One frequent question since Delphi 6
shipped has concerned the disappearance of Proxies.pas from the source.
This change is part of a larger trend.
Borland
chose not to ship DsgnIntf.dcu
with Delphi 5, apparently to force compliance with the Delphi
and C++Builder license agreements. The design-time code
had been inadvertently used at runtime by many components. In some ways Borland encouraged
this behavior: If you use the new component wizard you will see that this wizard
creates only one unit, putting both the component skeleton code (runtime) and the Register
procedure (design-time) in the same unit.
With Delphi 6,
Borland has taken the next step.
Not only was DsgnIntf
replaced with DesignIntf
, but the property
editors were also pulled out into DesignEditors
, DesignMenus
,
DesignWindows
and other design-time files. DesignEditors
in
particular uses another IDE file named Proxies
. (The Proxies
code resides in DesignIDE.bpl
.)
Needless to say, these changes can result in errors at compile time.
If your code is already segregated in
terms of runtime versus design-time then the fix is very simple. Open up your design-time
package, select the requires folder and hit the Add button. Type designide.dcp
and hit OK. Recompile your package and the error should go away.
But how can this problem be fixed when design-time and runtime code has been mixed together?
DesignIDE.bpl
is not a redistributable package in Delphi.
So even in situations where the "design-time only" package has the component's runtime code and only
the component dcu is used, there can still be a problem.
In 99.99% of the cases this is actually
very easy to fix. Your runtime code isn't actually using the design-time code; things just are not
properly segregated. The segregation lines are fairly simple, however.
The design-time package should include:
- All registration statements.
- All property editors.
- All Component editors.
- Should require DesignIDE and each runtime package that holds the components themselves.
The runtime package should include:
- The components themselves only.
- Optionally, any forms the editors may use IF the component can call the form itself at runtime
The only place where there is a little confusion is if the property/component editor uses a form. If that
form is available at runtime to the component, it belongs in the runtime package. If it is only available at
design-time, it goes in the design-time package. A very common misperception is that the form itself is the
editor, but it is not. It is the component editor that calls the form that is the design-time editor.
You should get in the habit of always separating your components into two packages even if you only statically
link your application, because mixing design-time and runtime code leads to code bloat. Your design-time code
can't be executed in the runtime, but the linker doesn't know that so it links it in anyway.
(This is why
DsgnIntf
is trying to get linked in.)
Let's walk though a very simple component to see how to
break the design-time code from the runtime:
{ TMixedComponent }
TMixedComponent = class(TComponent)
private
FFileName: String;
published
property FileName : String read FFileName write FFileName;
{ Published declarations }
end;
{ TMixedFileNameProperty }
TMixedFileNameProperty = class(TPropertyEditor)
function AllEqual: boolean; override;
procedure Edit; override;
function GetAttributes: TPropertyAttributes; override;
function GetValue: string; override;
procedure SetValue (const Value: string); override;
end;
procedure Register;
implementation
procedure Register;
begin
RegisterPropertyEditor(TypeInfo(string), TMixedComponent, 'FileName', TMixedFileNameProperty);
RegisterComponents('Samples', [TMixedComponent]);
end;
function TMixedFileNameProperty.AllEqual: boolean;
var
FirstVal: string;
i: Integer;
begin
FirstVal := GetStrValue;
Result := True;
i := 1;
while Result and (i < PropCount) do
begin
Result := Result and (GetStrValueAt(i) = FirstVal);
Inc(i);
end;
end;
procedure TMixedFileNameProperty.Edit;
var
Dlg: TOpenDialog;
begin
Dlg := TOpenDialog.Create(Application);
try
with Dlg do
begin
Title := 'File for ' + TComponent(GetComponent(0)).Name;
FileName:= Value;
if Execute then Value := FileName;
end;
finally
FreeAndNil(Dlg);
end
end;
function TMixedFileNameProperty.GetAttributes: TPropertyAttributes;
begin
Result := [paDialog]
end;
function TMixedFileNameProperty.GetValue: string;
begin
Result := GetStrValue;
end;
procedure TMixedFileNameProperty.SetValue(const Value: string);
begin
SetStrValue(Value);
end;
end.
The easiest way to segregate the design-time code from runtime code is to take all the code
that requires DesignIntf and DesignEditors and put it in its own unit. That unit will need
to use the component's unit. The component itself does not have need to know about the
IDE editors that will work with it. So for a start, remove the design-time units DesignIntf
and DesignEditors from the uses clause component unit and let the compiler/linker tell
you which classes need to be moved into their own unit:
- [Error] MixedComponent.pas(23): Undeclared identifier: 'TPropertyEditor'
- [Error] MixedComponent.pas(23): Class type required
- [Error] MixedComponent.pas(24): Method 'AllEqual' not found in base class
- [Error] MixedComponent.pas(25): Method 'Edit' not found in base class
- [Error] MixedComponent.pas(26): Undeclared identifier: 'TPropertyAttributes'
- [Error] MixedComponent.pas(27): Method 'GetValue' not found in base class
- [Error] MixedComponent.pas(28): Method 'SetValue' not found in base class
- [Error] MixedComponent.pas(35): Undeclared identifier: 'RegisterPropertyEditor'
- [Error] MixedComponent.pas(35): Undeclared identifier: 'TMixedFile'
- [Error] MixedComponent.pas(46): Undeclared identifier: 'GetStrValue'
- [Error] MixedComponent.pas(49): Undeclared identifier: 'PropCount'
- [Error] MixedComponent.pas(51): Undeclared identifier: 'GetStrValueAt'
- [Error] MixedComponent.pas(51): Operator not applicable to this operand type
- [Error] MixedComponent.pas(64): Undeclared identifier: 'GetComponent'
- [Error] MixedComponent.pas(65): Undeclared identifier: 'Value'
- [Error] MixedComponent.pas(75): Undeclared identifier: 'paDialog'
- [Error] MixedComponent.pas(80): Undeclared identifier: 'GetStrValue'
- [Error] MixedComponent.pas(85): Undeclared identifier: 'SetStrValue'
- [Fatal Error] JOComponents.dpk(33): Could not compile used unit 'MixedComponent.pas'
The next step is to create a new unit to hold the design-time code. Name it something like
MixedComponentReg. Move the Register procedure over to that unit. Now start going through the
error messages and start evaluating them. The first error, [Error]
MixedComponent.pas(23): Undeclared identifier: 'TPropertyEditor', indicates that the whole
class inherits from something in one of the design-time units we removed. This is a clear indication
that this is only design-time code and the whole class needs to be moved over to the newly created unit.
At this point the runtime package now compiles cleanly (if not, keep pulling design-time code
out until it compiles cleanly without errors). Now there is no need for Proxies.pas
or any other design-time units for the component to work in your application at runtime. The runtime
component unit is much simplified. It looks like this:
unit MixedComponent;
interface
uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs;
type
{ TMixedComponent }
TMixedComponent = class(TComponent)
private
FFileName: String;
published
property FileName : String read FFileName write FFileName;
{ Published declarations }
end;
implementation
end.
The final step is to get the component and its property editors compiled into a design-time
package and installed into the IDE.
Create a new package by doing File | New | Other and
select package. Bring up the packages options and select design-time
only. Give a descriptive name in the Description field. Select the Requires
folder and hit the Add button.
In the Requires Package edit box type Designide.dcp and hit OK.
Also add the dcp for the
runtime package that the component resides in. In this case it was put it in JOComponents.dpk,
so JOComponents.dcp is added to the requires section. The requires section has three items:
JOComponents, designide and rtl. Finally, select the Contains folder and add MixedComponentReg.pas
to the package.
We're almost done!
Open up MixedComponentReg.pas to add a couple of
units in the uses section. Which section depends on whether your component or property editor uses
the component in its declaration (more complicated editors sometimes need knowledge
of the component). If it does, then add it to the Interface uses clause. If not,
put
it in the implementation uses. In our example we don't need the information so MixedComponent goes in the
implementation uses clause. DesignIntf and DesignEditors belong in the Interface uses.
SysUtils, Forms, Dialogs, and Classes are all used internally in different ways in the property
editor, so they belong in the implementation section. The final MixedComponentReg looks like this:
unit MixedComponentReg;
interface
uses DesignIntf, DesignEditors;
type
{ TMixedFileNameProperty }
TMixedFileNameProperty = class(TPropertyEditor)
function AllEqual: boolean; override;
procedure Edit; override;
function GetAttributes: TPropertyAttributes; override;
function GetValue: string; override;
procedure SetValue (const Value: string); override;
end;
procedure Register;
implementation
uses MixedComponent, SysUtils, Forms, Dialogs, Classes;
procedure Register;
begin
RegisterPropertyEditor(TypeInfo(string), TMixedComponent, 'FileName', TMixedFileNameProperty);
RegisterComponents('Samples', [TMixedComponent]);
end;
function TMixedFileNameProperty.AllEqual: boolean;
var
FirstVal: string;
i: Integer;
begin
FirstVal := GetStrValue;
Result := True;
i := 1;
while Result and (i < PropCount) do
begin
Result := Result and (GetStrValueAt(i) = FirstVal);
Inc(i);
end;
end;
procedure TMixedFileNameProperty.Edit;
var
Dlg: TOpenDialog;
begin
Dlg := TOpenDialog.Create(Application);
try
with Dlg do
begin
Title := 'File for ' + TComponent(GetComponent(0)).Name;
FileName:= Value;
if Execute then Value := FileName;
end;
finally
FreeAndNil(Dlg);
end
end;
function TMixedFileNameProperty.GetAttributes: TPropertyAttributes;
begin
Result := [paDialog]
end;
function TMixedFileNameProperty.GetValue: string;
begin
Result := GetStrValue;
end;
procedure TMixedFileNameProperty.SetValue(const Value: string);
begin
SetStrValue(Value);
end;
end.
All that is left is to compile and install the design-time package.
The runtime
code is now completely segregated from the design-time code.
While this is a fairly
simple example, the only time it gets a little more complicated is when the property
editor uses a form to retrieve the data, and that form is also available at runtime.
In those cases the form stays in the runtime package, and the design-time
property editor will call that form from the runtime package.
If you get in the habit of always having a runtime package for the components and
a design-time package for the registration and editors, you won't have any more problems,
even if you only intend to statically link in the DCUs.
By Jeff Overcash (TeamB).
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