How to return a record with data from Delphi?

Pascal Script
1

Hello,

I hvae a record type that is registered to PascalScript during startup and i want to return that record type (with data) from a Delphi function or procedure.

What i have tried so far (and the results):

procedure ReadData(aData: TDataRecord); // as Parameter
begin
   FillChar(aData, SizeOf(TDataRecord), #0);
   aData.IntVar := 4711;
   aData.StringVar := 'Test';
   // Results in an empty record in PascalScript...
end;

procedure ReadData(var aData: TDataRecord); // as var paramerte
begin
   FillChar(aData, SizeOf(TDataRecord), #0);
   aData.IntVar := 4711;
   aData.StringVar := 'Test';
   // Results in an access violation
end;

function ReadData: TDataRecord; // as Result
begin
   FillChar(Result, SizeOf(TDataRecord), #0);
   Result.IntVar := 4711;
   Result.StringVar := 'Test';
   // Results in an empty record in Pascalscript
end;

The procedure (or function) is called from a PascalScript but i cannot get the data that was assigned in Delphi.

What goes wrong here? The procedures or the functions are registered according to the version i have tried out and they compile without error.

Thanks in advance,
Ralf

2

define it as “packed” on the Delphi side. Then the middle one should work.

3

I have now declared the record as “packed record” in the Delphi definition but i have the same situation. When using the record as VAR parameter i run into an access violation, Using the record as normal parameter results in an empty record (the record have a lot of more fields than in the samples).

Could fields from type “string” cause such errors, maybe changing them to “string[xxx]” will help? - Will try that tomorrow…

4

The access violation could be many things, depends on how you call it.

5

What do you men with “how you call it”?

Here ist the test code (PascalScript) :

program PScript;

procedure RunTest;
var
   dr: TDataRecord;
begin
   dr.StringVar := 'TEST';
   ReadData(dr);
   WriteLn( 'StringVar = ' + dr.StringVar );
   // StringVar ist still "TEST" here!
end;

begin
  RunTest;
end.

If i run the version that does not generate an access violation then it looks like the result is not written to the record because i still find the value i assigned before the call.

Do i need to return the result in another way from Delphi to Pascalscript? (rather than simply assign the value)

6

Well readdata needs to be defined as “var” on the Delphi side too.

7

I know. And it is.

Meanwhile i think the cause of the errors is not the method that returns the record. It is the record itself.

The record contains several strings, some byte-Variables and some char-variables. If i comment out the char variables the returning of the values is working as expected., Only when the record contains char-variables i get those access violations.

Can you make a guess why char variables in the record cause an access violation?

Thanks in advance,
Ralf

8

They shouldn’t. Char is a very basic type.

9

But they do! I have just changed all char variables into strings and the access violation does not longer happen. Changing one of them back to char results in the access violation again.
[EDIT]: When i change the char-fields to WideChar there is no access violation either. I think i will work with WideChar for the moment…