const constructor bool.fromEnvironment

Returns the boolean value of the environment declaration name.

The boolean value of the declaration is true if the declared value is the string "true", and false if the value is "false".

In all other cases, including when there is no declaration for name, the result is the defaultValue.

The result is the same as would be returned by:

(const String.fromEnvironment(name) == "true")
    ? true
    : (const String.fromEnvironment(name) == "false")
        ? false
        : defaultValue

Example:

const loggingFlag = const bool.fromEnvironment("logging");

If you want to use a different truth-string than "true", you can use the String.fromEnvironment constructor directly:

const isLoggingOn = (const String.fromEnvironment("logging") == "on");