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digitalmars.D.learn - Accepting function or delegate as function argument

reply chmike <christophe meessen.net> writes:
I have implemented the following class (simplified ;) )

----
class Foo(K,T) {
     this(T delegate (K) factory) { m_factory = factory; }
     T delegate (K) m_factory;
     T bar(K key) { return m_factory(key); }
}

string dummyFactory(string key) { return "Hello "~key; }

void main()
{
     auto foo = new Foo!(string,string)(&dummyFactory);
     writeln(foo.bar("world"));
}
----

The compiler complains that dummyFactory is a pointer to a 
function and not a delegate.
How can I modify the class definition so that it accepts a 
function or a delegate transparently from the user perspective ?

Two constructors, one accepting a function and the other one 
accepting a delegate would do the job for the API. Is there a 
simple method to convert a function pointer into a delegate 
pointer that is also efficient ?
May 04 2016
next sibling parent Adam D. Ruppe <destructionator gmail.com> writes:
On Wednesday, 4 May 2016 at 14:54:39 UTC, chmike wrote:
 Two constructors, one accepting a function and the other one 
 accepting a delegate would do the job for the API. Is there a 
 simple method to convert a function pointer into a delegate 
 pointer that is also efficient ?
Do the overload and convert function to delegate with std.functional.toDelegate http://dpldocs.info/experimental-docs/std.functional.toDelegate.html stored_dg = toDelegate(passed_function);
May 04 2016
prev sibling parent reply Rene Zwanenburg <renezwanenburg gmail.com> writes:
On Wednesday, 4 May 2016 at 14:54:39 UTC, chmike wrote:
 Two constructors, one accepting a function and the other one 
 accepting a delegate would do the job for the API. Is there a 
 simple method to convert a function pointer into a delegate 
 pointer that is also efficient ?
http://dlang.org/phobos/std_functional.html#.toDelegate You can also make your constructor a template, constrain it on isCallable if you wish, and then use toDelegate. If the argument is already a delegate toDelegate will avoid doing extra work.
May 04 2016
parent Gary Willoughby <dev nomad.so> writes:
On Wednesday, 4 May 2016 at 15:23:20 UTC, Rene Zwanenburg wrote:
 On Wednesday, 4 May 2016 at 14:54:39 UTC, chmike wrote:
 Two constructors, one accepting a function and the other one 
 accepting a delegate would do the job for the API. Is there a 
 simple method to convert a function pointer into a delegate 
 pointer that is also efficient ?
http://dlang.org/phobos/std_functional.html#.toDelegate You can also make your constructor a template, constrain it on isCallable if you wish, and then use toDelegate. If the argument is already a delegate toDelegate will avoid doing extra work.
import std.functional; import std.stdio; import std.traits; class Foo(K,T) { private T delegate(K) m_factory; public this(T)(T factory) if (isCallable!(T)) { this.m_factory = toDelegate(factory); } public T bar(K key) { return this.m_factory(key); } } string dummyFactory(string key) { return "Hello " ~ key; } void main() { auto foo = new Foo!(string, string)(&dummyFactory); writeln(foo.bar("world")); }
May 06 2016