 + testval2 testval3' compares the keyvalue to the sum of testval1-3 and
       yields an error if the values are not equal. check/math = '<= - testval1 * testval2 testval3' tests if
       the keyvalue is less than or equal to testval1 - (testval2 * testval3) and yields an error if not.

       Full example:

           kdb mount mathcheck.dump /example/mathcheck dump mathcheck
           kdb set user/example/mathcheck/a 3.1
           kdb set user/example/mathcheck/b 4.5
           kdb set user/example/mathcheck/k 7.6
           kdb setmeta user/example/mathcheck/k check/math "== + a b"
           kdb set user/example/mathcheck/k 7.7   # fails

       To calculate values on-demand you can use:

           kdb setmeta user/example/mathcheck/k check/math ":= + a b"
           kdb get user/example/mathcheck/k       # 12.5
           kdb set user/example/mathcheck/a 5.5
           kdb get user/example/mathcheck/k       # 10

       It also works with constants:

           kdb setmeta user/example/mathcheck/k check/math ":= + a '5'"
           kdb get user/example/mathcheck/k       # 10.5
           kdb set user/example/mathcheck/a 8.0
           kdb get user/example/mathcheck/k       # 13