EUserHlExample: +EUser High Level example

Purpose

This +example demonstrates the following features of EUserHL:

String handling
Object creation and +automatic resource management
Memory usage by EUserHL +classes

Download

Click +on the following link to download the example: EUserHlExample.zip

Click: browse to view the example code.

Design and +implementation

The example implements three main functions:

WalkthroughStringsL() demonstrates +string handling.
WalkthroughManagedL() demonstrates +object creation and resource management.
WalkthroughUsageL() demonstrates +memory usage by EUserHL library classes.

String handling

LString is designed +to be a self-managing, resizable alternative to some of the existing descriptor +types.

WalkthroughStringsL() demonstrates how LString can +be used in similar ways to the existing TDesC and TDes descriptor +classes, as well as showing some additional functions, including:

LString::SetMaxlengthL()
LString::ReserveFreeCapacityL()
LString::Compress()
LString::Reset()

CStringUserTwoPhase is used to demonstrate the +use of LString s in the two-phase construction pattern. LCleanedupPtr is +used in place of the CleanupStack in the NewL() function.

CStringUserSinglePhase is +used to demonstrate the use of LString s in the single +phase construction pattern. A macro CONSTRUCTORS_MAY_LEAVE is +declared to ensure cleanup is correctly handled if the constructor leaves.

Object +creation and automatic resource management

The LCleanedUpXxx classes LCleanedupPtr, LCleanedupHandle, LCleanedupArray, LCleanedupGuard and LCleanedupRef classes +provide automatic resource management that avoids the need for the programmer +to use the cleanup stack.

WalkthroughManagedL() shows +how the various LCleanedUpXxx classes are used. It shows +how objects declared locally to a function (a pointer, a resource handle, +an array, and an object cleaned up using a TCleanupItem) +are deleted automatically when they go out of scope.

CManagedUserTwoPhase demonstrates +the use of the management classes in the two-phase construction pattern. LCleanedupPtr is +used in the NewL() function in place of the CleanupStack. LManagedXxx classes +(for example LManagedPtr and LManagedHandle) +are used to handle cleanup of member data.

Related APIs

CleanupStack

LCleanedupArray

LCleanedupGuard

LCleanedupHandle

LCleanedupPtr

LCleanedupRef

LManagedHandle

LManagedPtr

TCleanupItem

Memory +usage

WalkthroughUsageL() API demonstrates the +memory overhead of using EUserHL.

Building and +configuring

To build the example:

You can build the example +from your IDE or the command line.

If you use an IDE, import the bld.inf file +of the example into your IDE, and use the build command of the IDE.

If +you use the command line, open a command prompt, and set the current directory +to the source code directory of the example. You can then build the example +with the SBSv1 build tools with the following commands:

bldmake +bldfiles

abld build

How to use bldmake and How to use abld describe +how to use the SBSv1 build tools.
For the emulator, the +example builds an executable called euserhlexample.exe in +the epoc32\release\winscw\<udeb or urel>\ folder.

Running the +example

This is a console application. The user presses any key +to step through it and the emulator closes down on exit.