Variables

Variable is just a simple GObject that holds a value.

Tip

The global Variable is a function that returns an instance If you want to subclass this instead of Service import the class

import { Variable as Var } from 'resource:///com/github/Aylur/ags/variable.js'
class MyVar extends Var {
    static { Service.register(this) }
}

Polling and Listening to executables

const myVar = Variable('initial-value', {
    // listen is what will be passed to Utils.subprocess, so either a string or string[]
    listen: App.configDir + '/script.sh',
    listen: 'bash -c "some-command"',
    listen: ['bash', '-c', 'some-command'],

    // can also take a transform function
    listen: [App.configDir + '/script.sh', out => JSON.parse(out)],
    listen: [['bash', '-c', 'some-command'], out => JSON.parse(out)],

    // poll is a [interval: number, cmd: string[] | string, transform: (string) => any]
    // cmd is what gets passed to Utils.execAsync
    poll: [1000, 'some-command'],
    poll: [1000, 'some-command', out => 'transformed output: ' + out],
    poll: [1000, ['bash', '-c', 'some-command'], out => 'transformed output: ' + out],

    // or [number, function]
    poll: [1000, () => { return new Date(); }],
    poll: [1000, Math.random],
});

Updating its value

myVar.value = 'new-value'
myVar.setValue('new-value')

Caution

using setValue will force a new value and thus signal changed, while setting value only signal if it gets a new value

const myVar = Variable({ key: "value" })
const value = myVar.value
value["new-key"] = "value"
myVar.value = value // won't emit, because its still the same object
myVar.setValue(value) // will emit the signal

Getting its value

print(myVar.value)
print(myVar.getValue())

Temporarily stopping it

variable.stopListen() // this kills the subprocess
variable.stopPoll()

Starting it

It will start on construction, no need to explicitly call this.

variable.startListen() // launches the subprocess again
variable.startPoll()

Getting if its active

print(variable.isListening)
print(variable.isPolling)

Usage with widgets

const label = Widget.Label({
    label: myVar.bind(),

    // optional transform method
    label: myVar.bind().as(value => value.toString()),

    // hook to do more than an assignment on changed
    setup: self => self.hook(myVar, () => {
        self.label = myVar.value.toString();
    })
})

Connecting to it directly

myVar.connect('changed', ({ value }) => {
    console.log(value);
});

Dispose if no longer needed

This will stop the interval and force exit the subprocess

myVar.dispose();

Example RAM and CPU usage

const divide = ([total, free]) => free / total

const cpu = Variable(0, {
    poll: [2000, 'top -b -n 1', out => divide([100, out.split('\n')
        .find(line => line.includes('Cpu(s)'))
        .split(/\s+/)[1]
        .replace(',', '.')])],
})

const ram = Variable(0, {
    poll: [2000, 'free', out => divide(out.split('\n')
        .find(line => line.includes('Mem:'))
        .split(/\s+/)
        .splice(1, 2))],
})

const cpuProgress = Widget.CircularProgress({
    value: cpu.bind()
})

const ramProgress = Widget.CircularProgress({
    value: ram.bind()
})

Derived Variables

const a = Variable(2)
const b = Variable(3)

// first argument is a list of dependencies
// second argument is a transform function
const c = Utils.derive([a, b], (a, b) => {
    return a * b
})