>The only other thing I thought of was to use a varargs-type parameter
>list (i.e., pointer to an array with the number of elements passed as
>a separate parameter) but instead of passing a null-terminated string,
>you pass something like a pascal string except that the count would be
>stored as a 4-byte integer instead of as single byte. Saves a few
>mallocs (which is always good), but does require some casting (which
>isn't).
Scott,
There's just one problem with this: Once we introduce UniCode or wide
chars, we'll be royally screwed up with this. Or we'd have to add a flag to
each such object telling whether it's Unicode or ASCII.
Since most hosts already have a built-in string object, maybe we could
create an opaque object type instead (I have to admit, since Apple began
using opaque types, I'm a real sucker for these critters). Anyway, in that
case we'd have a pseudo-OO design that will be much more easily extendable.
Well, we'd define a data type that is the size of a memory address
(pointer) as being a ParamStrRef. And then we provide callbacks (they're
not too costly these days, speed-wise, are they?) to create such an object,
to manipulate it etc.
ParamStrRef CreateEmptyString();
ParamStrRef CreateStringFromCString( char* str );
ParamStrRef CreateStringFromText( unsigned long length, char* txt );
void CopyCStringToString( ParamStrRef str, char* inStr );
void CopyTextToString( ParamStrRef str, char* inStr,
unsigned long inLength );
void CopyStringToCString( ParamStrRef str, char* outStr,
unsigned long maxLength );
void CopyStringToText( ParamStrRef str, char* outStr,
unsigned long *ioLength );
void ReleaseString( ParamStrRef str );
Later when UniCode arrives we could extend these callbacks to create and
copy strings from/to Unicode strings, etc. And best of all, if the host
internally uses Unicode, one would just have to make the ASCII-string
callbacks convert from Unicode. This is so flexible that we could even (if
we wanted) provide access to other data types besides strings, e.g. arrays,
or even longs, shorts, colors etc. although we might then change the name
from ParamStrRef to XCMDParamRef or something like that.
>So who'd be responsible for deleting these beasties?
I guess it'd be best if we established a general rule. All strings are to
be released by the external, except those that need to exist befor or after
the external call (i.e. parameters and result belong to the host).
BTW -- "Text" is what I call a non-terminated string with a length long.
Choose any other name if it suits you better, this is just a draft to help
where my English fails.
Tsch�ss,
-- M. Uli Kusterer
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