Re: [jamboost] default properties question

From: David Abrahams (dave_at_[hidden])
Date: 2003-03-07 10:30:01

Vladimir Prus <ghost_at_[hidden]> writes:

> David Abrahams wrote:
>> Vladimir Prus <ghost_at_[hidden]> writes:
>> > The first target will be build with default value <rtti>on. What about
>> > the second:
>> > 1. Should we request it with <rtti>on and get an error, or
>> > 2. Should we request if without any <rtti> setting and allow it to be
>> > built with <rtti>off
>> >
>> > I think (1) is way safer. But interested in other opinions.
>>
>> I agree with you that it's safer. I was going to say that the only
>> other potentially viable option is:
>>
>> 3. The <rtti>off is propagated back towards the first target by the
>> second, much like a use-requirement.
>>
>> However, as I consider it, I think there's a real use-case for "I
>> know what I'm doing; I want <rtti>on on the first target, and I just
>> won't do anything evil with the library which causes me to need
>> <rtti>on with it."
>
> I'm sorry, I don't understand you. What is "won't do anything evil" 

What's evil clearly depends on the compiler. One likely example would
be attempting to use typeid(X) on a class X defined in the library
built with <rtti>off.

> and what's "need <rtti>on with it"?

In other words, if I *did* use typeid(X), I would need lib to be
built with <rtti>on.

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