Re: Add Element to list not Working
On 04/01/2012 10:45 PM, Chris Pons wrote:
I'm trying to add an element to a list with insert but that doesn't seem
to do anything at all. If I try using ~= it says that Error: cannot
append type Node to type SList!(Node). I'm pretty confused about using
~= because it works fine for arrays but apperantly not for lists.
How do I add an element to a list?
import std.stdio;
import std.container;
void main()
{
auto l = SList!int();
l.insert(42);// inserts front
l.insert(43);// this too
assert(l == SList!int(43, 42));
// inserts after the specified range (l[] is the entire list)
l.insertAfter(l[], 44);
assert(l == SList!int(43, 42, 44));
// This doesn't work because SList.Range doesn't define opOpAssign!~
// l[] ~= 45;
}
Ali
Re: Add Element to list not Working
On 2 April 2012 17:45, Chris Pons cmp...@gmail.com wrote: I'm trying to add an element to a list with insert but that doesn't seem to do anything at all. If I try using ~= it says that Error: cannot append type Node to type SList!(Node). I'm pretty confused about using ~= because it works fine for arrays but apperantly not for lists. How do I add an element to a list? opAppend (or whatever it is) isn't defined for alot of types that it probably should be. There should be an append method that you can use though. -- James Miller
Re: Add Element to list not Working
Thanks. I tried doing this and the list didn't update:
void AddToList( SList!int list, int i )
{
list.insert( i );
}
SList!int intList;
AddToList( intList, 42 );
but when I switched to this, it worked:
SList!int intList;
void AddToList( int i )
{
intList.insert( i );
}
AddToList( 42 );
The first method didn't give an error it just didn't update the
list as I thought. Any idea?
On Monday, 2 April 2012 at 06:07:40 UTC, Ali Çehreli wrote:
On 04/01/2012 10:45 PM, Chris Pons wrote:
I'm trying to add an element to a list with insert but that
doesn't seem
to do anything at all. If I try using ~= it says that Error:
cannot
append type Node to type SList!(Node). I'm pretty confused
about using
~= because it works fine for arrays but apperantly not for
lists.
How do I add an element to a list?
import std.stdio;
import std.container;
void main()
{
auto l = SList!int();
l.insert(42);// inserts front
l.insert(43);// this too
assert(l == SList!int(43, 42));
// inserts after the specified range (l[] is the entire
list)
l.insertAfter(l[], 44);
assert(l == SList!int(43, 42, 44));
// This doesn't work because SList.Range doesn't define
opOpAssign!~
// l[] ~= 45;
}
Ali
Re: Add Element to list not Working
On 04/01/2012 11:18 PM, Chris Pons wrote:
Thanks. I tried doing this and the list didn't update:
void AddToList( SList!int list, int i )
{
list.insert( i );
}
Oh, that has nothing to do with SList. SList is a struct and as a
fundamental rule of D, structs are copied to functions. SList happens to
be a struct. The list parameter of AddToList and the list variable that
is passed to the function as an argument are two different variables.
SList!int intList;
AddToList( intList, 42 );
but when I switched to this, it worked:
SList!int intList;
void AddToList( int i )
{
intList.insert( i );
}
Global variables are not a good solution of course. :(
The solution here is to pass the argument by-reference by the 'ref' keyword:
void AddToList( ref SList!int list, int i )
{
// ...
}
Ali
P.S. There is this chapter that covers 'ref' and most (but not all)
types of function parameters:
http://ddili.org/ders/d.en/function_parameters.html
Re: Add Element to list not Working
Ah, thank you. I didn't realize taht SList is a struct and that
it used value semantics. That clears this up.
On Monday, 2 April 2012 at 14:22:25 UTC, Ali Çehreli wrote:
On 04/01/2012 11:18 PM, Chris Pons wrote:
Thanks. I tried doing this and the list didn't update:
void AddToList( SList!int list, int i )
{
list.insert( i );
}
Oh, that has nothing to do with SList. SList is a struct and as
a fundamental rule of D, structs are copied to functions. SList
happens to be a struct. The list parameter of AddToList and the
list variable that is passed to the function as an argument are
two different variables.
SList!int intList;
AddToList( intList, 42 );
but when I switched to this, it worked:
SList!int intList;
void AddToList( int i )
{
intList.insert( i );
}
Global variables are not a good solution of course. :(
The solution here is to pass the argument by-reference by the
'ref' keyword:
void AddToList( ref SList!int list, int i )
{
// ...
}
Ali
P.S. There is this chapter that covers 'ref' and most (but not
all) types of function parameters:
http://ddili.org/ders/d.en/function_parameters.html
Re: Add Element to list not Working
On Monday, April 02, 2012 20:27:18 Chris Pons wrote: Ah, thank you. I didn't realize taht SList is a struct and that it used value semantics. That clears this up. It really shouldn't be using value semantics (though it wouldn't surprise me if it is - I haven't used it). std.container's containers are supposed to be reference types, but how that's going to be implemented exactly is still in flux - in part due to the pending custom allocator design. In the long run, std.container's containers will likely be ref-counted structs in the long run, but they may end up being classes. - Jonathan M Davis
Add Element to list not Working
I'm trying to add an element to a list with insert but that doesn't seem to do anything at all. If I try using ~= it says that Error: cannot append type Node to type SList!(Node). I'm pretty confused about using ~= because it works fine for arrays but apperantly not for lists. How do I add an element to a list?
