Re: [boost] [function types] New tag type logic

From: David Abrahams (dave_at_[hidden])
Date: 2005-06-30 22:05:20

Rob Stewart <stewart_at_[hidden]> writes:

> From: David Abrahams <dave_at_[hidden]>
>> Rob Stewart <stewart_at_[hidden]> writes:
>> >
>> >    When classifying types, it is often necessary to test for any
>> >    one of several variations of an aspect.  A common case is
>> >    ignoring an aspect which means to allow a match for any
>> >    variation of that aspect 
>> 
>> No, way too twisty.  You just lost me.  Does the aspect mean "to
>> allow...", or is it an "aspect that means (intends) to allow..." or is
>> it "ignoring an aspect" that "means to allow...?"
>
> I don't see the problem.  Please suggest an alternative that you
> don't find "way too twisty."

I don't have time to do that right now, and it's so ambiguous that I
don't even know which of the 5 or 6 meanings I should represent.

>> Try to resist the temptation to pack all the meaning into one sentence.
>
> Neither quoted sentence seems long or complex.  Perhaps there
> was something you snipped to which you were referring?

No.

> Here's the full text of my suggestion:
>
>    When classifying types, it is often necessary to test for any
>    one of several variations of an aspect.  A common case is
>    ignoring an aspect which means to allow a match for any
>    variation of that aspect and is only useful when also testing
>    for other aspects.  Ignoring an aspect means using an
>    "unspecified_*" tag.  For example, allowing a match for any
>    decoration requires using the <tt>unspecified_decoration</tt>
>    tag.
>
> Are you referring to the second sentence?  

Yes.

> I could split it at "and" forming two sentences:
>
>    A common case is ignoring an aspect which means to allow a
>    match for any variation of that aspect.  That is only useful
>    when also testing for other aspects.
>
> Is that what you wanted?  

No, all the same questions apply.  It can be read several different
ways:

        (ignoring an aspect) which means (to allow a match for any
        variation of that aspect.)

or

        ignoring (an aspect (which means to allow a match for any
        variation of that aspect))

or

        ignoring (an aspect which means to allow a match)) for (any
        variation of that aspect)

or...

        There really are many many more.  

And you don't really mean to say that "A common case" is doing the
ignoring, do you?

And there should be a comma before "which."

> I still find the original to be fine,

Of course you do; you wrote it.  It's still ambiguous in many ways.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com