schrodinger

Version

1.0.0

Introduction

Schrödinger's cat is a thought experiment devised by Austrian physicist Erwin Schrödinger in 1935. This experiment propose to introduce a cat inside a close box with a probabilistic radiactive device that going to cause the cat's death without knowing when does the cat die. Only if someone opened the box, then they would be able to know if cat is dead or alive. This micro-library does not aim to clarify anything about this paradoxical quantum experiment.

Conversely it provides a Schrodinger class that builds instances with undetermined value inside. This value is only determined if the user gets the value or forces the value setting it. Once the value is determined, this value is unmodifiable. This library also provides a set of errors that are thrown if it is attempted to change the value if it has been already determined.

Therefore, Schrodinger is a class with a get and set methods. But get is not commonly getter and requires a seed parameter to determine which of all possible values is returned.

Instancing Schrodinger class

Firstly, when it is instanced a Schrodinger class, the value that contains is undetermined. Nevertheless, constructor of class requires a set of values to determine the value subsequently. This set of values can be passed using an array or a function with seed parameter:

var Schrodinger = require('schrodinger')

// passing an array:
var a = new Schrodinger([5, /\d+/, 'bar']) // it potentially determines to 5, /\d+/ or 'bar'

// passing a function:
var b = new Schrodinger(function (seed) {
    return seed * seed % 7
}) // it potentially determines to any value that function returns.

Value determination

Determination by set method

The simplest way to determine value of Schrodinger instance is setting it using setmethod:

var instance = new Schrodinger([1, 3, 6, 10]) // undetermined value
instance.set(6) // from now, if it is gotten the value, it always returns 6

Notice: set method might throw an exception in certain circumstances.

Determination by get method

If value determination is not forced by any set method. The first call of get method determines the value using a seed. If set of possibles values is determined using an array, then the value is detetermined getting the value in seed % values.length position. For example:

var a = new Schrodinger(['apple', 'orange', 'banana'])
a.get(5) // 5 % 3 === 2 --> returns 'banana'

var b = new Schrodinger(['apple', 'orange', 'banana'])
b.get(12) // 12 % 3 === 0 --> returns 'apple'

If set of values is determined by a function, then get method determines the value calling this function:

var a = new Schrodinger(function (seed) {
    return (seed * seed) % 7
})
a.get(5) // (5 * 5) % 7 === 4 --> returns 4

Unmodifiable value after determination and throwing errors

Once value is determined, get method will return this value forever, and set method will not overwrite this value. Depending on second parameter of constructor, get and set might throw errors if it is attempted to set a value that is already determined or get the value with another seed. To know more about errors see API documentation.

The following example shows how Shrodinger instance keeps the value unmodified and does not throw any error because the second parameter of constructor is false:

var instance = new Schrodinger([1, 2, 4, 8, 16], false)
var seed1 = 12753
var seed2 = 843832

instance.set(4) // from now, value is determined to 4
instance.get() // returns 4
instance.get(seed1) // returns 4 (ignoring seed)
instance.set(7) // do nothing
instance.get(seed2) // returns 4 (ignoring seed)

API Documentation

constructor (values, errorConfig = true) : throws SchrodingerError

It builds an instance with undetermined value among a set of possible values passed in first parameter.

parameters

values

• Type: Array | Function

errorConfig

• Type: Object | Boolean
• Default: true

It defines an object where each key with true value represents an error that is allowed to throw. These errors are thrown depending on order that are called get and set methods and their parameters. Also it is allowed to pass a boolean shortcut like false or true:

false is an alias of {} (it does not report errors)

true is an alias of the most strict option (it reports the whole errors):

{
    GetWithDifferentSeedError: true,
    SetAfterGetError: true,
    SetAfterSetError: true,
    SetDifferentValueError: true,
    SetInvalidValueError: true
}

errors

InvalidEmptyListError

Constructor throws this error when first parameter is an empty array. It is not possible to build a Schrodinger instance with empty list of options to get.

InvalidParamConstructorError

Constructor throws this error when first parameter is not an array or a function.

get (seed) : throws SchrodingerError

• If value is undetermined, a value is determined using seed and is returned.
• If value is determined, it returns this value or throws an error depending on errorConfig constructor parameter.

To know more about value determination see the value determination section.

parameters

seed

• Type: Integer

It determines the value that returns get if it is called the first time.

errors

GetWithDifferentSeedError

If errorConfig parameter has property GetWithDifferentSeedError on true and get is called with seed different from seed which get was called the first time, then it throws GetWithDifferentSeedError error.

Example

var Schrodinger = require('schrodinger')
var firstSeed = 9
var secondSeed = 11
var instance = new Schrodinger([2, 3, 5, 7, 11, 13], {
    GetWithDifferentSeedError: true
})

instance.get(firstSeed) // returns 7
instance.get(secondSeed) // throws GetWithDifferentSeedError

set (value) : throws SchrodingerError

• If value is undetermined it sets value or throws an error depending on errorConfig.
• If value is determined, it does not modify it and throws error or not depending on errorConfig.

To know more about value determination see the value determination section.

parameters

value

• Type: *

It is the value that is attempeted to set.

errors

SetAfterGetError

If errorConfig parameter has property SetAfterGetError on true and set is called after having previously called get method, then it throws SetAfterGetError error.

Example

var Schrodinger = require('schrodinger')
var seed = 9
var instance = new Schrodinger([2, 3, 5, 7, 11, 13], {
    SetAfterGetError: true
})

instance.get(seed) // returns 7
instance.set(7) // it throws a SetAfterGetError

SetAfterSetError

If errorConfig parameter has property SetAfterSetError on true and set is called after having previously called set method, then it throws SetAfterSetError error.

Example

var Schrodinger = require('schrodinger')
var seed = 9
var instance = new Schrodinger([2, 3, 5, 7, 11, 13], {
    SetAfterSetError: true
})

instance.set(5) // set 5
instance.set(5) // it throws a SetAfterSetError

SetDifferentValueError

If errorConfig parameter has not properties SetAfterGetError and SetAfterSetError but has property SetDifferentValueError on true and set is called with value different from which it was determined the first time, then it throws SetDifferentValueError error.

Example

var Schrodinger = require('schrodinger')
var seed = 9
var instance = new Schrodinger([2, 3, 5, 7, 11, 13], {
    SetDifferentValueError: true
})

instance.set(5) // set 5
instance.set(5) // it does not throws error because SetAfterSetError property is not true
instance.set(7) // it throws a SetDifferentValueError

SetInvalidValueError

If errorConfig parameter has property SetInvalidValueError on true, it was passed an array of values on first parameter of constructor and set is called with value not included in values, then it throws SetInvalidValueError error.

Example

var Schrodinger = require('schrodinger')
var seed = 9
var instance = new Schrodinger([2, 3, 5, 7, 11, 13], {
    SetInvalidValueError: true
})

instance.set(8) // throws a SetInvalidValueError because 8 is not in list of possible values.

License

MIT