Naming conventions

As you use PowerBuilder to develop your application, you create many different components that require names. These components include objects such as windows and menus, controls that go into your windows, and variables for your event and function scripts.

You should devise a set of naming conventions and follow them throughout your project. When you are working in a team, this is critical to enforcing consistency and enabling others to understand your code. This section provides tables of common naming conventions. PowerBuilder does not require you to use these conventions, but they are followed in many PowerBuilder books and examples.

All identifiers in PowerBuilder can be up to 255 characters long. The first few characters are typically used to specify a prefix that identifies the kind of object or variable, followed by an underscore character, followed by a string of characters that uniquely describes this particular object or variable.

Object naming conventions

Table 5-2 shows common prefixes for objects that you create in PowerBuilder.

**Table 5-2: Common prefixes for objects**
Prefix	Description
w_	Window
m_	Menu
d_	DataWindow
pipe_	Data Pipeline
q_	Query
n_ or n_standardobject_	Standard class user object, where standardobject represents the type of object; for example, n_trans
n_ or n_cst	Custom class user object
u_ or u_standardobject_	Standard visual user object, where standardobject represents the type of object; for example, u_cb
u_	Custom visual user object
f_	Global function
of_	Object-level function
s_	Global structure
str_	Object-level structure
ue_	User event

Variable naming conventions

The prefix for variables typically combines a letter that represents the scope of the variable and a letter or letters that represent its datatype. Table 5-3 lists the prefixes used to indicate a variable’s scope. Table 5-4 lists the prefixes for standard datatypes, such as integer or string.

The variable might also be a PowerBuilder object or control. Table 5-5 lists prefixes for some common PowerBuilder system objects. For controls, you can use the standard prefix that PowerBuilder uses when you add a control to a window or visual user object. To see these prefixes, open the Window painter, select Design>Options, and look at the Prefixes 1 and Prefixes 2 pages.

**Table 5-3: Prefixes that indicate the scope of variables**
Prefix	Description
a	Argument to an event or function
g	Global variable
i	Instance variable
l	Local variable
s	Shared variable

**Table 5-4: Prefixes for standard datatypes**
Prefix	Description
a	Any
blb	Blob
b	Boolean
ch	Character
d	Date
dtm	DateTime
dc	Decimal
dbl	Double
e	Enumerated
i	Integer
l	Long
r	Real
s	String
tm	Time
ui	UnsignedInteger
ul	UnsignedLong

**Table 5-5: Prefixes for selected PowerBuilder system objects**
Prefix	Description
ds	DataStore
dw	DataWindow
dwc	DataWindowChild
dwo	DWobject
env	Environment
err	Error
gr	Graph
inet	Inet
ir	InternetResult
lvi	ListViewItem
mfd	MailFileDescription
mm	MailMessage
mr	MailRecipient
ms	MailSession
msg	Message
nvo	NonVisualObject
tr	Transaction
tvi	TreeViewItem