I've run into a use case where I'd like to use a mapped_iterator to
iterator the 1st (or 2nd) items in a sequence of std::pairs. Does
select1st/select2nd exist somewhere within LLVM or is there some
equivalent? If not, I'll add it.
-Dave
Is this making the resultant loop simpler? C++ without lambda's isn't very friendly to functors, what is the before/after effect of doing this?
-Chris
I believe he's referring to this:
I'm familiar with it. I'm asking why it is better to use it than an explicit loop.
-Chris
Chris Lattner <clattner@apple.com> writes:
I've run into a use case where I'd like to use a mapped_iterator to
iterator the 1st (or 2nd) items in a sequence of std::pairs. Does
select1st/select2nd exist somewhere within LLVM or is there some
equivalent? If not, I'll add it.Is this making the resultant loop simpler? C++ without lambda's isn't
very friendly to functors, what is the before/after effect of doing
this?
It's going to unify the DagInit constructors into one piece of code.
The problem now is there are two constructors. One takes a vector of
pairs and the other takes two vectors. They each make sense in their
use contexts but it results in a lot of code duplication when moving
DagInit to a uniqued pool implementation. I wanted to put the
processing code in a third function which would be called with various
types of iterators over those vectors.
-Dave
Scott Conger <scott.conger@gmail.com> writes:
I believe he's referring to this:
Right. It's in libstdc++ as an extension but that's not portable.
-Dave
The problem that I have with this sort of higher order metaprogramming in C++'98 is that you're trading one set of complexity for another. Please just introduce a helper function or something and duplicate the loop.
-Chris
Chris Lattner <clattner@apple.com> writes:
The problem that I have with this sort of higher order metaprogramming
Metaprogramming? This isn't template metaprogramming if that's what you
mean.
in C++'98 is that you're trading one set of complexity for another.
What's the other complexity?
-Dave
I'm talking about mapped iterator + select1st.
-Chris
Chris Lattner <clattner@apple.com> writes:
I'm talking about mapped iterator + select1st.
Right. It's just functional programming (mostly). Isn't this why
mapped_iterator exists?
In any event, if you really object, I guess I will write separate loops.
Seems like we're throwing away a lot of the power of C++, though.
-Dave