On Mon, 12 Oct 2009 05:26:58 -0400, bearophile <bearophileh...@lycos.com>
wrote:
What's wrong with this code?
struct MemoryPool(T) {
alias T[100_000 / T.sizeof] Chunk;
Chunk*[] chunks;
}
struct Foo {
int x;
MemoryPool!(Foo) pool;
}
void main() {}
It prints "Error: struct problem.Foo no size yet for forward reference".
T.sizeof must be 8 in all cases.
So I have tried to pull pool out:
struct MemoryPool(T) {
alias T[100_000 / T.sizeof] Chunk;
Chunk*[] chunks;
}
MemoryPool!(Foo) pool;
struct Foo {
int x;
// here uses pool
}
void main() {}
But there's a problem still:
Error: struct problem2.Foo no size yet for forward reference
To compile the code I have to move pool forward still:
struct MemoryPool(T) {
alias T[100_000 / T.sizeof] Chunk;
Chunk*[] chunks;
}
struct Foo {
int x;
// here uses pool
}
MemoryPool!(Foo) pool;
void main() {}
When possible it's better to avoid global variables. To avoid the global
variable I may pass the instance pool to Foo. But to do this Foo has to
become a struct template. But I am not sure how I can do this.
Do you have any comments or suggestions?
It looks strange what you are doing. A Foo can have a memory pool of a
lot of Foo's? Do you mean to make the memory pool static? I think that
might work.
I think the main problem is you are defining MemoryPool!(Foo).Chunk which
specifically needs to know the size of Foo before Foo is completely
declared.
It's like you are doing this:
struct X
{
X x;
}
Which clearly is incorrect.
-Steve
