Interval interface

[DartBot]

This issue was originally filed by @seaneagan

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see https://gist.github.com/2719638

One use case is in dart:unittest...

The "contains" matcher could be extended to match against Intervals.
// e.g.
expect(new Interval(0, 100), contains(x));

Then the following matchers could all be removed:

inInclusiveRange
inExclusiveRange
inOpenClosedRange
inClosedOpenRange

Another sensible name would be "Range".

[DartBot]

This comment was originally written by @seaneagan

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actually, an "in" matcher (issue #3679) would work better than "contains".

expect(x, in(new Interval(0, 100))

[sethladd]

Removed Type-Defect label.
Added Type-Enhancement, Area-Library, Library-Collections, Triaged labels.

[lrhn]

I think it's a good idea. It's basically an immutable collection of integers, which can be useful in various cases. Possibly with some Range-specific extra functionality like "overlaps".
Another possible name is Range, matching the corresponding concept in, e.g., Python or Scala.

[lrhn]

Added Accepted label.

[DartBot]

This comment was originally written by @seaneagan

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I think Range could extend Interval<int> if there were integer specific functionality desired such as iterability, as intervals are useful for all Comparables (e.g. Date intervals), not just integers:

interface Range extends Interval<int>, Iterable<int> {}

[gramster]

I don't see how an interval would eliminate all four of those matchers. One, yes, but that isn't buying anything.

[DartBot]

This comment was originally written by @seaneagan

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@gram, here's what I was thinking:

instead of:

inInclusiveRange(0, 5)
inExclusiveRange(0, 5)
inOpenClosedRange(0, 5)
inClosedOpenRange(0, 5)

you would have:

in(new Interval(0, 5, includeMax: true))
in(new Interval(0, 5, includeMin: false))
in(new Interval(0, 5, includeMin: false, includeMax: true))
in(new Interval(0, 5))

alternatively Interval could have named constructors:

in(new Interval.inclusive(0, 5))
in(new Interval.exclusive(0, 5))
in(new Interval.openClosed(0, 5))
in(new Interval.closedOpen(0, 5)) // this could potentially be unnamed

[dgrove]

Removed Library-Collections label.
Added Library-Collection label.

[DartBot]

This comment was originally written by @seaneagan

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This could also replace the KeyRange class in dart:indexed_db:

http://api.dartlang.org/docs/bleeding_edge/dart_indexed_db/KeyRange.html

[floitschG]

We discussed this frequently.
In the end the main argument against it, is that ranges and intervals may include or exclude their boundaries. Depending on the context you usually assume one or the other. The additional complexity (API wise or concept wise) pushes it from "we should have it" to "would be nice, but not in core".

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Added NotPlanned label.

[DartBot]

This comment was originally written by @seaneagan

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I added an interval package to pub for this:

https://pub.dartlang.org/packages/interval