[M3devel] m3gap.... what is it and what does this mean?

[Jay K]

The names are generated in the backend.
Use of leading underscore is therefore good -- it can't clash with "real" data.

 - Jay

________________________________
> From: hosking at cs.purdue.edu
> Date: Tue, 5 Oct 2010 16:04:06 -0400
> To: rodney_bates at lcwb.coop
> CC: m3devel at elegosoft.com
> Subject: Re: [M3devel] m3gap.... what is it and what does this mean?
>
> M3 ids cannot begin with "_".
>
> Antony Hosking | Associate Professor | Computer Science | Purdue University
> 305 N. University Street | West Lafayette | IN 47907 | USA
> Office +1 765 494 6001 | Mobile +1 765 427 5484
>
>
>
>
> On 5 Oct 2010, at 15:26, Rodney M. Bates wrote:
>
>
>
> Jay K wrote:
> Hey, look, until August, stock gdb never showed any fields!
> The front does layout, it might tell the backend:
> struct {
> integer a at offset 4, size 4
> integer b at offset 12, size 4
> }
> in which case the backend will generate a "gap" field at offset 8, size 4
> I suspect we might not have to generate the fields.
> I'm nervous that the backend might do its own layout and move up b to
> offset 8 otherwise.
> And there was other code in the backing doing similar.
> We are in complete control of the name.
> If you want we can call it "_m3_padding_for_alignment"
> or "-m3_nothing_to_see_here"
> or "http://m3.org/faq1.html" (not sure they have to be valid C identifiers)
>
> I doubt it, but they might need to be valid linker identifiers. If
> there is a
> character that is not legal in Modula-3 identifiers but legal here, it
> would be nice
> to use it in generated things like this. Then a debugger could
> normally suppress
> displaying it, yet not be fooled by a Modula-3 programmer's actually
> declaring, e.g.,
> _m3gap_8_56 in source code. There are other places this comes up.
>
> - Jay
> ----------------------------------------
> From: dragisha at m3w.org
> To: m3devel at elegosoft.com
> Date: Tue, 5 Oct 2010 15:32:30 +0200
> Subject: [M3devel] m3gap.... what is it and what does this mean?
>
> (gdb) p event
> $1 = {type = 8 '\b', _m3gap_8_56 = {}, window = 0x6924c0, send_event =
> 0 '\000', _m3gap_136_56 =
> {}, time = 210453397504, state = 1, keyval = 0, length = 22953024,
> _m3gap_352_32 = {},
> string = 0xa , hardware_keycode = 0, group = 0 '\000', _m3gap_472_40 = {}}
>
>
> VAR
> event: Gdk.EventKey;
>
> EventKey = RECORD
> type: EventType;
> window: WindowStar;
> send_event: char;
> time: unsigned_long_int;
> state: unsigned_int;
> keyval: unsigned_int;
> length: int;
> string: char_star;
> hardware_keycode: unsigned_short_int;
> group: unsigned_char;
> END;
>
> also with m3gdb....
>
> (m3gdb) p event
> $1 = {4type = 8 '\b', _m3gap_8_56 = {}, window = 0x0,
> send_event = 0 '\000',
> _m3gap_136_56 = {}, time = 49, state = -937844736,
> keyval = 32616, length = 23801648,
> _m3gap_352_32 = {}, string = 0x7f68c839be10 "\001
> \000", hardware_keycode = 0, group = 0 '\000',
> _m3gap_472_40 = {}}
>
> --
> Dragiša Durić
>
>