(Off list) Re: [boost] Re: MPL containers and algorithms

From: Terje Slettebø (tslettebo_at_[hidden])
Date: 2002-08-13 15:32:15

>From: "David Abrahams" <dave_at_[hidden]>

>>From: "Terje Slettebø" <tslettebo_at_[hidden]>

>> It depends on how the sort is implemented, I guess (one isn't present in
>the
>> library, yet). As you know, C++ MP isn't mutating, so such a sort would
>> return a sorted copy of the half of the sequence. Likely stored in the
>same
>> kind of sequence as the original, to preserve the characteristics of the
>> original sequence.

>No, and I'm pretty sure this is in part why MPL uses sequences instead of
>iterators: the algorithms that produce new sequences generally take an
>empty version of the new sequence as an input, and "append" their results
>to it.

>From the docs (http://www.mywikinet.com/mpl/ref/Table_of_Content.html), the
way you describe here doesn't appear to be used a lot. copy/copy_if works
that way. However, other algorithms, like transform, doesn't work that way.

In fact, there isn't a lot of algorithms that take an empty sequence, and
returns new sequence of the same type. Could you give more examples than the
ones above? Preferable listed in the docs. :)

Even though transform doesn't take an empty sequence as a parameter, it says
that it returns a sequence with the same characteristics as the input
sequence. Which I why I assumed a sort could behave similarly.

Regards,

Terje