Macro grade::build

macro_rules! build {
    { 
	        $parent:ident$(:$parent_alias:ident)? {
	            $( $field:ident:$val:expr, )*
	            $( => $signal:path: $callback:expr, )*
	            $( -- $([$pack_func:ident $(,$pack_arg:expr)*])? $child:ident$(:$child_alias:ident)? {$($child_body:tt)*})*
	            $( .. $meth:ident($($meth_body:expr),*) )*
	        } 
	    } => { ... };
}

Instantiate a buildable Object from an inline macro