Delphi: do NOT use duplicate GUIDs on interfaces
Posted by jpluimers on 2019/04/04
One of the things when fixing bugs in an old codebase is wading through technical debt.
A quick win is to get rid of duplicate GUIDs when interface portions have been copy-paste re-used:
- interfaces with the same GUID are treated the same with
ascasts even if they are different. - the compiler does not warn about duplicate GUID values**
These searches help big time: it shows the duplicate GUIDs if they have been indented all the same way. Good enough for most situations.
grep -Sh "\[\'{" *.pas | sort
grep -rh "\[\'{" *.pas | sort
It depends which flavour of grep you use (gnu or regular) to specify recursion.
Note that findstr doesn’t cut it as it always shows the filename: [WayBack] List files recursively showing only full path and file size from Windows Command Prompt – Super User
** this compiles without warning:
program NoWarningOnDuplicateInterfaceGUID;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils;
type
IInterface1 = interface
['{ECF26C39-CBFF-488E-A3AB-2629726F1005}']
end;
IInterface2 = interface
['{ECF26C39-CBFF-488E-A3AB-2629726F1005}']
end;
var
Subject: IInterface;
begin
try
(Subject as IInterface1)._Release;
(Subject as IInterface2)._release;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
end.
–jeroen
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| program NoWarningOnDuplicateInterfaceGUID; | |
| {$APPTYPE CONSOLE} | |
| {$R *.res} | |
| uses | |
| System.SysUtils; | |
| type | |
| IInterface1 = interface | |
| ['{ECF26C39-CBFF-488E-A3AB-2629726F1005}'] | |
| end; | |
| IInterface2 = interface | |
| ['{ECF26C39-CBFF-488E-A3AB-2629726F1005}'] | |
| end; | |
| var | |
| Subject: IInterface; | |
| begin | |
| try | |
| (Subject as IInterface1)._Release; | |
| (Subject as IInterface2)._release; | |
| except | |
| on E: Exception do | |
| Writeln(E.ClassName, ': ', E.Message); | |
| end; | |
| end. |
The Wiert Corner - irregular stream of stuff 
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