Naming Conventions

1
Naming Conventions

• Objects and variables must have a unique name
• Default names
• Rename, as a minimum, all objects that are
  influenced by code
• Do it before you write code!
• Cmd Command Buttons Chk CheckBox
• Lbl Label Cbo ComboBox
• Txt TextBox Lst ListBox
• Opt Option/Radio Button Img Image

2
Wizard Code

• Private Sub CmdOpenSplitting_Click()
• On Error GoTo Err_CmdOpenSplitting_Click
• Dim stDocName As String
• Dim stLinkCriteria As String
• stDocName "Splitting lines of code"
• DoCmd.OpenForm stDocName, , , stLinkCriteria
• Exit_CmdOpenSplitting_Click
• Exit Sub
• Err_CmdOpenSplitting_Click
• MsgBox Err.Description
• Resume Exit_CmdOpenSplitting_Click
• End Sub

3
Housekeeping

• Delete an object with code and the code remains
• Re-create the object and you get duplicate code
• Tidy up as you go

4
Control Constructs

• Control the flow of a program
• Sequence
• Each line of code is performed in order
• Selection
• One block of code is performed rather than
  another
• Iteration
• A block of code is repeated a number of times

5
The If Statement

• Syntax
• If condition Then statements Else else
  statements
• Example
• txtInput.SetFocus
• If txtInput.Text Fred Then txtInput.BackColor
  RGB(100, 150, 175)

6
The If Statement

• Syntax
• If condition Then
• statements
• ElseIf condition-n Then
• elseif statements
• Else
• else statements
• End If

• Example
• txtInput1.Text.SetFocus
• If txtInput1.Text Fred Then
• txtOutput.SetFocus
• txtOutput.Text Hello Fred
• ElseIf txtInput1.Text Peter Then
• txtOutput.SetFocus
• txtOutput.Text Hello Peter
• Else
• txtOutput.SetFocus
• txtOutput.Text Hello whoever you are
• End If

7
The Select Case Statement

• Syntax
• Select Case testexpressionCase expressionlist-n
  statements-n ...Case Else else statements
• End Select
• Example
• txtThree.SetFocus
• Select Case txtThree.Text
• Case "1"
• txtOutput.SetFocus
• txtOutput.Text "You typed 1"
• Case "2"
• txtOutput.SetFocus
• txtOutput.Text "You typed 2"
• Case Else
• txtOutput.SetFocus
• txtOutput.text What you have typed in not 1
  or 2
• End Select

8
The Do Statement

• Syntax
• Do While Until condition
• statementsExit Do
• statements
• Loop
• Or
• Do
• statementsExit Dostatements
• Loop While Until condition

• Example - Factorials e.g. 4! 4321
• Dim input_value
• Dim multiplier As Integer
• Dim result As Long
• txtInput.SetFocus
• input_value txtInput.Text
• multiplier input_value
• result input_value
• Do Until multiplier 1
• result result (multiplier - 1)
• multiplier multiplier - 1
• Loop
• TxtOutput.SetFocus
• TxtOutput.Text input_value "! " result

9
The For Next Statement

• Syntax
• For counter start To end Step step
• statementsExit Forstatements
• Next counter

• Example
• Dim input_value
• Dim multiplier As Integer
• Dim result As Long
• txtInput.SetFocus
• input_value txtInput.Text
• result input_value
• For multiplier input_value To 2 Step -1
• result result (multiplier - 1)
• Next multiplier
• TxtOutput.SetFocus
• TxtOutput.Text input_value "! " result

10
Low-level Documentation

• Code is not like English
• Intimate knowledge of code doesnt last
• Help others to understand your code

11
White Space

• VBA ignores its use
• Blank lines
• groups blocks of code
• Indentation
• shows association
• Line Continuation
• If first_number gt 50 And second_number gt 50 And
  third_number gt 50 Then
• If first_number gt 50 And second_number gt 50 _
• And third_number gt 50 Then

12
In-line Comments

• Anything after a single quote on one line is
  ignored by VBA
• Comments
• Debugging
• The If statement tests if the three numbers are
  greater than 50 resulting in an appropriate
  message
• If first_number gt 50 And second_number gt 50 And
  third_number gt 50 Then
• Text1.SetFocus
• Text1.Text "these are both big numbers"
• Else
• Text1.SetFocus
• Text1.Text "at least one of these numbers
  is small"
• End If

13
High-level Documentation

• How do all the objects in your system fit
  together?
• How do you know where form/report or module code
  is used?

14
System Hierarchy Chart

• Create shapes that represent each object
• Use them consistently
• Connecting lines have arrows that show sequence
• Split diagram across more than one page
• Use drawing tool or by hand

15
Partial System Hierarchy Chart
16
Annotated Screenshots (1)

• Draw by hand or captured from the system
• Point to object with line and explain its
  function
• Use a numeric key for screens with large numbers
  of objects

17
Annotated Screenshots (2)
Form demonstrating different data types
1 - Text1 Assigned maximum integer value 2 -
Text2 Assigned a Long 3 - Text3 Assigned a
decimal number 4 - Text4 Assigned a date 5 -
Text5 A text value assigned to a variant
Command0 When clicked will assign
appropriate values to the textboxes
18
Testing (1)

• Black Box Testing
• Tests outputs against inputs
• White Box Testing
• Tests all the paths in a program
• Unit Testing
• Validating input
• Test system elements
• Integration Testing
• Putting it all together

19
Testing (2)

• Test Data
• Boundary testing
• Type testing
• Testing Regime
• What you are testing
• Data used
• Anticipated result
• Actual Result