From: Panicz Maciej Godek <godek.maciek@gmail.com>
To: kawa@sourceware.org
Subject: Type information seems to be erased in macros
Date: Wed, 29 Dec 2021 23:12:37 +0100 [thread overview]
Message-ID: <CAMFYt2YrXxPx84adKFH+ig=ZJN2rSKUaEhmLrAMS6R+NM3MmGQ@mail.gmail.com> (raw)
Hi,
I have defined a macro:
(define-syntax-rule (with-translation screen (x y) . actions)
(let ((x! x)
(y! y))
(screen:translate! x! y!)
(let ((result (begin . actions)))
(screen:translate! (- x!) (- y!))
result)))
which (presumably) operates on Screen interface, which provides translate!
method.
I use it in a context which makes it clear that the type of the first
argument passed to with-translation is Screen:
(define (draw! object #!optional (screen::Screen (current-screen)))::Extent
...
(with-translation screen (left top) ...)
...)
However, when I import (to the REPL) a module containing this code, I get
the following complaint near the use of the with-translation macro:
warning - no known slot 'translate!' in java.lang.Object
Does the macro system erase type information from objects?
If I add explicit casts in the macro, is it likely to cause some
performance penalty?
next reply other threads:[~2021-12-29 22:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-29 22:12 Panicz Maciej Godek [this message]
2021-12-29 23:30 ` Per Bothner
2021-12-30 8:52 ` Panicz Maciej Godek
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