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[BGL] setting a breakpoint in an algorithm visitor
by Chris Russell 16 Sep '02

16 Sep '02

p.156 of the BGL book: "... visitors are passed by value..." I was attempting to set a breakpoint in a visitor event handler (that I know is executing) but the breakpoint is seemingly ignored by my debugger. This is because the visitor I construct and subsequently pass to the algorithm is not the object that is actually dispatched by the algorithm. Correct? Using the Intel compiler under MS DevStudio 6 on Windows, I inserted a ::DebugBreak() (asm int 3) into the visitor and *do* hit that but only have assembly language and not source to step through at that point. Why are visitors passed to algorithms by value? Any suggestions for debugging visitor code at the C++ source level and not in assembly? - Regards Chris

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[BGL] Property map question
by Chris Russell 16 Sep '02

16 Sep '02

What determines when boost::get(Graph, vertex_myproperty_t) returns a boost::property_map<graph_t, vertex_myproperty>::type vs. a ::const_type? Suppose: enum vertex_myproperty_t { vertex_myproperty = 12345}; BOOST_INSTALL_PROPERTY(vertex,myproperty); typedef property<vertex_myproperty_t, MyPropertyObject, ....> vertex_properties_t; typedef adjacency_list<vecS,vecS,bidirectionalS, vertex_properties_t> graph_t; typedef property_map<graph_t, vertex_myproperty_t>::type vertex_myproperty_map_t; graph_t Graph;

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Re: Thanks for the help...
by Peter Dimov 16 Sep '02

16 Sep '02

From: "someuserat" <marktutt(a)excite.com> > > If I can impose, I've got another question that I think is in the same > area... > > I couldn't think of a way to call Widget::operator()(const WidgetPtr > w) through the smart pointer, so I wrote an equivalent method called > equals to try to imlement the following function. > > void WidgetMgr::dropWidget(const WidgetPtr w){ > > col.erase(remove_if(col.begin(),col.end(),boost::b > ind2nd(boost::mem_fn(&Widget::equals),c))); > } ... where Widget::equals takes a WidgetPtr? Based on this information, I think that you need boost::bind(&Widget::equals, _1, w) (Please use the boost-users list.) > Is there any reference to the boost libraries that goes into more > detail? I've got several books on STL that never seem to address the > issues I'm running into with smart pointers, I'm afraid what I may run > into once I really get into the meat of this project.

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RE: [Boost-Users] lexical_cast question
by Björn Karlsson 16 Sep '02

16 Sep '02

> From: Mark Snelling [mailto:mark@bakedbeans.com] > > Ok, I guess I'll just make my own temporary one based on the > original in > the meantime :) > > Mark. > Or, you could use the version with proposed changes - it's in the Files section at YahooGroups. Bjorn

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RE: [Boost-Users] lexical_cast question
by Björn Karlsson 16 Sep '02

16 Sep '02

> From: Mark Snelling [mailto:mark@bakedbeans.com] > > Hi, > Does the boost::lexical_cast library support wide character sets for > example: > > #include <boost/lexical_cast.hpp> > > using namespace boost; > using namespace std; > > void main () > { > wstring wtext(L"1234"); > int val = lexical_cast<int>(wtext); > } > Not the current version of lexical_cast - the implementation uses stringstream to perform the conversion. A proposed change to lexical_cast does handle wide characters correctly. I'm not sure about the status of that proposal, though. Bjorn Karlsson

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lexical_cast question
by Mark Snelling 16 Sep '02

16 Sep '02

Hi, Does the boost::lexical_cast library support wide character sets for example: #include <boost/lexical_cast.hpp> using namespace boost; using namespace std; void main () { wstring wtext(L"1234"); int val = lexical_cast<int>(wtext); }

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How to build boost threads library on AIX 4.3.3 with VisualAge 5
by robertpsather 16 Sep '02

16 Sep '02

Building Boost on AIX is difficult. Here's a recipe that worked for me, for building on the following platform: Boost source download version 28 AIX 4.3.3 on RS/6000 VisualAge 5.0 Jam: downloaded binary of Boost.Jam Version 3.1.0. OS=AIX. bash shell Building Boost Setup: Downloaded version 28 tar.gz file to ~/boost. Un-gzipped and untarred. Set export BOOST_ROOT=/home/satherb/boost/boost_1_28_0 Attempt: jam "-sTOOLS=vacpp" Result: Many compilation errors, in building of regexp library. For example: Error: "libs/regex/build/../src/cpp_regex_traits.cpp", line 196.39: 1540-0257 (S) An object or reference of type "std::messages_base::catalog" cannot be initialized with an expression of type "int". Attempt: in cpp_regex_traits.cpp", line 196, changed "-1" to "(size_t) 1" Result: compiler says "cannot be initialised with type unsigned long." for the same line. Attempt: Noted that www.boost.org says that threads lib does not depend on regex or python. Edited Jamfile to comment out unnecessary targets python and regex. Result: Most errors are "Thread support is unavailable". Looking at source indicates this is because BOOST_HAS_THREADS macro is undefined. Attempt: export BOOST_HAS_THREADS=1 Result: same errors. Attempt: run ./configure Result: configure gives error message that says "compiler does not produce output" (or something like that) However, running configure again worked! Here were the recent settings of environmental variables: export BOOST_ROOT=/home/satherb/boost/boost_1_28_0 export _MT=1 export CC=xlC_r export CXX=xlC export _POSIX_THREADS=1 export LIBS=-lpthread (I don't know which of these was the key. If you discover the answer, please let me know.) Attempt: Did as configure suggested: "Adjustments to boost configuration have been written to user.hpp, copy this to boost/config/user.hpp to use "as is" " Result: jam still gives "Thread support is unavailable" errors. Attempt: added a line to boost/config/user.hpp: #define BOOST_HAS_THREADS Result: builds! (Don't know yet if it works properly, of course. The examples don't build.) Bob Sather bob.sather(a)lloydstsb.delete_this_part.co.uk

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graph vertices / IRIX / GCC
by yg-boost-users＠m.gmane.org 16 Sep '02

16 Sep '02

Hello, Q: one can construct a graph using adjacency_list<> and then immediately iterate over the vertices, right? The program below writes out the numbers 0 to 9 when compiled using gcc 3.2 on linux. Ditto on my IRIX system, *unless* I try to optimize. I expect this is a GCC optimizer bug, but I just want to be sure I haven't overlooked something in the boost docs. Thanks, -S #include <iostream> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<boost::edge_weight_t,float> > Graph; typedef boost::graph_traits<Graph>::vertex_descriptor vertex_descriptor; typedef boost::graph_traits<Graph>::edge_descriptor edge_descriptor; int main() { Graph g( 10 ); boost::graph_traits<Graph>::vertex_iterator ui, ui_end; for (boost::tie(ui, ui_end) = boost::vertices(g); ui != ui_end; ++ui) { std::cout << "*ui = " << *ui << std::endl; } return 0; }

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graph vertices / IRIX / GCC
by Steve M. Robbins 16 Sep '02

16 Sep '02

Hello, Q: one can construct a graph using adjacency_list<>(N) and then immediately iterate over the vertices, right? The program below writes out the numbers 0 to 9 when compiled using gcc 3.2 on linux. Ditto on my IRIX system, *unless* I try to optimize. I expect this is a GCC optimizer bug, but I just want to be sure I haven't overlooked something in the boost docs. Thanks, -S #include <iostream> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::undirectedS, boost::no_property, boost::property<boost::edge_weight_t,float> > Graph; int main() { Graph g( 10 ); boost::graph_traits<Graph>::vertex_iterator ui, ui_end; for (boost::tie(ui, ui_end) = boost::vertices(g); ui != ui_end; ++ui) { std::cout << "*ui = " << *ui << std::endl; } return 0; }

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ASCII Code Problem.. Please Help me.
by Sean Lee 15 Sep '02

15 Sep '02

I am currently trying to use Regex++ and I almost got there. However, I try to use Regex++ with XML parser and I got some problem. Here is the xml expression. <subtree name="itinerary" regex="(<\\s*TR\\s*VALIGN=TOP>\\s*<TD\\s*WIDTH=250>\\s*<\\s*B \\s*>[^>]+AM</B>?)"> Since "<" and ">" are not valid in XML Syntax, I have to use "<" and ">". I have loaded the xml file in my program and did following thing. char* regex=NULL; _bstr_t strRegex; strRegex=pIXMLDOMNode->text; // regex="(<\\s*TR\\s*VALIGN=TOP>\\s*<TD\\s*WIDTH=250>\\s*<\\s*B \\s*> //[^>]+AM</B>?)"> regex = (char*)malloc(_bstr_t(strRegex).length()); lstrcpy(regex,strRegex); AfxMessageBox(regex); // got the same string. But when I compared with following string and I got "FALSE". char* temp="(<\\s*TR\\s*VALIGN=TOP>\\s*<TD\\s*WIDTH=250>\\s*<\\s*B\\s*>[^>]+AM</B> ?)"; if(lstrcmp(temp,regex)==0) Please help me. Thank you very much. Sean Lee slee(a)qixo.com

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