Difference between revisions of "Microsoft Access VBA Naming Conventions"

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     SELECT Book.Isbn
 
     SELECT Book.Isbn
 
       FROM Book
 
       FROM Book
INNER JOIN Order
+
INNER JOIN Stock
         ON Book.Isbn = Order.BookIsbn
+
         ON Book.Isbn = Stock.BookIsbn
 
</syntaxhighlight>
 
</syntaxhighlight>
  

Revision as of 14:26, 1 April 2011

General

As novice developer you usually define names for constants, variables and methods as they occur; you look at a problem, think of a function, add some parameters and that's it.

After a few years of coding—especially once you are forced to refactor some of your legacy coding—you will realize that the code is hard to read; it somehow feels "inconsistent".

Also during normal development you will notice that you keep stumpling upon the same issues again and again: you're trying to access variables, which are not accessible, you try to use a variable for a text value and run in to an error as it has been defined for numbers: the list of little annoyances which are implied when not sticking to consistent conventions is long—add your favourite annoyance here.

The naming conventions depend on the language you are using, but for VBA it is common conviction to use either the Reddick VBA Naming Conventions or the Leszynski VBA Naming Conventions, which are both versions of the Hungarian notation.

The main idea is to prefix everything with a tag which indicates the type of the variable.


Name

All names will be in singular form. A table, for example, represents many uniformed records. Do we want to talk about many records or do we talk about the entity that table has been designed for? It is the entity.

Let's look at it with a semantic focus: We have a table "Books" which has a field "ISBN". When we are talking about "Books.ISBN", do we mean all ISBNs of all Books? Or the ISBN of a certain Book? It is usually the latter. It also makes SQL statements and code much more readable besides the fact that mixing plural ("Books") and singular ("ISBN") does not make sense. Example:

    SELECT Book.Isbn
      FROM Book
INNER JOIN Stock
        ON Book.Isbn = Stock.BookIsbn

Another advantage of generally applying singular names is the option to denote collections and arrays with a plural form, which leads to easily understandable code like

For Each varBook In varBooks
    varBook.Isbn = "unknown"
Next varBook


Tag

A tag is a usually three letter long lowercase mnemonic for the variable type. As there is not a tag for every kind of variable, you sometimes need to "invent" a tag of your own. The usual steps for finding an appropriate tag are:

  1. Take the name of the object type
  2. Remove all vowels from the name; you may keep the first vowel if necessary
  3. Take the first three letters

As soon as you found a tag you should consider the following questions too:

  • Is the tag already taken by another object type?
  • Does it phonetically sound like the object type?

If you should answer one of these questions with "yes", you should adjust the tag name accordingly.

Access Object

Tag: Access Object
Data Type Tag
Top Level Objects
Table tbl
Query qry
Form frm
Sub Form sfr
Report rpt
Sub Report srp
Module mod
Class cls
Related Objects
Field fld
Control ctl
Label lbl
Text Box txt
Combo Box cmb
List Box lst
Check Box chk
Button btn
Option Group grp
Option Button opt
Tab Control tab
Tab Control Page tpg
Frame fra
Frame bound frb
Frame unbound fru
Image img
Line lin
Page Break brk
  • cmb vs cbo
  • btn vs cmd
  • tpg vs pge
  • tgl vs btn


Data Type

Tag: Data Type
Data Type Tag
Boolean bln
Integer int
Long lng
Single sng
Double dbl
Currency cur
String str
Date dat
Variant var
Array arr, var
Type typ
Object obj