On Friday, 4 January 2019 at 11:45:24 UTC, Jacob Shtokolov wrote:
On Friday, 4 January 2019 at 10:34:07 UTC, Basile.B wrote:
Show us some code.
Here is the simple example:
https://run.dlang.io/gist/1a06dd703bea5548ee72b4713a7ce5f6
The thing I'm trying to do is to make an experimental port (for
education purposes) of https://github.com/fthomas/refined
library for Scala, which allows to set constraints on basic
types like numeric, bool, string, etc.
For example, you can force an integer variable to take a range
between 0 and 15. And if constraint is not satisfied, you get a
compile time error.
There is no predicate in my example, but even if I add one
(using alias template parameter), it shows the same error.
So is that possible in D?
You have'd to use a template to "construct" your variables;
struct ConstrainedInt
{
int val;
alias val this;
}
template makeConstrainedInt(int Value)
{
static assert(Value <= 15 && Value >= 0);
enum makeConstrainedInt = ConstrainedInt(Value);
}
However this relies on your virtue not to call constraintInt
constructor directly.
and always use the template.
