[](https://travis-ci.org/chris-morgan/anymap)
-If you’re familiar with Go and Go web frameworks, you may have come across the common “environment” pattern for storing data related to the request. It’s typically something like ``map[string]interface{}`` and is accessed with arbitrary strings which may clash and type assertions which are a little unwieldy and must be used very carefully.
+If you’re familiar with Go and Go web frameworks, you may have come across the common “environment” pattern for storing data related to the request. It’s typically something like ``map[string]interface{}`` and is accessed with arbitrary strings which may clash and type assertions which are a little unwieldy and must be used very carefully. (Personally I would consider that it is just *asking* for things to blow up in your face.) In a language like Go, lacking in generics, this is the best that can be done; such a thing cannot possibly be made safe without generics.
-This is madness. Hare-brained, stark, raving madness, just *asking* for things to blow up in your face. Unfortunately for people in Go, it’s the best that they can have because of its weak type system; such a thing cannot possibly be made safe without generics.
+As another example of such an interface, JavaScript objects are exactly the same—a mapping of string keys to arbitrary values. (There it is actually *more* dangerous, because methods and fields/attributes/properties are on the same plane.)
-Fortunately, we can do better in Rust. Our type system is quite equal to easy, robust expression of such problems.
+Fortunately, we can do better than these things in Rust. Our type system is quite equal to easy, robust expression of such problems.
-The ``AnyMap`` type is a friendly wrapper around a ``HashMap<TypeId, Box<Any>:'static>``, exposing a nice, easy typed interface, perfectly safe and absolutely robust.
+The ``AnyMap`` type is a friendly wrapper around a ``HashMap<TypeId, Box<Any>>``, exposing a nice, easy typed interface, perfectly safe and absolutely robust.
What this means is that in an ``AnyMap`` you may store zero or one values for every type.
Instructions
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- make
+Cargo all the way: it is `anymap` on crates.io.
-Future work
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-
-I think that the only thing left for this is filling out additional methods from ``HashMap`` as appropriate.
-
-It’s a very simple thing.
+There is an optional `clone` feature on the `anymap` crate; if enabled, your `AnyMap` will require contained types to implement `Clone` and will itself satisfy `Clone`.
Author
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