Constructors & Funcs

Constructors must validate all required dependencies using enforce helpers and return pointer types. Only to be used in the context of when being called from a cmd package.

New

• Prefer NewX() constructors over global initialisation unless it’s the only constructor in the package then it will be written as New().

Enforce

• Not nil values → enforce.NotNil()
• Boolean conditions → enforce.True()
• Equality / inequality → enforce.Equal() or enforce.NotEqual()
• Absence of error → enforce.NoError()

These helpers provide simple runtime guarantees and will exit the program with a helpful message if a condition fails.

This package can be found in github.com/ainsleydev/webkit/pkg.

Example:

 1func NewGenerator(fs afero.Fs, manifest *manifest.Tracker, printer *printer.Console) *FileGenerator {
 2	enforce.NotNil(fs, "file system is required")
 3	enforce.NotNil(manifest, "manifest is required")
 4	enforce.NotNil(printer, "printer is required")
 5
 6	return &FileGenerator{
 7		Printer:  printer,
 8		fs:       fs,
 9		manifest: manifest,
10	}
11}

Context

Use context.Context as the first parameter for functions that perform I/O or can be cancelled.

Example:

1    func Run(ctx context.Context, cmd Command) (Result, error) {
2	select {
3		case <-ctx.Done():
4			return Result{}, ctx.Err()
5		default:
6			// Execute command
7	}
8}