Re: [boost] Interest for a perl6-like-junctions-class?

From: Pavel Vozenilek (pavel_vozenilek_at_[hidden])
Date: 2005-08-02 09:43:56

<FlSt_at_[hidden]> wrote:

> I uploaded a new version of the junction comparison of ranges to boost
> sandbox file vault ( flos_junction_v6.zip ).

I wrote down few notes.
/Pavel

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1. I compiled and tested the library under Intel 7.0
   (plugged in VC6 IDE).

   BCB 6.4 and VC6.5 failed as lambda doesn't
   support these compilers.

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2. The header may have:

#if (defined_MSC_VER) && (_MSC_VER >= 1200)
#  pragma once
#endif

on the top (after guard macros) to help
a little bit with compilation time for
Intel and VC.

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3. There should be overloads  of "xyz_of"
   who take pair of iterators,
   in the old-fashioned STL way.

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4. Perhaps the could be rewritten not
   to use macros as code generators.

   It is not possible to debug it as
   it is now, for example.

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5. The classes like conjuction etc may be likely
   moved into sub-namespace like boost::junction_details.

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6. Would it be possible to have other qualifiers,
   e.g.: "more_than_half_of"

 if (more_than_half_of(a) >= any_of(b)) ...

or more complex versions like:

  more_than(10).items_of(a) >= ...
  more_than(30.1).percents_of(a) == ...

 less_than(2).items_of(a) >= ...
 less_than(95).percents_of(a) == ...

  between(1, 5).items_of(a) >= ...
  between(10.5, 20.0).percents_of(a) == ....

  exactly(10).items_of(a) >= ....

Comparison between two "mores" would be
disabled.

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7. Will it be possible to use other predicates than
   >, <=, etc  in following form:

  if ( is_true_that(all_of(a), a_binary_functor, one_of(b)) ) ...

where the functor could be lambda:

  if (is_true_that(all_of(a), _1 >= _2, one_of(b)) ....

It feels more natural than the asymetric "do_comparison".

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8. If the "is_true_that" will be implemented than
   a filter "where" could be considered, like:

   if ( is_true_that(all_of(a), _1 >= _2, 
one_of(b) ).where(_1->does_fulfill_condition()) ) ...

and the "where" fould have unary predicate as parameter,
this predicate would filter out undesirable items from
both ranges.
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EOF