Allow extend to work across media directives when the queries are compatible.

[chriseppstein]

Consider:

@media screen and (min-width: 500px) {
  .foo { color: red; }
}

@media screen and (min-width: 400px) {
  .bar { @extend .foo; }
}

This will generate a deprecation warning. But in all cases where .foo is defined, the media query it is in is a propery subset of the media query where .bar is defined. So this it is safe for sass to perform this operation.

[nex3]

I'm not sure we want to perform the operation for this query in particular, since that requires knowledge of the semantics of min-width.

[nathggns]

Call the the value of the first media query x (500) and the value of the second y (400).

It's easy enough to do some simple logic based on the prefixes.

min = x > y
max = x < y
no prefix = x = y

You don't really need to care out the property.

[chriseppstein]

Yep, @nathggns is right, the semantics of min/max are standardized in media queries -- this can be done safely.

[nex3]

I'm uncomfortable with the general principle of that level of semantic knowledge about the specific media queries. Understanding that screen and X is a subquery of screen is one thing; understanding what min-width means is another.

[nathggns]

You don't need to understand what min-width means, as I just explained.

Nathaniel Higgins
Sent with Sparrow (http://www.sparrowmailapp.com/?sig)

On Friday, 24 August 2012 at 22:45, Nathan Weizenbaum wrote:

I'm uncomfortable with the general principle of that level of semantic knowledge about the specific media queries. Understanding that screen and X is a subquery of screen is one thing; understanding what min-width means is another.

—
Reply to this email directly or view it on GitHub (#501 (comment)).

[chriseppstein]

I'm not uncomfortable with this. Min and max have well established meanings in the spec -- independent of the property names they are attached to.

[nex3]

Oh, I see, I misunderstood. That does make it better.