Re: Type information seems to be erased in macros

[Per Bothner <per@bothner.com>]

On 12/29/21 14:12, Panicz Maciej Godek via Kawa wrote:
> Does the macro system erase type information from objects?

Not in general, but it is possible that a compond name
like screen:translate! might not survive the macro-expansion process.

The --debug-print-expr flag may be useful to see what is happening.
It prints out the syntax tree after name lookup and macro-expansion,
but before type analysts and optimizations.

It you post a short self-contained program I can take a look.

There is a good chance you might have better luck with:

     (invoke screen 'translate! x! y!)

That should avoid any issues with compound symbols.

> If I add explicit casts in the macro, is it likely to cause some
> performance penalty?

Almost certainly nothing you'd notice: Probably just an extra checkcast
instruction in the bytecode.  Which means some extra work, but pretty minor.

If end up needing run-time reflection (which is what you get if
you ignore the warning), that is a lot more expensive.
-- 
	--Per Bothner
per@bothner.com   http://per.bothner.com/