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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for March 19th, 2013

Porting Delphi 2006 to XE2, fields versus properties: tightened compiler error E2197

Posted by jpluimers on 2013/03/19

When porting some communications code that used records as properties from Delphi 2006 to Delphi XE2, I came across a tightened compiler error “E2197 Constant object cannot be passed as var parameter“.

Let me first explain the good oldĀ occurrenceĀ of E2197 with some code that uses my last Variant Records example:

Just look at TPacket.InitializePacket and TPacketBase.InitializeFPacket: Basically even though the Packet property has storageĀ specifiers indicating itĀ directly reads from a field and directly writes to a field, you cannot pass it as a var parameter in the FillChar method.

Of course you can with a field, you can pass it to FillChar without trouble as TPacketBase.InitializeFPacket shows. Read the rest of this entry »

Posted in Delphi, Delphi 2006, Delphi XE2, Delphi XE3, Development, Software Development | 3 Comments »

 
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