Re: [gentoo-portage-dev] has_version and built_with_use ignore package.provided

[Thomas de Grenier de Latour]

On Tue, 08 Aug 2006 00:54:29 +0100,
Paul Bredbury <brebs@××××.com> wrote:

> > 3. package has not been built. (?)
>
> The answer is False, not unknown, as I keep saying.

You keep trying to reason based on a function name ("built_with_use").
>From a litteral english point of view, i would agree with you that a
package which was not built at all is not built with any particular
flag.  But, see, this is just a function name, and that's not what
defines its expected semantics.  There is nothing one can "prove" by
logic here¹, but just a choice to make.  The only thing which matters is
what devs think is the most convenient for their needs, and it is clear
from this discussion that they all prefer a function which is only
defined for installed packages (and dies when missused, so that
missuses are detected and fixed).  Maybe a better name would have been:
was_the_installed_package_foo_built_with_the_flag_bar_comma_where_foo_is_first_argument_and_bar_the_second_one_question_mark
...but that's a bit too long, and this kind of details should rather go
to the documentation.


> There, you'll meet "conditional probability". If A is False, then the
> probability of B, given that B *depends* on A, is zero.

Take probabilities of a coin flip, apply them to a dice, and you can
"prove" it always falls on tails, since it can't fall on heads. Or
maybe it's the opposite, oh well...

Again, reasoning out of the definition domain gives nothing meaningful.
For "build_with_use", it has been decided that the definition domain
would be installed packages.  Deal with it.


----
¹ the only thing one really bored could try to prove is that the actual
implementation of the function fits its expected semantics.  But that's 
a different topic.


-- 
TGL.

-- 
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