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D - D: nice, although still puzzling

reply Chr. Grade <Chr._member pathlink.com> writes:
/*
** My first D-day; got three newbie questions:
** (1) Is there a way to avoid using malloc() in order to
**     create instances of a structure? Something D-like?
**     [Other than "Free Lists"] see: CreateMyList() below
** (2) Does the garbage collector manage memory that has
**     been allocated with the c-lib funcs? ->
**     Say, I pluck a node out of my list, never use it
**     again during runtime, but won't free it explicitly.
** (3) Are there any new os-independent facilities that
**     make file accesses more convenient in D?
*/

import std.c.stdlib;

struct MyList
{
uint     nFoo;
MyList*  psNext;
}

MyList* CreateMyList(uint nNodes)
{
MyList* psFirstNode = (MyList*)malloc(MyList.size);
MyList* psTempNode  = psFirstNode;

printf("\n New Node at: 0x%X", psTempNode);
psTempNode.nFoo = --nNodes;

// I initially feared this coding style wouldn't be allowed.
while(nNodes--)
psTempNode = psTempNode.psNext = (MyList*)malloc(MyList.size),
printf("\n New Node at: 0x%X", psTempNode),
psTempNode.nFoo = nNodes;

return (psFirstNode);
}

uint main()
{
// Great! This nonsense still works :)
"D somehow", "well", "feels like C" && "that's nice";

MyList* psFirstNode = CreateMyList(0xFF);

do printf("\n Val: %u", psFirstNode.nFoo);
while(psFirstNode.nFoo != 0,
psFirstNode = psFirstNode.psNext);

// Well, but where's that gone...
// psFirstNode.psNext = ((void*)0);

return (0x0);
}
Apr 21 2004
next sibling parent "C. Sauls" <ibisbasenji yahoo.com> writes:
Chr. Grade wrote:
 ** (1) Is there a way to avoid using malloc() in order to
 **     create instances of a structure? Something D-like?
 **     [Other than "Free Lists"] see: CreateMyList() below

I've yet to ever even use malloc() from D. As to your provided program... consider the following (untested) re-write: ------------------------------ struct MyList { uint foo; MyList* next; static MyList* create(uint nodes) { MyList first; MyList* tmp = &first; void report() { printf("\n New Node at: 0x%X", tmp); } report(); tmp.foo = --nodes; while (nodes--) { tmp.next = new MyList; tmp = tmp.next; report(); tmp.foo = nodes; } return &first; } } int main() { MyList* node = MyList.create(0xFF); while (node) { printf("\n Val: %u", node.foo); node = node.next; } return 0; } ------------------------------ -C. Sauls -Invironz
Apr 21 2004
prev sibling parent "Walter" <walter digitalmars.com> writes:
"Chr. Grade" <Chr._member pathlink.com> wrote in message
news:c66du7$1nd8$1 digitaldaemon.com...
 /*
 ** My first D-day; got three newbie questions:
 ** (1) Is there a way to avoid using malloc() in order to
 **     create instances of a structure? Something D-like?
 **     [Other than "Free Lists"] see: CreateMyList() below

Yes. new MyList;
 ** (2) Does the garbage collector manage memory that has
 **     been allocated with the c-lib funcs? ->

No. If a program goes outside of the gc, then the programmer is totally in charge of that <g>.
 **     Say, I pluck a node out of my list, never use it
 **     again during runtime, but won't free it explicitly.

If it was allocated with malloc(), it must be explicitly free()'d.
 ** (3) Are there any new os-independent facilities that
 **     make file accesses more convenient in D?

std.file offers a few.
Apr 21 2004