• ParticlePeter (4/4) May 18 2015 I get the point to an array from a c function, the data size from
• tcak (7/11) May 18 2015 char* dataPtr;
• ParticlePeter (3/14) May 18 2015 Thanks, works. Should be in the "Interfacing to C" Reference
• John Colvin (3/14) May 18 2015 No need to worry about the GC here, it only scans the stack and
• Marco Leise (9/11) May 18 2015 And even if you add a root it wont free anything it did not

"ParticlePeter" <ParticlePeter gmx.de> writes:

I get the point to an array from a c function, the data size from 
another function. The data should be only readable at the D side, 
but I would like to use it as a D slice without copying the data. 
Is this possible ?

"tcak" <tcak gmail.com> writes:

On Monday, 18 May 2015 at 09:18:33 UTC, ParticlePeter wrote:
 I get the point to an array from a c function, the data size 
 from another function. The data should be only readable at the 
 D side, but I would like to use it as a D slice without copying 
 the data. Is this possible ?

char* dataPtr;
size_t dataLen;

auto data = dataPtr[0 .. dataLen];

This doesn't do any copying. BUT I am not sure what GC would be 
doing about it. After you use it, you might want to set `data` to 
null in case of a problem.

"ParticlePeter" <ParticlePeter gmx.de> writes:

On Monday, 18 May 2015 at 09:23:26 UTC, tcak wrote:
 On Monday, 18 May 2015 at 09:18:33 UTC, ParticlePeter wrote:
 I get the point to an array from a c function, the data size 
 from another function. The data should be only readable at the 
 D side, but I would like to use it as a D slice without 
 copying the data. Is this possible ?

 char* dataPtr;
 size_t dataLen;

 auto data = dataPtr[0 .. dataLen];

 This doesn't do any copying. BUT I am not sure what GC would be 
 doing about it. After you use it, you might want to set `data` 
 to null in case of a problem.

Thanks, works. Should be in the "Interfacing to C" Reference 
Article.

"John Colvin" <john.loughran.colvin gmail.com> writes:

On Monday, 18 May 2015 at 09:23:26 UTC, tcak wrote:
 On Monday, 18 May 2015 at 09:18:33 UTC, ParticlePeter wrote:
 I get the point to an array from a c function, the data size 
 from another function. The data should be only readable at the 
 D side, but I would like to use it as a D slice without 
 copying the data. Is this possible ?

 char* dataPtr;
 size_t dataLen;

 auto data = dataPtr[0 .. dataLen];

 This doesn't do any copying. BUT I am not sure what GC would be 
 doing about it. After you use it, you might want to set `data` 
 to null in case of a problem.

No need to worry about the GC here, it only scans the stack and 
its own heap (unless you specifically add a new root).

Marco Leise <Marco.Leise gmx.de> writes:

Am Mon, 18 May 2015 09:51:48 +0000
schrieb "John Colvin" <john.loughran.colvin gmail.com>:

 No need to worry about the GC here, it only scans the stack and 
 its own heap (unless you specifically add a new root).

And even if you add a root it wont free anything it did not
allocate itself! You could even append to your C array. It
will check how much capacity the slice still has on the GC
heap and after realizing the .ptr is not even in one of its
pools, allocate a GC copy of the C array right away.

-- 
Marco