34 lines
2 KiB
Markdown
34 lines
2 KiB
Markdown
``AnyMap``, a safe and convenient store for one value of each type
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==================================================================
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[](https://travis-ci.org/chris-morgan/anymap)
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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.
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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.)
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Fortunately, we can do better than these things in Rust. Our type system is quite equal to easy, robust expression of such problems.
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The ``AnyMap`` type is a friendly wrapper around a ``HashMap<TypeId, Box<Any>>``, exposing a nice, easy typed interface, perfectly safe and absolutely robust.
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What this means is that in an ``AnyMap`` you may store zero or one values for every type.
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Instructions
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------------
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Cargo all the way: it is `anymap` on crates.io.
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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`.
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Author
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------
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[Chris Morgan](http://chrismorgan.info/) ([chris-morgan](https://github.com/chris-morgan)) is the primary author and maintainer of AnyMap.
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License
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-------
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This library is distributed under similar terms to Rust: dual licensed under the MIT license and the Apache license (version 2.0).
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See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.
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