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spec out handleUndo (just a rough idea, and probably not actually the right solution) #3

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spec out handleUndo (just a rough idea, and probably not actually the right solution) #3

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38 changes: 33 additions & 5 deletions machine-def.struct.js
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Original file line number Diff line number Diff line change
Expand Up @@ -12,13 +12,35 @@ module.exports = {
moreInfoUrl: 'http://hello.com',


sideEffects: 'idempotent', // either omit or set as "cacheable" or "idempotent"
habitat: 'sails', // either omit or set as "request", "sails", "node", or "browser".


habitat: 'sails', // either omit or set as "request" or "sails"
//sync: true, // either omit or set as `true`


sync: true, // either omit or set as `true`
// sideEffects: 'idempotent', // either omit or set as "cacheable" or "idempotent"


handleUndo: async function(inputs){ // either omit or set as a function
// ^^ should never be defined for a "cacheable" machine

// Reverse `fn`'s side effect.
// (Note that this is not a GLOBAL UNDO!!! In this example, this code could
// not attempt to handle any changes that might have befallen the global var
// from other logic. It can really only attempt to reverse the side effects
// of running `fn` with these inputs, and even then only assuming `fn`
// triggered its success exit.)

// Realistically, it's not super possible w/ this example, but we can at
// least fudge it a little bit:
if (global.foo) {
// if we knew how much to subtract, we could do that here, for example
}

// (In reality, this example isn't really reversible, so we would not
// want to define a handleUndo function at all!)

},


inputs: {
Expand All @@ -35,15 +57,18 @@ module.exports = {
},


fn: function (inputs, exits) {
fn: async function (inputs, exits) {

// Import any dependencies here
var _ = require('@sailshq/lodash');

// Do asynchronous things with callbacks if you like
// (or better yet, use `await`!)
setTimeout(function (){

try {

var luckyNum = Math.random();
let luckyNum = Math.random();
if (luckyNum > 0.5) {
throw new Error('whatever');
}
Expand All @@ -62,6 +87,9 @@ module.exports = {

// --• OK so if we made it here, `luckyNum` must be between 0.1 and 0.5 (exclusive).

// Maybe do some kind of side effect.
global.foo = (global.foo || 0) + luckyNum;

// Exit `success` with no output.
return exits.success();
// > NOTE:
Expand Down