Mason Codepad

Like DartPad, but with a full IDE (Visual Studio Code, Cursor, or custom editor) and access to the entire pub.dev ecosystem.

codepad is a Mason brick created by Randal Schwartz to quickly scaffold Dart and Flutter playgrounds for testing code snippets and prototyping ideas.

Check out the demo video to see it in action.

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🚀 Prerequisites

1. Dart / Flutter SDK installed and available in your PATH.
2. Mason CLI: Install via Pub:

   dart pub global activate mason_cli

3. Editor: Visual Studio Code (code), Cursor, or another editor launcher in your PATH.

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📦 Installation

From Brickhub (Recommended)

Install codepad globally from Brickhub:

mason add -g codepad

From GitHub Source

To install directly from the GitHub repository:

mason add -g codepad --git-url https://github.com/RandalSchwartz/mason-codepad.git --git-path codepad

Local Development / Repository Usage

If working within this repository, initialize the brick locally:

mason get

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🛠️ Usage & Helper Scripts (dplay & fplay)

Add helper scripts to a directory in your PATH (e.g., ~/bin or /usr/local/bin):

dplay (Dart Playground)

Create executable script named dplay:

#!/bin/sh
exec mason make codepad -o "${2:-/tmp}" --dart=true --name="${1:-UUID}" --editor="${3:-${CODEPAD_EDITOR:-code}}" </dev/null

fplay (Flutter Playground)

Create executable script named fplay:

#!/bin/sh
exec mason make codepad -o "${2:-/tmp}" --dart=false --name="${1:-UUID}" --editor="${3:-${CODEPAD_EDITOR:-code}}" </dev/null

Editor Environment Configuration

You can set export CODEPAD_EDITOR=cursor in your shell profile (~/.zshrc / ~/.bashrc), and dplay and fplay will automatically default to opening your playgrounds in your preferred editor!

Examples

• dplay — Spawns a new Dart playground in /tmp/<uuid> using $CODEPAD_EDITOR or code.
• fplay — Spawns a new Flutter playground in /tmp/<uuid> using $CODEPAD_EDITOR or code.
• dplay my_test — Spawns a Dart playground named my_test in /tmp/my_test.
• fplay my_widget ~/Projects cursor — Spawns a Flutter playground in ~/Projects/my_widget explicitly opened with cursor.

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🗂️ Project Structure

.
├── mason.yaml             # Mason configuration linking the local brick
├── analysis_options.yaml  # Analyzer config excluding generated brick templates
├── pubspec.yaml           # Root test suite manifest
├── test/                  # Integration tests for brick generation
└── codepad/               # The Codepad Mason brick package
    ├── brick.yaml         # Brick manifest and variable definitions (v0.17.0)
    ├── README.md          # Brick-specific documentation
    ├── hooks/             # Pre-gen & post-gen lifecycle hooks (tested)
    │   ├── pre_gen.dart   # Auto-generates UUID names, checks CODEPAD_EDITOR, validates path
    │   └── post_gen.dart  # Runs pub get and launches configured editor
    └── __brick__/         # Template files for generated Dart/Flutter projects

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📄 License

MIT