# Gauges

Gauges are used to measure the instantaneous value of something.

## Creating

(use '[metrics.gauges :only (gauge)])

(def files-open
(gauge "files-open"
(return-number-of-files-open ...)))


That's it. Pretty simple.

gauge is a macro. If you need a function instead you can use gauge-fn, but you have to pass it a function, not just a body:

(use '[metrics.gauges :only (gauge-fn)])

(def files-open
(gauge-fn "files-open"
#(return-number-of-files-open ...)))


## Writing

There is no writing. Gauges execute the form(s) (or function) you passed when creating them every time they're read. You don't need to do anything else.

### value

You can read the value of a gauge at any time with value:

(use '[metrics.gauges :only (value)])

(value files-open)

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