ASP.NET Web PDF Document Viewer/Editor Control Library

Now that execution has been suspended, you re free to perform tasks such as inspecting variable values and viewing the call stack to determine the exact order of execution. So far, the hard breakpoint has probably worked exactly as you expected it to work. Now, how about the future breakpoint How can you suspend execution at the future breakpoint since there is no action or event that you control that causes its execution Recall that JavaScript code that exists outside the body of a function is executed as soon as the page is loaded. So, to encounter the breakpoint at line 11, you need to switch to the browser window and click the Reload button. Doing so will reload the page and suspend

how to print a barcode in excel 2010, free barcode generator excel 2013, excel barcode add-in, how to add barcode font to excel 2003, microsoft excel 2007 barcode add in, barcode font excel 2016, barcode plugin for excel free, barcode in excel vba, create barcode labels in excel 2010, excel barcode inventory template,

#light let mutable number = "one" phrase <- 1 When attempting to compile this code, you ll get the following error message: Prog.fs(9,10): error: FS0001: This expression has type int but is here used with type string The other major difference is where these changes are visible. When you redefine an identifier, the change is visible only within the scope of the new identifier. When it passes out of scope, it reverts to its old value. This is not the case with mutable identifiers. Any changes are permanent, whatever the scope. The next example demonstrates this: #light let redefineX() = let x = "One" printfn "Redefining:\r\nx = %s" x if true then let x = "Two" printfn "x = %s" x else () printfn "x = %s" x let mutableX() = let mutable x = "One" printfn "Mutating:\r\nx = %s" x if true then x <- "Two" printfn "x = %s" x else () printfn "x = %s" x redefineX() mutableX() The results are as follows: Redefining: x = One x = Two x = One Mutating: x = One x = Two x = Two

Avoiding objects is one of the first objectives for a robot. Most of the time it s better not to even touch objects, and that s where the NXT Ultrasonic Sensor comes in (see Figure 1-16).

Identifiers defined as mutable are somewhat limited because they can t be used within a subfunction. You can see this in the next example: #light let mutableY() = let mutable y = "One" printfn "Mutating:\r\nx = %s" y let f() = y <- "Two" printfn "x = %s" y f() printfn "x = %s" y The results of this example, when compiled and executed, are as follows: Prog.fs(35,16): error: The mutable variable 'y' has escaped its scope. Mutable variables may not be used within an inner subroutine. You may need to use a heapallocated mutable reference cell instead, see 'ref' and '!'. As the error messages says, this is why the ref type, a special type of mutable record, has been made available to handle mutable variables that need to be shared among several functions. I discuss mutable records in the next section and the ref type in the section after that.

Figure 1-5. Amazon s diamond search If it isn t exactly new, the approach that is the meat of Ajax is an important shift in the Internet s default request/response paradigm. Web application developers are now free to interact with the server asynchronously, meaning they can perform many tasks that before were limited to thick clients. For example, when a user enters a zip code, you can validate it and populate other parts of a form with the city and state; or when they select United States, you can populate a state drop-down list. We ve been able to mimic these approaches before, but it s much simpler to do with Ajax.

In 3, when you first met record types, I did not discuss how to update their fields. This is because record types are immutable by default. F# provides special syntax to allow the fields in record types to be updated. You do this by using the keyword mutable before the field in a record type. I should emphasize that this operation changes the contents of the record s field rather than changing the record itself. #light type Couple = { her : string ; mutable him : string } let theCouple = { her = "Elizabeth Taylor " ; him = "Nicky Hilton" } let print o = printf "%A\r\n" o let changeCouple() = print theCouple; theCouple.him <- "Michael Wilding"; print theCouple; theCouple.him <- "Michael Todd"; print theCouple; theCouple.him <- "Eddie Fisher"; print theCouple;

Figure 1-16. NXT Ultrasonic Sensor The guts of the sensor are shown in Figure 1-17. The two cylindrical objects connected with wires to the PCB are the ultrasonic speaker and microphone.