Course of Raku / Advanced / Modules / Modules basics / Exercises / Load at run time

Solution: Load at run time

Here is a possible solution to the task.

Code

The program, require-import.raku:

sub MAIN(Bool :$quiet) {
    if $quiet {
        say 'Silence.';
    }
    else {
        require Greeting <&hello>;
        say hello('Sam');
    }
}

🦋 You can find both source files in the exercises/advanced/modules-basics/require-at-runtime directory.

Output

$ raku -I. require-import.raku
Hello, Sam!

$ raku -I. require-import.raku --quiet
Silence.

Comments

  1. require loads the module at run time rather than at compile time. On its own it imports nothing, which is why a bare hello would be unknown.

  2. The <&hello> list tells require to import that one symbol, so after the statement hello('Sam') can be called directly, giving Hello, Sam!.

  3. This is what require is for: because it runs at run time, it can sit inside an if. When --quiet is given, that branch is skipped and the module is never loaded — something a compile-time use could not avoid.

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