Is there a identity_view? about fusion

[djowel]

No, there is no identity_view. Would you like to contribute one?

[djowel]

The easiest way is to use transform_view.

[denzor200]

Yes, transform_view is a good idea. But it's view has no at_key_impl, key_of_impl, and so others for associative sequence.
Respectively, if we get boost::fusion::map and wrap it into transform_view, then our map will lose its associative character.

Is that intended, or is this a flaw on the transform_view side?

[denzor200]

@djowel I implemented this in a rather cheeky way 😄
https://godbolt.org/z/3qn4x8ns5

[djowel]

Is that intended, or is this a flaw on the transform_view side?

It is not documented (*), but the ideal behavior would be that views should inherit the properties of its subjects. Again, PR would be great. It seems you have familiarity with fusion.

(* https://www.boost.org/doc/libs/1_65_1/libs/fusion/doc/html/fusion/view.html)

[denzor200]

Again, PR would be great. It seems you have familiarity with fusion.

PR in process.. I started with the tests. The way I see it:
https://godbolt.org/z/3Y93n3dvd

I propose to make a set of generic tests that will be check any Sequence for compliance with the Concept.
Now in the fusion, view tests are absolutely not scalable:(

[denzor200]

My example above show already implemented test for ForwardSequence concept.
filter_view passed this test good. But the current filter_view will fail test for AssociativeSequence concept, i suppose

[denzor200]

13593be