Renaming Flag!"" in API

aliak something at
Mon Oct 12 11:31:02 UTC 2020

On Monday, 12 October 2020 at 10:24:44 UTC, FreeSlave wrote:
> Let's say I use Flag type named 'myflagname' in API like this:
> import std.typecons;
> void func(Flag!"myflagname" flag)
> {
> //...
> }
> void main()
> {
>     func(Yes.myflagname);
> }
> Later I realize that 'myflagname' is a bad name and I want to 
> change it to something else. But if I do so, I break the 
> existing code using this API as Flag with different name will 
> be a different type and Yes.myflagname and No.myflagname won't 
> fit in. I can't use alias as Yes and No relies on string 
> literal.
> Can this issue overcome somehow? Looks like a fundamental flaw 
> with std.typecons.Flag.

One of the reason's Flag is there is because of what's known as 
the boolean trap [0]. If someone changes the name of a parameter, 
that can potentially mean the semantics have changed. Should Flag 
work then? And if it should, why not straight up bool?

More information about the Digitalmars-d-learn mailing list