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Re: <c-string> vs <byte-string>?
On Tue, 7 Dec 1999 16:45:05 -0500 (EST), Scott Ribe <sribe@miqs.com> wrote:
> Is it supposed to work this way, or is there some bug?
>
> I call make (<c-string>, size: 256) and pass that into SQLDescribeCol
> which takes an argument of type <LPSQLCHAR>. After that call I can use
> the string in a call to format-out and it prints just fine. But if I put
> it into a sequence and instantiate a <list-box> with that sequence it
> displays garbage. (I can inspect the sequence & strings in the debugger
> with no problem.)
>
> If I call make (<byte-string>, size: 256) and use that instead,
> format-out prints all 256 characters while the list box looks OK (of
> course, the extra spaces might still be there).
>
> The only way I have found is to instantiate and use <c-string> for the
> call into the odbc-ffi library, then convert it when adding to my
> sequence using as (<byte-string>, ...).
>
> This is not exactly the end of the world to have to do this ;-) But it
> does seem a little clunky. Am I missing something, or is this the way to
> do it?
That seems to be the way to do it. The DUIM Win32 backend use as(<byte-string>
on <C-string>s before returning them, for example.
> And, more interesting, (to me at least) is that if I creat a pane as
> follows:
>
> make(<list-box>, items: *colnames*);
>
> I get the behavior described, garbage when *colnames* is a sequence of
> <c-string>, but I can use the same code to build *colnames*, and the
> following pane definition works just fine:
>
> make (<table-control>, headings: #["name"],
> items: range (from: 0, to: *colnames*.size - 1),
> generators: vector (method (idx) *colnames*[idx] end));
>
> So how is it that a list box cannot get its values from a sequence of
> <c-string> but a <table-control> can? Is there some coercion going on
> within the <table-control> call to the generator functions? If so, why
> not the same coercion with the <list-box>?
Dunno why that is. Perhaps the original <C-string> that you passed to SQL is
getting trashed in that case?
> (BTW, I do need to be using the odbc-ffi library right now instead of
> the higher-level access.)
Dunno. Not my speciality.
__Jason
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