The Reddick VBA (RVBA) Naming Conventions, Version

时　间:2011-07-01 20:26:08
作　者:Aaron   ID：20267  城市：闵行
摘　要:The Reddick VBA (RVBA) Naming Conventions, Version 6.01
正　文:

The Reddick VBA (RVBA) Naming Conventions, Version 6.01
Copyright © 1992-1999 by Greg Reddick
The purpose of the Reddick VBA (RVBA) Naming Conventions is to provide a guideline for naming
objects in the Visual Basic for Applications (VBA) language. Having conventions is valuable in any
programming project. When you use them, the name of the object conveys information about the meaning
of the object. These conventions attempt to provide a way of standardizing that meaning across the body of
VBA programmers.
VBA is implemented to interact with a host application-for example, Microsoft Access, Microsoft Visual
Basic, AutoCAD, and Visio. The RVBA conventions cover all implementations of the VBA language,
regardless of the host application. Some of the tags described in this document may not necessarily have an
implementation within some of the particular host programs for VBA. The word object, in the context of
this document, refers to simple variables and VBA objects, as well as to objects made available by the
VBA host program.
While I am the editor of these conventions, they are the work of many people, including Charles Simonyi,
who invented the Hungarian conventions on which these are based, and Stan Leszynski, who co-authored
several versions of the conventions. Many others, too numerous to mention, have also contributed to the
development and distribution of these conventions, but I’d especially like to thank Paul Litwin and Ken
Getz who have made substantial contributions over the years.
These conventions are intended as a guideline. If you disagree with a particular part of the conventions,
simply replace that part with what you think works better. However, keep in mind that future generations of
programmers may need to understand those changes, and place a comment in the header of a module
indicating what changes have been made. To be concise, the conventions are presented without
rationalizations for how they were derived although each of the ideas presented has a considerable history
to it.
Changes to the Conventions
Some of the tags in the version of the conventions presented here have changed from previous versions.
Consider all previous tags to be grandfathered into the conventions--you don’t need to go back and make
changes. For new development work, I leave it up to you to decide whether to use the older tags or the ones
suggested here. In a few places in this document, older tags are shown in {braces}. As updates to this
document are made, the current version can be found at the Xoc Software web site, http://www.xoc.net.
An Introduction to Hungarian
The RVBA conventions are based on the Hungarian conventions for constructing object names, named for
the native country of the inventor, Charles Simonyi. The objective of Hungarian is to convey information
about the object concisely and efficiently. Hungarian takes some getting used to, but once adopted, it
quickly becomes second nature. The format of a Hungarian object name is
[prefixes]tag[BaseName[Suffixes]]
The square brackets indicate optional parts of the object name. These components have the following
meanings:
Component Meaning
Prefixes Modify the tag to indicate additional information. Prefixes are all
lowercase. They are usually picked from a standardized list of prefixes,
given later in this document.
Tag Short set of characters, usually mnemonic, that indicates the type of the
object. The tag is all lowercase. It is usually selected from a
standardized list of tags, given later in this document.
BaseName One or more words that indicate what the object represents. Capitalize
the first letter of each word in the BaseName.
Suffixes Additional information about the meaning of the BaseName. Capitalize
the first letter of each word in the Suffix. They are usually picked from
a standardized list of suffixes, given later in this document.
Notice that the only required part of the object name is the tag. This may seem counterintuitive; you may
feel that the BaseName is the most important part of the object name. However, consider a generic
procedure that operates on any form. The fact that the routine operates on a form is the important thing, not
what that form represents. Because the routine may operate on forms of many different types, you do not
necessarily need a BaseName. However, if you have more than one object of a type referenced in the
routine, you must have a BaseName on all but one of the object names to differentiate them. In addition,
unless the routine is generic, the BaseName conveys information about the variable. In most cases, a
variable should include a BaseName.
Tags
Use the techniques described in the following sections to construct tags to indicate the data type of an
object.
Variable tags
Use the tags listed in Table 1 for VBA data types. You can also use a specific tag instead of obj for any
data type defined by the host application or one of its objects. (See the section “Host Application and
Component Extensions to the Conventions” later in this document.)
Table 1: Tables for VBA Variables
Tag Object Type
bool {f, bln} Boolean
byte {byt} Byte
cur Currency
date {dtm} Date
dec Decimal
dbl Double
int Integer
lng Long
obj Object
sng Single
str String
stf String (fixed length)
var Variant
Here are several examples:
lngCount
intValue
strInput
You should explicitly declare all variables, each on a line by itself. Do not use the old-type declaration
characters, such as %, &, and $. They are extraneous if you use the naming conventions, and there is no
character for some of the data types, such as Boolean. You should always explicitly declare all variables of
type Variant using the As Variant clause, even though it is the default in VBA. For example:
Dim intTotal As Integer
Dim varField As Variant
Dim strName As String
Constructing Properties Names
Properties of a class present a particular problem: should they include the naming convention to indicate
the type? To be consistent with the rest of these naming conventions, they should. However, it is permitted
to have property names without the tags, especially if the class is to be made available to customers who
may not be familiar with these naming conventions.
Collection Tags
You treat a collection object with a special tag. You construct the tag using the data type of the collection
followed by the letter s. For example, if you had a collection of Longs, the tag is lngs. If it was a collection
of forms, the tag for the collection is frms. Although, in theory, a collection can hold objects of different
data types, in practice, each of the data types in the collection is the same. If you do want to use different
data types in a collection, use the objs tag. For example:
intsEntries
frmsCustomerData
objsMisc
Constants
Constants always have a data type in VBA. Because VBA will choose this data type for you if you don’t
specify it, you should always specify the data type for a constant. Constants declared in the General
Declarations section of a module should always have a scope keyword of Private or Public, and be prefixed
by the scope prefixes m or g, respectively. A constant is indicated by appending the letter c to the end of the
data type for the constant. For example:
Const intcGray As Integer = 3
Private Const mdblcPi As Double = 3.14159265358979
Although this technique is the recommended method of naming constants, if you are more concerned about
specifying that you are dealing with constants rather than their data type, you can alternatively use the
generic tag con instead. For example:
Const conPi As Double = 3.14159265358979
Menu Items
The names of menu items should reflect their position in the menu hierarchy. All menu items should use
the tag mnu, but the BaseName should indicate where in the hierarchy the menu item falls. Use Sep in the
BaseName to indicate a menu separator bar, followed by an ordinal. For example:
mnuFile (on menu bar)
mnuFileNew (on File popup menu)
mnuFileNewForm (on File New flyout menu)
mnuFileNewReport (on File New flyout menu)
mnuFileSep1 (first separator bar on file popup menu)
mnuFileSaveAs (on File popup menu)
mnuFileSep2 (second separator bar on file popup menu)
mnuFileExit (on File popup menu)
mnuEdit (on menu bar)
Creating Data Types
VBA gives you three ways to create new data types: enumerated types, classes, and user-defined types. In
each case, you will need to invent a new tag that represents the data type that you create.
Enumerated types
Groups of constants of the long data type should be made an enumerated type. Invent a tag for the type,
append a “c,” and then define the enumerated constants using that tag. Because the name used in the Enum
line is seen in the object browser, you can add a BaseName to the tag to spell out the abbreviation indicated
by the tag. For example:
Public Enum ervcErrorValue
ervcInvalidType = 205
ervcValueOutOfBounds
End Enum
The BaseName should be singular, so that the enumerated type should be ervcErrorValue, not
ervcErrorValues. The tag that you invent for enumerated types can then be used for variables that can
contain values of that type. For example:
Dim erv As ervcErrorValue
Private Sub Example(ByVal ervCur As ervcErrorValue)
While VBA only provides enumerated types of groups of the long type, you can still create groups of
constants of other types. Just create a set of constant definitions using an invented tag. For example:
Public Const estcError205 As String = "Invalid type"
Public Const estcError206 As String = "Value out of bounds"
Unfortunately, because this technique doesn’t actually create a new type, you don’t get the benefit of the
VBA compiler performing type checking for you. You create variables that will hold constants using a
similar syntax to variables meant to hold instances of enumerated types. For example:
Dim estError As String
Tags for classes and user-defined types
A class defines a user-defined object. Because these invent a new data type, you will need to invent a new
tag for the object. You can add a BaseName to the tag to spell out the abbreviation indicated by the tag.
User-defined types are considered a simple class with only properties, but in all other ways are used the
same as class modules. For example:
gphGlyph
edtEdit
Public Type grbGrabber
You then define variables to refer to instances of the class using the same tag: For example:
Dim gphNext As New gphGlyph
Dim edtCurrent as edtEdit
Dim grbHandle as grbGrabber
Polymorphism
In VBA, you use the Implements statement to derive classes from a base class. The tag for the derived class
should use the same tag as the base class. The derived classes, though, should use a different BaseName
from the base class. For example:
anmAnimal (base class)
anmZebra (derived class of anmAnimal)
anmElephant (derived class of anmAnimal)
This logic of naming derived classes is used with forms, which are all derived from the pre-defined Form
base class and use the frm tag. If a variable is defined to be of the type of the base class, then use the tag, as
usual. For example:
Dim anmArbitrary As anmAnimal
Dim frmNew As Form
On the other hand, if you define a variable as an instance of a derived class, include the complete derived
class name in the variable name. For example:
Dim anmZebraInstance As anmZebra
Dim anmElephantExample As anmElephant
Dim frmCustomerData As frmCustomer
Constructing Procedures
VBA procedures require you to name various items: procedure names, parameters, and labels. These
objects are described in the following sections.
Constructing Procedure Names
VBA names event procedures, and you cannot change them. You should use the capitalization defined by
the system. For user-defined procedure names, capitalize the first letter of each word in the name. For
example:
cmdOK_Click
GetTitleBarString
PerformInitialization
Procedures should always have a scope keyword, Public or Private, when they are declared. For example:
Public Function GetTitleBarString() As String
Private Sub PerformInitialization
Naming Parameters
You should prefix all parameters in a procedure definition with ByVal or ByRef, even though ByRef is
optional and redundant. Procedure parameters are named the same as simple variables of the same type,
except that arguments passed by reference use the prefix “r.” For example:
Public Sub TestValue(ByVal intInput As Integer, ByRef rlngOutput As Long)
Private Function GetReturnValue(ByVal strKey As String, _
ByRef rgph As Glyph) As Boolean
Naming Labels
Labels are named using upper and lower case, capitalizing the first letter of each word. For example:
ErrorHandler:
ExitProcedure:
Prefixes
Prefixes modify an object tag to indicate more information about an object.
Arrays of Objects Prefix
Arrays of an object type use the prefix “a.” For example:
aintFontSizes
astrNames
Index Prefix
You indicate an index into an array by the prefix i, and for consistency the data type should always be a
long. You may also use the index prefix to index into other enumerated objects, such as a collection of
user-defined classes. For example:
iaintFontSizes
iastrNames
igphsGlyphCollection
Prefixes for Scope and Lifetime
Three levels of scope exist for each variable in VBA: Public, Private, and Local. A variable also has a
lifetime of the current procedure or the lifetime of the object in which it is defined. Use the prefixes in
Table 2 to indicate scope and lifetime.
Table 2: Scope prefixes
Prefix Object Type
(none) Local variable, procedure-level lifetime, declared with “Dim”
s Local variable, object lifetime, declared with “Static”
m Private (module) variable, object lifetime, declared with “Private”
g Public (global) variable, object lifetime, declared with “Public”
You also use the “m” and “g” constants with other objects, such as constants, to indicate their scope. For
example:
intLocalVariable
mintPrivateVariable
gintPublicVariable
mdblcPi
VBA allows several type declaration words for backward compatibility. The older keyword “Global”
should always be replaced by “Public,” and the “Dim” keyword in the General Declarations section should
be replaced by “Private.”
Other Prefixes
Table 3 lists and describes some other prefixes:
Table 3: Other commonly-used prefixes
Prefix Object Type
c Count of some object type
h Handle to a Windows object
r Parameter passed by reference
Here are some examples:
castrArray
hWndForm
Suffixes
Suffixes modify the base name of an object, indicating additional information about a variable. You’ll
likely create your own suffixes that are specific to your development work. Table 4 lists some generic VBA
suffixes.
Table 4: Commonly-used suffixes
Suffix Object Type
Min The absolute first element in an array or other kind of list
First The first element to be used in an array or list during the current operation
Last The last element to be used in an array or list during the current operation
Lim The upper limit of elements to be used in an array or list. Lim is not a valid
index. Generally, Lim equals Last + 1
Max The absolutely last element in an array or other kind of list
Cnt Used with database elements to indicate that the item is a Counter. Counter
fields are incremented by the system and are numbers of either type Long or
type Replication Id.
Here are some examples:
iastrNamesMin
iastrNamesMax
iaintFontSizesFirst
igphsGlyphCollectionLast
lngCustomerIdCnt
varOrderIdCnt
File Names
When naming items stored on the disk, no tag is needed because the extension already gives the object
type. For example:
Test.Frm (frmTest form)
Globals.Bas (globals module)
Glyph.Cls (gphGlyph class module)
Host Application and Component Extensions to the
Conventions
Each host application for VBA, as well as each component that can be installed, has a set of objects it can
use. This section defines tags for the objects in the various host applications and components.
Access 2000, Version 9.0 Objects
Table 5 lists Access object variable tags. Besides being used in code to refer to these object types, these
same tags are used to name these kinds of objects in the form and report designers.
Table 5: Access object variable tags
Tag Object Type
aob AccessObject
aops AccessObjectProperties
aop AccessObjectProperty
app Application
bfr BoundObjectFrame
chk CheckBox
cbo ComboBox
cmd CommandButton
ctl Control
ctls Controls
ocx CustomControl
dap DataAccessPage
dcm DoCmd
frm Form
fcd FormatCondition
fcds FormatConditions
frms Forms
grl GroupLevel
hyp Hyperlink
img Image
lbl Label
lin Line
lst ListBox
bas Module
ole ObjectFrame
opt OptionButton
fra OptionGroup (frame)
brk PageBreak
pal PaletteButton
prps Properties
shp Rectangle
ref Reference
refs References
rpt Report
rpts Reports
scr Screen
sec Section
sfr SubForm
srp SubReport
tab TabControl
txt TextBox
tgl ToggleButton
Some examples:
txtName
lblInput
For ActiveX custom controls, you can use the tag ocx as specified in Table 5 or more specific object tags
that are listed later in this document in Tables 14 and 15. For an ActiveX control that doesn't appear in the
Tables 14 or 15, you can either use ocx or invent a new tag.
DAO 3.6 Objects
DAO is the programmatic interface to the Jet database engine shared by Access, Visual Basic, and Visual
C++. The tags for DAO 3.6 objects are shown in Table 6.
Table 6: DAO object tags
Tag Object Type
cnt Container
cnts Containers
db Database
dbs Databases
dbe DBEngine
doc Document
docs Documents
err Error
errs Errors
fld Field
flds Fields
grp Group
grps Groups
idx Index
idxs Indexes
prm Parameter
prms Parameters
pdbe PrivDBEngine
prp Property
prps Properties
qry QueryDef
qrys QueryDefs
rst Recordset
rsts Recordsets
rel Relation
rels Relations
tbl TableDef
tbls TableDefs
usr User
usrs Users
wrk Workspace
wrks Workspaces
Here are some examples:
rstCustomers
idxPrimaryKey
Table 7 lists the tags used to identify types of objects in a database.
Table 7: Access Database Explorer object tags
Tag Object Type
tbl Table
qry Query
frm Form
rpt Report
mcr Macro
bas Module
dap DataAccessPage
If you wish, you can use tags that are more exact or suffixes to identify the purpose and type of a database
object. If you use the suffix, use the tag given from Table 7 to indicate the type. Use either the tag or the
suffix found along with the more general tag, but not both. The tags and suffixes are shown in Table 8.
Table 8: Specific object tags and suffixes for Access Database Explorer objects
Tag Suffix Object Type
tlkp Lookup Table (lookup)
qsel (none) Query (select)
qapp Append Query (append)
qxtb XTab Query (crosstab)
qddl DDL Query (DDL)
qdel Delete Query (delete)
qflt Filter Query (filter)
qlkp Lookup Query (lookup)
qmak MakeTable Query (make table)
qspt PassThru Query (SQL pass-through)
qtot Totals Query (totals)
quni Union Query (union)
qupd Update Query (update)
fdlg Dlg Form (dialog)
fmnu Mnu Form (menu)
fmsg Msg Form (message)
fsfr SubForm Form (subform)
rsrp SubReport Form (subreport)
mmnu Mnu Macro (menu)
Here are some examples:
tblValidNamesLookup
tlkpValidNames
fmsgError
mmnuFileMnu
When naming objects in a database, do not use spaces. Instead, capitalize the first letter of each word. For
example, instead of Quarterly Sales Values Table, use tblQuarterlySalesValues.
There is strong debate over whether fields in a table should have tags. Whether you use them is up to you.
However, if you do use them, use the tags from Table 9.
Table 9: Field tags (if you decide to use them)
Tag Object Type
lng Autoincrementing (either sequential or random) Long (used with the suffix Cnt)
bin Binary
byte Byte
cur Currency
date Date/time
dbl Double
guid Globally unique identified (GUID) used for replication AutoIncrement fields
int Integer
lng Long
mem Memo
ole OLE
sng Single
str Text
bool Yes/No
Visual Basic 6.0 Objects
Table 10 shows the tags for Visual Basic 6.0 objects.
Table 10: Visual Basic 6.0 object tags
Tag Object Type
app App
chk CheckBox
clp Clipboard
cbo ComboBox
cmd CommandButton
ctl Control
dat Data
dir DirListBox
drv DriveListBox
fil FileListBox
frm Form
fra Frame
glb Global
hsb HScrollBar
img Image
lbl Label
lics Licenses
lin Line
lst ListBox
mdi MDIForm
mnu Menu
ole OLE
opt OptionButton
pic PictureBox
prt Printer
prp PropertyPage
scr Screen
shp Shape
txt TextBox
tmr Timer
uctl UserControl
udoc UserDocument
vsb VscrollBar
Microsoft ActiveX Data Objects 2.1 Tags
Office 2000 provides version 2.1 of the ActiveX Data Objects library. Table 11 lists the recommended tags
for this version of ADO.
Note: Many of the ADO, ADOX, and JRO tags overlap with existing DAO tags. Make sure you include the
object library name in all references in your code, so there’s never any possibility of confusion. For
example, use
Dim rst As ADODB.Recordset
or
Dim cat As ADOX.Catalog
rather than using the object types without the library name. This will not only make your code more explicit
and avoid confusion about the source of the object, but will also make your code run a bit faster.
Table 11: ADO 2.1 Object tags
Tag Object Type
cmn {cmd} Command
cnn {cnx} Connection
err Error
errs Errors
fld Field
flds Fields
prm Parameter
prms Parameters
prps Properties
prp Property
rst Recordset
Microsoft ADO Ext. 2.1 for DDL and Security (ADOX) Tags
In order to support DDL and security objects within Jet database, Microsoft provides ADOX, an additional
ADO library of objects. Table 12 lists tags for the ADOX objects.
Table 12: ADOX Object tags
Tag Object Type
cat Catalog
clms Column
clm Columns
cmd Command
grp Group
grps Groups
idx Index
idxs Indexes
key Key
keys Keys
prc Procedure
prcs Procedures
prps Properties
prp Property
tbl Table
tbls Tables
usr User
usrs Users
vw View
vws Views
Microsoft Jet and Replication Objects 2.1
In order to support Jet’s replication features, ADO provides another library (JRO). Table 13 lists suggested
tags for the JRO objects.
Table 13: JRO object tags
Tag Object Type
flt Filter
flts Filters
jet JetEngine
rpl Replica
Microsoft SQL Server and Microsoft Data Engine (MSDE) Objects
Table 14 lists RVBA tags for Microsoft SQL Server and the Microsoft Data Engine (a limited-connection
version of SQL Server 7) objects.
Table 14: SQL Server/MSDE object tags
Tag Object Type
tbl table
proc stored procedure
trg trigger
qry view
dgm database diagram
pk primary key
fk foreign key
idx other (non-key) index
rul check constraint
def default
Microsoft Common Control Objects
Windows 95 and Windows NT have a set of common controls that are accessible from VBA. Table 15 lists
the tags for objects created using these controls.
Table 15: Microsoft Common Control Object tags.
Tag Object Type
ani Animation
btn Button (Toolbar)
bmn ButtonMenu (Toolbar)
bmns ButtonMenus (Toolbar)
bnd Band (CoolBar)
bnds Bands (CoolBar)
bnp BandsPage (CoolBar)
btns Buttons (Toolbar)
cbr CoolBar
cbp CoolBarPage (CoolBar)
hdr ColumnHeader (ListView)
hdrs ColumnHeaders (ListView)
cbi ComboItem (ImageCombo)
cbis ComboItems (ImageCombo)
ctls Controls
dto DataObject
dtf DataObjectFiles
dtp DTPicker
fsb FlatScrollBar
imc ImageCombo
iml ImageList
lim ListImage
lims ListImages
lit ListItem (ListView)
lits ListItems (ListView)
lsi ListSubItem (ListView)
lsis ListSubItems (ListView)
lvw ListView
mvw MonthView
nod Node (TreeView)
nods Nodes (TreeView)
pnl Panel (Status Bar)
pnls Panels (Status Bar)
prb ProgressBar
sld Slider
sbr StatusBar
tab Tab (Tab Strip)
tabs Tabs (Tab Strip)
tbs TabStrip
tbr Toolbar
tvw TreeView
udn UpDown
Other Custom Controls and Objects
Finally, Table 16 lists the tags for other commonly used custom controls and objects.
Table 16: Tags for commonly-used custom controls
Tag Object Type
cdl CommonDialog (Common Dialog)
dbc DBCombo (Data Bound Combo Box)
dbg DBGrid (Data Bound Grid)
dls DBList (Data Bound List Box)
gau Gauge (Gauge)
gph Graph (Graph)
grd Grid (Grid)
msg MAPIMessages (Messaging API Message Control)
ses MAPISession (Messaging API Session Control)
msk MaskEdBox (Masked Edit Textbox)
key MhState (Key State)
mmc MMControl (Multimedia Control)
com MSComm (Communication Port)
out Outline (Outline Control)
pcl PictureClip (Picture Clip Control)
rtf RichTextBox (Rich Textbox)
spn SpinButton (Spin Button)
Summary
Using a naming convention requires a considerable initial effort on your part. The payoff comes when
either you or another programmer has to revisit your code later. Using the conventions given here will
make your code more readable and maintainable.
Greg Reddick is the President of Xoc Software, a software development company developing programs in
Visual Basic, Microsoft Access, C/C++, and for the web. He leads training seminars in Visual Basic for
Application Developers Training Company (AppDev). In a previous life, he worked for four years on the
Access development team at Microsoft. Greg can be reached at mailto:grr@xoc.net or from the Xoc
Software web site, http://www.xoc.net.

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