environment.opBinaryRight

bool opBinaryRight(string op : "in")(scope const(char)[] name) @trusted

Identify whether a variable is defined in the environment.

Because it doesn't return the value, this function is cheaper than get. However, if you do need the value as well, you should just check the return of get for null instead of using this function first.

Example: ------------- // good usage if ("MY_ENV_FLAG" in environment) doSomething();

// bad usage if ("MY_ENV_VAR" in environment) doSomething(environment["MY_ENV_VAR"]);

// do this instead if (auto var = environment.get("MY_ENV_VAR")) doSomething(var); -------------