This week I used some record helpers for intrinsic types and I think that they are a wonderful feature. This means that you should update at least to XE3 to use this great feature.<\/p>\n
But as always there are some issues: I had an resourcestring and wanted to access to the length.<\/p>\n
\r\nprogram TestHelper;\r\n\r\n{$APPTYPE CONSOLE}\r\n\r\nuses\r\n System.SysUtils;\r\n\r\nresourcestring\r\n SAnswer = '42';\r\n\r\nbegin\r\n Writeln('The length of ' + SAnswer + ' is:');\r\n Writeln(SAnswer.Length);\r\n Readln;\r\nend.<\/pre>\nI tried to compile this code and it doesn’t! The compiler doesn’t know the method length although in System.SysUtils there is the TStringHelper with this method! I had been very surprised but then I thought that a resourcestring is not a string but only assignable to a string, something like a type string.<\/p>\n
With XE4 this code does compile which is the expected behavior! Many thanks for this fix.<\/p>\n
I talked about this issue to a friend (Many thanks to him!) and he told me that I should try a record helper for a WideString.<\/p>\n
program TestHelper;\r\n\r\n{$APPTYPE CONSOLE}\r\n\r\nuses\r\n System.SysUtils;\r\n\r\nresourcestring\r\n SAnswer = '42';\r\n\r\ntype\r\n TWideStringHelper = record helper for WideString\r\n public\r\n function Length: Integer; inline;\r\n end;\r\n\r\n{ TWideStringHelper }\r\n\r\nfunction TWideStringHelper.Length: Integer;\r\nbegin\r\n Result := System.Length(Self);\r\nend;\r\n\r\nbegin\r\n Writeln('The length of ' + SAnswer + ' is:');\r\n Writeln(SAnswer.Length);\r\n Readln;\r\nend.\r\n<\/pre>\nAnd this code does compile! This means that a resourcestring is a WideString. Again, I’m surprised. But run this small project. It shows that the length of ’42’ is 1. This is a bug!!! My friend told me that a there is already the Quality Central item 112844 for this bug. This means that you shouldn’t use a record helper for resourcestrings in XE3. I hope that this bug will be fixed in XE4, so stay tuned….<\/p>\n
Again, under XE4 the resourcestring works like a string. This means that a TWideStringHelper doesn’t work, instead the TStringHelper does. And the length is the correct value. So many thanks for this fix. This is a very good reason to move to XE4.<\/p>\n","protected":false},"excerpt":{"rendered":"
This week I used some record helpers for intrinsic types and I think that they are a wonderful feature. This means that you should update at least to XE3 to use this great feature. But as always there are some … Continue reading