This library provides Ensure trait that is useful for objects with unknown initial state that can be brought to some target state. For example a file may or may not exist. By implementing Ensure we can call met() to create new file only if it did not exist already.

Closures returning TryMetResult that also return closure in TryMetResult::MeetAction variant automatically implement Ensure trait. Helper function ensure can be used to call met() on such closure.

Example

This program will create file only if it does not exist.

```rust use std::path::Path; use std::fs::File; use ensure::ensure; use ensure::TryMetResult::*;

fn main() { let path = Path::new("/tmp/foo.txt");

ensure(|| {
    if path.exists() {
        Met(())
    } else {
        MeetAction(|| {
            File::create(&path).unwrap();
        })
    }
});

} ```