• Gary Willoughby (37/37) Oct 25 2013 Just noticed something interesting in the std.allocator source,
• Brad Anderson (9/46) Oct 25 2013 Yeah, it sets the lexer to the end of file so it stops. See
• evilrat (3/3) Oct 26 2013 as replied, version(none) allows removing some code from build

"Gary Willoughby" <dev nomad.so> writes:

Just noticed something interesting in the std.allocator source, 
right at the very bottom. An EOF and some code? Does the compiler 
stop at the EOF? If so why add code beyond that? Also 
version(none), eh?

https://github.com/andralex/phobos/blob/allocator/std/allocator.d#L4071

What's going on there?

...
__EOF__

version(none) struct TemplateAllocator
{
     enum alignment = platformAlignment;
     static size_t goodAllocSize(size_t s)
     {
     }
     void[] allocate(size_t)
     {
     }
     bool owns(void[])
     {
     }
     bool expand(ref void[] b, size_t)
     {
     }
     bool reallocate(ref void[] b, size_t)
     {
     }
     void deallocate(void[] b)
     {
     }
     void deallocateAll()
     {
     }
     void[] allocateAll()
     {
     }
     static shared TemplateAllocator it;
}

"Brad Anderson" <eco gnuk.net> writes:

On Friday, 25 October 2013 at 16:03:24 UTC, Gary Willoughby wrote:
 Just noticed something interesting in the std.allocator source, 
 right at the very bottom. An EOF and some code? Does the 
 compiler stop at the EOF? If so why add code beyond that? Also 
 version(none), eh?

 https://github.com/andralex/phobos/blob/allocator/std/allocator.d#L4071

 What's going on there?

 ...
 __EOF__

 version(none) struct TemplateAllocator
 {
     enum alignment = platformAlignment;
     static size_t goodAllocSize(size_t s)
     {
     }
     void[] allocate(size_t)
     {
     }
     bool owns(void[])
     {
     }
     bool expand(ref void[] b, size_t)
     {
     }
     bool reallocate(ref void[] b, size_t)
     {
     }
     void deallocate(void[] b)
     {
     }
     void deallocateAll()
     {
     }
     void[] allocateAll()
     {
     }
     static shared TemplateAllocator it;
 }

Yeah, it sets the lexer to the end of file so it stops.  See 
Special Tokens section: http://dlang.org/lex.html

Andrei is using it to include a pattern of the general structure 
you'd need to write your own allocator that the compiler doesn't 
even bother looking at.  He could have commented it out too.  The 
version(none) also accomplishes this.  __EOF__ just makes it so 
the compiler doesn't even bother looking at it (you can shave a 
few microseconds off your build time!)

"evilrat" <evilrat666 gmail.com> writes:

as replied, version(none) allows removing some code from build 
but it still parses and spew errors in it, there is also 
version(all) to re-enable code.