vvvv Patching Patterns

Dataflow Basics

Left-to-right, top-to-bottom execution order
Links carry data between pads (input/output connection points)
Spreading — connecting a Spread<T> to a single-value input auto-iterates the node
Every frame, the entire connected graph evaluates; disconnected subgraphs are skipped

Both visual patches and C# source projects operate in a live environment — edits take effect immediately while the program runs. Patch changes preserve node state; C# code changes trigger a node restart (Dispose → Constructor). You can adjust parameters, add connections, and restructure patches while seeing results in real-time.

When to Patch vs Write C#

Patch	Code (C#)
Data flow routing, visual connections	Performance-critical algorithms
Prototyping and parameter tweaking	Complex state machines
UI composition and layout	.NET library interop
Simple transformations	Native resource management

As a rule: patch the data flow, code the algorithms.

Regions

Regions are visual constructs that control execution flow:

Region	Purpose	C# Equivalent
ForEach	Iterate over Spread elements	`foreach` loop
If	Conditional execution	`if/else`
Switch	Multi-branch selection	`switch`
Repeat	Loop N times	`for` loop
Accumulator	Running aggregation	`Aggregate/Fold`

Process Nodes in Patches

Process nodes are the primary way to add state to patches:

They have a Create region (runs once) and an Update region (runs each frame)
Internal state persists between frames
Can contain sub-patches for complex logic

Channels — Reactive Data Flow

Channels provide two-way data binding:

IChannel<T> — observable value container
.Value — read or write the current value
Channels persist state across sessions
Connect channels between nodes for reactive updates without explicit links

Event Handling

Bang — a one-frame true pulse (trigger)
Toggle — alternates between true and false
FrameDelay — delays a value by one frame (breaks circular dependencies)
Use Changed node to detect when a value changes between frames

Patch Organization

Naming Conventions

Use PascalCase for patch names and node names
Group related operations under a common category
Use descriptive names that indicate the operation (verb + noun)

Structure

Keep patches focused — one purpose per patch
Extract reusable logic into sub-patches
Use IOBox nodes for exposing parameters
Add Pad nodes to create input/output pins on the patch boundary

Common Anti-Patterns

Circular dependencies — use FrameDelay to break cycles
Too many nodes in one patch — extract sub-patches
Polling instead of reacting — use Channels for reactive updates
Ignoring Nil — always handle null/empty Spread inputs gracefully

For common patterns reference, see patterns.md.

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