In the series “avoid Variants when coding in Delphi”: the comparison operator

For Variant types, the = comparison operator in Delphi maps to the VarCompareValue in the Variants unit.

That function fails to handle various comparisons and for some it knows it can handle raises a VarInvalidOp through various code paths (like CheckType) to VarInvalidOp because the implementation limits itself to varEmpty..varUInt64, which I think means that these are unsupported:

• varRecord
• varStrArg
• varObject
• varUStrArg
• varString
• varAny
• varUString
• varArray
• varByRef

This fails when using the = operator:

What is this code supposed to do, if v1 and v2 are variant arrays with the same content?

if v1 = v2 then
  WriteLn('equal')
else
  WriteLn('not equal');

Spring4d has a function SameValue in the Spring.pas unit which handles more cases, at least the case when both operands are arrays having the same content.

Source: [WayBack] I think I may have mentioned that I hate Variants: What is this code supposed to do, if v1 and v2 are variant arrays with the same content? if v1 = v2… – Thomas Mueller (dummzeuch) – Google+

Thanks to Thomas Mueller and Stefan Glienke for this.

–jeroen