On 2/4/13 12:39 AM, TONGARI wrote:
2013/2/3 Joel de Guzman <djowel@gmail.com>
On 2/3/13 11:24 PM, TONGARI wrote:
2013/2/3 Joel de Guzman <djowel@gmail.com>
On 2/3/13 9:59 PM, TONGARI wrote:
Just uploaded to:
https://github.com/jamboree/****Boost.FusionEx<https://github.com/jamboree/**Boost.FusionEx> <https://github.**com/jamboree/Boost.FusionEx<https://github.com/jamboree/Boost.FusionEx>
There are: + mapping + left_mapping + full_mapping
Simple tests contained. Comments/improvements are welcome :^)
By looking at the sample code, it seems I misunderstood your original post by a long shot.
How did you understand it then?
I guess it's irrelevant how I understood it then. What's important is how I can understand it now and I really want to understand what it is exactly you are trying to achieve.
There's a bit different than what I originally wrote.
The first thought was to map-assign the data:
mapping(dst, src)
And now it's more general:
result = mapping(a, b, binary_op_on_data)
Good idea. But it's better if you can provide both versions. Something similar to filter and filter_if.
I don't see how they related. The original one gives an immediate result,
What original one?
while the later is lazily evaluated.
what later one? filter & filter_if are both lazily
evaluated. Are you suggesting a shorthand for mapping(a, b, _2)?
returns a view which is also associative
FWIW, "mapping/left_mapping/full_**mapping" are analog to "inner join/left join/full join" in relational DB.
Perhaps mapping is not a good name? Then of course, we already have "join".
Well, I don't have a better one, do you?
Not sure.
I still don't understand "view" and "eval" enough. Pardon me for being slow. It would be best to collect all your thoughts in a single, complete explanation of all these new additions so that we don't have any misunderstandings.
Maybe I have to implement all these to show what they really are... But I'll try to explain with a simple use-case here:
Given:
vector<int, string, int> v;
How would you assign to the ints in v?
foreach(filter<int>(v), _1 = 99);
Will that compile? No, you can't assign to read-only value. Why are they read-only? Because filter<int>(v) takes v as 'const&', there's no '&' overload.
Exactly what I was saying in a previous reply. I am considering allowing mutability (i.e. taking in & arguments). That way, your code above will work as-is.
So how could I do? Make something that takes v by reference, and that's what 'view' is for, and this time
foreach(filter<int>(view(v)), _1 = 99);
would work.
BTW, algorithms in GIL only work for Views, while Fusion takes both Sequence & View, I think it's a good idea to only accept View, but this is not the way that fusion was designed.
Let's take this off-line for discussion. Feel free to reply to me by email. Regards, -- Joel de Guzman http://www.boostpro.com http://boost-spirit.com