smf_dart_define

The SMF module that gives an app the values of its .env file through --dart-define-from-file, an option of the flutter tool. It provides the env role of SMF.

The modules of an app declare the values that a developer fills in after generating the app, such as the public key of a service, as keys of the env role. The role writes .env, which stays out of git, and .env.example, which has the same keys without values. This module adds lib/core/env/app_env.dart with AppEnv, which has a static getter for each key. A getter reads its value with const String.fromEnvironment and returns null while the value is empty or missing.

The flutter tool reads .env when a command that builds, runs or tests the app starts, given --dart-define-from-file=.env, and compiles each value into the app. No code is generated after you edit .env, and the analyzer sees the empty values, so a fresh clone of the app analyzes and builds. The module also adds run configurations that pass the argument. In VS Code, .vscode/launch.json passes it to Run and Debug (F5), to the Run and Debug links above main(), and to the tests run from their links or from the Testing view. In Android Studio, .run/main.run.xml passes it only to the run configuration named after the app, not to a test that you run there. The README of the app lists the commands.

Every value ends up in the app, where anyone who has the app can read it. So .env holds only values that may be public, never a secret.

Use with the SMF CLI

smf create asks which module provides the values in .env, and offers none as well. When a module of the app needs them and no other module provides them, it adds this module without the question. To choose it without the question:

smf create my_app -m dart_define

You don't add this package to an app yourself: smf create of the SMF CLI puts what the module generates into the app.

SMF generates apps for Flutter 3.44 or newer and Dart 3.12 or newer. It is tested on macOS, Linux and Windows.

Documentation

• The dart_define module