Re: How to create a mutable array of strings?
On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: It's annoying to have to dup each one. Yes, it's really annoying. However, the problem can be solved as follows: http://forum.dlang.org/thread/owxweucyzjwugpjwh...@forum.dlang.org?page=2#post-cqjevoldkqdkmdbenkul:40forum.dlang.org On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: But, you do have a couple other possibilities: auto s = ["foo".dup, "bar".dup]; import std.algorithm : map; import std.array : array; auto s = map!(a => a.dup)(["foo", "bar"]).array; // this will needlessly allocate an array for the strings Now imagine that you have a multi-dimensional array of strings. This will not work: auto s = map!(a => a.dup)([["foo", "baz"], ["bar", "test"]]).array; You have to apply to each line .dup :) auto s = [["foo".dup, "baz".dup], ["bar".dup, "test".dup]]; s[1][0][1] = 't'; On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote: But really, a string is immutable. There's not a way around that. A string is the most basic level of array primitive, not even mutable arrays of non-char types have that, and it's an annoyance. From there, you have to build the data out of ROM into the heap. Thank you. I do not know. And yet, the problem is easily solved. You just have to add .deepDup Phobos: http://forum.dlang.org/thread/owxweucyzjwugpjwh...@forum.dlang.org?page=2#post-cqjevoldkqdkmdbenkul:40forum.dlang.org
Re: How to create a mutable array of strings?
On Monday, 18 May 2015 at 14:43:33 UTC, Steven Schveighoffer
wrote:
Right, you'd apply the map/array combo to each element:
Yes, I knew it.
alias m = map!(a => a.dup); // too bad can't do array as well
auto s = [m(["foo", "baz"]).array, m(["bar", "test"]).array];
Or to get even more crazy:
auto s = map!(a => map!(a => a.dup)(a).array)(/* your input
array */).array;
Imagine a five-dimensional array will be :)
But this means you are duping more of the array literal than
you really should.
It's likely helpful to have somewhere in std.array a dupArray
function that does map!(a => a.dup).array work in one go (and
without making a temporary array):
auto s = [dupArray("foo", "baz"), dupArray("bar", "test")];
Yes, it would be nice. I believe that Phobos need such function.
deepDup would dup the whole thing. All you need to dup is the
string literals, as array literals constructed at runtime are
on the heap (and mutable) already. The literal already is
wasted even in my original suggestion, but this is doubly
wasteful.
Right.
Re: How to create a mutable array of strings?
On 5/18/15 9:55 AM, Dennis Ritchie wrote:
On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote:
It's annoying to have to dup each one.
Yes, it's really annoying. However, the problem can be solved as follows:
http://forum.dlang.org/thread/owxweucyzjwugpjwh...@forum.dlang.org?page=2#post-cqjevoldkqdkmdbenkul:40forum.dlang.org
On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote:
But, you do have a couple other possibilities:
auto s = ["foo".dup, "bar".dup];
import std.algorithm : map;
import std.array : array;
auto s = map!(a => a.dup)(["foo", "bar"]).array; // this will
needlessly allocate an array for the strings
Now imagine that you have a multi-dimensional array of strings. This
will not work:
auto s = map!(a => a.dup)([["foo", "baz"], ["bar", "test"]]).array;
Right, you'd apply the map/array combo to each element:
alias m = map!(a => a.dup); // too bad can't do array as well
auto s = [m(["foo", "baz"]).array, m(["bar", "test"]).array];
Or to get even more crazy:
auto s = map!(a => map!(a => a.dup)(a).array)(/* your input array */).array;
But this means you are duping more of the array literal than you really
should.
It's likely helpful to have somewhere in std.array a dupArray function
that does map!(a => a.dup).array work in one go (and without making a
temporary array):
auto s = [dupArray("foo", "baz"), dupArray("bar", "test")];
On Monday, 18 May 2015 at 13:14:38 UTC, Steven Schveighoffer wrote:
But really, a string is immutable. There's not a way around that. A
string is the most basic level of array primitive, not even mutable
arrays of non-char types have that, and it's an annoyance. From there,
you have to build the data out of ROM into the heap.
Thank you. I do not know.
And yet, the problem is easily solved. You just have to add ..deepDup
Phobos:
http://forum.dlang.org/thread/owxweucyzjwugpjwh...@forum.dlang.org?page=2#post-cqjevoldkqdkmdbenkul:40forum.dlang.org
deepDup would dup the whole thing. All you need to dup is the string
literals, as array literals constructed at runtime are on the heap (and
mutable) already. The literal already is wasted even in my original
suggestion, but this is doubly wasteful.
-Steve
Re: How to create a mutable array of strings?
On 5/17/15 5:15 AM, Dennis Ritchie wrote: This option is also a strange: char[][] s = ["foo".dup, "bar".dup]; s[1][1] = 't'; In my opinion, you need to add to D keyword mutable. It's annoying to have to dup each one. But, you do have a couple other possibilities: auto s = ["foo".dup, "bar".dup]; import std.algorithm : map; import std.array : array; auto s = map!(a => a.dup)(["foo", "bar"]).array; // this will needlessly allocate an array for the strings But really, a string is immutable. There's not a way around that. A string is the most basic level of array primitive, not even mutable arrays of non-char types have that, and it's an annoyance. From there, you have to build the data out of ROM into the heap. -Steve
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 10:05:34 UTC, Daniel Kozak wrote: Ouch ignore this one :D Yes, it will not work with multidimensional arrays :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:57:05 UTC, Daniel Kozak wrote:
On Sun, 17 May 2015 09:39:21 +
Dennis Ritchie via Digitalmars-d-learn
wrote:
I remembered code Ali Çereli. It really helped:
http://forum.dlang.org/thread/ulhtlyxxclihaseef...@forum.dlang.org#post-mihl6m:241che:241:40digitalmars.com
-
import std.stdio, std.traits, std.range, std.algorithm;
auto deepDup(A)(A arr)
if (isArray!A)
{
static if (isArray!(ElementType!A)) {
return arr.map!(a => a.deepDup).array;
} else {
return arr.dup;
}
}
void main() {
auto s = ["foo", "bar"].deepDup;
s[1][1] = 't';
writeln(s);
}
-
http://rextester.com/QBFH12695
P.S. Need to enable deepDup in Phobos.
allready there:
auto s = ["foo", "bar"].map!"a.dup".array;
:)
Ouch ignore this one :D
Re: How to create a mutable array of strings?
On Sun, 17 May 2015 09:39:21 +
Dennis Ritchie via Digitalmars-d-learn
wrote:
> I remembered code Ali Çereli. It really helped:
> http://forum.dlang.org/thread/ulhtlyxxclihaseef...@forum.dlang.org#post-mihl6m:241che:241:40digitalmars.com
>
> -
> import std.stdio, std.traits, std.range, std.algorithm;
>
> auto deepDup(A)(A arr)
> if (isArray!A)
> {
> static if (isArray!(ElementType!A)) {
> return arr.map!(a => a.deepDup).array;
>
> } else {
> return arr.dup;
> }
> }
>
> void main() {
>
> auto s = ["foo", "bar"].deepDup;
>
> s[1][1] = 't';
>
> writeln(s);
> }
> -
> http://rextester.com/QBFH12695
>
> P.S. Need to enable deepDup in Phobos.
allready there:
auto s = ["foo", "bar"].map!"a.dup".array;
:)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:37:56 UTC, Daniel Kozak wrote: So maybe this one would be ok with you too :) auto s = to!(char[][])(["foo", "bar"]); Now it works :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:36:33 UTC, anonymous wrote:
On Sunday, 17 May 2015 at 09:26:15 UTC, Dennis Ritchie wrote:
And no crashes on Windows :)
Yeah, on windows it's even worse.
void main()
{
auto s = cast(char[][])["foo", "bar"];
s[1][1] = 't';
import std.stdio;
writeln("bar");
}
Yes exactly.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:20:17 UTC, Dennis Ritchie wrote: On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: auto s = cast(char[][])["foo", "bar"]; Thanks. This version I was completely satisfied. So maybe this one would be ok with you too :) auto s = to!(char[][])(["foo", "bar"]);
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:26:15 UTC, Dennis Ritchie wrote:
And no crashes on Windows :)
Yeah, on windows it's even worse.
void main()
{
auto s = cast(char[][])["foo", "bar"];
s[1][1] = 't';
import std.stdio;
writeln("bar");
}
Re: How to create a mutable array of strings?
I remembered code Ali Çereli. It really helped:
http://forum.dlang.org/thread/ulhtlyxxclihaseef...@forum.dlang.org#post-mihl6m:241che:241:40digitalmars.com
-
import std.stdio, std.traits, std.range, std.algorithm;
auto deepDup(A)(A arr)
if (isArray!A)
{
static if (isArray!(ElementType!A)) {
return arr.map!(a => a.deepDup).array;
} else {
return arr.dup;
}
}
void main() {
auto s = ["foo", "bar"].deepDup;
s[1][1] = 't';
writeln(s);
}
-
http://rextester.com/QBFH12695
P.S. Need to enable deepDup in Phobos.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:24:19 UTC, anonymous wrote: On Sunday, 17 May 2015 at 09:20:17 UTC, Dennis Ritchie wrote: On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: auto s = cast(char[][])["foo", "bar"]; Thanks. This version I was completely satisfied. Remember that Daniel Kozak wrote "if you are sure thats what you really need". I'm confident that you're not sure it's what you need. For starters, this crashes on linux: auto s = cast(char[][])["foo", "bar"]; s[1][1] = 't'; And no crashes on Windows :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:21:58 UTC, Marc Schütz wrote: On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: On Sun, 17 May 2015 09:06:38 + Dennis Ritchie via Digitalmars-d-learn wrote: Hi, It seems to me, or D do not create mutable array of strings? How to create a mutable equivalent of a string array? - string[] s = ["foo", "bar"]; // s[1][1] = 't'; // immutable expression s[1][1] or you can use cast if you are sure thats what you really need: auto s = [cast(char[])"foo", cast(char[])"bar"]; or auto s = cast(char[][])["foo", "bar"]; That's not a good idea. I haven't checked, but this will likely segfault on mutation Yep, you are right, shame on me :)
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: On Sun, 17 May 2015 09:06:38 + Dennis Ritchie via Digitalmars-d-learn wrote: Hi, It seems to me, or D do not create mutable array of strings? How to create a mutable equivalent of a string array? - string[] s = ["foo", "bar"]; // s[1][1] = 't'; // immutable expression s[1][1] or you can use cast if you are sure thats what you really need: auto s = [cast(char[])"foo", cast(char[])"bar"]; or auto s = cast(char[][])["foo", "bar"]; That's not a good idea. I haven't checked, but this will likely segfault on mutation, because the string literals are placed into read-only memory. And multiple identical strings are merged (shared), so that this would modify all occurances of that string literal, even if it shouldn't segfault.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: On Sun, 17 May 2015 09:06:38 + Dennis Ritchie via Digitalmars-d-learn wrote: Hi, It seems to me, or D do not create mutable array of strings? How to create a mutable equivalent of a string array? - string[] s = ["foo", "bar"]; // s[1][1] = 't'; // immutable expression s[1][1] or you can use cast if you are sure thats what you really need: auto s = [cast(char[])"foo", cast(char[])"bar"]; or auto s = cast(char[][])["foo", "bar"]; But I am unsure if this will work in case where immutable data will occupied read only memory.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: auto s = cast(char[][])["foo", "bar"]; Thanks. This version I was completely satisfied.
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:20:17 UTC, Dennis Ritchie wrote: On Sunday, 17 May 2015 at 09:18:15 UTC, Daniel Kozak wrote: auto s = cast(char[][])["foo", "bar"]; Thanks. This version I was completely satisfied. Remember that Daniel Kozak wrote "if you are sure thats what you really need". I'm confident that you're not sure it's what you need. For starters, this crashes on linux: auto s = cast(char[][])["foo", "bar"]; s[1][1] = 't';
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:10:06 UTC, Dennis Ritchie wrote: It's uncomfortable: - char[][] s = [['f', 'o', 'o'], ['b', 'a', 'r']]; s[1][1] = 't'; auto s = ["foo".dup, "bar".dup]; s[1][1] = 't';
Re: How to create a mutable array of strings?
This option is also a strange: char[][] s = ["foo".dup, "bar".dup]; s[1][1] = 't'; In my opinion, you need to add to D keyword mutable.
Re: How to create a mutable array of strings?
On Sun, 17 May 2015 09:06:38 + Dennis Ritchie via Digitalmars-d-learn wrote: > Hi, > It seems to me, or D do not create mutable array of strings? > > How to create a mutable equivalent of a string array? > > - > string[] s = ["foo", "bar"]; > // s[1][1] = 't'; // immutable expression s[1][1] or you can use cast if you are sure thats what you really need: auto s = [cast(char[])"foo", cast(char[])"bar"]; or auto s = cast(char[][])["foo", "bar"];
Re: How to create a mutable array of strings?
On Sun, 17 May 2015 09:06:38 + Dennis Ritchie via Digitalmars-d-learn wrote: > Hi, > It seems to me, or D do not create mutable array of strings? > > How to create a mutable equivalent of a string array? > > - > string[] s = ["foo", "bar"]; > // s[1][1] = 't'; // immutable expression s[1][1] auto s = ["foo".dup, "bar".dup];
Re: How to create a mutable array of strings?
On Sunday, 17 May 2015 at 09:06:40 UTC, Dennis Ritchie wrote: Hi, It seems to me, or D do not create mutable array of strings? How to create a mutable equivalent of a string array? - string[] s = ["foo", "bar"]; // s[1][1] = 't'; // immutable expression s[1][1] It's uncomfortable: - char[][] s = [['f', 'o', 'o'], ['b', 'a', 'r']]; s[1][1] = 't';
