Procedure DSL

The CaptureGraph DSL (Domain-Specific Language) lets you define capture workflows as Python code. Procedures are structured as Directed Acyclic Graphs (DAGs) that serialize to JSON and execute on mobile devices.

Core Concepts

Concept	Description
Procedure	A node in the graph that does something (capture, compute, store)
PType	The type of data a procedure produces (PImage, PString, PVoid, etc.)
Target	The root project directory for a capture subject
Session	A timestamped subfolder for each procedure execution

How Procedures Execute

The iOS app processes your procedure graph by:

1. Topologically sorting nodes to determine execution order
2. Auto-running invisible nodes (computations, constants)
3. Blocking on visible nodes until user input is provided
4. Persisting all data at the end when the user completes the procedure

Section Contents

• Types and Nodes

Understand PTypes, the node taxonomy, and the PVoid workflow

• Targets and Sessions

File system structure and data organization patterns

• Fluent API

Method chaining: .save(), .cache(), .load(), and more

• Control Flow

Conditional logic, switch cases, and operator overloading

• Toolkits

Pre-built modules for location, notifications, and thumbnails

• Custom Procedures

Creating your own procedure nodes with @make_procedure