• Kagamin <spam here.lot> Mar 26 2011
• Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> Mar 26 2011

Kagamin <spam here.lot> writes:

Kagamin Wrote:

 Kagamin Wrote:
 
 Robert Jacques Wrote:
 
 Should be Algebraic!(T, void). If that doesn't currently compile, we  
 should make it compile.

 Andrei


 For what it's worth, both Algebraic!(T, void*) and Algebraic!(T, void)  
 compile on my branch of std.variant.


 can't assign null
 
 	alias Algebraic!(int,void) nint;
 	nint n1=5;
 	assert(n1==5);
 	n1=null;
 
 \std\variant.d:497: Error: static assert  "Cannot store a void* in a
VariantN!(maxSize,int,void). Valid types are (int, void)"
 test.d:45:        instantiated from here: opAssign!(void*)


 Ahh, there's a workaround:
 
 	alias Algebraic!(int,void) nint;
 	nint n1=5;
 	assert(n1.get!(int)==5);
 	n1=nint(); //uninitialized Variant, sort of null
 	assert(!n1.hasValue);
 	assert(n1.peek!(int)==null);
 	writeln("error here:");
 	assert(n1.get!(int)==0);


this also works without allowing void!

	alias Algebraic!(int) nint;
	nint n1=5;
	assert(n1.get!(int)==5);
	n1=nint(); //still null
	assert(!n1.hasValue);
	assert(n1.peek!(int)==null);
	writeln("error:");
	assert(n1.get!(int)==0);

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

On 3/26/11 5:33 PM, Kagamin wrote:
 Kagamin Wrote:

 Kagamin Wrote:

 Robert Jacques Wrote:

 Should be Algebraic!(T, void). If that doesn't currently compile, we
 should make it compile.

 Andrei


 For what it's worth, both Algebraic!(T, void*) and Algebraic!(T, void)
 compile on my branch of std.variant.


 can't assign null

 	alias Algebraic!(int,void) nint;
 	nint n1=5;
 	assert(n1==5);
 	n1=null;

 \std\variant.d:497: Error: static assert  "Cannot store a void* in a
VariantN!(maxSize,int,void). Valid types are (int, void)"
 test.d:45:        instantiated from here: opAssign!(void*)


 Ahh, there's a workaround:

 	alias Algebraic!(int,void) nint;
 	nint n1=5;
 	assert(n1.get!(int)==5);
 	n1=nint(); //uninitialized Variant, sort of null
 	assert(!n1.hasValue);
 	assert(n1.peek!(int)==null);
 	writeln("error here:");
 	assert(n1.get!(int)==0);


 this also works without allowing void!

 	alias Algebraic!(int) nint;
 	nint n1=5;
 	assert(n1.get!(int)==5);
 	n1=nint(); //still null
 	assert(!n1.hasValue);
 	assert(n1.peek!(int)==null);
 	writeln("error:");
 	assert(n1.get!(int)==0);


Awesome. Talk about forgetting my own code :o).

Andrei