# context

A context manager protocol for zepto.

## Installation

```
zeps install hellerve/context
```

## Context Managers?

Context managers provide the programmer with an easy way
to work with resources that need management, i.e. explicit
cleanup and/or deletion. Consider files for example: if
we want to use them, we need to open them, work with them
and then close them again. Context managers provide you with
a context in which a file will be open, managing the closing
itself when you are done.

An example:
```clojure
; reading the first line of a file, without a context manager
(define file (open-input-file "myfile.txt"))
(write (read-line file))
(close-input-file file)

; the same, this time with a context manager
(with (open-input-file "myfile.txt") file
  (write (read-line file)))
```

## Usage

The example above already showcases the most important function for
users, `with`. It takes a value, a name to bind it to and a context
in which this name should be defined.

```clojure
(with some-resource some-name
  (do-something some-name)
  (do-another-thing some-name))
```

The library also exposes a protocol `context-manager`, comprised of a
function `teardown` which will clean a resource up after use.

Use it like so:
```clojure
(defimpl context-manager my-resource?
         ((teardown (lambda (resource)
                      (begin
                        (cleanup-my-resource resource)
                        (delete-my-resource resource))))))
```

That's all, folks!

This library comes bundled with a context manager for files and sockets.

<hr/>

Have fun!