Put 'NSComparisonResult' after = and before ^ to declare the return value of
the block in the code below.
When that fails. Err. Not sure.
> NSComparisonResult (^comp)( id<DKStorableObject>, id<DKStorableObject> ) = ^(
> id<DKStorableObject> a, id<DKStorableObject> b ) {
On 4 Jul, 2012, at 13:40, Graham Cox <[email protected]> wrote:
> Why doesn't this compile?
>
>
> NSComparisonResult (^comp)( id<DKStorableObject>, id<DKStorableObject> ) =
> ^( id<DKStorableObject> a, id<DKStorableObject> b )
> {
> if( a.index < b.index )
> return NSOrderedAscending;
> else if ( a.index > b.index )
> return NSOrderedDescending;
> else
> return NSOrderedSame;
> };
>
> error: incompatible block pointer types initializing 'NSComparisonResult
> (^)(id<DKStorableObject>, id<DKStorableObject>)' with an expression of type
> 'int (^)(id<DKStorableObject>, id<DKStorableObject>)'
>
> Why does it assume that the return type is 'int"? There is nothing here that
> appears to suggest it is one. NSComparisonResult is a typedef of NSInteger.
> If I attempt to cast the result, I get an equally baffling error:
>
> error: invalid block pointer conversion initializing 'NSComparisonResult
> (^)(id<DKStorableObject>, id<DKStorableObject>)' with an expression of type
> 'NSComparisonResult' (aka 'long')
>
> I see there is a typedef for a generic comparator already, but I want to
> declare it as conforming to a protocol.
>
>
> Could the stupid block syntax be any less intuitive?
>
> --Graham
>
>
>
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