Working with object variables

WORKING WITH OBJECT VARIABLES

Visual Basic for Applications

Objectives

• Explain how properties and variables are stored in memory

• Create an object variable using the Dim statement

• Select the appropriate name and data type for an object variable

• Use the Set statement to assign an object’s address to an object variable

Objectives

• Excel:• Insert a row, value, and formula into a worksheet• Format an Excel worksheet

• Word:• Assign a theme to a Word document • Create a hyperlink in a Word document

• Access: • Open an Access report• Order the records in an Access report

Concept Lesson:Using object variables

• Every object has a set of properties

• Values of those properties control the object’s appearance and behavior

• VBA stores each property, along with its corresponding value in the internal memory

• VBA automatically reserves memory cells for the properties of every object it creates

• Memory cells have value, name and data type

Variables

• A programmer also can reserve memory cells for

storing information

• The memory cells reserved by the programmer

are called variables

• Variables created by the programmer must have

• Name

• data type

Variables

• Numeric variables• Store only numbers

• String variables• Store numbers, letters, and special characters

• Object variables• Store memory address of the object

• Make procedures easier to write and understand

• Help to improve the performance of a procedure

• Faster access to the property of an object: Application.Presentations(1).Slides(1).Name

An Object Variable and the Object to Which It Refers

Instructions to Display the First Slide Object’s Name and Layout

Properties

Exhibit 3-2: The instructions to display the first Slide object’s Name and Layout properties

Instructions to Display the First Slide Object’s Name and Layout

Properties• Without an object variable

• Application.Presentations(1).Slides(1). Name• Application.Presentations(1).Slides(1). Layout

• With object variable named sldFirst• sldFirst.Name• sldFirst.Layout

Object Variables

• Without an object variable: • VBA needs to locate the appropriate Application, Presentation, and Slide objects

in memory for each property

• With an object variable:

• VBA uses to the memory address of the object for each property

• The sldFirst object variable contains an address that points directly to the location of the Slide object in memory

Scope of Variables

• A variable’s scope refers to which procedures in the project can use the variable

• There are three scoping levels: • procedure-level

• private module-level (available only to procedures in that module)

• public module-level (available to all procedures in all modules)

• Module-level variables and constants are defined in the Declarations section of a module

• Module-level constants are private by default.

Reserving a procedure-level variable

• A procedure-level variable is declared, within a procedure, and it can be used only by the procedure in which it is declared

• Use Dim statement to reserve a procedure-level variable• The syntax of the Dim statement is

Dim variablename As datatype

where variablename represents the name of the variable

and datatype represents its data type

• Using Dim statement in a procedure VBA reserves a memory cell called variablename whose data type is datatype

Selecting the Appropriate Data Type and Name for an Object Variable

• Need to assign a data type to each variable• If an object variable will point to a

• Document object, then the object variable’s data type willbe Document

• Worksheet object, then the object variable’s data type will be Worksheet

• You also must assign a name to the variable• The variable name should help you remember

• data type • purpose of the variable

Data Types Corresponding to Some of the Objects Available

in the Microsoft Office Applications

Exhibit 3-3: The data types corresponding to some of the objects available in Microsoft Office applications

Naming Conventions• Following a naming convention is a valuable practice. • RVBA Naming Conventions

• http://www.xoc.net/standards/rvbanc.asp

• Leszynski Naming Conventions• http://en.wikipedia.org/wiki/Leszynski_naming_convention

• Microsoft Consulting Services Naming Conventions for Visual Basic• http://support.microsoft.com/?kbid=110264

• Object Hungarian Notation Naming Conventions for VB• http://support.microsoft.com/kb/q173738

• Our Notation: Define your variable beginning with three-character ID that identifies it’s data type

Data Types and Their Three-Character IDs

Exhibit 3-4: The data types and their three-character IDs

Rules and Examples for Variable Names

Exhibit 3-5: The rules and examples for variable names

Selecting the Appropriate Data Type and Name

for an Object Variable• VBA automatically initializes the object variable to the

keyword Nothing

Exhibit 3-6: Some examples of the Dim statement used to declare object variables

Using the Set Statement

• You use the Set statement to assign the address of an object to an object variable

• The syntax of the Set statement is • Set objectVariableName=object

• objectVariableName is the name of an object variable

• object is the object whose address you want to store in the variable

• The Set statement locates the object in memory and then stores the object’s address in the memory cell whose name is objectVariableName

Examples of the Set Statement

• Set sldFirst = Application.Presentations(1).Slides(1)

• Set docSales = Application.Documents(1)

• Set shtPay = Application.Workbooks(1).Workshees(1)

• Set rptBonus = Application.Reports(“bonus”)

• Set rngVBA = Application.Documents(“vba.doc”).Sentences(4)

Summary

To create a procedure-level object variable, and then assign an address to it:

• Use the Dim statement to create the variable

• Use the Set statement to assign the address of an object to an object variable

Excel: Creating the FormatWorksheet Macro Procedure

Exhibit 3-8: The sales workbook showing First Quarter worksheet

Worksheet Format Desired by the District Sales Manager

Exhibit 3-9: The worksheet format desired by the district manager

Worksheet Format Desired by the Regional Sales Manager

Exhibit 3-10: The worksheet format required by regional sales manager

Creating the FormatWorksheet Macro Procedure

Exhibit 3-11: The pseudocode for the FormatWorksheet procedure

Inserting Rows Into a Worksheet

• You insert a row into a worksheet using the syntax:• worksheetObject.Rows(rowNumber).Insert

• worksheetObject is the name of a Worksheet object• rowNumber is the row above which the new row will be inserted

Entering a Value and Formula Into aRange Object

• Recall that a row, a column, or a group of contiguous

or noncontiguous cells in a worksheet also are Excel

Range objects

Entering a Formula Into a Range Object

• You need to enter the following formulas in cells B13 through D13 in the worksheet:B13 formula = SUM (B4:B12)

C13 formula = SUM (C4:C12)

D13 formula = SUM (D4:D12)

Exhibit 3-13: The two ways of entering the SUM formulas into cells B13 through D13

Formatting and previewing Worksheet Objects

• A collection of predesigned worksheet formats is availablein Excel

Exhibit 3-14: The names of some of the Excel predesigned formats

Word Lesson:Creating the FormatPromo Macro Procedure

• A theme in Microsoft Word is a set of unified design elements and color schemes for

• Background images

• Bullets

• Fonts

• Horizontal lines

• Other document elements

Promo Document

Example of a Formatted Document

Exhibit 3-16: The formatted document

Pseudocode for theFormatPromo Procedure

Exhibit 3-17: The pseudocode for the FormatPromo procedure

Partial Listing of Themes Availablein Microsoft Word

• The default location for theme data folders is C:\Program Files\Common Files\Microsoft Shared\Themes

• You must use the folder name for the theme

Applying a Theme to a Document

• You use the ApplyTheme method to apply a theme to a document

• The syntax of the ApplyTheme method is:

• documentObject.ApplyTheme Name:=themeName

• documentObject is the name of a Document object

• themeName is the name of a theme

• Example:

• docVBA.applytheme name:=“Breeze"

ApplyTheme in Word 2007

Changing the Document’s Font Size

• You use the following syntax to change the size of the font used in the document: documentObject.Content.Font.Size=font Size

• Example:

docVBA.content.font.size = l2

Adding a Hyperlink to a Document

• You use the Add method of the Document object’s Hyperlinks collection to add a hyperlink to a document

• The syntax of the Add method is documentObject.Hyperlinks.Add Anchor:=rangeObject, Address:=linkAddress

• Example:docVBA.Hyperlinks.Add _Anchor:=docVBA.Sentences(1),Address:="http://www.Oakton.edu"

Hyperlinks.Add in Word 2010

Access Lesson:Creating and using object variables in

Access• Open Professor Martinez’s database, which is located in the

• Student Data\Tut03\Access folder

• View the StudentReport

Creating the DisplayByGrade Procedure

Exhibit 3-19: The pseudocode for the DisplayByGrade procedure

Opening an Access Report

• You use the OpenReport method of the DoCmd object to open an Access report

• The syntax of the OpenReport method is:• DoCmd.OpenReport Reportname:=reportName, View:=viewName

• where reportName is the name of a report

• viewName is the name of a view

• Example

• DoCmd.OpenReport Reportname:=“Students”

DoCmd.OpenReport in Access 2010

Valid View Names for the OpenReport Method’s

View Argument

Exhibit 3-20: The valid view names for the OpenReport method’s View argument

Ordering the Records in a Report

• To change the order of the records that appear in a report, you need first to set the Report object’s OrderByOn property to the Boolean value True