On Thursday, 24 October 2013 at 01:48:32 UTC, Jonathan M Davis
wrote:
On Tuesday, October 22, 2013 23:40:00 Timothee Cour wrote:
Following the recent thread "front evaluated multiple time
with joiner
depending on where extra arg given", I'd like to propose the
following
addition in std.range :
The goal is to ensure that a given range's 'front' method is
called only
once per element, allowing one to handle safely side effects
in 'front'
methods
Considering that front really isn't supposed to have side
effects, I'm inclined
to think that putting something like this in the standard
library is a bad
idea. It just encourages bad code. There's certainly no reason
why you can't
implement it for your own stuff if you want to, but I don't
think that it's
something that should be encouraged as it goes against the
range paradigm. The
getter property for front really should be logically const and
logically pure,
and a front with side effects should be something reserved for
debugging.
- Jonathan M Davis
range.map!(a => new Aboject(a))
And here you go. The delegate passed is pure.
