Am I doing this right? (File byChunk)

[Andrej Mitrovic]

Ah, silly me, disregard that code. I was working around the issue but
I didn't have to, here's the correct code:

foreach (ubyte[] buf; file.byChunk(4096))
{
	sendEditor(SCI_ADDTEXT, buf.length, cast(LPARAM)buf.ptr);
}

Now, the explanation. The sendEditor function takes an opcode (uint),
and 2 arguments. It uses message passing to communicate with
scintilla, the two arguments are aliased to uint (which is usually a
length argument but is sometimes ignored) and LPARAM (a pointer's
address as ULONG).

Scintilla converts the address back to a pointer, and passes it (and
the first argument) to the relevant function based on the opcode.
Here's the header of that function:

SCI_ADDTEXT(int length, const char *s)

The reason my first code was working is because the wrapper has two
overloaded sendEditor functions. With one you can pass an opcode, a
length and pointer address, with the other you can pass an opcode, a
length and a string, and the function makes a copy of the string, adds
a null terminator and uses its address and the other arguments to send
a message.

The ADDTEXT function creates a copy of the pointed-to contents to it's
internal scintilla buffers, so I don't have to keep any pointers
around after the call.

I hope I've explained this right (and didn't mess something up). :p


On Mon, Sep 13, 2010 at 3:47 AM, BCS <none at anon.com> wrote:
> Hello Andrej,
>
>> Here's a little snippet of code that interfaces with Scintilla (it
>> works btw.):
>>
>> File file = File("test.txt", "r");
>> foreach (ubyte[] buf; file.byChunk(4096))
>> {
>> sendEditor(SCI_ADDTEXT, buf.length, (cast(char[])buf).idup);
>> }
>> The cast looks ugly, but I *have* to send a copy.
>
> What do those have to do with each other?
>
>> Am I doing it right,
>
> It doesn't seem right to me either, because you are allocating memory in
> chunks and passing it to C without keeping pointers around. Also what does
> that function do with them? If it keeps them around, you might be faster to
> load the whole file in one go and make a single call (fewer allocations,
> fewer calls, no-extra memory usage, etc.)
>
>> or can I make this a bit simpler? Otherwise I can use file.byLine, but
>> I think this would be much slower (unless D reads the entire contents
>> at once into memory, but I think it does not).
>>
>> Actually, I shouldn't even complain. I can't believe how easy it is to
>> open a file, use buffers and send it all to a C interface. This is a
>> 4-liner, the C equivalent spans 20+ lines. Ha!
>>
> --
> ... <IXOYE><
>
>
>
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