Re: Static Parameter Function Specialization in D
On 11/11/2013 11:56 AM, Nordlöw wrote: Can I move or delete this post? I use Thunderbird and it's pretty easy to cancel my own messages: Just select the post, go to 'Message' menu and click 'Cancel message' The 'Delete' option is different though, it just deletes the message from your local computer while it still exists in the newsgroup for others to see.
Re: Static Parameter Function Specialization in D
On Tuesday, 12 November 2013 at 22:17:46 UTC, John J wrote: On 11/11/2013 11:56 AM, Nordlöw wrote: Can I move or delete this post? I use Thunderbird and it's pretty easy to cancel my own messages: Just select the post, go to 'Message' menu and click 'Cancel message' It will actually send a new message that says that previous one should be discarded. Some mail servers / clients can be configured to respect that request but I'd be surprised to see that for NG.
Static Parameter Function Specialization in D
I've read somewhere that D supports specialization of functions
to calls where arguments are compile-time constants. Typical use
of this is in matrix power functions (if exponent is 2 `x*x` is
often faster than the general case).
I want this in my member function
bool opIndexAssign(bool b, size_t i) @trusted pure nothrow
in {
assert(i len);// TODO: Add static assert(i
len) when i is constant
} body {
b ? bts(ptr, i) : btr(ptr, i);
return b;
}
of a statically sized `BitSet` struct I'm writing. This in order
to, when possible, get compile-time bounds checking on the index
variable `i`. I thought
bool opIndexAssign(bool b, const size_t i) @trusted pure
nothrow in {
static assert(i len);
} body {
b ? bts(ptr, i) : btr(ptr, i);
return b;
}
would suffice but then DMD complains as follows
dmd -debug -gc -gs -unittest -D
-Dd/home/per/.emacs.d/auto-builds/dmd/Debug-Boundscheck-Unittest/home/per/Work/justd/
-w -main ~/Work/justd/bitset.d /home/per/Work/justd/assert_ex.d
-of/home/per/.emacs.d/auto-builds/dmd/Debug-Boundscheck-Unittest/home/per/Work/justd/bitset
/home/per/Work/justd/bitset.d(58): Error:
bitset.BitSet!2.BitSet.opIndexAssign called with argument types
(bool, int) matches both:
/home/per/Work/justd/bitset.d(49): opIndexAssign(bool b,
ulong i)
and:
/home/per/Work/justd/bitset.d(65): opIndexAssign(bool b,
const(ulong) i)
/home/per/Work/justd/bitset.d(66): Error: variable i cannot
be read at compile time
/home/per/Work/justd/bitset.d(66):while evaluating:
static assert(i 2LU)
/home/per/Work/justd/bitset.d(58): Error:
bitset.BitSet!2.BitSet.opIndexAssign called with argument types
(bool, int) matches both:
/home/per/Work/justd/bitset.d(49): opIndexAssign(bool b,
ulong i)
Do I have to make parameter `i` a template parameter, say using
type `U`, and then use static if `someTypeTrait!U`. I tried this
but isMutable!Index always evaluates to true.
import std.traits: isIntegral;
bool opIndexAssign(Index)(bool b, Index i) @trusted pure
nothrow if (isIntegral!Index) in {
import std.traits: isMutable;
// See also:
http://stackoverflow.com/questions/19906516/static-parameter-function-specialization-in-d
static if (isMutable!Index) {
assert(i len);
} else {
import std.conv: to;
static assert(i len,
Index ~ to!string(i) ~ must be
smaller than BitSet length ~ to!string(len));
}
} body {
b ? bts(ptr, i) : btr(ptr, i);
return b;
}
Re: Static Parameter Function Specialization in D
On Monday, 11 November 2013 at 13:41:04 UTC, Nordlöw wrote:
I've read somewhere that D supports specialization of functions
to calls where arguments are compile-time constants. Typical
use of this is in matrix power functions (if exponent is 2
`x*x` is often faster than the general case).
I want this in my member function
bool opIndexAssign(bool b, size_t i) @trusted pure
nothrow in {
assert(i len);// TODO: Add static
assert(i len) when i is constant
} body {
b ? bts(ptr, i) : btr(ptr, i);
return b;
}
of a statically sized `BitSet` struct I'm writing. This in
order to, when possible, get compile-time bounds checking on
the index variable `i`. I thought
bool opIndexAssign(bool b, const size_t i) @trusted pure
nothrow in {
static assert(i len);
} body {
b ? bts(ptr, i) : btr(ptr, i);
return b;
}
would suffice but then DMD complains as follows
dmd -debug -gc -gs -unittest -D
-Dd/home/per/.emacs.d/auto-builds/dmd/Debug-Boundscheck-Unittest/home/per/Work/justd/
-w -main ~/Work/justd/bitset.d
/home/per/Work/justd/assert_ex.d
-of/home/per/.emacs.d/auto-builds/dmd/Debug-Boundscheck-Unittest/home/per/Work/justd/bitset
/home/per/Work/justd/bitset.d(58): Error:
bitset.BitSet!2.BitSet.opIndexAssign called with argument types
(bool, int) matches both:
/home/per/Work/justd/bitset.d(49): opIndexAssign(bool b,
ulong i)
and:
/home/per/Work/justd/bitset.d(65): opIndexAssign(bool b,
const(ulong) i)
/home/per/Work/justd/bitset.d(66): Error: variable i cannot
be read at compile time
/home/per/Work/justd/bitset.d(66):while evaluating:
static assert(i 2LU)
/home/per/Work/justd/bitset.d(58): Error:
bitset.BitSet!2.BitSet.opIndexAssign called with argument types
(bool, int) matches both:
/home/per/Work/justd/bitset.d(49): opIndexAssign(bool b,
ulong i)
Do I have to make parameter `i` a template parameter, say using
type `U`, and then use static if `someTypeTrait!U`. I tried
this but isMutable!Index always evaluates to true.
import std.traits: isIntegral;
bool opIndexAssign(Index)(bool b, Index i) @trusted pure
nothrow if (isIntegral!Index) in {
import std.traits: isMutable;
// See also:
http://stackoverflow.com/questions/19906516/static-parameter-function-specialization-in-d
static if (isMutable!Index) {
assert(i len);
} else {
import std.conv: to;
static assert(i len,
Index ~ to!string(i) ~ must be
smaller than BitSet length ~ to!string(len));
}
} body {
b ? bts(ptr, i) : btr(ptr, i);
return b;
}
It's possible that the compiler can inline the function and
optimize the code from there, but I don't know of any language
feature that can do this explicitly.
Re: Static Parameter Function Specialization in D
Please never post such questions to announcement list. There is a D.learn for that.
Re: Static Parameter Function Specialization in D
On Monday, 11 November 2013 at 14:41:14 UTC, Dicebot wrote: Please never post such questions to announcement list. There is a D.learn for that. I'm very sorry. It was a mistake. Can I move or delete this post?
Re: Static Parameter Function Specialization in D
On Monday, November 11, 2013 17:56:38 Nordlöw wrote: On Monday, 11 November 2013 at 14:41:14 UTC, Dicebot wrote: Please never post such questions to announcement list. There is a D.learn for that. I'm very sorry. It was a mistake. Can I move or delete this post? No. This forum has three front-ends - nntp newsgroup, mailing list, and the website - with nntp as the backend. So, in general, once it's out there, it's out there. Occasionally, Walter will remove spam from the nntp server so that it doesn't end up in the archives, but that's pretty much it. Just be more careful about where you post in the future. - Jonathan M Davis
