interfaces

type TemplateRenderer ¶

type TemplateRenderer interface {
	// Render renders a template by name with the given data and returns the result as a string.
	// The template name should include the .tmpl extension (e.g., "go.mod.tmpl").
	//
	// The data parameter accepts any type, but callers should use template.TemplateData
	// for standard project generation. See interface documentation for details on the
	// design rationale for using 'any'.
	//
	// Returns an error if the template does not exist or cannot be parsed/executed.
	Render(name string, data any) (string, error)

	// RenderToFile renders a template and writes it to the specified output path.
	// The output path should NOT include the .tmpl extension (e.g., "project/go.mod").
	// Parent directories will be created automatically if they don't exist.
	//
	// The data parameter accepts any type, but callers should use template.TemplateData
	// for standard project generation. See interface documentation for details on the
	// design rationale for using 'any'.
	//
	// Returns an error if rendering fails or the file cannot be written.
	RenderToFile(templateName string, data any, outputPath string) error

	// Validate checks if a template exists and has valid syntax.
	// Returns nil if the template is valid, or an error describing the problem.
	Validate(name string) error
}

TemplateRenderer handles template rendering with variable substitution.

This interface follows ADR-002: Interface Placement in Consumer Packages. It is defined by the consumer (generator package) rather than the provider (template package), allowing the generator to depend on abstractions rather than concrete implementations.

The interface provides methods to render templates from an embedded filesystem, write rendered templates to files, and validate template syntax.

Data Parameter Design:

The data parameter uses 'any' instead of a specific type (like TemplateData) to provide flexibility for future template rendering scenarios. While the current implementation exclusively uses template.TemplateData, the 'any' type allows the interface to support:

• Future data structure variations without interface changes
• Test scenarios with mock or simplified data structures
• Custom data types for specialized template rendering use cases

Implementations are expected to document their supported data types. The standard implementation (template.NewRenderer) accepts template.TemplateData.

Example usage:

renderer := template.NewRenderer(templateFS)
data := template.TemplateData{
    ModuleName:  "github.com/user/myapp",
    ProjectName: "myapp",
    GoVersion:   "1.25",
}
content, err := renderer.Render("go.mod.tmpl", data)
if err != nil {
    return fmt.Errorf("failed to render template: %w", err)
}

See also: internal/generator/template package for the concrete implementation.