Plugin: conditionals

• 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 global
• infos/metadata = check/condition assign/condition condition/validsuffix
• infos/description =

This plugin uses if-then-else like conditions. It also works as global plugin.

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.

Keynames

Keynames are all either relative to to-be-tested key (starting with ./ or ../), relative to the parentkey (starting with @/) or absolute (e.g. system/key).

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 "(./ == 'Hello') ? ('World')" # alternative: "(../hkey == 'Hello') ? ('World')
    kdb get user/tmount/conditionals/hkey # output: World

Global plugin example:

    % cat /tmp/main.ini
    key1 = val1
    [key1]
    check/condition = (./ == 'val1') ? (../sub/key == 'true')

    % cat /tmp/sub.ini
    key = false

    % kdb mount /tmp/main.ini system/test ni

    % kdb mount /tmp/sub.ini system/test/sub ini

    % kdb export system/test
    key1 = val1
    sub/key = false
    Error (#135) occurred!
    Description: Validation failed
    Ingroup: plugin
    Module: conditionals
    At: /home/thomas/Dev/Elektra/libelektra/src/plugins/conditionals/conditionals.c:696
    Reason: Validation of Key key1: (./ == 'val1') ? (../sub/key == 'true') failed. ((../sub/key == 'true') failed)
    Mountpoint: system/test
    Configfile: /tmp/main.ini

    % kdb set system/test/sub/key true
    Set string to true

    % kdb export system/test
    key1 = val1
    sub/key = true