IoC EnvUser Guide


Ioc Env is a library for determining the application environment, be it development, test or production.

It sniffs environment variables and program arguments, and offers a manual override option - useful for testing.


Install IoC Env with the Fantom Repository Manager ( fanr ):

C:\> fanr install -r afIocEnv

To use in a Fantom project, add a dependency to

depends = ["sys 1.0", ..., "afIocEnv 1.0+"]


Full API & fandocs are available on the Status302 repository.

Quick Start

using afIoc
using afIocConfig
using afIocEnv

class Example {
    @Inject IocEnv iocEnv             // --> Inject IocEnv service

    @Config { id="afIocEnv.isProd" }  // --> Inject Config values
    @Inject Bool isProd

    new make(|This| in) { in(this) }

    Void wotever() {
        echo("The environment is '${iocEnv.env}'")

        if (isProd) {
            echo("I'm in Production!")
        } else {
            echo("I'm in Development!!")

// ---- Standard afIoc Support Classes ----

class Main {
    Void main() {
        registry := RegistryBuilder().addModules([AppModule#, IocEnvModule#, IocConfigModule#]).build.startup
        example  := (Example) registry.dependencyByType(Example#)

class AppModule {
    static Void bind(ServiceBinder binder) {

Run the script from the command line:

C:\> fan -env PRODUCTION
[info] [afIocEnv] Setting from environment variable 'env' : development
[info] [afIocEnv] Overriding from cmd line argument '-env' : PRODUCTION
The environment is 'PRODUCTION'
I'm in Production!

Usage - IocEnv Injection

The IocEnv class is the main IoC service with handy utility methods. Inject it as usual:

using afIoc::Inject
using afIocEnv::IocEnv

@Inject IocEnv iocEnv


Void wotever() {
   if (iocEnv.isDev) {
      ... // dev only stuff

Usage - Config Injection

You can also inject IoC Config values. See IocEnvConfigIds for a a complete list of injectable values:

using afIoc::Inject
using afIocConfig::Config

@Config { id="afIocEnv.isDev" }
@Inject Bool isDev


Void wotever() {
   if (isDev) {
      ... // dev only stuff

Setting the Environment

To determine your environment, afIocEnv checks the following:

  • Environment Variables - if an environment variable named env or environment if found, it is taken to be your environment.
  • Program Arguments - if an option labelled -env or -environment if found, the environment is taken to be the argument following. Example, -env prod. This convention follows @Opt from util::AbstractMain.
  • Manual Override - the environment may be set / overridden when the IocEnv instance is created.

The ordering of checks mean program arguments override environment variables and a manual override trumps everything.

Note if no environment setting is found, it defaults to Production. This is because it's usually easier to configure dev and test boxes than it is to configure production ones. So it is one less thing to worry about!

ALIEN-AID: Because the environment default is production you need to set the environment on your dev machine. The easiest way to do this is to set a new environment variable called ENV to the value dev.

Overriding the Environment

Should you need to programmatically override the environment, do it by overriding the IocEnv service in your AppModule:

using afIoc
using afIocEnv

class AppModule {

    @Contribute { serviceType=ServiceOverrides# }
    static Void contributeServiceOverrides(Configuration config) {
        config[IocEnv#] = IocEnv.fromStr("Testing")


Release Notes




  • Chg: Updated to use IoC 1.6.4 - removed dependencies on deprecated methods.



  • New: Added IocEnv.abbr()


  • New: Initial Release