typed_key

Strongly-typed string keys for configuration.

A frequent task is to extract a typed value from an untyped Map<String, Object>. Typically, this is done via string keys: let port: u32 = map.get("port")?.parse()?. A slightly more type-safe approach is to associate certain types with corresponding string constants:

```rust

[macro_use]

extern crate typedkey; use typedkey::Key;

// PORT is basically "port" string with associated u32 type. const PORT: Key = typed_key!("port");

fn main() {}

```

This crate provides basic building block for such strongly-typed strings. See [example] for a complete example of reading configuration, and the [blog post] for a more long winded explanation of the pattern.

Using string keys is totally fine for small isolated cases, but if this pattern is pervasive, typed_key can provide the following benefits:

• Documentation: all possible keys are declared in one place, specify their type explicitly, and can have documentation comments.
• Type safety: because each key carries its type, it's impossible to read the value of wrong type. Unlike string keys, typed keys never need a turbofish operator.
• Typo safety: you can't misspell a type key on the call site.
• Navigation: with typed_keys, you can use "go to definition", "find usages", and refactor without fear.