Re: function argument accepting function or delegate?
On 1/17/16 1:27 AM, Jon D wrote: My underlying question is how to compose functions taking functions as arguments, while allowing the caller the flexibility to pass either a function or delegate. Simply declaring an argument as either a function or delegate seems to prohibit the other. Overloading works. Are there better ways? If you are looking for a runtime way to do this (the template alias way works too), you may look at std.functional.toDelegate which converts a function pointer to a delegate. But it is awkward to make this a requirement for your user. -Steve
Re: function argument accepting function or delegate?
On Sunday, 17 January 2016 at 06:49:23 UTC, rsw0x wrote:
On Sunday, 17 January 2016 at 06:27:41 UTC, Jon D wrote:
My underlying question is how to compose functions taking
functions as arguments, while allowing the caller the
flexibility to pass either a function or delegate.
[...]
Templates are an easy way.
---
auto call(F, Args...)(F fun, auto ref Args args) { return
fun(args); }
---
Would probably look nicer with some constraints from std.traits.
Thanks much, that works!
Re: function argument accepting function or delegate?
On Sunday, 17 January 2016 at 06:27:41 UTC, Jon D wrote:
My underlying question is how to compose functions taking
functions as arguments, while allowing the caller the
flexibility to pass either a function or delegate.
[...]
Templates are an easy way.
---
auto call(F, Args...)(F fun, auto ref Args args) { return
fun(args); }
---
Would probably look nicer with some constraints from std.traits.
function argument accepting function or delegate?
My underlying question is how to compose functions taking
functions as arguments, while allowing the caller the flexibility
to pass either a function or delegate.
Simply declaring an argument as either a function or delegate
seems to prohibit the other. Overloading works. Are there better
ways?
An example:
auto callIntFn (int function(int) f, int x) { return f(x); }
auto callIntDel (int delegate(int) f, int x) { return f(x); }
auto callIntFnOrDel (int delegate(int) f, int x) { return f(x); }
auto callIntFnOrDel (int function(int) f, int x) { return f(x); }
void main(string[] args) {
alias AddN = int delegate(int);
AddN makeAddN(int n) { return x => x + n; }
auto addTwo = makeAddN(2);// Delegate
int function(int) addThree = x => x + 3; // Function
// assert(callIntFn(addTwo, 4) == 6); // Compile error
// assert(callIntDel(addThree, 4) == 7); // Compile error
assert(callIntDel(addTwo, 4) == 6);
assert(callIntFn(addThree, 4) == 7);
assert(callIntFnOrDel(addTwo, 4) == 6);
assert(callIntFnOrDel(addThree, 4) == 7);
}
---Jon
