Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
On Sat, Nov 30, 2013 at 12:53:24AM -0500, Ashish Myles wrote: I have been waiting on integer parameters on traits since I first ran into Rust, but the rust team might be avoiding that to prevent getting Turing complete generics/templates. I assume we'll get to it eventually. Niko ___ Rust-dev mailing list Rust-dev@mozilla.org https://mail.mozilla.org/listinfo/rust-dev
Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
On Fri, Nov 29, 2013 at 6:33 PM, Ashish Myles marci...@gmail.com wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
The `Clone` and `DeepClone` traits are defined entirely in the
standard library. Of course, another issue is that fixed-size vectors
can't have methods implemented on them at the moment.
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Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
On 30/11/13 10:33, Ashish Myles wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
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Initialising a fixed size vector [T, ..n] by [foo(), .. n] unfortunately
requires that `T` is implicitly copyable (that is, it doesn't move
ownership when passed by value), and there's no way around this other
than [foo(), foo(), foo(),...].
Huon
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Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
Is there a plan to support fix-sized vector initialization without manual
replication? My example is just a simplified version -- this was part of a
macro that takes the size as input ($n:expr) and the initialization was
[Zero::zero(), .. $n]. Is this use case no longer intended to be
supported?
On Nov 29, 2013 6:47 PM, Huon Wilson dbau...@gmail.com wrote:
On 30/11/13 10:33, Ashish Myles wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
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Initialising a fixed size vector [T, ..n] by [foo(), .. n] unfortunately
requires that `T` is implicitly copyable (that is, it doesn't move
ownership when passed by value), and there's no way around this other than
[foo(), foo(), foo(),...].
Huon
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Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
If you're willing to use unsafe code and std::unstable, you can do it.
use std::num::Zero;
use std::unstable::intrinsics;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT: Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
let mut ary: [T, ..SZ];
unsafe {
ary = intrinsics::uninit();
for i in range(0u, SZ as uint) {
intrinsics::move_val_init(mut ary[i], Zero::zero());
}
}
Foo(ary)
}
}
-Kevin
On Nov 29, 2013, at 7:05 PM, Ashish Myles marci...@gmail.com wrote:
Is there a plan to support fix-sized vector initialization without manual
replication? My example is just a simplified version -- this was part of a
macro that takes the size as input ($n:expr) and the initialization was
[Zero::zero(), .. $n]. Is this use case no longer intended to be supported?
On Nov 29, 2013 6:47 PM, Huon Wilson dbau...@gmail.com wrote:
On 30/11/13 10:33, Ashish Myles wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
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Initialising a fixed size vector [T, ..n] by [foo(), .. n] unfortunately
requires that `T` is implicitly copyable (that is, it doesn't move ownership
when passed by value), and there's no way around this other than [foo(),
foo(), foo(),...].
Huon
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Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
That's some seriously nifty stuff, which got my stuff compiling again. :)
But for the long term, it would be nice to have a syntax that behaves
as was the case with the Copy trait -- it takes a single value and
clones it into the elements of the static array. Or perhaps the
developers disagree and consider it to be a niche use (static arrays
with sizes known a-priori when writing the code) -- it would be good
to get some clarity on this.
Thanks,
Ashish
On Fri, Nov 29, 2013 at 10:20 PM, Kevin Ballard ke...@sb.org wrote:
If you're willing to use unsafe code and std::unstable, you can do it.
use std::num::Zero;
use std::unstable::intrinsics;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT: Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
let mut ary: [T, ..SZ];
unsafe {
ary = intrinsics::uninit();
for i in range(0u, SZ as uint) {
intrinsics::move_val_init(mut ary[i], Zero::zero());
}
}
Foo(ary)
}
}
-Kevin
On Nov 29, 2013, at 7:05 PM, Ashish Myles marci...@gmail.com wrote:
Is there a plan to support fix-sized vector initialization without manual
replication? My example is just a simplified version -- this was part of a
macro that takes the size as input ($n:expr) and the initialization was
[Zero::zero(), .. $n]. Is this use case no longer intended to be supported?
On Nov 29, 2013 6:47 PM, Huon Wilson dbau...@gmail.com wrote:
On 30/11/13 10:33, Ashish Myles wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
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Initialising a fixed size vector [T, ..n] by [foo(), .. n] unfortunately
requires that `T` is implicitly copyable (that is, it doesn't move ownership
when passed by value), and there's no way around this other than [foo(),
foo(), foo(),...].
Huon
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Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
Personally, I think it would be nicer to just have a syntax that says create
an array of length N by executing the following expression (typically a
function call) N times.
Something along the lines of
let ary = [Foo::new().., ..32];
This would be more generic, because it will work with non-Clonable values, and
if you wanted cloned values you'd just say
let ary = [foo.clone().., ..32];
Although if we ever get the ability to make generics that have integral
parameters (which is necessary to implement traits on arbitrary arrays) then we
could do this in the libraries by writing a function like I had before.
Something like the following:
libstd/array.rs:
#[inline]
fn from_fnT, N as uint init(f: |uint| - T) - [T, ..N] {
let mut ary: [T, ..N];
unsafe {
ary = intrinsics::uninit();
for i in range(0u, N) {
intrinsics::move_val_init(mut ary[i], f(i));
}
}
ary
}
This would let you call it like Foo(array::from_fn(|_| Zero::zero())).
-Kevin
On Nov 29, 2013, at 8:37 PM, Ashish Myles marci...@gmail.com wrote:
That's some seriously nifty stuff, which got my stuff compiling again. :)
But for the long term, it would be nice to have a syntax that behaves
as was the case with the Copy trait -- it takes a single value and
clones it into the elements of the static array. Or perhaps the
developers disagree and consider it to be a niche use (static arrays
with sizes known a-priori when writing the code) -- it would be good
to get some clarity on this.
Thanks,
Ashish
On Fri, Nov 29, 2013 at 10:20 PM, Kevin Ballard ke...@sb.org wrote:
If you're willing to use unsafe code and std::unstable, you can do it.
use std::num::Zero;
use std::unstable::intrinsics;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT: Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
let mut ary: [T, ..SZ];
unsafe {
ary = intrinsics::uninit();
for i in range(0u, SZ as uint) {
intrinsics::move_val_init(mut ary[i], Zero::zero());
}
}
Foo(ary)
}
}
-Kevin
On Nov 29, 2013, at 7:05 PM, Ashish Myles marci...@gmail.com wrote:
Is there a plan to support fix-sized vector initialization without manual
replication? My example is just a simplified version -- this was part of a
macro that takes the size as input ($n:expr) and the initialization was
[Zero::zero(), .. $n]. Is this use case no longer intended to be supported?
On Nov 29, 2013 6:47 PM, Huon Wilson dbau...@gmail.com wrote:
On 30/11/13 10:33, Ashish Myles wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
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Initialising a fixed size vector [T, ..n] by [foo(), .. n] unfortunately
requires that `T` is implicitly copyable (that is, it doesn't move ownership
when passed by value), and there's no way around this other than [foo(),
foo(), foo(),...].
Huon
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Re: [rust-dev] Define copyable types for [T, ..2] static vector initialization
+1 on specifying function. That potentially lowers the requirements on
the Traits -- e.g. don't have to force clone-ability as long as you
can create+move it; perhaps even create it in place.
I have been waiting on integer parameters on traits since I first ran
into Rust, but the rust team might be avoiding that to prevent getting
Turing complete generics/templates.
Ashish
On Sat, Nov 30, 2013 at 12:39 AM, Kevin Ballard ke...@sb.org wrote:
Personally, I think it would be nicer to just have a syntax that says create
an array of length N by executing the following expression (typically a
function call) N times.
Something along the lines of
let ary = [Foo::new().., ..32];
This would be more generic, because it will work with non-Clonable values,
and if you wanted cloned values you'd just say
let ary = [foo.clone().., ..32];
Although if we ever get the ability to make generics that have integral
parameters (which is necessary to implement traits on arbitrary arrays) then
we could do this in the libraries by writing a function like I had before.
Something like the following:
libstd/array.rs:
#[inline]
fn from_fnT, N as uint init(f: |uint| - T) - [T, ..N] {
let mut ary: [T, ..N];
unsafe {
ary = intrinsics::uninit();
for i in range(0u, N) {
intrinsics::move_val_init(mut ary[i], f(i));
}
}
ary
}
This would let you call it like Foo(array::from_fn(|_| Zero::zero())).
-Kevin
On Nov 29, 2013, at 8:37 PM, Ashish Myles marci...@gmail.com wrote:
That's some seriously nifty stuff, which got my stuff compiling again. :)
But for the long term, it would be nice to have a syntax that behaves
as was the case with the Copy trait -- it takes a single value and
clones it into the elements of the static array. Or perhaps the
developers disagree and consider it to be a niche use (static arrays
with sizes known a-priori when writing the code) -- it would be good
to get some clarity on this.
Thanks,
Ashish
On Fri, Nov 29, 2013 at 10:20 PM, Kevin Ballard ke...@sb.org wrote:
If you're willing to use unsafe code and std::unstable, you can do it.
use std::num::Zero;
use std::unstable::intrinsics;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT: Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
let mut ary: [T, ..SZ];
unsafe {
ary = intrinsics::uninit();
for i in range(0u, SZ as uint) {
intrinsics::move_val_init(mut ary[i], Zero::zero());
}
}
Foo(ary)
}
}
-Kevin
On Nov 29, 2013, at 7:05 PM, Ashish Myles marci...@gmail.com wrote:
Is there a plan to support fix-sized vector initialization without manual
replication? My example is just a simplified version -- this was part of a
macro that takes the size as input ($n:expr) and the initialization was
[Zero::zero(), .. $n]. Is this use case no longer intended to be supported?
On Nov 29, 2013 6:47 PM, Huon Wilson dbau...@gmail.com wrote:
On 30/11/13 10:33, Ashish Myles wrote:
Previously we had the Copy trait, which when implemented by trait T
allowed one to write
[Zero::zero(), ..SZ] where T implemented the Zero trait. But now I am
not sure how to get that behavior. Concretely, here is the code I
want to get compiling. (Just to check, I added both Clone and
DeepClone, even though they don't automatically allow implicit
copyability).
use std::num::Zero;
enum Constants {
SZ = 2
}
struct FooT([T, ..SZ]);
implT : Clone + DeepClone + Zero FooT {
pub fn new() - FooT {
Foo([Zero::zero(), ..SZ])
}
}
The error I get is:
error: copying a value of non-copyable type `T`
tmp.rs:155 Foo([Zero::zero(), ..SZ])
Any way to do this? Or is this no longer supported for general types?
Any intentions to add this behavior again? Otherwise, I can't even
initialize my struct while being agnostic to the specific value of SZ.
Ashish
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Initialising a fixed size vector [T, ..n] by [foo(), .. n] unfortunately
requires that `T` is implicitly copyable (that is, it doesn't move
ownership
when passed by value), and there's no way around this other than [foo(),
foo(), foo(),...].
Huon
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