Public/View/New-ElmComponent.ps1
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function New-ElmComponent { <# .SYNOPSIS Creates a Component view node for embedding a sub-program in the view tree. .DESCRIPTION A Component node represents a nested TEA (The Elm Architecture) sub-program. It encapsulates its own SubModel and ViewFn. Measure-ElmViewTree automatically expands Component nodes by calling ViewFn with SubModel and measuring the resulting subtree — ConvertTo-AnsiOutput and Compare-ElmViewTree never see raw Component nodes. Messages for components are routed using New-ElmComponentMsg, which wraps an inner message with a ComponentId so the parent Update function can dispatch it to the correct component's Update scriptblock. .PARAMETER ComponentId A unique string identifier for this component instance. Used by New-ElmComponentMsg to route messages to the correct component. .PARAMETER SubModel The component's own model object (PSCustomObject). Passed as the first argument to ViewFn when the view tree is measured. .PARAMETER ViewFn Scriptblock with signature: param($SubModel) -> ViewNode Must return a valid view tree node (Text, Box, Row, or another Component). .OUTPUTS PSCustomObject with Type='Component', ComponentId, SubModel, and ViewFn. .EXAMPLE $counterView = { param($m) New-ElmText -Content "Count: $($m.Count)" } $counter = New-ElmComponent -ComponentId 'counter' ` -SubModel ([PSCustomObject]@{ Count = 0 }) ` -ViewFn $counterView .NOTES Component nodes are transparent after layout — all measured nodes in the output tree will be Text or Box types only. #> [CmdletBinding()] param( [Parameter(Mandatory)] [ValidateNotNullOrEmpty()] [string]$ComponentId, [Parameter(Mandatory)] [ValidateNotNull()] [PSCustomObject]$SubModel, [Parameter(Mandatory)] [ValidateNotNull()] [scriptblock]$ViewFn ) return [PSCustomObject]@{ Type = 'Component' ComponentId = $ComponentId SubModel = $SubModel ViewFn = $ViewFn } } |