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Converting Code To Verbose Syntax
f#classesasync

Gentlemen,

Following is the code from BeginningF#

how would one convert this to Verbose Syntax

i have tried and tried but something is always wrong.

it says one cannot have do with in if/then/else etc etc.. i am able to write verbose syntax in open module without classes but this asyn block and let bindings in class seems problametic.kindly help

it would clear lot of concepts for me of verbose

syntax.because i dont want to write in indented

syntax ( my apologies.. )

open System

open System.Threading

open System.ComponentModel

open System.Windows.Forms

open System.Drawing.Imaging

open System.Drawing

type Updates<'a> =

| AddValue of 'a

| GetValues of AsyncReplyChannel<list<'a>>

| Stop

type Collector<'a>(?updatesCount) =

let updatesCount = match updatesCount with Some x -> x | None -> 100

let context = AsyncOperationManager.SynchronizationContext

let runInGuiContext f =

context.Post(new SendOrPostCallback(fun _ -> f()), null)

let event = new Event<list<'a>>()

let mailboxWorkflow (inbox: MailboxProcessor<_>) =

let rec loop curr master =

async { // read a message

let! msg = inbox.Receive()

match msg with

| AddValue x ->

let curr, master = x :: curr, x :: master

if List.length curr > updatesCount then

do runInGuiContext(fun () -> event.Trigger(curr))

return! loop [] master

return! loop curr master

| GetValues channel ->

channel.Reply master

return! loop curr master

| Stop -> () }

calling "loop"

loop [] []

let mailbox = new MailboxProcessor<Updates<'a>>(mailboxWorkflow)

member w.AddValue (x) = mailbox.Post(AddValue(x))

member w.GetValues() = mailbox.PostAndReply(fun x -> GetValues x)

[<CLIEvent>]

member w.Updates = event.Publish

member w.Start() = mailbox.Start()

member w.Stop() = mailbox.Post(Stop)

let collector = new Collector<int*int*Color>()

let width, height = 500, 600

let form =

let bitmap = new Bitmap(width, height, PixelFormat.Format24bppRgb)

let form = new Form(Width = width, Height = height, BackgroundImage = bitmap)

collector.Updates.Add(fun points ->

List.iter bitmap.SetPixel points

form.Invalidate())

form.Load.Add(fun _ -> collector.Start())

form.Closed.Add(fun _ ->

let vals = collector.GetValues()

MessageBox.Show(sprintf "Values processed: %i" (List.length vals))

|> ignore

collector.Stop())

form

let startWorkerThread() =

let fakeSimulation() =

let rand = new Random()

let colors = [| Color.Red; Color.Green; Color.Blue |]

while true do

collector.AddValue(rand.Next(width),

rand.Next(height),

colors.[rand.Next(colors.Length)])

Thread.Sleep(rand.Next(100))

let thread = new Thread(fakeSimulation, IsBackground = true)

thread.Start()

for _ in 0 .. 5 do startWorkerThread()

Application.Run form

Thanking you

RIGHT_THEN

.

You should have a look at

[link:msdn.microsoft.com]

and pick a smaller code sample for starters.

By on 5/13/2010 5:32 AM ()

Thanks Mr. brianmcn

already tried that but didnot work

RIGHT_THEN

By on 5/13/2010 8:31 AM ()

1.) Maybe you can tell us the error you're getting? What sort of syntax errors are you seeing?

2.) Are you attempting to run this under FSI or are you attempting to compile it?

3.) I agree with Brian. Start with a smaller, simpler chunk of code and see if you can get that working.

By on 5/13/2010 11:04 AM ()

Thanks Mr. Onorio for your interest

now i have been able to make it work

with verbose but not word by word

i had to restyle many things because of my

lack of knowledge namely.

i was not able to get it right in implicit

class defination manner. so i tried changing it

to explicit class defination .

in that all let bindings had to go .i converted

all that seemed like identifier let bindings to properties

and all let bindings that seemed like Functions

i converted them to members.

the do bindings i converted to let bindings that were inside the functions. thou there is just one do binding

inside async block.

i was not able to get the updates value right so i changed it to a constant numeric value just to get it

working and it worked.

now here are some questions.

1)in verbose code inside implicit classes

are do bindings not allowed even inside

of function body??

2) i understand that all Vals have to be

initialized inside class constructors. but how to

give them null values. or what is the equivalent of null in f# like

val SomeVal:SomeClass

new () ={

SomeVal = null ; // never works

// it has to be

SomeVal = new SomeClass() ;

}

but this thing creates problems .

what if i had to pass a function pointer/delegate

inside the SomeClass() constructor that was defined inside this class the error comes that i cannot use

a memeber before class is initialized in the constructor like in the statement

let mailbox = new MailboxProcessor<Updates<'a>>(mailboxWorkflow)

this let i converted to property mailbox which

returns mailbox_val when its get() is invoked.but since

mailbox_val is a Val inside the class it has to be initialized inside new(){}; there i cannot write

new () {

mailbox_val = new MailboxProcessor<Updates<'a>>(mailboxWorkflow)

}

it gives error saying mailboxWorkflow is not approchable before class is initialised .So i had to

put the body of mailboxWorkflow through (fun -> )

here instead of mailboxWorkflow.

3) i understand how to make static members. and i can reference them outside like ClassObject.StaticMember(); but how to use them

from within a class itself.because before writing the

body of mailboxWorkflow right there inside the

constructor i tried converting it to static member

and then referencing it inside the class constructor

mailbox_val = new MailboxProcessor<Updates<'a>>(mailboxWorkflow)

but it did not work.

i have long list of questions but i think this post is allready a bother so i will leave it for next post.

now if you would be so kind

and yes i have tried smaller codes

and was able to work with them.

ThankingYou

RIGHT_THEN

By on 5/14/2010 1:25 AM ()

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