Re: [boost] Small utility templates

From: Victor A. Wagner, Jr. (vawjr_at_[hidden])
Date: 2002-07-25 01:49:32

At Wednesday 2002/07/24 23:15, you wrote:
>I've noticed in our coding, we sometimes need a comparison operator that 
>works on just a single element in a struct, instead of the "entire 
>struct".  If we need to sort the container using just this "key"; we, of 
>course, write the comparison function/functor and then:
>
>std::sort(c.begin(), c.end(), ourfunction);
>
>I decided to write a couple templates and helper functions called (the 
>ones you'd use) less_element() and greater_element().
>
>if then we have, e.g. :
>struct person{
>std::string firstname;
>std::string lastname:
>.....other stuff
>};
>
>and a container of them, we can:

<sigh> this will teach me to do this kind of thing from memory

>std::sort(c.begin(), c.end(), less_element(firstname));
>or....
>std::sort(c.begin(), c.end(), greater_element(lastname));

of course I _meant_ to type:
std::sort(c.begin(), c.end(), less_element(&person::firstname));
or....
std::sort(c.begin(), c.end(), greater_element(&person::lastname));

>I'm sorry to be so wordy, but neither of us in this group has ever worked 
>in a large (>4) staff using C++, so maybe we're just missing a whole lot 
>(discussion of wisdom of public variables aside...we use them), or these 
>may be useful to others also.
>
>We'd be happy to clean them up and boostify them if there is interest.
>Victor A. Wagner Jr.      http://rudbek.com
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>The five most dangerous words in the English language:
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>
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Victor A. Wagner Jr.      http://rudbek.com
PGP RSA fingerprint = 4D20 EBF6 0101 B069 3817 8DBF C846 E47A
PGP D-H fingerprint = 98BC 65E3 1A19 43EC 3908 65B9 F755 E6F4 63BB 9D93
The five most dangerous words in the English language:
               "There oughta be a law"