I have an object created with
function makeMyObject(eventName, idzName, classzName){
function eDetails(eventName, idzName, classzName) {
this.eventName = eventName;
this.idzName = idzName;
this.classzName = classzName;
}
let cObj = new eDetails(eventName, idzName, classzName);
console.log(cObject)
return cObj;}
}
► eventDetails {eventName: "event1", idzName: "A", classzName: "L1"}
this is correct,
when it return to the calling function and I ..
let cObjct = makeMyObject(eventName, idzName, classzName);
console.log(cObjct);
► eventDetails {eventName: "event1", idzName: "A", classzName: "L1"}
this is also correct,
now I want to push that object to the array.
Function makeEventList(orgObjct) {
let evntList = [];
evntList.push(orgObject);
console.log(evntList);
return evntList;
}
let myArray = makeEventList(orgObjct;
console.log(myArray);
► eventDetails
eventDetails {eventName: "event1", idzName: "A", classzName: "L1"}
length:1
proto:Array(0)
however, now I wish to place 1 of those into a variable.
function myFunction (myArray, cObjct){
let x = cObjct.idzName
console.log(x);
return x;}
► undefined
I've also tried,
function myFunction (cObjct){
let x = $(cObjct).prop(idzName);
console.log(x);}
► A >> This is only partially CORRECT. A is the idzName. if $.prop() get the first property name fo cObject, it should be 'event1', further where's the 3rd property name? how do I access that?
I've also tried
function myFunction (cObjct, idzName)
let x = $(cObjct).prop(idzName);
console.log(x);
return x;}
same result -> ► A >> This is only partially CORRECT. A is the idzName. if $.prop() get the first property name fo cObject, it should be 'event1', further where's the 3rd property name? how do I access that?
i've also tried doing 2 function 1 like first another like this
function myFunction (cObjct, idzName)
let x = $(cObjct).prop(idzName);
console.log(x);
return x;}
► undefined
So how do I correctly get the value of a specified property name from an array object?
thanks
Related
"first part" &&&& fun _ ->
let ident
"second part" &&&& fun _ ->
ident ....
I need to use variable "ident".
I just need to pass value of variable from first part of test to second one...
I want to ask you if there is any easy way how to define and use global variable or even if you have better (and easy) idea of doing that
Keep in mind, please, that I am a beginner, so I would prefer easier ones.
Global variables will often make your code difficult to work with - particularly if they are mutable.
Instead, consider returning the values you need to keep track of as composite values. An easy data type to start with would be a tuple:
let ``first part`` id =
let someOtherValue = "Foo"
someOtherValue, id + 1
This function takes an int (the current ID) as input, and returns string * int (a tuple where the first element is a string, and the second element and int) as output.
You can call it like this:
> let other, newId = ``first part`` 42;;
val other : string = "Foo"
val newId : int = 43
Notice that you can use pattern matching to immediately destructure the values into two named symbols: other and newId.
Your second function could also take an ID as input:
let ``second part`` id otherArgument =
// use id here, if you need it
"Bar"
You can call it like this, with the newId value from above:
> let result = ``second part`` newId "Baz";;
val result : string = "Bar"
If you find yourself doing this a lot, you can define a record for the purpose:
type Identifiable<'a> = { Id : int; Value : 'a }
Now you can begin to define higher-order functions to deal with such a type, such as e.g. a map function:
module Identifiable =
let map f x = { Id = x.Id; Value = f x.Value }
// Other functions go here...
This is a function that maps the Value of an Identifiable from one value to another, but preserves the identity.
Here's a simple example of using it:
> let original = { Id = 42; Value = "1337" };;
val original : Identifiable<string> = {Id = 42;
Value = "1337";}
> let result' = original |> Identifiable.map System.Int32.Parse;;
val result' : Identifiable<int> = {Id = 42;
Value = 1337;}
As you can see, it preserves the value 42, but changes the Value from a string to an int.
You can still change the ID explicitly, if you want to do that:
> let result'' = { result' with Id = 7 };;
val result'' : Identifiable<int> = {Id = 7;
Value = 1337;}
Since this was getting out of hand for comments this is how I would do it for an example
let mutable t = 0
let first =
t <- 1 + 1
//other stuff
let second =
//can use t here and it will have a value of 2
In some cases you have to use a ref:
let t = ref 0
let first =
t := 1 + 1
//other stuff
let second =
//can use t here and it will have a value of 2 -
// you use "!t" to get the value
If you define ident at the top of your file like this :
let ident = "foo"
// rest of your code using ident
ident are global and you can use in the next part of your file.
EDIT :
If ident wil change in the next part of your code, use this :
let ident = ref "foo"
In looking at the documentation for WebSharper's local storage, the SetItem item is string * string -> unit (and GetItem is string -> string).
This means that I'll need to convert anything I want to store into strings and do the reverse to retrieve them. Or, to put it in another way, I'll need to serialize and de-serialize them. Is there a way to use the behind-the-scenes conversion that WebSharper already does for RPC calls, or am I stuck with using a server-side library like FsPicker?
Not built in yet, I have been using this helper module to make local storage usable the same way as a ref cell:
open IntelliFactory.WebSharper
// Helper for handling localstorage, making a stored value work like a ref cell.
[<JavaScript; AutoOpen>]
module LocalStorage =
open IntelliFactory.WebSharper.Html5
let localStorage = Window.Self.LocalStorage
type IValue<'T> =
abstract Value: 'T with get, set
let [<Inline>] ( ! ) (x: IValue<_>) = x.Value
let [<Inline>] ( := ) (x: IValue<_>) v = x.Value <- v
// Redefining Ref to use IValue
type Ref<'T> (value: 'T) =
let mutable v = value
interface IValue<'T> with
member this.Value
with get() = v
and set value = v <- value
let [<Inline>] ref v = Ref v
let incr i = i := !i + 1
let decr i = i := !i - 1
type IStorageItem<'T> =
inherit IValue<'T>
abstract Save: unit -> unit
abstract Delete: unit -> unit
type JSONStorageItem<'T>(key, defaultVal) =
let mutable value = None
let getValue() =
match value with
| Some v -> v
| _ ->
let v =
match localStorage.GetItem key with
| null -> defaultVal
| s ->
Json.Parse s :?> _
value <- Some v
v
interface IStorageItem<'T> with
member this.Value
with get() = getValue()
and set v =
try localStorage.SetItem(key, Json.Stringify v)
value <- Some v
with _ -> JavaScript.Alert "Saving data to storage failed."
member this.Save() =
try localStorage.SetItem(key, Json.Stringify (getValue()))
with _ -> JavaScript.Alert "Saving data to storage failed."
member this.Delete() =
localStorage.RemoveItem key
value <- None
let [<Inline>] getJSONStorage key defaultVal = JSONStorageItem<_>(key, defaultVal) :> IStorageItem<_>
However this can currently only stringify/parse straight data objects: record, list, array, tuple and union types are ok, but no prototypes are restored.
I just started programming in lua and I created sort of oop structure following this tutorial: http://tylerneylon.com/a/learn-lua/
Problem is, when I created function that returns object or table of objects and call it inside constructor, it returns nil.
Here is my code for first object:
require "ObjectB"
ObjectA = {}
function ObjectA:new(num)
newInstance = {}
newInstance.var = self:foo(num)
self.__index = self
return setmetatable(newInstance, self)
end
function ObjectA:foo(num)
return ObjectB:new(num)
end
, and for second object:
ObjectB = {}
function ObjectB:new(num)
newInstance = {}
newInstance.num = num
self.__index = self
return setmetatable(newInstance, self)
end
When I do this:
myObject = ObjectA:new(5)
print(myObject.var.num)
, I get error: "Error: main.lua:14: attempt to index field 'var' (a nil value)".
But when I do this:
myObject = ObjectA:new(5)
myObject.var = ObjectA:foo(5) //setting var by calling foo outside of constructor
print(myObject.var.num)
, everything seems to work fine and print result is really 5. Can anyone tell me what is reason for this strange behaviour or what am I doing wrong here?
Variables are global by default, so the two variables newInstance in ObjectA:new and ObjectB:new are the same global variables, you assign it a new value, the previous value is gone.
Instead, use local variables like this:
function ObjectA:new(num)
local newInstance = {}
--the rest
end
and
function ObjectB:new(num)
local newInstance = {}
--the rest
end
I have an array, and I would like to make a function onRelease for all of the array positions.
The code would be like:
pick = new Array(2,3,4);
var botoes1:MovieClip = lev.attachMovie("block", "block_"+lev.getNextHighestDepth(), lev.getNextHighestDepth(), {_x:550, _y:1*22});
_root.botoes1.gotoAndStop(pick[1]);
var botoes2:MovieClip = lev.attachMovie("block", "block_"+lev.getNextHighestDepth(), lev.getNextHighestDepth(), {_x:550, _y:2*22});
_root.botoes2.gotoAndStop(pick[2]);
var botoes3:MovieClip = lev.attachMovie("block", "block_"+lev.getNextHighestDepth(), lev.getNextHighestDepth(), {_x:550, _y:3*22});
_root.botoes3.gotoAndStop(pick[3]);
for(i=0;i<3;i++){
_root['botoes'+i].onRelease() = Function () {
}
}
but it doesn't work this way...
and if possible, how can I make the MovieClip declaring for all the buttons in an for loop?
Couple syntax errors there, here's what this line should look like:
_root['botoes' + i].onRelease = function()
{
// Function body.
//
}
Your previous code was trying to assign the result of _root['botoes' + i].onRelease() (which would have been undefined) to the result of Function() (which would have been a Function object).
Given a number of functions test1, test2, ... belonging to a module:
module Checks =
let test1 x = ...
let test2 x = ...
...
how can the (?) operator be used to give access to both the function name and the function itself? The result should look like:
let name, func = Checks?test1
assert(name = "test1")
assert(func(x) = Checks.test1(x)) //whatever x is (test1 is known to be pure)
You cannot use the ? operator to access functions in a module, because the construct Checks?test1 is not syntactically correct (this would be translated to (?) Checks "test" and you cannot use module names as values).
However, it should be possible to do this for members of a type using an instance of the object (e.g. obj?test). Alternatively you could write a "fake" object instance (that knows the name of the module). The implementation of ? would then look for the module and search static members in the module.
The simplest implementation (of the first case) would look like this:
let (?) obj s =
let memb = obj.GetType().GetMethod(s)
// Return name and a function that runs the method
s, (fun args -> memb.Invoke(obj, args))
// Type that contains tests as members
type Check() =
member x.test1 () = 32
// We need to create instance in order to use '?'
let ch = Check()
let s,f = ch?test1
// Function 'f' takes array of objects as an argument and
// returns object, so the call is not as elegant as it could be
let n = ((f [| |]) :?> int)
You could also add some wrapping to make the function 'f' a little bit nicer, but I hope this demonstrates the idea. Unfortunately, this cannot work for modules.
Here's some sample code that shows off some of this. I use D as the 'dynamic' access of the Checks module plus function name.
module Checks =
let test1(x) = printfn "test1 %d" x
let test2(x,y) = printfn "test2 %s %d" x y
type MyDynamic() = class end
let D = new MyDynamic()
let (?) (md:MyDynamic) fname : (string * ('a -> 'r)) =
let a = md.GetType().Assembly
let t = a.GetType("Program+Checks")
let m = t.GetMethod(fname)
let f arg =
let at = arg.GetType()
let fsharpArgs =
if at.IsGenericType && at.GetGenericTypeDefinition().FullName.StartsWith("System.Tuple`") then
Microsoft.FSharp.Reflection.FSharpValue.GetTupleFields(arg)
else
[| box arg |]
unbox(m.Invoke(null, fsharpArgs))
fname, f
let Main() =
let x = 42
let s = "foo"
let name, func = D?test1
assert(name = "test1")
assert(func(x) = Checks.test1(x))
let name, func = D?test2
assert(name = "test2")
assert(func(s,x) = Checks.test2(s,x))
System.Console.ReadKey()
Main()