Yet another "static" confusion

[monarch_dodra]

On Wednesday, 20 February 2013 at 08:03:48 UTC, Lubos Pintes 
wrote:
> Hi,
> I want to allocate a buffer which I use in a function which 
> reads data from socket.
> So I did as a first line in that function:
> static char[] buffer=new char[4096];
>
> The compiler (2.062) complained that it cannot evaluate new 
> char[] at compile time.
> I Then tried to move the declaration before function, the same 
> thing happened. Allocating statically sized array bloats the 
> executable.
> My idea is to return only a slice of array if less than 4K data 
> was read and prevent new allocation on every read.
>
> So what I am doing wrong or is this not possible?
> Thank.

In D (and unlike C++), anything static MUST have an initial state 
that is statically evaluable. "new char[4096]" is a run-time 
call, so it cannot be done.

The truth is that this actually isn't much different from C++, 
which hides an invisible "is_initialized" bool somewhere to make 
it work.

You can try to run-time initialize your buffer the module 
constructor, for example. Or just create an accessor to get an 
initialized buffer:

void getBuffer() @safe nothrow
{
     static char[] buffer;
     if (buffer.empty)
         buffer = new char[4096];
     return buffer;
}