Delphi Handle in negative

Question

I am working on a project in delphi XE5. Different Popup menus are created at run time using same function. Names are given each time to pop up using "Handle" from Tcomponent class.

popupname := 'XYZ' + IntToStr(handle);

On some system I get "Handle" value as negative, when I try to give name with "-" sign to a component i get error message "XYZ-5645 not a valid component name"

Can you please suggest me a way out?

In XE3 `THandle = NativeUInt;` Note unsigned type. How it is defined in XE5? Are you sure that handle value is negative? — MBo, Nov 10 '16 at 06:26
@MBo IntToStr accepts signed int so there is an implicit cast to signed. — David Heffernan, Nov 10 '16 at 06:54
Although on XE7, the Int64 overload is selected first, so I think you need a 64 bit target before you could hit this condition........ Perhaps there are a different set of overloads in the XE5 RTL. — David Heffernan, Nov 10 '16 at 08:22
Since handle is unsigned you can use `UIntToStr(handle)` instead. — LU RD, Nov 10 '16 at 09:53
@LU not on x64, and since the type floats with pointer size, and is a pointer surely its best treated that way — David Heffernan, Nov 10 '16 at 13:05
@DavidHeffernan, but will the compiler not select the overloaded uint64 version on x64? — LU RD, Nov 10 '16 at 13:08
@DavidHeffernan, Looking into latest [documentation](http://docwiki.embarcadero.com/Libraries/Berlin/en/System.THandle), `type THandle = Cardinal;` indicates that it does not float with pointer size. But docs have been wrong before. — LU RD, Nov 10 '16 at 13:17
[THandle type is wrongly documented](https://quality.embarcadero.com/browse/RSP-16295) — LU RD, Nov 10 '16 at 13:45

David Heffernan · Accepted Answer · 2016-11-10T13:32:05.807

10

Instead of IntToStr, which accepts a signed integer, you can treat the handle as a pointer, and so represent the numeric value as hex:

popupname := Format('XYZ%p', [Pointer(Handle)]);

This makes sense because a handle in Windows is, as defined in the header files, an untyped pointer, void*.

As an added benefit your code will now be correct on both 32 and 64 bit platforms.

Thinking outside the box, perhaps the component does not need a name at all. If so, remove this code, leave it unmanned and thus side-step your problem.

edited Nov 10 '16 at 13:32

answered Nov 10 '16 at 06:38

David Heffernan

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@poonam Do take heed of the last sentence. If you're compelled to give a runtime generated component a `.Name` to solve some sort of problem, it's extremely likely that it is simply the wrong solution and that there is a better way to produce the same behaviour. – J... Nov 10 '16 at 11:21
"Untapped"? Did you mean "untyped"? – Rudy Velthuis Nov 10 '16 at 13:31
Yes I did mean that – David Heffernan Nov 10 '16 at 13:32

Delphi Handle in negative

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