Table of Contents

• Multi-language CLI subcommand
  • Using Marketplace Gpacks (Recommended)
    • 1. Install Language-Specific Gpacks
    • 2. Generate Across Languages
    • 3. Verify Deterministic Output
  • Using Local Templates (Advanced)
  • Determinism Verification
    • Gpack Version Locking
    • Lockfile Management
  • Cross-Language Consistency
  • Best Practices
    • Gpack Selection
    • Version Management
    • Testing Multi-Language Output

Multi-language CLI subcommand

Using Marketplace Gpacks (Recommended)

Generate the same CLI subcommand across multiple languages using curated gpacks.

1. Install Language-Specific Gpacks

# Install gpacks for different languages
ggen add io.ggen.rust.cli-subcommand
ggen add io.ggen.python.cli-subcommand
ggen add io.ggen.bash.cli-subcommand
ggen add io.ggen.go.cli-subcommand

2. Generate Across Languages

# Generate Rust CLI subcommand
ggen gen io.ggen.rust.cli-subcommand:cli/subcommand/rust.tmpl name=hello description="Print a greeting"

# Generate Python CLI subcommand
ggen gen io.ggen.python.cli-subcommand:cli/subcommand/python.tmpl name=hello description="Print a greeting"

# Generate Bash CLI subcommand
ggen gen io.ggen.bash.cli-subcommand:cli/subcommand/bash.tmpl name=hello description="Print a greeting"

# Generate Go CLI subcommand
ggen gen io.ggen.go.cli-subcommand:cli/subcommand/go.tmpl name=hello description="Print a greeting"

3. Verify Deterministic Output

# Check that all outputs are consistent
ls -la src/cmds/hello.rs commands/hello.py commands/hello.sh cmd/hello.go

# Verify determinism by regenerating
ggen gen io.ggen.rust.cli-subcommand:cli/subcommand/rust.tmpl name=hello description="Print a greeting"
# Should produce identical output

Produces:

src/cmds/hello.rs
commands/hello.py
commands/hello.sh
cmd/hello.go

Using Local Templates (Advanced)

For custom multi-language generation using local templates:

ggen gen cli subcommand --vars cmd=hello summary="Print a greeting"

Produces, if templates exist:

src/cmds/hello.rs
commands/hello.py
commands/hello.sh

Determinism Verification

Gpack Version Locking

Gpacks ensure determinism through version locking:

# Check installed versions
ggen packs

# Output:
# ID                                    VERSION    KIND       TAGS
# io.ggen.rust.cli-subcommand           0.2.1      template   rust, cli, clap
# io.ggen.python.cli-subcommand         0.1.8      template   python, cli, click
# io.ggen.bash.cli-subcommand            0.1.2      template   bash, cli, getopts

Lockfile Management

# View lockfile
cat ggen.lock

# Update to latest compatible versions
ggen update

# Verify determinism
ggen gen io.ggen.rust.cli-subcommand:cli/subcommand/rust.tmpl name=hello description="Print a greeting" --dry

Cross-Language Consistency

All generated subcommands share the same semantic model:

• Same RDF ontology across all languages
• Consistent variable binding via SPARQL queries
• Identical frontmatter structure
• Deterministic output through version locking

Best Practices

Gpack Selection

# Search for multi-language gpacks
ggen search cli subcommand

# Look for gpacks with multiple language support
ggen show io.ggen.rust.cli-subcommand

Version Management

# Pin specific versions for production
ggen add io.ggen.rust.cli-subcommand@0.2.1
ggen add io.ggen.python.cli-subcommand@0.1.8

# Update carefully
ggen update --dry  # Preview updates
ggen update        # Apply updates

Testing Multi-Language Output

# Test all languages
for lang in rust python bash go; do
  ggen gen io.ggen.${lang}.cli-subcommand:cli/subcommand/${lang}.tmpl name=test description="Test command"
done

# Verify consistency
diff <(grep -o 'name.*test' src/cmds/test.rs) <(grep -o 'name.*test' commands/test.py)

Same RDF + seed + gpack versions ⇒ byte-identical outputs across all languages.