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VBScript

Session 11

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What we learn last session?

VBScript string manipulation.VBScript string math.VBScript date manipulation.VBScript Formatting Strings.

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Subjects for session 11

The OOP model.Objects.COM objects.Set statement.Nothing keywordCreateObject function.New keyword.FileSystem object.

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OOP Model

AbstractionsEncapsulationPolymorphismInheritanceReusabillity

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OOP ModelAbstractions

The ability for a program to ignore some aspects of the information it's manipulating, i.e. the ability to focus on the essential.An abstract class cannot be instantiated. An abstract class may contain abstract methods and accessors. An abstract class can be partially implemented, or not at all implemented. Abstract classes are useful when creating components because they allow you specify an invariant level of functionality in some methods, but leave the implementation of other methods until a specific implementation of that class is needed.

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OOP ModelEncapsulation

The ability for the program to hide information about the implementation of a module from its users, i.e. the ability to prevent users from breaking the invariants of the program.The term encapsulation refer to Information hiding in software.

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OOP ModelPolymorphism

Polymorphism is the ability for classes to provide different implementations of methods that are called by the same name. Polymorphism allows a method of a class to be called without regard to what specific implementation it provides.

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OOP ModelPolymorphism

• You might have a class named Road which calls the Drive method of an additional class.

• This Car class may be SportsCar, or SmallCar, but both would provide the Drive method.

• Though the implementation of the Drive method would be different between the classes, the Road class would still be able to call it, and it would provide results that would be usable and interpretable by the Road class.

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OOP ModelInheritance

Defining classes as extensions of existing classes. In computer science, the term inheritance may be applied to a variety of situations in which certain characteristics are passed on from one context to another. The term originates with the biological  concept of a parent passing on certain traits to a child

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DimensionsFlanks

Rectangle

Shape

Triangle

Circle

Area

Perimeter

Radious*pi angles

HeightWidth

3D depth

Where is the right place for this action?

Volume

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OOP ModelReusabillity

reusability is the likelihood a segment of structured code can be used again to add new functionalities with slight or no modification. Reusable code reduces implementation time, increases the likelihood that prior testing and use has eliminated bugs and localizes code modifications when a change in implementation is required. Subroutines or functions are the simplest form of reuse. A chunk of code is regularly organized using module or namespace. Proponents claim that objects and software components offer a more advanced form of reusability.

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Object Model

Object.Collection.Container object.Method.Event.Property.Attribute.

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Object Model Objects

In computer science , an object is a data structure (incorporating data and methods) whose instance is unique and separate from other objects, although it can "communicate" with other objects.In some occasions, some object can be conceived of as a sub program which can communicate with others by receiving or giving instructions based on its, or the other's, data or methods. Data can consist of numbers, literal strings , variables, and references.the object lifetime (or life cycle) of an object  in OOP  is the time between an object's creation (also known as instantiation or construction) till the object is no longer used, and is destructed or freed.

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Object Model Collection

An object that contains zero or more objects (member). Collections normally contain objects of the same class. Also referred to as a collection object or an object collection.Collection has normally two single read-only properties, Item and Countyou usually use the Item property or method and pass the name or index number of the member.

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Object Model Container Object

An object that contains other objects from different classes.Collection can have properties and/or methods.

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Object ModelMethods

Method is a function or subroutine that is associated with a class in OPP. Like a function in procedural languages, it may contain a set of program statements that perform an action, and (in most computer languages ) can take a set of input arguments and can return some kind of result. The purpose of a method is to provide a mechanism for changing or accessing information stored in an object of the class.

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Object ModelMethods

A method should preserve invariants associated with the class, and should be able to assume that every invariant is valid on entry to the methodA method can have parameters.method may produce output, which are constrained by postconditions  of the method. If the arguments  to a method do not satisfy their preconditions, a method can raise an exception

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Object Model Event

In the context of programming, the occurrence of some particular action or the occurrence of a change of state that can be handled by an application or COM object that is invoked in response to the triggering of an event. . For example, the arrival of a message to the SMTP service is an event that can be handled by any number of Applications or objects.

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Object ModelProperty

Properties are like smart fields. A property is an information that is associated with an object. Each property has a value. value is a keyword in the syntax for the property definition. The variable value is assigned to the property in the calling code. The type of value must be the same as the declared type of the property to which it is assigned. properties fall into two categories: run-time properties and persistent properties.

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Object ModelAttribute

Each property has attributes. Attributes provide information about the property. For example, the First Name property has the following attributes: Name, Display Name, Description, and Type. Attributes include information such as the data type of the profile property (for example, number, text, decimal, or site term), and whether the property is single-valued (for example, only one First Name entry is allowed per user) or multi-valued.

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COMComponent Object Model

An architecture for defining interfaces (a set of abstract methods and properties that encompass some common purpose) and interaction among objects implemented by widely varying software applications. All COM interfaces are extend and derived from the IUnknown, interface which includes the methods QueryInterface, AddRef, and Release. COM interfaces additionally define a binary signature that acts as a contract between the interface designer and client applications written to use the interface COM classes provide concrete implementations of COM interfaces.

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COMIUnknown

The fundamental COM interface, which must be extended by every valid COM interface. IUnknown exposes three methods:

QueryInterface, used to find out if the object supports a certain interface and return the interface if it does. AddRef, to increment the interface reference count.Release, to decrement the interface reference count.

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COMCOM Class

An implementation of one or more COM interfaces. COM objects are instances of COM classes.

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COMCOM Interface

A pointer to a vtable pointer where the first three methods in that table are QueryInterface, AddRef, and Release.

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COM ObjectsCOM Extensions Technologies

COM+(Component Services )ActiveX, OLESOM, DSOM – IBM’s System object modelDCOM (Distributed COM)

Distributed COM

CORBA – Common Object Request Broker ArchitectureRMI, JavaBeans – SUN Microsystems technologies.RPC – Remote Procedure Call.

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COM objects Where they are?

In the registry under HKEY_CLASSES_ROOT you will se all the classes registered in your system.You can find there the Scripting.FileSystemObject Key, Excel.Application key etcAll those classes can be used in VBScript.Each class has a description, a CLSID entry and some a version entry.In CLSID you will find the class identifier.If you move to HKEY_CLASSES_ROOT\CLSID you will see wich dll’s using this class.For more information search for <registration> Element topic in VBScript documentation.

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Set statement

Assigns an object reference to a variable or property, or associates a procedure reference with an event.To be valid, object must be an object type consistent with the object being assigned to it. The Dim, Private, Public, or ReDim statements only declare a variable that refers to an object. No actual object is referred to until you use the Set statement to assign a specific object. Generally, when you use Set to assign an object reference to a variable, no copy of the object is created for that variable. Instead, a reference to the object is created. More than one object variable can refer to the same object. Because these variables are references to (rather than copies of) the object, any change in the object is reflected in all variables that refer to it.

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Nothing Keyword

The Nothing keyword in VBScript is used to disassociate an object variable from any actual object. Use the Set statement to assign Nothing to an object variable. For example:

Set MyObject = Nothing

Several object variables can refer to the same actual object. When Nothing is assigned to an object variable, that variable no longer refers to any actual object. When several object variables refer to the same object, memory and system resources associated with the object to which the variables refer are released only after all of them have been set to Nothing, either explicitly using Set, or implicitly after the last object variable set to Nothing goes out of scope.

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CreateObject Function

CreateObject(servername.typename [, location])

Creates and returns a reference to an Automation object. servername - Required. The name of the application providing the object. typename - Required. The type or class of the object to create. location - Optional. The name of the network server where the object is to be created.

Automation servers provide at least one type of object. For example, a word-processing application may provide an application object, a document object, and a toolbar object.

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CreateObject Function

For example, a word-processing application may provide an application object, a document object, and a toolbar object. To create an Automation object, assign the object returned by CreateObject to an object variable:

Dim ExcelSheet

Set ExcelSheet = CreateObject("Excel.Sheet")

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CreateObject Function

Once an object is created, refer to it in code using the object variable you defined. you can access properties and methods of the new object using the object variable.

Creating an object on a remote server can only be accomplished when Internet security is turned off. You can create an object on a remote networked computer by passing the name of the computer to the servername argument of CreateObject. That name is the same as the machine name portion of a share name. For a network share named "\\myserver\public", the servername is "myserver". In addition, you can specify servername using DNS format or an IP address.

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CreateObject FunctionSummary

Creating an objectSet myDoc = CreateObject (“Word.Document”)

Using The objectMyDoc.content = “abc”MyDoc.SaveAs “Doc1.doc”MyDoc.Close

Free the objectSet Mydoc = Nothing

Type COMLibrary Class

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FileSystemObject ObjectBasics

When writing scripts it's often important to add, move, change, create, or delete folders and files.It may also be necessary to get information about and manipulate drives attached to the machine.Scripting allows you to process drives, folders, and files using the FileSystemObject (FSO) object model.

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New Keyword

Keyword used to create a new instance of a class. If objectvar contained a reference to an object, that reference is released when the new one is assigned. The New keyword can only be used to create an instance of a class.Using the New keyword allows you to concurrently create an instance of a class and assign it to an object reference variable. The variable to which the instance of the class is being assigned must already have been declared with the Dim (or equivalent) statement.

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FileSystemObejct Object Model

The FileSystemObject (FSO) object model allows you to use the familiar object.method syntax with a rich set of properties, methods, and events to process folders and files.The FSO object model gives to the QTP the ability to create, alter, move, and delete folders, or to detect if particular folders exist, and if so, where. You can also find out information about folders, such as their names, the date they were created or last modified, and so forth.The FSO object model also makes it easy to process files. When processing files, the primary goal is to store data in a space- and resource-efficient, easy-to-access format. You need to be able to create files, insert and change the data, and output (read) the data.

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FileSystemObejct Object Model

The FSO object model, which is contained in the Scripting type library (Scrrun.dll), supports text file creation and manipulation through the TextStream object. Although it does not yet support the creation or manipulation of binary files, future support of binary files is planned.

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FileSystemObject ObjectsMain

Main object.Contains methods and properties that allow you to create, delete, gain information about, and generally manipulate drives, folders, and files. Many of the methods associated with this object duplicate those in other FSO objects; they are provided for convenience.

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FileSystemObject ObjectsDrive Object

Contains methods and properties that allow you to gather information about a drive attached to the system, such as its share name and how much room is available. Note that a "drive" isn't necessarily a hard disk, but can be a CD-ROM drive, a RAM disk, and so forth. A drive doesn't need to be physically attached to the system; it can be also be logically connected through a network.

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FileSystemObject ObjectsDrive Collection

Provides a list of the drives attached to the system, either physically or logically. The Drives collection includes all drives, regardless of type. Removable-media drives need not have media inserted for them to appear in this collection.

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FileSystemObject ObjectsFile Object

Contains methods and properties that allow you to create, delete, or move a file. Also allows you to query the system for a file name, path, and various other properties.

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FileSystemObject ObjectsFiles Collection

Provides a list of all files contained within a folder.

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FileSystemObject ObjectsFolder Object

Contains methods and properties that allow you to create, delete, or move folders. Also allows you to query the system for folder names, paths, and various other properties.

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FileSystemObject ObjectsFolders Collection

Provides a list of all the folders within a Folder.

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FileSystemObject ObjectsTextStream Object

Allows you to read and write text files.

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Programming the FileSystemObject

Use the CreateObject method to create a FileSystemObject object. Use the appropriate method on the newly created object. Access the object's properties. Set objFSO = CreateObject("Scripting.FileSystemObject") Scripting is the name of the type library and FileSystemObject is the name of the object that you want to create.

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Accessing Existing Drives, Files, and Folders

To gain access to an existing drive, file, or folder, use the appropriate "get" method of the FileSystemObject object:

GetDrive GetFolder GetFile

Do not use the "get" methods for newly created objects, since the "create" functions already return a handle to that object. For example, if you create a new folder using the CreateFolder method, don't use the GetFolder method to access its properties, such as Name, Path, Size, and so forth. Just set a variable to the CreateFolder function to gain a handle to the newly created folder, then access its properties, methods, and events.

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Accessing the Object's Properties

Once you have a handle to an object, you can access its properties. For example, to get the name of a particular folder, first create an instance of the object, then get a handle to it with the appropriate method (in this case, the GetFolder method, since the folder already exists).

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Working with Drives and Folders

With the FileSystemObject (FSO) object model, you can work with drives and folders programmatically just as you can in the Windows Explorer interactively. You can copy and move folders, get information about drives and folders, and so forth.

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Getting Information About Drives

The Drive object allows you to gain information about the various drives attached to a system, either physically or over a network.

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Getting Information About Drives

The total size of the drive in bytes (TotalSize property).How much space is available on the drive in bytes (AvailableSpace or FreeSpace properties).What letter is assigned to the drive (DriveLetter property).What type of drive it is, such as removable, fixed, network, CD-ROM, or RAM disk (DriveType property).The drive's serial number (SerialNumber property).The type of file system the drive uses, such as FAT, FAT32, NTFS, and so forth (FileSystem property).Whether a drive is available for use (IsReady property) The name of the share and/or volume (ShareName and VolumeName properties) The path or root folder of the drive (Path and RootFolder properties)

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Working With Folders

Create a folder - FileSystemObject.CreateFolder Delete a folder - Folder.Delete or FileSystemObject.DeleteFolder Move a folder - Folder.Move or FileSystemObject.MoveFolder Copy a folder - Folder.Copy or FileSystemObject.CopyFolder Retrieve the name of a folder - Folder.Name Find out if a folder exists on a drive - FileSystemObject.FolderExistsGet an instance of an existing Folder object - FileSystemObject.GetFolder Find out the name of a folder's parent folder - FileSystemObject.GetParentFolderName Find out the path of system folders - FileSystemObject.GetSpecialFolder

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Working With Files

There are two major categories of file manipulation

Creating, adding, or removing data, and reading files.Moving, copying, and deleting files.

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Creating Files

There are three ways to create an empty text file.The first way is to use the CreateTextFile method. The second way to create a text file is to use the OpenTextFile method of the FileSystemObject object with the ForWriting flag set.A third way to create a text file is to use the OpenAsTextStream method with the ForWriting flag set.

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Adding Data to the File

Once the text file is created, add data to the file using the following three steps:Open the text file. Write the data. Close the file. To open an existing file, use either the OpenTextFile method of the FileSystemObject object or the OpenAsTextStream method of the File object.To write data to the open text file, use the Write, WriteLine, or WriteBlankLines methods of the TextStream object according to your task.To close an open file, use the Close method of the TextStream object. Note   The newline character contains a character or characters to advance the cursor to the beginning of the next line. Be aware that the end of some strings may already have such nonprinting characters.

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Reading Files

To read data from a text file, use the Read, ReadLine, or ReadAll method of the TextStream object. If you use the Read or ReadLine method and want to skip to a particular portion of data, use the Skip or SkipLine method. The resulting text of the read methods is stored in a string which can be displayed in a control, parsed by string functions (such as Left, Right, and Mid), concatenated, and so forth.

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Moving, Copying, and Deleting Files

The FSO object model has two methods each for moving, copying, and deleting files

Move a file - File.Move or FileSystemObject.MoveFileCopy a file - File.Copy or FileSystemObject.CopyFileDelete a file - File.Delete or FileSystemObject.DeleteFile

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Lab 11.1

Tip Const DRV_UNKNOWN = 0 Const DRV_REMOVABLE = 1 Const DRV_FIXED = 2 Const DRV_NETWORK = 3 Const DRV_CDROM = 4 Const DRV_RAMDISK = 5

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Lab 11.2

Declare the follow constants :Constants returned by Drive.DriveType

Const conDriveTypeRemovable = 1 Const conDriveTypeFixed = 2 Const conDriveTypeNetwork = 3 Const conDriveTypeCDROM = 4 Const conDriveTypeRAMDisk = 5

Constants returned by File.Attributes Const conFileAttrNormal = 0 Const conFileAttrReadOnly = 1 Const conFileAttrHidden = 2 Const conFileAttrSystem = 4 Const conFileAttrVolume = 8 Const conFileAttrDirectory = 16 Const conFileAttrArchive = 32 Const conFileAttrAlias = 64 Const conFileAttrCompressed = 128

Constants for opening files Const conOpenFileForReading = 1 Const conOpenFileForWriting = 2 Const conOpenFileForAppending = 8

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Lab 11.2

Write the following functions.ShowDriveType(objDrive) - Generates a string describing the drive type of a given Drive object.ShowFileAttr(objFile) - Generates a string describing the attributes of a file or folder. GenerateDriveInformation(objFSO) – reports about the Drive Letter,Path, Type, IsReady, ShareName, VolumeName, TotalSize, FreeSpace, AvailableSpace, and SerialNumber.GenerateFileInformation(objFile) – File Name, Type, File Attributes, Date Created, Last Accessed, Last Modified and SizeGenerateFolderInformation(objFolder) – Folder Name, Folder Attributes, Date Created, Last Accessed, Last Modified and Size

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Lab 11.1

Create a Folder in the D:\ drive, if not exist in C:\ Drive.The name of the folder is VBSInfo.Create a file in the folder, TestInfo.txtThe file will contain the report of the program.The data will displayed like a table (rows and columns with headers) use the vbTab for separate the data.For getting information about the directories and files, please DON’T do it an all drives, select only the drive were you created your file.

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Lab 11.1

Create a Folder in the D:\ drive, if not exist in C:\ Drive.The name of the folder is VBSInfo.Create a file in the folder, TestInfo.txtThe file will contain the report of the program.The data will displayed like a table (rows and columns with headers) use the vbTab for separate the data.For getting information about the directories and files, please DON’T do it an all drives, select only the drive were you created your file.

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What’s Next

What means error handling.When to use On Error statements.Using the error object.Raising our own errors.

The next session is for advanced users.

Make sure to visit us

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