Delphi Developer's Guide Coding Standards Document
Copyright © 1998 Xavier Pacheco and Steve
Teixeira
Modifications © 1998 Econos -
Stefan Hoffmeister
Version 1.1.0
29 September 1998
Republished with
permission
Introduction
General Source
Code Formatting Rules
Object Pascal
Files
Forms and
Data Modules
Packages
Components
Introduction
This document describes the coding standards for Delphi programming as used
in Delphi 4 Developer's Guide. In general, this document follows the
often "unspoken" formatting guidelines used by Borland International with a few
minor exceptions. The purpose for including this document in Delphi 4
Developer's Guide is to present a method by which development teams can
enforce a consistent style to the coding that they do. The intent is to make it
so that every programmer on a team can understand the code being written by
other programmers. This is accomplished by making the code more readable by use
of consistency.
This document by no means includes everything that might exist in a coding
standard. However, it does contain enough detail to get you started. Feel free
to use and modify these standards to fit your needs. We don't recommend,
however, that you deviate too far from the standards used by Borland's
development staff. We recommend this because as you bring new programmers to
your team, the standards that they are most likely to be most familiar with are
Borland's. Like most coding standards documents, this document will evolve as
needed. Therefore, you will find the most updated version online at http://www.xapware.com/ddg/.
[Note: this applies to the original, unmodified version of
this document] This document does not cover user interface
standards. This is a separate but equally important topic. Enough
third-party books and Microsoft documentation cover such guidelines that we
decided not to replicate this information but rather to refer you to the
Microsoft Developers Network and other sources where that information may be
available.
Material changes applied to this document by Econos -
Stefan Hoffmeister have been coloured in red. Material changes
are understood to be changes or additions to the original document, but not
changes in the layout or in the formatting of the original document.
General Source Code Formatting Rules
Indentation
Indenting will be two spaces per level. Do not save tab characters to source
files. The reason for this is because tab characters are expanded to different
widths with different users settings and by different source management
utilities (print, archive, version control, etc.).
You can disable saving tab characters by turning off the "Use tab character"
and "Optimal fill" check boxes on the Editor page of the Environment Options
dialog (accessed via Tools | Environment).
Margins
Margins will be set to 80 characters. In general, source shall not exceed
this margin with the exception to finish a word, but this guideline is somewhat
flexible. Wherever possible, statements that extend beyond one line should be
wrapped after a comma or an operator. When a statement is wrapped, it should be
indented so that logically grouped segments are on the same
level of indentation.
Comments
For commenting, usually { } pairs shall be used.
The alternative notation of (* *) shall be reserved for temporarily removing code ("commenting
out") during development.
The use of // shall be restricted to
one-line comments.
Conditional Defines
Conditional defines shall be created with curly braces - "{",
"}" - and with the conditional command in uppercase.
Each conditional define is named again in the closing block to
enhance readability of the code.
They shall be indented in the same manner as blocks - for
example
if ... then
begin
{$IFDEF VER90}
raise Exception.CreateRes(SError);
{$ELSE}
raise Exception.Create(SError);
{$ENDIF VER90}
end;
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Begin..End Pair
The begin statement appears on its own line. For
example, the following first line is incorrect; the second line is correct:
for I := 0 to 10 do begin // Incorrect, begin on same line as for
for I := 0 to 10 do // Correct, begin appears on a separate line
begin
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An exception to this rule can be
made when the begin statement appears as part of
an else clause - for example,
if some statement = ... then
begin
...
end
else begin
SomeOtherStatement;
end;
|
but the preferred way of writing this is
if some statement = ... then
begin
...
end
else
begin
SomeOtherStatement;
end;
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so that the begin statement always
appears indented on the same level as the corresponding if statement.
The end statement always appears on its own line.
When the begin statement is not part of an else clause, the corresponding end
statement is always indented to match its begin part.
Object Pascal
Parenthesis
There shall never be white space between an open parenthesis and the next
character. Likewise, there shall never be white space between a closed
parenthesis and the previous character. The following example illustrates
incorrect and correct spacing with regard to parentheses:
CallProc( AParameter ); // incorrect
CallProc(AParameter); // correct
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Never include extraneous parentheses in a statement. Parentheses should only
be used where required to achieve the intended meaning in source code. The
following examples illustrate incorrect and correct usage:
if (I = 42) then // incorrect - extraneous parentheses
if (I = 42) or (J = 42) then // correct - parentheses required
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Reserved Words and Key Words
Object Pascal language reserved words and key words shall always be
completely lowercase. By default, the syntax high-lighting
feature of the IDE will already print these words in bold face. You shall not
use uppercase for any of these words..
Procedures and Functions (Routines)
Naming / Formatting
Routine names shall always begin with a capital letter and be camel-capped
for readability. The following is an example of an incorrectly formatted
procedure name:
procedure thisisapoorlyformattedroutinename;
|
This is an example of an appropriately capitalized routine name:
procedure ThisIsMuchMoreReadableRoutineName;
|
Routines shall be given names meaningful to their content. Routines that
cause an action to occur will be prefixed with the action verb, for example:
procedure FormatHardDrive;
|
Routines that set values of input parameters shall be prefixed with the word
set - for example,
Routines that retrieve a value shall be prefixed with the word get - for example,
function GetUserName: string;
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Formal Parameters
Formatting
Where possible, formal parameters of the same type shall be combined into one
statement:
procedure Foo(Param1, Param2, Param3: Integer; Param4: string);
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Naming
All formal parameter names will be meaningful to their purpose and typically
will be based off the name of the identifier that was passed to the routine.
When appropriate, parameter names will be prefixed with the character A - for example,
procedure SomeProc(AUserName: string; AUserAge: integer);
|
The "A" prefix is a convention to disambiguate when the parameter name is the
same as a property or field name in the class.
Ordering of Parameters
The following formal parameter ordering emphasizes taking advantage of
register calling conventions calls.
Most frequently used (by the caller) parameters shall be in the first
parameter slots. Less frequently used parameters shall be listed after that in
left to right order.
Input lists shall exist before output lists in left to right order.
Place most generic parameters before most specific parameters in left to
right order. For example: SomeProc(APlanet, AContinent, ACountry, AState,
ACity).
Exceptions to the ordering rule are possible, such as in the case of event
handlers, when a parameter named Sender of type TObject is often passed as the first parameter.
Constant Parameters
When parameters of record, array, ShortString, or
interface type are unmodified by a routine, the formal parameters for that
routine shall mark the parameter as const. This ensures
that the compiler will generate code to pass these unmodified parameters in the
most efficient manner.
Parameters of other types may optionally be marked as const if they are unmodified by a routine. Although this will
have no effect on efficiency, it provides more information about parameter use
to the caller of the routine.
Name Collisions
When using two units that each contain a routine of the same name, the
routine residing unit appearing last in the uses clause will be invoked if you
call that routine. To avoid these uses-clause-dependent ambiguities, always
prefix such method calls with the intended unit name-for example,
or
Windows.FindClose(Handle);
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Variables
Variable Naming and Formatting
Variables will be given names meaningful to their purpose.
Loop control variables are generally given a single character name such as
I, J, or K.
It is acceptable to use a more meaningful name as well such as UserIndex.
Boolean variable names must be descriptive enough so that their meanings of
True and False values will be
clear.
Declaring Variables
When declaring variable, there shall be no multiple declarations
for one type. Each variable is assigned always assigned a specific type - for
example
var
i: Integer;
j: Integer;
|
It is acceptable to prefix each variable declaration with the
var keyword - for example
var i: Integer;
var j: Integer;
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Local Variables
Local variables used within procedures follow the same usage and naming
conventions for all other variables. Temporary variables will be named
appropriately.
When necessary, initialization of local variables will occur immediately upon
entry into the routine. Local AnsiString variables are
automatically initialized to an empty string, local interface and dispinterface
type variables are automatically initialized to nil, and local Variant and OleVariant type variables
are automatically initialized to Unassigned.
Use of Global Variables
Use of global variables is discouraged. However, they may be used when
necessary. When this is the case, you are encouraged to keep global variables
within the context where they are used. For example, a global variable may be
global only within the scope of the a single unit's implementation section.
Global data that is intended to be used by a number of units shall be moved
into a common unit used by all.
Global data may be initialized with a value directly in the var section. Bear in mind that all global data is automatically
zero-initialized, so do not initialize global variables to "empty" values such
as 0, nil, '', Unassigned, and so on. One reason for this is because
zero-initialized global data occupies no space in the exe file. Zero-initialized
data is stored in a 'virtual' data segment that is allocated only in memory when
the application starts up. Non-zero initialized global data occupies space in
the exe file on disk.
To explicitly document the assumption that global variables are
zero-initialized, a comment to make this clear should be added - for example
Types
Capitalization Convention
Type names that are reserved words shall be completely lowercase. Win32 API
types are generally completely uppercase, and you should follow the convention
for a particular type name shown in the Windows.pas or other API unit. For other
variable names, the first letter shall be uppercase, and the rest shall be
camel-capped for clarity. Here are some examples:
var
MyString: string; // reserved word
WindowHandle: HWND; // Win32 API type
I: Integer; // type identifier introduced in System unit
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Floating Point Types
Use of the Real type is discouraged because it exists
only for backward compatibility with older Pascal code. Use Double for general purpose floating point needs. Also, Double
is what the processor instructions and busses are optimized for and is an IEEE
defined standard data format. Use Extended only when more
range is required than that offered by Double. Extended is an Intel specified type and not supported on Java.
Use Single only when the physical byte size of the
floating point variable is significant (such as when using other-language DLLs).
Enumerated Types
Names for enumerated types must be meaningful to the purpose of the
enumeration. The type name must be prefixed with the T
character to annotate it as a type declaration. The identifier list of the
enumerated type must contain a lowercase two to three character prefix that
relates it to the original enumerated type name-for example,
TSongType = (stRock, stClassical, stCountry);
|
Variable instances of an enumerated type will be given the same name as the
type without the T prefix (SongType) unless there is a
reason to give the variable a more specific name such as FavoriteSongType1, FavoriteSongType2,
and so on.
Variant and OleVariant
The use of the Variant and OleVariant types is discouraged in general, but these types are
necessary for programming when data types are known only at runtime, such as is
often the case in COM and database development. Use OleVariant for COM-based programming such as Automation and
ActiveX controls, and use Variant for non-COM programming. The reason is that a
Variant can store native Delphi strings efficiently (same as a string var), but
OleVariant converts all strings to Ole Strings (WideChar strings) and are not
reference counted-they are always copied.
Structured Types
Array Types
Names for array types must be meaningful to the purpose for the array. The
type name must be prefixed with a T character. If a
pointer to the array type is declared, it must be prefixed with the character
P and declared immediately prior to the type declaration
- for example,
type
PCycleArray = ^TCycleArray;
TCycleArray = array[1..100] of Integer;
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When practical, variable instances of the array type will be given the same
name as the type name without the T prefix.
Record Types
A record type shall be given a name meaningful to its purpose. The type
declaration must be prefixed with the character T. If a
pointer to the record type is declared, it must be prefixed with the character
P and declared immediately prior to the type declaration.
The type declaration for each element may optionally be aligned in a column to
the right - for example,
type
PEmployee = ^TEmployee;
TEmployee = record
Name: string;
Rate: Double;
end;
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Statements
if Statements
The most likely case to execute in an if/then/else statement shall be placed in
the then clause, with less likely cases residing in the
else clause(s).
Try to avoid chaining if statements and use case statements instead if at all
possible.
Do not nest if statements more than five levels deep. Create a clearer
approach to the code.
Do not use extraneous parentheses in an if statement.
If multiple conditions are being tested in an if statement, conditions should
be arrange from left to right in order of least to most computation intensive.
This enables your code to take advantage of short-circuit Boolean evaluation
logic built into the compiler. For example, if Condition1
is faster than Condition2 and Condition2 is faster than Condition3,
then the if statement should be constructed as follows:
if Condition1 and Condition2 and Condition3 then
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When multiple conditions are tested it, sometimes is advisable
to have each condition on a line of its own. This is particularly important in
those cases, where one or more conditional statements are long. If this style is
chosen, the conditions are indented, so that they align to each other - for
example
if Condition1 and
Condition2 and
Condition3 then
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Reading top-to-bottom usually is easier than reading
left-to-right, especially when dealing with long, complex constructs.
When a part of an if statement extends
beyond a single line, a begin/end
pair shall be used to group these lines. This rule shall also apply when only a
comment line is present or when a single statement is spread over multiple
lines.
The else clause shall always be aligned
with the corresponding if clause.
case Statements
General Topics
The individual cases in a case statement should be
ordered by the case constant either numerically or alphabetically. If you use a user-defined type, order the individual statements
according to the order of the declaration of the type.
In some situations it may be advisable to order the case
statements to match their importance or frequency of hit.
The actions statements of each case should be kept simple and generally not
exceed four to five lines of code. If the actions are more complex, the code
should be placed in a separate procedure or function. Local
procedures and functions are well-suited for this.
The use of the else clause of a case statement should be used only for legitimate defaults.
It should always be used to detect errors and document
assumptions, for instance by raising an exception in the else clause.
All separate parts of the case statement
have to be indented. All condition statements shall be written in begin..end
blocks. The else clause aligns with the case statement - for example:
case Condition of
condition:
begin
...
end;
else { case }
...
end;
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The else clause of the case statement shall have a comment indicating that it belongs
to the case statement.
Formatting
case statements follow the same formatting rules as
other constructs in regards to indentation and naming conventions.
while Statements
The use of the Exit procedure to exit a while loop is discouraged; when possible, you should exit the
loop using only the loop condition.
All initialization code for a while loop should occur directly before
entering the while loop and should not be separated by
other non-related statements.
Any ending housekeeping shall be done immediately following the loop.
for Statements
for statements should be used in place of while statements when the code must execute for a known number
of increments.
In those cases, where stepping is needed, use a while statement
that starts from the known end of the loop down to start condition - for
example:
i := AList.Count-1;
while i => 0 do
i := i - 2;
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repeat statements
repeat statements are similar to while loops and should follow the same general guidelines.
with Statements
General Topics
The with statement should be used sparingly and with
considerable caution. Avoid overuse of with statements
and beware of using multiple objects, records, and so on in the with statement. For example:
These things can confuse the programmer and can easily lead to
difficult-to-detect bugs.
Formatting
with statements follow the same formatting rules in
regard to naming conventions and indentation as described in this document.
Structured Exception Handling
General Topics
Exception handling should be used abundantly for both error correction and
resource protection. This means that in all cases where resources are allocated,
a try..finally must be used to ensure proper deallocation
of the resource. The exception to this is cases where resources are allocated /
freed in the initialization / finalization of a unit or the constructor /
destructor of an object.
Use of try..finally
Where possible, each allocation will be matched with a try..finally construct. For example, the following code could
lead to possible bugs:
SomeClass1 := TSomeClass.Create
SomeClass2 := TSomeClass.Create;
try
{ do some code }
finally
SomeClass1.Free;
SomeClass2.Free;
end;
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A safer approach to the above allocation would be:
SomeClass1 := TSomeClass.Create
try
SomeClass2 := TSomeClass.Create;
try
{ do some code }
finally
SomeClass2.Free;
end;
finally
SomeClass1.Free;
end;
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Use of try..except
Use try..except only when you want to perform some
task when an exception is raised. In general, you should not use try..except to simply show an error message on the screen
because that will be done automatically in the context of an application by the
Application object. If you want to invoke the default
exception handling after you have performed some task in the except clause, use
raise to re-raise the exception to the next handler.
Use of try..except..else
The use of the else clause with try..except is discouraged because it will block all
exceptions, even those for which you may not be prepared.
Classes
Naming / Formatting
Type names for classes will be meaningful to the purpose of the class. The
type name must have the T prefix to annotate it as a type
definition-for example,
type
TCustomer = class(TObject)
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Instance names for classes will generally match the type name of the class
without the T prefix - for example,
Note: See the section on User-defined
Components for further information on naming components.
Fields
Naming / Formatting
Class field names follow the same naming conventions as variable identifiers
except that they are prefixed with the F annotation to
signify they are field names.
Visibility
All fields should be private. Fields that are accessible outside the class
scope will be made accessible through the use of a property.
Declaration
Each field shall be declared with a separate type on a separate
line - for example
TNewClass = class(TObject)
private
FField1: Integer;
FField2: Integer;
end;
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Methods
Naming / Formatting
Method names follow the same naming conventions as described for procedures
and functions in this document.
Use of Static Methods
Use static methods when you do not intend for a method to be overridden by
descendant classes.
Use of virtual / dynamic Methods
Use virtual methods when you intend for a method to be overridden by
descendant classes. Dynamic should only be used on classes to which there will
be there will be many descendant (direct or indirect). For example, a class
containing one infrequently overridden method and 100 descendent classes should
make that method dynamic to reduce the memory use by the 100 descendent classes.
It is not guaranteed, though, that making a method dynamic
instead of virtual will reduce the memory requirements. Additionally, the
benefits from using dynamic in terms of resource consumption are so negligible
that is is possible to say:
Always make methods virtual, and only under
exceptional circumstances dynamic.
Use of Abstract Methods
Do not use abstract methods on classes of which instances will be created.
Use abstract only on base classes that will never be created.
Property Access Methods
All access methods must appear in the private or protected sections of the
class definition.
Property access methods naming conventions follow the same rules as for
procedures and functions. The read accessor method (reader method) must be
prefixed with the word Get. The write accessor method
(writer method) must be prefixed with the word Set. The
parameter for the writer method will have the name Value,
and its type will be that of the property it represents - for example,
TSomeClass = class(TObject)
private
FSomeField: Integer;
protected
function GetSomeField: Integer;
procedure SetSomeField(Value: Integer);
public
property SomeField: Integer read GetSomeField write SetSomeField;
end;
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Properties
Naming / Formatting
Properties that serve as accessors to private fields will be named the same
as the fields they represent without the F annotator.
Property names shall be nouns, not verbs. Properties represent data, methods
represent actions.
Array property names shall be plural. Normal property names shall be
singular.
Use of Access Methods
Although not required, it is encouraged to use at a minimum a write access
method for properties that represent a private field.
Files
Project Files
Project files will be given descriptive names. For example, The Delphi 4
Developer's Guide Bug Manager is given the project name: DDGBugs.dpr. A system information program will be given a name
like SysInfo.dpr.
Form Files
A form file will be given a name descriptive of the form's purpose postfixed
with the three characters Frm. For example, the About
Form will have a filename of AboutFrm.dpr. The Main Form
will have the filename MainFrm.dpr.
Data Module Files
A data module will be given a name that is descriptive of the datamodule's
purpose. The name will be postfixed with the two characters DM. For example, the Customers data module will have a form
filename of CustomersDM.dfm.
Remote Data Module Files
A remote data module will be given a name that is descriptive of the remote
datamodule's purpose. The name will be postfixed with the three characters RDM. For example, the Customers remote data module will have a
form filename of CustomersRDM.dfm.
Unit Files
Unit Name
Unit files will be given descriptive names. For example, the unit containing
an application's main form might be called MainFrm.pas.
Uses Clauses
The uses clause in the interface section will only contain units required by
code in the interface section. Remove any extraneous unit names that might have
been automatically inserted by Delphi.
The uses clause of the implementation section will only contain units
required by code in the implementation section. Remove any extraneous unit
names.
Interface Section
The interface section will contain declarations for only those types,
variables, procedure / function forward declarations, and so on that are to be
accessible by external units. Otherwise, these declarations will go into the
implementation section.
Implementation Section
The implementation section shall contain any declarations for types,
variables, procedures / functions and so on that are private to the containing
unit.
Initialization Section
Do not place time-intensive code in the initialization section of a unit.
This will cause the application to seem sluggish when first appearing.
Finalization Section
Ensure that you deallocate any items that you allocated in the Initialization
section.
Form Units
A unit file for a form will be given the same name as its corresponding form
file. For example, the About Form will have a unit name of AboutFrm.pas. The Main Form will have the unit filename of
MainFrm.pas.
Data Module Units
Unit files for data modules will be given the same names as their
corresponding form files. For example the Customers data module unit will have a
unit name of CustomersDM.pas.
General Purpose Units
A general purpose unit will be given a name meaningful to the unit's purpose.
For example, a utilities unit will be given a name of BugUtilities.pas. A unit
containing global variables will be given the name of CustomerGlobals.pas.
Keep in mind that unit names must be unique across all packages used by a
project. Generic or common unit names are not recommended.
Component Units
Component units will be placed in a separate directory to distinguish them as
units defining components or sets of components. They will never be placed in
the same directory as the project. The unit name must be meaningful to its
content.
Note: See the section on User-defined
Components for further information on component naming standards.
File Headers
Use of informational file header is encouraged for all source files, project
files, units, and so on. A proper file header must contain the following
information:
{
Copyright © YEAR by AUTHORS
}
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Usually this header will be augmented with contact information
and a one-line description of the unit's purpose. An example of this would be
{***************************************************************}
{ }
{ This line describes the purpose of the unit }
{ }
{ Copyright (c) 1998 WidgetMakers, Ltd. }
{ [email protected] }
{ }
{ All rights reserved. }
{ }
{***************************************************************}
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Forms and Data Modules
Forms
Form Type Naming Standard
Forms types will be given names descriptive of the form's purpose. The type
definition will be prefixed with a T. A descriptive name
will follow the prefix. Finally, Form will postfix the
descriptive name. For example, the type name for the About Form will be
TAboutForm = class(TForm)
|
The main form definition will be
The customer entry form will have a name like
TCustomerEntryForm = class(TForm)
|
Form Instance Naming Standard
Form instances will be named the same as their corresponding types without
the T prefix. For example, for the preceding form types,
the instance names will be as follows:
| Type Name |
Instance Name |
| TAboutForm |
AboutForm |
| TMainForm |
MainForm |
| TCustomerEntryForm |
CustomerEntryForm |
Auto-creating Forms
Only the main form will be auto-created unless there is good reason to do
otherwise. All other forms must be removed from the auto-create list in the
Project Options dialog box. See the following section for more information.
Modal Form Instantiation Functions
All form units will contain a form instantiation function that will create,
set up, show the form modally, and free the form. This function will return the
modal result returned by the form. Parameters passed to this function will
follow the "parameter passing" standard specified in this document. This
functionality is to be encapsulated in this way to facilitate code reuse and
maintenance.
The form variable will be removed from the unit and declared locally in the
form instantiation function. Note, that this will require that the form be
removed from the auto-create list in the Project Options dialog box. See Auto-Creating
Forms in this document.
For example, the following unit illustrates such a function for a GetUserData form.
unit UserDataFrm;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics,
Controls, Forms, Dialogs, StdCtrls;
type
TUserDataForm = class(TForm)
edtUserName: TEdit;
edtUserID: TEdit;
private
{ Private declarations }
public
{ Public declarations }
end;
function GetUserData(var aUserName: string; var aUserID: Integer): Word;
implementation
{$R *.DFM}
function GetUserData(var aUserName: string; var aUserID: Integer): Word;
var
UserDataForm: TUserDataForm;
begin
UserDataForm := TUserDataForm.Create(Application);
try
UserDataForm.Caption := 'Getting User Data';
Result := UserDataForm.ShowModal;
if Result = mrOK then
begin
aUserName := UserDataForm.edtUserName.Text;
aUserID := StrToInt(UserDataForm.edtUserID.Text);
end;
finally
UserDataForm.Free;
end;
end;
end.
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Data Modules
Data Module Naming Standard
A DataModule type will be given a name descriptive of
the data module's purpose. The type definition will be prefixed with a T. A descriptive name will follow the prefix. Finally, the name
will be postfixed with the word "DataModule". For example, the type name for the
Customer data module would be something like:
TCustomerDataModule = class(TDataModule)
|
The Orders data module would have a name like
TOrdersDataModule = class(TDataModule)
|
Data Module Instance Naming Standard
Data module instances will be named the same as their corresponding types
without the T prefix. For example, for the preceding form
types, the instance names will be as follows:
| Type Name |
Instance Name |
| TCustomerDataModule |
CustomerDataModule |
| TOrdersDataModule |
OrdersDataModule |
Packages
Use of Runtime vs Design Packages
Runtime packages will contain only units / components required by other
components in that package. Other, units containing property / component editors
and other design only code shall be placed into a design package. Registration
units will be placed into a design package.
File Naming Standards
Packages will be named according to the following templates:
"iiilibvv.pkg" - design package
"iiistdvv.pkg" - runtime package
where the characters "iii" signify a 3-character identifying prefix. This
prefix may be used to identify the company, person or any other identifying
entity.
The characters "vv" signify a version for the package corresponding to the
Delphi version for which the package is intended.
Note that the package name contains either "lib" or "std" to signify it as a
runtime or design time package.
Where there are both design and runtime packages, the files will be named
similarly. For example, packages for Delphi 4 Developer's Guide are named as:
DdgLib40.pkg - design package
DdgStd40.pkg - runtime package
Components
User-defined Components
Components shall be named similarly to classes as defined in the section
entitled "Classes" with the exception that they are given a 3-character
identifying prefix. This prefix may be used to identify the company, person or
any other entity. For example, a clock component written for Delphi 4
Developer's Guide would be defined as:
TddgClock = class(TComponent)
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Note that the 3-character prefix is in lower case.
Component Units
Component units shall contain only one major component. A major component is
any component that appears on the Component Palette. Any ancillary components /
objects may also reside in the same unit for the major component.
Use of Registration Units
The registration procedure for components shall be removed from the component
unit and placed in a separate unit. This registration unit shall be used to
register any components, property editors, component editors, experts, etc.
Component registering shall be done only in design packages, therefore the
registration unit shall be contained in the design package and not in the
runtime package.
It is suggested that registration units are named as:
Where the "Xxx" shall be a 3-character prefix used to identify a company,
person or any other entity. For example, the registration unit for the
components in the Delphi 4 Developer's Guide would be named DdgReg.pas.
Component Instance Naming Conventions
All components must be given descriptive names. No components will be left
with their default names assigned by Delphi. Components will have a lowercase
prefix to designate their type. The reasoning behind prefixing component names
rather than post-fixing them is to make searching component names in the Object
Inspector and Code Explorer easier by component type.
Component Prefixes
The following prefixes will be assigned to the standard components that ship
with Delphi 4. Please add to this list for third-party components as they are
added.
Standard Tab
| Prefix |
Component |
| mm |
TMainMenu |
| pm |
TPopupMenu |
| mmi |
TMainMenuItem |
| pmi |
TPopupMenuItem |
| lbl |
TLabel |
| edt |
TEdit |
| mem |
TMemo |
| btn |
TButton |
| chk |
TCheckBox |
| rb |
TRadioButton |
| lb |
TListBox |
| cb |
TComboBox |
| scb |
TScrollBar |
| gb |
TGroupBox |
| rg |
TRadioGroup |
| pnl |
TPanel |
| cl |
TCommandList |
Additional Tab
| Prefix |
Component |
| bbtn |
TBitBtn |
| sb |
TSpeedButton |
| me |
TMaskEdit |
| sg |
TStringGrid |
| dg |
TDrawGrid |
| img |
TImage |
| shp |
TShape |
| bvl |
TBevel |
| sbx |
TScrollBox |
| clb |
TCheckListbox |
| spl |
TSplitter |
| stx |
TStaticText |
| cht |
TChart |
Win32 Tab
| Prefix |
Component |
| tbc |
TTabControl |
| pgc |
TPageControl |
| il |
TImageList |
| re |
TRichEdit |
| tbr |
TTrackBar |
| prb |
TProgressBar |
| ud |
TUpDown |
| hk |
THotKey |
| ani |
TAnimate |
| dtp |
TDateTimePicker |
| tv |
TTreeView |
| lv |
TListView |
| hdr |
THeaderControl |
| stb |
TStatusBar |
| tlb |
TToolBar |
| clb |
TCoolBar |
System Tab
| Prefix |
Component |
| tm |
TTimer |
| pb |
TPaintBox |
| mp |
TMediaPlayer |
| olec |
TOleContainer |
| ddcc |
TDDEClientConv |
| ddci |
TDDEClientItem |
| ddsc |
TDDEServerConv |
| ddsi |
TDDEServerItem |
Internet Tab
| Prefix |
Component |
| csk |
TClientSocket |
| ssk |
TServerSocket |
| wbd |
TWebDispatcher |
| pp |
TPageProducer |
| tp |
TQueryTableProducer |
| dstp |
TDataSetTableProducer |
| nmdt |
TNMDayTime |
| nec |
TNMEcho |
| nf |
TNMFinger |
| nftp |
TNMFtp |
| nhttp |
TNMHttp |
| nMsg |
TNMMsg |
| nmsg |
TNMMSGServ |
| nntp |
TNMNNTP |
| npop |
TNMPop3 |
| nuup |
TNMUUProcessor |
| smtp |
TNMSMTP |
| nst |
TNMStrm |
| nsts |
TNMStrmServ |
| ntm |
TNMTime |
| nudp |
TNMUdp |
| psk |
TPowerSock |
| ngs |
TNMGeneralServer |
| html |
THtml |
| url |
TNMUrl |
| sml |
TSimpleMail |
Data Access Tab
| Prefix |
Component |
| ds |
TDataSource |
| tbl |
TTable |
| qry |
TQuery |
| sp |
TStoredProc |
| db |
TDataBase |
| ssn |
TSession |
| bm |
TBatchMove |
| usql |
TUpdateSQL |
Data Controls Tab
| Prefix |
Component |
| dbg |
TDBGrid |
| dbn |
TDBNavigator |
| dbt |
TDBText |
| dbe |
TDBEdit |
| dbm |
TDBMemo |
| dbi |
TDBImage |
| dblb |
TDBListBox |
| dbcb |
TDBComboBox |
| dbch |
TDBCheckBox |
| dbrg |
TDBRadioGroup |
| dbll |
TDBLookupListBox |
| dblc |
TDBLookupComboBox |
| dbre |
TDBRichEdit |
| dbcg |
TDBCtrlGrid |
| dbch |
TDBChart |
Decision Cube Tab
| Prefix |
Component |
| dcb |
TDecisionCube |
| dcq |
TDecisionQuery |
| dcs |
TDecisionSource |
| dcp |
TDecisionPivot |
| dcg |
TDecisionGrid |
| dcgr |
TDecisionGraph |
QReport Tab
| Prefix |
Component |
| qr |
TQuickReport |
| qrsd |
TQRSubDetail |
| qrb |
TQRBand |
| qrcb |
TQRChildBand |
| qrg |
TQRGroup |
| qrl |
TQRLabel |
| qrt |
TQRText |
| qre |
TQRExpr |
| qrs |
TQRSysData |
| qrm |
TQRMemo |
| qrrt |
TQRRichText |
| qrdr |
TQRDBRichText |
| qrsh |
TQRShape |
| qri |
TQRImage |
| qrdi |
TQRDBMImage |
| qrcr |
TQRCompositeReport |
| qrp |
TQRPreview |
| qrch |
TQRChart |
Dialogs Tab
The dialog box components are really forms
encapsulated by a component. Therefore, they will follow a convention similar to
the form naming convention. The type definition is already defined by the
component name. The instance name will be the same as the type instance without
the numeric prefix, which is assigned by Delphi. Examples are as follows:
| Type |
Instance Name |
| TOpenDialog |
OpenDialog |
| TSaveDialog |
SaveDialog |
| TOpenPictureDialog |
OpenPictureDialog |
| TSavePictureDialog |
SavePictureDialog |
| TFontDialog |
FontDialog |
| TColorDialog |
ColorDialog |
| TPrintDialog |
PrintDialog |
| TPrintSetupDialog |
PrinterSetupDialog |
| TFindDialog |
FindDialog |
| TReplaceDialog |
ReplaceDialog |
Win31 Tab
| Prefix |
Component |
| dbll |
TDBLookupList |
| dblc |
TDBLookupCombo |
| ts |
TTabSet |
| ol |
TOutline |
| tnb |
TTabbedNoteBook |
| nb |
TNoteBook |
| hdr |
THeader |
| flb |
TFileListBox |
| dlb |
TDirectoryListBox |
| dcb |
TDriveComboBox |
| fcb |
TFilterComboBox |
Samples Tab
| Prefix |
Component |
| gg |
TGauge |
| cg |
TColorGrid |
| spb |
TSpinButton |
| spe |
TSpinEdit |
| dol |
TDirectoryOutline |
| cal |
TCalendar |
| ibea |
TIBEventAlerter |
ActiveX Tab
| Prefix |
Component |
| cfx |
TChartFX |
| vsp |
TVSSpell |
| f1b |
TF1Book |
| vtc |
TVTChart |
| grp |
TGraph |
Midas Tab
| Prefix |
Component |
| prv |
TProvider |
| cds |
TClientDataSet |
| qcds |
TQueryClientDataSet |
| dcom |
TDCOMConnection |
| olee |
TOleEnterpriseConnection |
| sck |
TSocketConnection |
| rms |
TRemoteServer |
| mid |
TmidasConnection |
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