lazy

Documentation

Overview

Package lazy allows for lazily-initialized variables via New(). These are often used for globals representing dependencies. The following example shows how to use enve and lazy to configure and initialize a postgres database using github.com/lib/pq.

	import (
    	"gitlab.com/efronlicht/estd/enve"
    	"gitlab.com/efronlicht/estd/lazy"
    	"database/sql"
 	_ "github.com/lib/pq" // register postgres sql driver
	)
		var Postgres = lazy.New[*sql.DB](lazy.Unwrap(func() *sql.DB, error) {
			return sql.Open("postgres", pgConnStrFromEnv())
		})
		func pgConnStrFromEnv() string
			const (
				defaultUser = "efron"
				defaultDBName = "examples"
				defaultSSLMode = "require"
			)
			return fmt.Sprintf("user=%s dbname=%s sslmode=%s",
				enve.StringOr("PG_USER", defaultUser),
				enve.StringOr("PG_DBNAME", defaultDB),
				enve.StringOr("sslmode", defaultSSL),
			)
		}

Index

• func New[T any](f func() T) *lazy[T]
• func Unwrap[T any](f func() (T, error)) func() T

Functions

func New

func New[T any](f func() T) *lazy[T]

New creates a lazy-evaluating value of type T. The first (and ONLY the first) call to Get() on the resulting value will call f() and cache and return it's value. Subsequent calls will return the same value.

func Unwrap

func Unwrap[T any](f func() (T, error)) func() T

Unwrap turns a func()(T, error) into a func() T, panicking if the error wasn't nil. Useful for lazily-evaluted dependencies.