Tutorial 2: Adding Variables

Add variable substitution to your template. This enables dynamic content generation based on variables, making your templates reusable across different projects.

The Change: GlobType.Template

In Tutorial 1, we used GlobType.Copy which simply copies files. To enable variable substitution, change to GlobType.Template:

cyan/index.ts


files: [
  {
    root: 'templates',
    glob: '**/*',
    exclude: [],
- type: GlobType.Copy
+ type: GlobType.Template
  }
]

cyan/index.py


files=[
    CyanGlob(
        root="templates",
        glob="**/*",
        exclude=[],
- type=GlobType.Copy
+ type=GlobType.Template
    )
]

cyan/Program.cs


Files =
[
    new CyanGlob
    {
        Root = "templates",
        Glob = "**/*",
        Exclude = [],
- Type = GlobType.Copy
+ Type = GlobType.Template
    }
]

Using GlobType.Template on binary files (images, PDFs) will corrupt them. See Tutorial 3 for handling mixed file types.

Define Variables in Config

Add variables to your processor configuration:

cyan/index.ts

config: {
  vars: {
    name: 'my-project',
    author: 'Your Name',
    version: '1.0.0'
  }
}

cyan/index.py

config={
    "vars": {
        "name": "my-project",
        "author": "Your Name",
        "version": "1.0.0"
    }
}

cyan/Program.cs

Config = new
{
    vars = new
    {
        name = "my-project",
        author = "Your Name",
        version = "1.0.0"
    }
}

Use Variables in Template Files

The default processor uses var__name__ syntax for variable substitution.

Create templates/README.md:

templates/README.md

# var__name__

Welcome to var__name__!

**Author:** var__author__
**Version:** var__version__

Variable Syntax

The default processor uses Eta templating with custom delimiters:

Syntax	Description
`var__name__`	Variable substitution
`var__user.name__`	Nested variable access

The default delimiter var__ and __ is chosen to avoid conflicts with common template syntaxes like ${} or {{}}.

Complete Code

Update your template logic with all the changes:

Update cyan/index.ts:

cyan/index.ts

import { startTemplateWithFn, GlobType } from '@atomicloud/cyan-sdk';

startTemplateWithFn(async (i, d) => {
  const name = await i.text('What is your project name?', 'myuser/my-first-template/name');

  return {
    processors: [{
      name: 'cyan/default',
      files: [
        {
          root: 'templates',
          glob: '**/*',
          exclude: [],
          type: GlobType.Template
        }
      ],
      config: {
        vars: {
          name,
          author: 'Your Name',
          version: '1.0.0'
        }
      }
    }]
  };
});

Note that name comes from user input while author and version are hardcoded defaults.

Update cyan/index.py:

cyan/index.py

from cyanprintsdk import start_template_with_fn, GlobType
from cyanprintsdk.domain.core.cyan import Cyan, CyanProcessor, CyanGlob

async def my_template(i, d):
    name = await i.text("What is your project name?", "myuser/my-first-template/name")

    return Cyan(
        processors=[
            CyanProcessor(
                name="cyan/default",
                files=[
                    CyanGlob(
                        root="templates",
                        glob="**/*",
                        exclude=[],
                        type=GlobType.Template
                    )
                ],
                config={
                    "vars": {
                        "name": name,
                        "author": "Your Name",
                        "version": "1.0.0"
                    }
                }
            )
        ]
    )

start_template_with_fn(my_template)

Note that name comes from user input while author and version are hardcoded defaults.

Update cyan/Program.cs:

cyan/Program.cs

using sulfone_helium;
using sulfone_helium.Domain.Core;

CyanEngine.StartTemplate(args, async (i, d) =>
{
    var name = await i.Text("What is your project name?", "myuser/my-first-template/name");

    return new Cyan
    {
        Processors =
        [
            new CyanProcessor
            {
                Name = "cyan/default",
                Files =
                [
                    new CyanGlob
                    {
                        Root = "templates",
                        Glob = "**/*",
                        Exclude = [],
                        Type = GlobType.Template
                    }
                ],
                Config = new
                {
                    vars = new
                    {
                        name,
                        author = "Your Name",
                        version = "1.0.0"
                    }
                }
            }
        ]
    };
});

Note that name comes from user input while author and version are hardcoded defaults.

Test Your Template

Use the try command to test your template:

cyanprint try template . ./test-output

When prompted, enter a project name like my-project.

Check the Output

cat ./test-output/README.md

Expected output:

# my-project

Welcome to my-project!

**Author:** Your Name
**Version:** 1.0.0

The variables have been replaced with their values.

Development Workflow

Iterate quickly with the try command:

# Make changes to your template or variables...

# Test again
rm -rf ./test-output
cyanprint try template . ./test-output

What You Learned

How to change GlobType.Copy to GlobType.Template for variable processing
How to define variables in processor config
How to use var__name__ syntax for substitution in template files
How to combine user input with hardcoded default values

Next Steps

Learn how to handle different file types with different processing strategies:

Next: Changing Glob Patterns

Tutorial 2 - Adding Variables

Tutorial 2: Adding Variables

The Change: GlobType.Template

Define Variables in Config

Use Variables in Template Files

Variable Syntax

Complete Code

Test Your Template

Check the Output

Development Workflow

What You Learned

Next Steps

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