# modtools/random-trigger

Tags: dev

Command: `modtools/random-trigger`

Randomly select DFHack scripts to run.

Trigger random dfhack commands with specified probabilities. Register a few scripts, then tell it to “go” and it will pick one based on the probability weights you specified.

Events are mutually-exclusive - register a list of scripts along with relative weights, then tell the script to select and run one with the specified probabilities. The weights must be positive integers, but they do NOT have to sum to any particular number.

The outcomes are mutually exclusive: only one will be triggered. If you want multiple independent random events, call the script multiple times.

99% of the time, you won’t need to worry about this, but just in case, you can specify a name of a list of outcomes to prevent interference from other scripts that call this one. That also permits situations where you don’t know until runtime what outcomes you want. For example, you could make a modtools/reaction-trigger that registers the worker as a mayor candidate, then run this script to choose a random mayor from the list of units that did the mayor reaction.

Arguments:

    -outcomeListName name
        specify the name of this list of outcomes to prevent interference
        if two scripts are registering outcomes at the same time.  If none
        is specified, the default outcome list is selected automatically.
    -command [ commandStrs ]
        specify the command to be run if this outcome is selected
        must be specified unless the -trigger argument is given
    -weight n
        the relative probability weight of this outcome
        n must be a non-negative integer
        if not specified, n=1 is used by default
    -trigger
        selects a random script based on the specified outcomeList
        (or the default one if none is specified)
    -preserveList
        when combined with trigger, preserves the list of outcomes so you
        don't have to register them again.
    -withProbability p
        p is a real number between 0 and 1 inclusive
        triggers the command immediately with this probability
    -seed s
        sets the random seed for debugging purposes
        (guarantees the same sequence of random numbers will be produced)
        use
    -listOutcomes
        lists the currently registered list of outcomes of the outcomeList
        along with their probability weights, for debugging purposes
    -clear
        unregister everything

Note

`-preserveList` is something of a beta feature, which should be avoided by users without a specific reason to use it.

It is highly recommended that you always specify `-outcomeListName` when you give this command to prevent almost certain interference. If you want to trigger one of 5 outcomes three times, you might want this option even without `-outcomeListName`.

The list is NOT retained across game save/load, as nobody has yet had a use for this feature. Contact expwnent if you would use it; it’s not that hard but if nobody wants it he won’t bother.