Public/Subscriptions/New-ElmTimerSub.ps1
|
function New-ElmTimerSub { <# .SYNOPSIS Creates a timer subscription for use in a SubscriptionFn. .DESCRIPTION Returns a subscription descriptor that fires a handler scriptblock at a fixed millisecond interval, producing a message for the Update function. Timer state (last-fired timestamp) is managed by Invoke-ElmSubscriptions across loop iterations. If the same IntervalMs value appears in multiple calls to the SubscriptionFn, the state is shared (keyed by interval). Timer subscriptions are only active when present in the array returned by SubscriptionFn. Removing a timer sub from the array pauses it; adding it back resets the interval clock. .PARAMETER IntervalMs Firing interval in milliseconds. Must be a positive integer. .PARAMETER Handler Scriptblock invoked when the interval elapses. Receives no arguments. Must return a message object or $null. Example: { 'Tick' } Example: { [PSCustomObject]@{ Type = 'Timer'; At = [datetime]::Now } } .OUTPUTS PSCustomObject with Type='Timer', IntervalMs, and Handler properties. .EXAMPLE New-ElmTimerSub -IntervalMs 1000 -Handler { 'Tick' } .EXAMPLE New-ElmTimerSub -IntervalMs 100 -Handler { [PSCustomObject]@{ Type='Frame' } } .NOTES Use inside a SubscriptionFn passed to Start-ElmProgram via -SubscriptionFn. For conditional timers (e.g., pause/resume), check model state inside the SubscriptionFn and only add the timer sub when needed. #> [CmdletBinding()] param( [Parameter(Mandatory)] [ValidateRange(1, 2147483647)] [int]$IntervalMs, [Parameter(Mandatory)] [scriptblock]$Handler ) return [PSCustomObject]@{ Type = 'Timer' IntervalMs = $IntervalMs Handler = $Handler } } |