On Monday, 19 September 2016 at 19:53:27 UTC, Basile B. wrote:
On Monday, 19 September 2016 at 19:38:37 UTC, Jonathan Marler
wrote:
If you have a template where:
1) All parameters are optional
2) The parameters cannot be deduced
Would it be reasonable to instantiate the template with the
default parameter values? For example:
template Foo(string str = "some string", T...)
{
class Foo
{
// class implementation
this() { }
}
}
auto foo = new Foo!()(); // OK
auto foo = new Foo(); // Error: cannot deduce template
parameters
In this example, there's no way to deduce the template
parameters for Foo, however, since they are not specified,
would it be reasonable to just use the defaults? str would be
"some string" and T would be empty?
My understanding of this case is that the usage of the
eponymous member must include all the template parameters
because for example we could have:
template Foo(string str = "some string", T...)
{
class Foo
{
T[0] a;
T[1] b;
// class implementation
this() { }
}
}
The way "new Foo" is used must tells what are the parent
template parameters.
Yes that's why the template cannot deduce the parameters. The
question is, when the parameters cannot be deduced, and they are
all optional, would it be reasonable for the compiler to infer
that the user intended to use the default parameters?
