ReDim

A stateful UI framework for Excel worksheets. Build interactive, async-aware applications out of worksheet shapes and form controls the way you would with a component framework on the web. No UserForms, no ActiveX, no add-ins, no VBIDE access.

ReDim sits on top of ROneCOne, which supplies delegates, typed events, structured exceptions, and cooperative tasks. ReDim adds what ROneCOne's one-file invariant cannot carry: the host loop (ROneCOne ADR 0007 anticipated exactly this), a retained component model with diffed rendering, a state store with bindings, and an async engine that keeps Excel responsive while work runs.

Watch: ReDim in action

Dim app As ReDimUI

Set app = ReDimUI.Mount(Sheet1, "Dashboard")

app.Button("run").At("B2:C3").Text("Run Report").Primary.OnClickAsync "Demo.BuildReport"
app.ProgressBar("prg").At("B5:F5").BindValue "progress"
app.Label("status").At("B7:F7").BindText "statusMsg", "Status: {0}"

app.Render

Clicking Run disables the button, swaps its caption to busy text, runs Demo.BuildReport through the pump, and restores the button when the work completes or fails. While a chunked job runs, app.SetState "progress", 40 moves the bar and "statusMsg" updates the label, all while the user keeps working in the workbook.

What it does

• Components over shapes. Button, Label, Card, ProgressBar, Spinner, Toggle, TickBox, RadioGroup, Stepper, SlideBar (press-drag), SelectBox, ComboBox (editable, filtering live as you type), TransferList (dual listbox with move buttons), CheckList (checkbox list with a tri-state select-all header), Image (embedded picture fills), TextInput, Toast, and a shapes-based modal overlay with Confirm - every control drawn from shapes and fully themed, with light and dark presets, no native form controls anywhere, no cells required (text fields float free of the grid via a keyboard focus layer, or anchor to a cell if you want one), and no dependencies beyond a stock Excel 365 install.
• Stateful. Each app owns a key-value store. BindText, BindValue, BindVisible, and BindEnabled re-render only what changed. OnStateChanged registers workbook procedures as state listeners. WritesTo flows control values back into state. The store is deliberately in-memory and session-scoped: persistence belongs to the host application, which can read the store, save it wherever fits (ROneCOne's JSON serializer is on board), and reseed on build with SetStateDefault, which never clobbers a value already in play.
• Composable layout. Anchor to ranges with At, to points with AtRect, or to other components with Below and RightOf. Render prunes shapes orphaned by renamed components, so iterating on app code never litters the sheet.
• Windows. Sheets as forms: AsWindow registers a window, Navigate shows one at a time (others go very-hidden), NavigateBack walks the stack, OnShow and OnHide fire like form lifecycle events, a button becomes a nav link with NavigatesTo, and NavBar renders window tabs with the active one highlighted. Background windows keep pumping. ProtectSurface turns an app sheet into a true application surface.
• Genuinely async. A SetTimer pump ticks whenever Excel idles and steps ROneCOne tasks without anyone blocking on Await. Fire-and-forget ops disable their controls, spin a spinner, and fire done, fail, or cancel handlers. HTTP, database, shell, and delay tasks overlap for real; CPU-bound VBA runs as chunked jobs inside a per-tick millisecond budget, or paced jobs for game loops and animations. Cancellation rides ROneCOne CancellationTokenSource.
• Crash-railed. The timer callback is a single guarded call that never lets an error escape, kills itself after repeated faults, stops when idle, records its timer id in a workbook name so orphans from VBA state loss are killed before re-arming, and tears down on workbook close.
• Idempotent. Re-running setup code adopts existing shapes instead of duplicating them, so an unhandled error that resets VBA state never leaves a broken sheet.

Installation

1. Import ROneCOne.cls (from the ROneCOne release, 1.8.1 or later) into your macro-enabled workbook.
2. Import src/ReDimUI.cls.
3. Import src/ReDimHost.bas.

Three imports, no references, no registration. Windows x64 Microsoft 365 Excel, the same target as ROneCOne.

Demos

Built workbooks are attached to each release. They are build artifacts rather than sources, so they are not tracked here; python tools/build_workbooks.py regenerates them into demo/ from the VBA in demo/vba/. Open one with macros enabled and it builds itself (each ships an Auto_Open); the entry macro rebuilds on demand.

Workbook	Shows	Entry macro
ReDim_Mission_Control.xlsm	Three cancellable feeds with live progress, toasts, KPI cards, dark mode, confirm modal	BuildMissionControl
ReDim_Widget_Gallery.xlsm	Every component wired to a live state inspector	BuildWidgetGallery
ReDim_Snake.xlsm	A real game loop: paced pump job, arrow-key steering, score state, game-over modal	BuildSnake
ReDim_Navigator.xlsm	Sheets as forms: Navigate, back stack, lifecycle hooks	BuildNavigator
ReDim_ReDex.xlsm	The full-framework showcase: a living Pokedex on PokeAPI - async HTTP + JSON, sprite images, tweened stat bars, team building, custom theme with night mode	BuildPokeDex

Documentation

• Getting started and API
• The async engine
• Architecture and design contract

Development

VBA sources are plain files; workbooks are built artifacts.

pip install -r requirements-dev.txt
python tools/check.py          # pyvbaanalysis static gate, zero findings required
python tools/build_workbooks.py
python -m pytest tests/python  # live Excel suite via pyvbaharness

The live suite covers mount and adoption, dispatch and guards, bindings, batching, theming, the async op lifecycle, jobs, cancellation, every widget, a real armed-timer end-to-end run, a VBA compile gate for every shipped workbook, and smoke runs of all five demos.

It drives a real Excel instance, so it cannot run on hosted CI. Continuous integration runs the static gate only, over the same sources plus the ROneCOne runtime; the live suite is a local step before release.

License

MIT