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| From | BartC <bc@freeuk.com> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Sugestions for runtime polymorphism |
| Date | 2016-09-14 23:10 +0100 |
| Organization | A noiseless patient Spider |
| Message-ID | <nrchsv$qld$1@dont-email.me> (permalink) |
| References | <b0659440-88ee-4d0f-861e-d5bb1cd0890d@googlegroups.com> <cc1b9c3e-76df-4ae5-9802-2b9d99aeb354@googlegroups.com> <c0d123f6-6075-408c-bfa0-fcb317597023@googlegroups.com> |
On 14/09/2016 22:25, Thiago Adams wrote:
> On Wednesday, September 14, 2016 at 6:17:22 PM UTC-3, luser droog wrote:
>> On Wednesday, September 14, 2016 at 2:01:49 PM UTC-5, Thiago Adams wrote:
>>> I need to create an array of "TypeSpecifiers" that are polymorphic. I have the list of all possible types.
>>>
>>> Does anyone have suggestions to implement this?
>>>
>>
>> Here's an overview of the object structure in my PostScript interpreter.
>> Each object carries a small integer which is used like an enum (mostly).
>> http://stackoverflow.com/a/6971534/733077
>>
>> Another writeup of the same idea:
>> http://stackoverflow.com/a/26773579/733077
>>
>> For the entire evolution of the idea, see this thread:
>> https://groups.google.com/d/topic/comp.lang.postscript/VsFzRwnuM_E/discussion
>
> Do you use a "variant" type?
> I think this is a good solution only if the objects have similar sizes, otherwise memory is wasted.
I use a 'variant' type but within the context of an interpreted
language; not for direct use within the implementation language (eg. C)
where the following would be unwieldy.
Probably not very efficient but in outline it's something like this:
typedef struct { // usually 16 bytes in total
int tag; // type indicator
union {
int64_t value;
uint64_t uvalue;
double xvalue;
object* objptr;
}
} variant;
The stack-based execution model pushes and pops variant structs.
Anything other than a simple type (void, integer, float) uses a pointer
to heap-allocated storage of an 'object' descriptor. This is currently a
fixed 32-byte struct for all such types for simplicity.
However, your array descriptor you posted elsewhere is 24 bytes on
64-bit systems, so is not far off 32 bytes.
The objects descriptor contains bounds, allocate sizes and pointers to
the actual data, also on the heap. (For this system, there is also a
reference count).
Object types includes dynamic and extendible data such as lists (arrays
of variants), strings, sets, dicts, as well as arrays of 'packed' types
like C arrays, but flexible.
--
Bartc
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Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 12:01 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 13:15 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 13:27 -0700
Re: Sugestions for runtime polymorphism Richard Heathfield <rjh@cpax.org.uk> - 2016-09-14 21:50 +0100
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 14:20 -0700
Re: Sugestions for runtime polymorphism "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-14 17:32 -0400
Re: Sugestions for runtime polymorphism Keith Thompson <kst-u@mib.org> - 2016-09-14 16:30 -0700
Re: Sugestions for runtime polymorphism "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-14 17:54 -0400
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 17:34 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 17:58 -0700
Re: Sugestions for runtime polymorphism Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-14 19:50 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-15 05:03 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-15 10:43 +0100
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-15 05:29 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-15 19:49 +0100
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-15 11:58 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-15 20:29 +0100
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-15 14:00 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-16 07:27 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-16 16:34 +0100
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-16 09:36 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-20 12:59 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-20 14:08 -0700
Re: Sugestions for runtime polymorphism Ian Collins <ian-news@hotmail.com> - 2016-09-21 15:53 +1200
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-21 07:38 -0700
Re: Sugestions for runtime polymorphism Ian Collins <ian-news@hotmail.com> - 2016-09-23 09:12 +1200
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-21 05:26 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-21 05:35 -0700
Re: Sugestions for runtime polymorphism Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-21 06:01 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-22 01:44 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-22 13:16 +0100
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-22 08:02 -0700
Re: Sugestions for runtime polymorphism Keith Thompson <kst-u@mib.org> - 2016-09-22 11:44 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-22 09:52 -0700
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-23 09:49 +0200
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-23 07:55 -0700
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-24 16:29 +0200
Re: Sugestions for runtime polymorphism Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-24 15:56 +0100
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-24 17:50 +0200
Re: Sugestions for runtime polymorphism "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-24 13:45 -0400
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-24 11:26 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 10:38 -0700
Re: Sugestions for runtime polymorphism Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-24 21:03 +0100
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-25 12:43 +0200
Re: Sugestions for runtime polymorphism "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-25 11:48 -0400
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-25 18:39 +0200
Re: Sugestions for runtime polymorphism "James R. Kuyper" <jameskuyper@verizon.net> - 2016-09-25 13:14 -0400
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-25 13:47 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 10:39 -0700
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-25 23:25 +0200
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-25 13:10 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-25 12:55 -0700
Re: Sugestions for runtime polymorphism Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-25 20:38 +0100
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-25 23:20 +0200
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 07:15 -0700
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-28 21:29 +0200
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-24 10:52 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-24 10:33 -0700
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-25 12:46 +0200
Re: Sugestions for runtime polymorphism Keith Thompson <kst-u@mib.org> - 2016-09-24 13:58 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-28 04:46 -0700
Re: Sugestions for runtime polymorphism Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-24 00:07 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-23 08:52 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-23 09:56 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-23 12:00 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-22 08:45 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-22 09:36 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-23 12:06 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-23 15:29 -0700
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-29 07:56 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-30 10:54 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-30 11:18 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-30 19:26 +0100
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-30 12:41 -0700
Re: Sugestions for runtime polymorphism Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-09-30 21:07 +0100
Re: Sugestions for runtime polymorphism Malcolm McLean <malcolm.mclean5@btinternet.com> - 2016-09-30 23:30 -0700
Re: Sugestions for runtime polymorphism Ben Bacarisse <ben.usenet@bsb.me.uk> - 2016-10-01 11:35 +0100
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-10-01 14:44 -0700
Re: Sugestions for runtime polymorphism Richard Heathfield <rjh@cpax.org.uk> - 2016-09-14 22:56 +0100
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-15 13:19 +0200
Re: Sugestions for runtime polymorphism James Kuyper <jameskuyper@verizon.net> - 2016-09-15 08:07 -0400
Re: Sugestions for runtime polymorphism David Brown <david.brown@hesbynett.no> - 2016-09-15 14:24 +0200
Re: Sugestions for runtime polymorphism Richard Heathfield <rjh@cpax.org.uk> - 2016-09-15 15:34 +0100
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-15 05:10 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-15 09:12 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-14 23:32 +0100
Re: Sugestions for runtime polymorphism "Chris M. Thomasson" <invalid@invalid.invalid> - 2016-09-14 17:35 -0700
Re: Sugestions for runtime polymorphism Ian Collins <ian-news@hotmail.com> - 2016-09-15 16:24 +1200
Re: Sugestions for runtime polymorphism Keith Thompson <kst-u@mib.org> - 2016-09-15 10:31 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-14 22:53 +0100
Re: Sugestions for runtime polymorphism Keith Thompson <kst-u@mib.org> - 2016-09-14 16:56 -0700
Re: Sugestions for runtime polymorphism supercat@casperkitty.com - 2016-09-14 15:58 -0700
Re: Sugestions for runtime polymorphism Keith Thompson <kst-u@mib.org> - 2016-09-14 18:49 -0700
Re: Sugestions for runtime polymorphism luser droog <luser.droog@gmail.com> - 2016-09-14 14:17 -0700
Re: Sugestions for runtime polymorphism Thiago Adams <thiago.adams@gmail.com> - 2016-09-14 14:25 -0700
Re: Sugestions for runtime polymorphism luser droog <luser.droog@gmail.com> - 2016-09-14 14:40 -0700
Re: Sugestions for runtime polymorphism luser droog <luser.droog@gmail.com> - 2016-09-14 14:57 -0700
Re: Sugestions for runtime polymorphism BartC <bc@freeuk.com> - 2016-09-14 23:10 +0100
Re: Sugestions for runtime polymorphism Tim Rentsch <txr@alumni.caltech.edu> - 2016-09-15 11:23 -0700
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