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Web Database Developer's Guide with Visual Basic 5

World Wide Web Database Developer's Guide with Visual Basic 5





-B-

Visual Basic 5 Naming Conventions

With Visual Basic 5, VBScript, and Active Server Page development, it is more important than ever for you to develop naming standards and conventions for applications, components, and Web pages. If you are a single developer or you work in a team with several other developers, naming conventions will make your code and script files easier to read and maintain. By using the same prefixes for objects and variables, it will be easier for you and your colleagues to read through code and script files without having to refer back to a variable or object to determine the type. I recommend using standard Visual Basic naming conventions published by Microsoft in the Visual Basic 5.0 Programmers Guide in the section "Visual Basic Coding Conventions." Many programmers and software shops have made the published Microsoft standards their own, so you will find moving from job to job easier. Regardless of whose naming standards you or your organization adopts, make sure that you use some sort of naming standards; don't code without them!


TIP: Always use many, many comments in your script files and code. It makes life so much easier for you and anyone who has to maintain your code


Module, Class, Function, and Procedure Headers

When you develop Visual Basic modules, you should make sure that each module includes a header with an overview of the module's use. You can use the same type of header in a Visual Basic form, a VBScript, a file, or a Active Server Page. Listing B.1 shows an example of these headers.

Listing B.1. A module, form, VBScript, or Active Server Page header.

`*******************************************************
`               Sams Publishing
`*******************************************************
`
`Purpose:
`
`
`*******************************************************
`History:
`   Mark Spenik     10/31/96
` Initial Release
`
`*******************************************************

A class module should have a header as well. Also, make sure that you document the class so that descriptions can be viewed by using the Object Browser. Listing B.2 shows a class header.

Listing B.2. A class page header.

`***************************************************************************
`               Sams Publishing
`
`Class:
`Purpose:
`
`  Notes:
`
`History:
`   Mark Spenik     05/28/96
` Initial Release
`

`***************************************************************************

Procedures and functions should have a descriptive header with less detail, as shown in Listing B.3.

Listing B.3. A procedure or function header.

`Description:
`Input Parameters:
`Outputs:
`History

Control Naming Conventions

The naming conventions listed in Table B.1 are for common ActiveX controls. These naming conventions are suggested by Microsoft. I have found them to be widely accepted in the industry, so I recommend that you use them. You can find a similar detailed list in the Visual Basic Developers Guide that ships with Visual Basic 5. When using the naming standards, make sure that you choose a descriptive name that describes the control (spell it out). The prefix for a textbox is txt, for example. If you will have a textbox that will hold a person's first name, a good name for the control would be txtFirstName--not txtfrstname.

Table B.1. Naming Prefixes for Commonly Used Controls.

Control Prefix
Checkbox chk
Combo box cbo
Command button cmd
Common dialog box dlg
Data control dat
Data-bound combo box dbcbo
Data-bound grid dbgrd
Data-bound listbox dblst
Form frm
Frame fra
Graph gra
Image img
Label lbl
Listbox lst
OLE ole
Picture pic
Progress bar prg
Report rpt
Textbox txt
Timer tmr
Toolbar tlb


Other Naming Conventions

You should use naming conventions as well for data-access objects and variables. I have not seen the Microsoft standards for variables and data-access objects as widely adopted as the control standards, so this section takes a look at a few naming conventions. Again, regardless of the naming standard, it is important that you use one and use it consistently.

Variable Scope

The most common naming standard to help a programmer determine the scope of a variable is to use the first letter of the variable name as the scope. A global variable starts with a lowercase g, a module-level variable starts with a lowercase m, and local variables have no prefix. (Table B.2 provides some examples.)

Variable Naming Conventions

I like the variable naming standards provided by Microsoft. I think they are consistent with the naming conventions of controls, because they use a three-digit prefix to name the variable. I have been beaten up a few times in standards meetings by other programmers who wanted a simpler variable naming convention, though. Table B.2 lists the variables, the Microsoft- suggested standard, and a common standard I have seen used quite frequently.

Table B.2. Variable Naming Nonventions.

Type Microsoft Standard Other
Boolean bln bool
Currency cur c
Date dtm dtm
Double dbl d
Integer int i
Long lng l
Object obj o
String str s
Variant vnt v


An integer status value might have the following names, for example (notice the use of the scope prefix):

Data-Access Naming Conventions

I have seen more naming conventions in data-access objects (DAOs) than in any of the other areas described here. I have seen some companies use the prefix ds to represent a DAO dynaset and ss to represent a DAO snapshot. I prefer standards that can be used by DAO, Remote Data Objects (RDOs), and Active Data Objects (ADOs) for data-access objects. Table B.3 lists some common prefixes for data-access objects. In the Microsoft DAO column, Yes means that the standard is a Microsoft-suggested DAO standard; No means that it is not a Microsoft standard for DAO. You can use the naming conventions in this table for DAO, RDO, and ADO.

Table B.3. Data-access Naming Conventions.

Data Object Prefix Microsoft DAO
Connection cnn No
DAO QueryDef/ qry Yes
RDO query object
DAO Recordset rec Yes
Database db Yes
Resultset rst No