Cargo Generate

cargo-generate — Project Scaffolding from Git Templates

cargo-generate expands a git repository of real files into a new project, substituting Liquid expressions in file contents and in path names. It is the Rust ecosystem's standard scaffolding tool — Bevy, wasm-pack, and most framework starters ship templates for it.

When to Use This Skill

Installation

cargo install cargo-generate --locked
cargo generate --version

It is a cargo subcommand (cargo generate) and also a standalone binary (cargo-generate), which is what a test harness should invoke.

Generating a project

# From a GitHub template (gh:/gl:/bb:/sr: prefixes also work)
cargo generate --git https://github.com/TheBevyFlock/bevy_new_2d --name my_game

# From a local directory — the form to use while authoring a template
cargo generate --path ./templates/my-template --name my-project

# Pin to a branch, tag, or revision
cargo generate --git <url> --branch main --name my-project

# Expand into the current directory instead of creating a new one
cargo generate --git <url> --init

Nothing about the tool is Rust-specific: a template needs no Cargo.toml, and generating a TypeScript, Python, or config-only project works the same way.

Non-interactive use

This is what makes cargo-generate usable from a skill or CI job — prompts would otherwise block:

cargo generate --path ./templates/my-template \
  --name my-project \
  --define 'display_name=My Project' \
  --define variant=app \
  --vcs none \
  --silent

Authoring a template

A template is a directory (usually a git repo) with a cargo-generate.toml at its root:

[template]
cargo_generate_version = ">=0.23.0"
ignore = ["hooks"]                    # dropped from the output entirely
exclude = ["ci.yml"]                  # copied verbatim, never rendered

[hooks]
pre = ["hooks/derive.rhai"]           # runs after placeholders resolve

[placeholders]
display_name = { type = "string", prompt = "Human-readable title" }
variant = { type = "string", prompt = "Shape", choices = ["basic", "app"], default = "basic" }
enable_ci = { type = "bool", prompt = "Add CI?", default = true }

# `ignore` drops files when the expression is TRUE, so name the cases that
# should NOT get the file.
[conditional.'variant != "app"']
ignore = ["src/app.ts", "templates"]

Built-in variables and filters

project-name (as given, kebab-cased), crate_name, crate_type, authors, username, os-arch, is_init, within_cargo_project.

Case filters: kebab_case, snake_case, pascal_case, lower_camel_case, upper_camel_case, title_case, shouty_snake_case, shouty_kebab_case.

Path names are rendered too, so styles/{{ module_id }}.css works.

Rhai hooks

Use a hook for values that should be derived, not asked for — anything a prompt could get inconsistent with something else:

let name = variable::get("project-name");
if !name.starts_with("prefix-") {
    abort("name must start with 'prefix-'");
}
variable::set("short_name", name.sub_string(7));

let now = system::date();
variable::set("year", "" + now.year);   // strings only — see gotchas

Available: variable::get/set/is_set/prompt, file::exists/rename/delete/write/listdir, system::date, system::command (needs --allow-commands), abort, and the to_kebab_case()-style converters.

Gotchas

Liquid eats other {{ }} languages. GitHub Actions ${{ … }}, Handlebars, Jinja, and Vue interpolations all render to the empty string if the file is templated. Two fixes:

Only an opening {{ needs escaping; a bare }} means nothing to Liquid.

variable::set takes strings only. Passing an integer — including system::date().year — fails with Function not found: variable::set (…, i64). Concatenate with "" first.

The project name is kebab-cased before hooks run. --name My_Project becomes my-project silently. A hook cannot reject a malformed name because it never sees one; if the exact spelling matters, validate before invoking.

.liquid is a magic suffix. A file named x.rs.liquid is rendered and emitted as x.rs. To ship a literal .liquid file, double the extension.

Agentic Optimizations

Quick Reference

Templates in this marketplace

foundryvtt-plugin/templates/foundryvtt-module/ is a worked example — three variants via [conditional], a derived id via a Rhai pre-hook, both brace collisions above, and a parity test against the generator it ports. See foundryvtt-plugin/templates/README.md.