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Procedure header for 'XXX' does not match.

Velox reports Procedure header for '<EventName>' does not match. when a procedure uses one of eight reserved event names but its compiled signature does not satisfy the host contract. XXX in this catalogue title is replaced by the recognised event name.

Example​

This procedure has a value parameter instead of a var parameter:

procedure ScriptEvent(Value: Variant); // Error: header does not match
begin
  Value := 'complete';
end;

Use the exact event contract:

procedure ScriptEvent(var Value: Variant);
begin
  Value := 'complete';
end;

Verified event signatures​

Reserved procedureRequired signature shape
OnMapEventProcedure; one var Variant parameter
BeforeMapEventProcedure; one var Variant parameter
AfterMapEventProcedure; one var Variant parameter
AfterDetailMapEventProcedure; one var Variant parameter
ScriptEventProcedure; one var Variant parameter
LinkedDataEventProcedure; one var class parameter; use TdaQueryDataView as documented for the host contract
OnStartMapEventProcedure; no parameters
OnEndMapEventProcedure; no parameters

Parameter identifiers can differ from Value or LinkedData; their names are not part of the compiled signature.

How Velox verifies it​

After PascalScript has compiled an internal procedure, Velox's event verifier compares:

  • the presence or absence of a function result;
  • the exact number of parameters;
  • each parameter's compiler mode (var is the in/out mode); and
  • each parameter's PascalScript base type.

The verifier emits an ecCustomError containing the specific reserved event name. Other user-defined procedure names are not subject to these event checks.

LinkedData verifier quirk​

The current LinkedDataEvent check compares only the PascalScript base type class, not the exact registered class identity. A different class-typed var parameter can therefore pass this compiler check but still be incompatible with the delegate and host value Velox actually uses. Declare the documented TdaQueryDataView parameter; do not rely on the broader verifier.

Correction procedure​

  1. Read the complete message to identify the reserved event name.
  2. Compare procedure versus function, parameter count, var mode and type with the table above.
  3. Remove a return type from an event procedure.
  4. Preserve the correct event name; renaming it avoids the verifier only by preventing Velox from finding the event.
  5. Recompile and resolve any ordinary type or declaration errors first if they obscure the header.
  • ScriptEvent - general event value contract.
  • LinkedData - required linked-data class and ownership contract.
  • OnStartMap and OnEndMap - no-parameter sequence events.
  • Forward Parameter Mismatch - a script implementation differs from its own forward declaration.

External references​