[Openmcl-devel] Calling STRETs without SEND
R. Matthew Emerson
rme at clozure.com
Tue Jun 2 12:01:32 PDT 2009
On Jun 2, 2009, at 12:41 PM, Ron Garret wrote:
> Following an recent admonition that SEND is deprecated, I've been
> converting all my old code to call ObjC methods directly using the #/
> reader macro. However, this doesn't seem to work for STRET calls,
> (ccl::slet ((event-location (#/locationInWindow event)) ...
> gives me:
>> Error: Unrecognized STRET call in (NEXTSTEP-FUNCTIONS:|
> locationInWindow| EVENT)
>> While executing: CCL::SLETIFY, in process Listener(7).
> (ccl::slet ((event-location (send event 'location-In-Window)) ...
> The examples in the manual also use SEND.
> What is the proper way to call STRETs?
When using #/ notation, you don't need to make a distinction between
methods that return a structure by value, and those that don't. So
you can just say
(let ((event-location (#/locationInWindow event)))
and forget about SLET entirely.
There's some information about the use of the #/ reader macro in
ccl:doc;release-notes-1.1.txt; here's an excerpt:
ObjC methods that "return" structures return them as gcable pointers
when called via dispatch functions. E.g., if "my-window" is an
NS:NS-WINDOW instance, then
will return a gcable pointer to a structure that describes that
frame rectangle. (The good news is that there's no need to use SLET
or special structure-returning message send syntax; the bad news is
that #_malloc, #_free, and the GC are all involved in the creation
and eventual destruction of structure-typed return values. Unless
and until those factors negatively affect performance, the advantages
seem to outweigh the disadvantages.)
Sorry that section 13 of the manual is so out-of-date.
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