VBScript

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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 keyword
• CreateObject function.
• New keyword.
• FileSystem object.

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OOP Model

• Abstractions
• Encapsulation
• Polymorphism
• Inheritance
• Reusabillity

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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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Shape
Dimensions Flanks
Area
Perimeter
Circle
Radious pi
Rectangle
Triangle
Height Width
angles
3D
depth
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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 Count
• you 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 method
• A 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, OLE
• SOM, DSOM IBMs System object model
• DCOM (Distributed COM)
• Distributed COM
• CORBA Common Object Request Broker Architecture
• RMI, 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 etc
• All 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 dlls using this class.
• For more information search for ltregistrationgt
  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 object
• Set myDoc CreateObject (Word.Document)
• Using The object
• MyDoc.content abc
• MyDoc.SaveAs Doc1.doc
• MyDoc.Close
• Free the object
• Set Mydoc Nothing
• Type COM
• Library 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.FileSystemObj
  ect")
• 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.Mo
  veFolder
• Copy a folder - Folder.Copy or FileSystemObject.Co
  pyFolder
• Retrieve the name of a folder - Folder.Name
• Find out if a folder exists on a drive -
  FileSystemObject.FolderExists
• Get 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.MoveFi
  le
• Copy a file - File.Copy or FileSystemObject.CopyFi
  le
• Delete a file - File.Delete or FileSystemObject.De
  leteFile

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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

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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 Size
• GenerateFolderInformation(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.txt
• The 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 DONT 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.txt
• The 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 DONT do it an all drives, select
  only the drive were you created your file.

62
Whats 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.

63
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