On Fri, 13 Aug 2004 01:52:05 -0700, Victor A. Wagner Jr. wrote:

std::list forest; of course you'll have to allocate (new) them before putting their pointers in the list, but that's not a huge issue.

Not at all, so long as I use explicit temopries when calling new as the docs say. I've found I also have to change "iter->grow();" to "(*iter)->grow();", but I think i've found a mechanism to solve this. I create a wrapper around the iterator whose operator* and operator-> returns a value_type& (i.e., *iter). The modified code is attached, any suggestions? -- Matthew Peltzer -- goochrules@gmail.com

"Peter Dimov" writes:

goochrules! wrote:

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std::list forest; of course you'll have to allocate (new) them before putting their pointers in the list, but that's not a huge issue. Not at all, so long as I use explicit temopries when calling new as

On Fri, 13 Aug 2004 01:52:05 -0700, Victor A. Wagner Jr. wrote: the docs say. I've found I also have to change "iter->grow();" to "(*iter)->grow();", but I think i've found a mechanism to solve this. I create a wrapper around the iterator whose operator* and operator-> returns a value_type& (i.e., *iter). The modified code is attached, any suggestions?

You can also use mem_fn:

for_each( forest.begin(), forest.end(), mem_fn(&tree::grow) );

or bind, if grow takes arguments:

for_each( forest.begin(), forest.end(), bind(&tree::grow, _1, 5) );

And, BTW, your iterator is not conforming and doesn't seem to be doing what you want. See http://www.boost.org/libs/iterator/doc/indirect_iterator.html for a conforming solution. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com

goochrules! writes:

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You can also use mem_fn:

for_each( forest.begin(), forest.end(), mem_fn(&tree::grow) );

or bind, if grow takes arguments:

for_each( forest.begin(), forest.end(), bind(&tree::grow, _1, 5) );

And, BTW, your iterator is not conforming and doesn't seem to be doing what you want. See http://www.boost.org/libs/iterator/doc/indirect_iterator.html for a conforming solution.

Indeed, boost::shared_ptr and boost::idirect_iterator are exactly what I'm looking for.

But I'm at a complete loss as to how to get them to work with std::for_each:

36: typedef boost::shared_ptr< tree > item_t; 37: typedef std::list< item_t > list_t; 38: typedef std::list< item_t >::iterator iter_t; 39: list_t forest; 40: 41: forest.push_back(item_t(new oak)); 42: forest.push_back(item_t(new pine)); 43: 44: boost::indirect_iterator< iter_t, tree > first(forest.begin()), 45: last(forest.end()); 46: std::for_each(first, last, std::mem_fun(&tree::grow));

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g++ -Wall -O0 -o inherit inherit.cpp /usr/include/gcc/darwin/3.3/c++/bits/stl_algo.h: In function `_Function std::for_each(_InputIter, _InputIter, _Function) [with _InputIter = boost::indirect_iterator, _Function = std::mem_fun_t]': inherit.cpp:46: instantiated from here /usr/include/gcc/darwin/3.3/c++/bits/stl_algo.h:166: error: no match for call to `(std::mem_fun_t) (tree&)' /usr/include/gcc/darwin/3.3/c++/bits/stl_function.h:613: error: candidates are: void std::mem_fun_t::operator()(_Tp*) const [with _Tp = tree]

Use boost::mem_fn instead. I think you don't even need indirect_iterator in that case... but if you want to keep using indirect_iterator, I think std::mem_fun_ref is what you're after. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com