On Wednesday, 5 February 2014 at 10:03:52 UTC, Jens Mueller wrote:
Dear lovely D community,
recently I refactored some code into component style (see
Component
Programming in D by Walter
http://www.drdobbs.com/architecture-and-design/component-programming-in-d/240008321)
It looks about like this
someInputRange
.filter!()
.map!()
Next I want to discard all elements but perform some last
operation on
each element. The problem is that map forces me to pass a
function that
returns. Of course I could return a fake value. But that
doesn't look
proper. Another option is to iterate using the foreach loop.
Does not
look better either, does it?
This makes me believe that std.algorithm misses an algorithm.
The
for_each algorithm (see for_each in STL
http://www.cplusplus.com/reference/algorithm/for_each/).
To rephrase the problem more general (because maybe I'm just
not seeing
how to fit the pieces together): How do you perform some
arbitrary
operation on the elements of a range?
myRange
.each!((e)
{
e.someOperation();
});
Jens
Consuming an input range in the functional style should be done
by std.algorithm.copy (passing an output range) or by simply
passing the input range to the consumer algorithm.
Sometimes this isn't possible, which means reverting to foreach,
i.e. a mix of functional and imperative style. This is the
equivalent of STL's `for_each`.
I think adding an `each` function to Phobos is problematic. It is
syntax sugar for foreach, but with the downside of obfuscating
what is essentially imperative code. IMO, imperative code should
look like imperative code, which with foreach is by no means ugly.
