On 05/14/2015 01:42 PM, Laeeth Isharc via Digitalmars-d-learn wrote:
On Thursday, 14 May 2015 at 18:42:56 UTC, Charles Hixson wrote:
What are the downsides to simulating a new type with a struct.
What I have in mind is something along the lines of:
struct myType
{ uint64_t value;
}
The goal of this type is to prevent accidental conversions from
myType into ints, uint64_ts, etc.
http://dlang.org/phobos/std_typecons.html#.Typedef
Yes, that looks as if it would do the job, but what are its advantages
over a simple struct? I'd be hesitant to try to predict the RAM layout
of a templated variable, but it's my understanding that a struct has
neither compile time nor runtime penalties over a simple variable, and
that it doesn't increase RAM comsumption when included within another
struct, or in a static array.
What I was really wondering was whether the limitation of access caused
by enclosing a variable within a struct was worth the benefit.
Templates add a whole 'nother layer of complexity. For that matter I
was thinking that, if I so chose, I could at some point add limits along
the lines of Ada's types. I like being *able* to define conversions for
types, but frequently I'd rather not have them arbitrarily assumed.
Otherwise I'd just use alias, which almost does what I want. (E.g., one
thing I might eventually want to do is use a couple of bits at the top
of the uint64_t as flags, so if I did define operations I'd need to be
able to mask the flag bits off before the operation and reapply them to
the result, in some defined way of combining the flags. Not good if
sometimes the value is going to be automatically reinterpreted as a
plain number.)
