• NN (9/9) Jan 21 2007 Why there is no string view in D ?
• Lionello Lunesu (5/14) Jan 21 2007 char* p = ....;
• Daniel Keep (18/38) Jan 21 2007 A more in-depth explanation:
• =?ISO-8859-1?Q?Lu=EDs_Marques?= (6/8) Jan 23 2007 Maybe I'm nitpicking but it might be better to refer to slices as an
• Daniel Keep (9/21) Jan 24 2007 I could be completely wrong, but this is how I've always looked at it:

NN <nn-mail bk.ru> writes:

Why there is no string view in D ?

Assume I have pointer in memory pointing to zero ending string:
char* p;

I want to create a string from it but i do not want to copy it.
Assume I have a special class for this:
StringView s(p);

But what would I do if function receives char[] ? There will be a copy.
What if I do not want a copy ?

Thanx.

"Lionello Lunesu" <lionello lunesu.remove.com> writes:

char* p = ....;
char[] stringview = p[0..strlen(p)];
assert( stringview.ptr is p );

"NN" <nn-mail bk.ru> wrote in message 
news:ep0ic7$1a9c$1 digitaldaemon.com...
 Why there is no string view in D ?

 Assume I have pointer in memory pointing to zero ending string:
 char* p;

 I want to create a string from it but i do not want to copy it.
 Assume I have a special class for this:
 StringView s(p);

 But what would I do if function receives char[] ? There will be a copy.
 What if I do not want a copy ?

 Thanx. 

Daniel Keep <daniel.keep+lists gmail.com> writes:

Lionello Lunesu wrote:
 char* p = ....;
 char[] stringview = p[0..strlen(p)];
 assert( stringview.ptr is p );
 
 "NN" <nn-mail bk.ru> wrote in message 
 news:ep0ic7$1a9c$1 digitaldaemon.com...
 
Why there is no string view in D ?

Assume I have pointer in memory pointing to zero ending string:
char* p;

I want to create a string from it but i do not want to copy it.
Assume I have a special class for this:
StringView s(p);

But what would I do if function receives char[] ? There will be a copy.
What if I do not want a copy ?

Thanx. 


A more in-depth explanation:

D has "slices" which are a combination of a pointer and a length (number 
of elements).  Slices are effectively the same thing as arrays (they 
work in precisely the same way).

You can take a slice of an array, *or* a pointer using the

   ptr[first..(last+1)]

syntax.  The reason you use the last index you want to slice + 1 is that 
this allows things like

   ptr[0..0]

for an empty slice and

   arr[0..$]

which is a slice over an entire array (where "$" is the array's length).

So, in your example, to convert a null-terminated C string into a D 
array (WITHOUT copying), you would use the code Lionello posted.  Just 
note that by doing so, you strip off the trailing NULL (D doesn't use 
trailing NULLs since all arrays know their own bounds).

	-- Daniel

=?ISO-8859-1?Q?Lu=EDs_Marques?= <luismarques gmail.com> writes:

Daniel Keep wrote:
 Slices are effectively the same thing as arrays (they 
 work in precisely the same way).

Maybe I'm nitpicking but it might be better to refer to slices as an 
operation, returning a new array reference, instead of comparing them to 
arrays directly.

--
Luís

Daniel Keep <daniel.keep+lists gmail.com> writes:

Luís Marques wrote:
 Daniel Keep wrote:
 
 Slices are effectively the same thing as arrays (they work in 
 precisely the same way).

 
 
 Maybe I'm nitpicking but it might be better to refer to slices as an 
 operation, returning a new array reference, instead of comparing them to 
 arrays directly.
 
 -- 
 Luís

I could be completely wrong, but this is how I've always looked at it:

slice, n: a section of memory denoted by a starting address and a number 
of elements.

slice, v: the operation of creating a new slice given a starting address 
and a number of elements from a section of memory.

So "slices" is the plural of the noun "slice", not the verb "slice" :P

I think.  Maybe.

   -- Daniel