dsgnintf.pas單元在D6及D7中找不到的解決方法 |
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What ever happened to Proxies.pas?
Abstract: This article illustrates a scheme for properly segregating runtime code from design-time code in Delphi. By Jeff Overcash.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:
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: >unit MixedComponent; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, DesignIntf, DesignEditors; type { 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:
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). </BODY>
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