infos = Information about the conditionals plugin is in keys below
infos/author = Thomas Waser thoma.nosp@m.s.wa.nosp@m.ser@l.nosp@m.ibel.nosp@m.ektra.nosp@m..org
infos/licence = BSD
infos/provides =
infos/needs =
infos/recommends =
infos/placements = postgetstorage presetstorage
infos/status = maintained unittest nodep libc preview
infos/metadata = check/condition assign/condition condition/validsuffix
infos/description =

This plugin uses if-then-else like conditions.

Check Syntax

Stored in the metakey check/condition to validate data is:

(IF-condition) ? (THEN-condition) : (ELSE-condition) where the ELSE-condition is optional

Condition: Key Operation `('String' | '1234.56' | Key | '')`

Operations: !=, ==, <, <=, =>, >, :=, where:

:= is used to set a key value
others are for comparison as in C

Testing if Key exists

(! a/key) evaluates to true if the key a/key doesn't exist, to false if it exists.

Assign Syntax

`(IF-condition) ? ('ThenValue') : ('ElseValue')`

Depending on if the condition is met, either 'ThenValue' or 'ElseValue' will be assigned as key value if the metakey assign/condition is used.

EXPERIMENTAL: Nested Conditions

Multiple conditions can be nested and combined using parentheses and && (logical AND) or || (logical OR). Additional parentheses must be used to form valid conditions again. ( (condition 1) && (condition 2) )

valid suffix

The condition/validsuffix can be used to define a list of valid suffixes to numeric values. If two operants have the same valid suffix or one of them no suffix they will be treated by their numeric value ignoring their suffix. `condition/validsuffix = 'm', 'cm', 'km'would treat2.3mjust as the numeric value2.3` when comparing to another value having the same or no suffix.

Example

`(this/key != 'value') ? (then/key == some/other/key) : (or/key <= '125')`

Meaning: IF this/key NOT EQUAL TO 'value' THEN then/key MUST EQUAL some/other/key ELSE or/key MUST BE LESS THAN 125

Another full example:

    kdb mount conditionals.dump /tmount/conditionals conditionals dump
    kdb set user/tmount/conditionals/fkey 3.0
    kdb set user/tmount/conditionals/hkey hello
    kdb setmeta user/tmount/conditionals/key check/condition "(hkey == 'hello') ? (fkey == '3.0')" # success
    kdb setmeta user/tmount/conditionals/key check/condition "(hkey == 'hello') ? (fkey == '5.0')" # fail

Assignment example:

    kdb mount conditionals.dump /tmount/conditionals conditionals dump
    kdb set user/tmount/conditionals/hkey Hello
    kdb setmeta user/tmount/conditionals/hkey assign/condition "(hkey == 'Hello') ? ('World')"
    kdb get user/tmount/conditionals/hkey # output: World