error-pages/internal/env/env.go

// Package env contains all about environment variables, that can be used by current application.
package env

import "os"

type envVariable string

const (
	ListenAddr       envVariable = "LISTEN_ADDR"        // IP address for listening
	ListenPort       envVariable = "LISTEN_PORT"        // port number for listening
	TemplateName     envVariable = "TEMPLATE_NAME"      // template name
	ConfigFilePath   envVariable = "CONFIG_FILE"        // path to the config file
	DefaultErrorPage envVariable = "DEFAULT_ERROR_PAGE" // default error page (code)
)

// String returns environment variable name in the string representation.
func (e envVariable) String() string { return string(e) }

// Lookup retrieves the value of the environment variable. If the variable is present in the environment the value
// (which may be empty) is returned and the boolean is true. Otherwise the returned value will be empty and the
// boolean will be false.
func (e envVariable) Lookup() (string, bool) { return os.LookupEnv(string(e)) }