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Re: [boost] Re: RPC library
by Iain Hanson 03 Mar '05

03 Mar '05

On Thu, 2005-03-03 at 13:54 +0000, Jarl Lindrud wrote: > Iain Hanson <Iain.Hanson <at> videonetworks.com> writes: > > > > > So anything less than CORBA should not be considered? For RPC, Yes. > > My experience with CORBA is that you _do_ pay for things you don't need. Try > building a simple server/client app with my RPC library, and then build it with > ACE TAO, and I wonder which method you'll find to be simpler/easier/faster... Here is an example CORBA client. And it doen not matter which ORB you use. #include <iostream> #include "echoC.hpp" // generated from the idl file int main ( int ArgV , char * ArgV ) { try { // _var types are smart ptrs to ref counted objects. CORBA::ORB_var Orb = CORBA::ORB_init ( ArgC , ArgV , "TAO"); // get IOR from a file so we can talk to server CORBA::Object_var Factory_Object = Orb->string_to_object ( ArgV [ 1 ] ); // This is a CORBA safe downcast My::Echo_Factory_var Factory = My::Echo_Factory::_narrow ( Factory_Object.in( ) ); My::Echo_Server_var EchoServer = Factory->get_server ( ArgV [ 2 ] ); CORBA::String_var Echoed = EchoServer-> ( "Hello World" ); } catch ( CORBA::Exception & E ) { std::cerr << "CORBA exception raised!" << std::endl; } } I don't think 5 lines of code is exactly heavyweight. I could of done it in 3 lines if I did not use a factory, but that would have been unrealistic. I won't show the server but it 2 classes the factory publicly inherits from Echo_Factory and implements a single function get_server. Likewise like for EchoServer. > Which code is less invasive, more intuitive, and more proportional to the task? > And oh I forgot, don't forget to first build all of ACE and TAO, and then link > the whole shebang to your own 5 lines of code. To me it feels like I'm getting > far, far more than I asked for. But that's just me :-) ACE is nothing to do with CORBA. It just happens to be what TAO uses internally. Building Open source or installing per build libs has nothing to do with how easy it is to use. Your comparing apples and carrots. >If you need scaleability, then obviously CORBA is one of the few >options you have. But if you don't need scaleability, or naming >services, or whatever, what's wrong with using something much simpler? Because when you app grows you will have to re-write it. More likely, is that won't happen and people will re-invent the again. Take a look at the development of SOAP :-(. /ikh

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regexes matching empty strings
by Michael Goldshteyn 03 Mar '05

03 Mar '05

Why can I not construct a regex of the form: "|abc" (throws exception based on REG_EMPTY) for use with regex_match, if I want to match either "abc" or the empty string "". I understand thatn in a regex_search the empty string would always match (per Perl like semantics), and abc would never be considered. But, I want to use this with regex_match, where the empty string would have to match the entire string being searched. Work arounds such as "(?:)|abc" and "^$|abc" seem to get around this deficiency, but I am wondering why it is there in the first place. Thanks, Michael Goldshteyn

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One more test message. Please delete it
by Pavel Chikulaev 03 Mar '05

03 Mar '05

Ok?

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Running regression tests
by Jody Hagins 03 Mar '05

03 Mar '05

Trying to run the regression tests for BCB6/Windows, using current CVS head... set BOOST_ROOT=C:\boost set TOOLS=borland I can run bjam stage and everything that is supposed to build, builds (serialization, and wave do not build). However, when I follow the directions, I have problems. Can someone please help?!? I tried cd up into boost root, and it seemed to work better, but links in the html files wanted to access directories ".." so that failed too. What am I doing wrong? Thanks! C:\boost>cd status C:\boost\status>bjam --dump-tests test >bjam.log 2>&1 C:\boost\status>echo %BOOST_ROOT% C:\boost C:\boost\status>echo %TOOLS% borland C:\boost\status>process_jam_log < bjam.log Usage: bjam [bjam-args] | process_jam_log [--echo] [--create-directories] [locat e-root] locate-root - the same as the bjam ALL_LOCATE_TARGET parameter, if any. Default is boost-root. create-directories - if the directory for xml file doesn't exists - creates it. usually used for processing logfile on different machine boost_root: C:/boost/status/.. locate_root: C:/boost/status/.. no errors detected C:\boost\status>compiler_status %BOOST_ROOT% cs-win32.html **** exception(205): std::exception: boost::filesystem::directory_iterator const ructor: "C:\boost\status\bin": The system cannot find the path specified. ******** errors detected; see standard output for details ******** C:\boost\status>compiler_status Usage: compiler_status [options...] boost-root status-file [links-file] boost-root is the path to the boost tree root directory. status-file and links-file are paths to the output files. Must be run from directory containing Jamfile options: --compiler name Run for named compiler only --ignore-pass Do not report tests which pass all compilers --no-warn Warnings not reported if test passes --locate-root path Path to ALL_LOCATE_TARGET for bjam; default boost-root. --comment path Path to file containing HTML to be copied into status-file. --notes path Path to file containing HTML to be copied into status-file. --notes-map path Path to file of toolset/test,n lines, where n is number of note bookmark in --notes file. --jamfile path Path to Jamfile. By default "Jamfile". Example: compiler_status --compiler gcc /boost-root cs.html cs-links.html Note: Only the leaf of the links-file path and --notes file string are used in status-file HTML links. Thus for browsing, status-file, links-file, and --notes file must all be in the same directory. **** error return code: 1 ******** errors detected; see standard output for details ******** C:\boost\status>

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Test. Please delete this thread
by Pavel Chikulaev 03 Mar '05

03 Mar '05

I just couldn't have get access to developers list

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Preview of the Function Types library (function_traits replacement)
by Tobias Schwinger 03 Mar '05

03 Mar '05

Dear Boosters, a preview of the Function Types library is available, now. [ Online documentation: http://tinyurl.com/4fw9n ] [ Downloadable archive: http://tinyurl.com/6u77y ] It is the third (nearly) complete rewrite and the design finally feels right for me. However, I am very curious to hear any of your opinions about it ! So, if you have been hoping for the retirement of function_traits, please take a few minutes to find out if this would suit your needs. Regards, Tobias

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patch against boost threads library
by Ulrich Eckhardt 03 Mar '05

03 Mar '05

Short notes: * thread_exception::message() is broken beyond repair, as it returns a pointer to local storage (via std::string::c_str()) * any program using it is broken, too. * it is unused by boost itself(!) which is why it can be removed * it is the only reason why a helper-function 'system_message()' is needed, which can then be removed, too. * system_message() is the only reason several headers and a hack for strerror() were needed, which can then also be removed. * system_message() requires a char-based API on win32, which is not available under MS Windows CE, strerror() is also not available there, making two more reasons to remove it. cheers Uli

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[range] BOOST_RANGE_DEDUCED_TYPENAME
by Jody Hagins 03 Mar '05

03 Mar '05

In range/config.hpp, I see this code... #if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564)) #define BOOST_RANGE_DEDUCED_TYPENAME #else #define BOOST_RANGE_DEDUCED_TYPENAME BOOST_DEDUCED_TYPENAME #endif Why is there a special version of this? It is only defined to empty, or BOOST_DEDUCED_TYPENAME. What is wrong with simply using BOOST_DEDUCED_TYPENAME? If there is a problem with the "stock" one? If so, shouldn't that be changed instead?

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Preprocessor warning from BOOST_PP_SEQ_ELEM
by Edward Bishop 03 Mar '05

03 Mar '05

Hi All, When I run the following code through the preprocessor, it emits the correct output: alpha is simple; beta is simple; gamma is complex and color is red; delta is simple; epsilon is complex ; but it also emits the folowing warning (several times): macro "BOOST_PP_SEQ_ELEM_III" requires 2 arguments, but only 1 given My question is, how can I eliminate the warning. Thanks in advance for any comments/advice. # include <boost/preprocessor/library.hpp> #define IS_SIMPLE(t) BOOST_PP_NOT_EQUAL(3, BOOST_PP_SEQ_SIZE(t)) #define PROPERTIES(t) BOOST_PP_SEQ_ELEM(2,t) #define HAS_COLOR(t) BOOST_PP_EQUAL(2, BOOST_PP_SEQ_ELEM(0, \ PROPERTIES(t))) #define COLOR(t) BOOST_PP_SEQ_ELEM(1, PROPERTIES(t)) #define FSIMPLE(a, s, i, t) \ BOOST_PP_SEQ_ELEM(0,t) is simple; #define FCOMPLEX(a, s, i, t) \ BOOST_PP_SEQ_ELEM(0,t) is complex \ BOOST_PP_IF(HAS_COLOR(t), and color is COLOR(t) , ); #define FCHOICE(a, s, i, t) \ BOOST_PP_IF(IS_SIMPLE(t), \ FSIMPLE(a, s, i, t), \ FCOMPLEX(a, s, i, t)) #define T(s)\ BOOST_PP_SEQ_FOR_EACH_I(FCHOICE, s, s) \ T ( // ID Frequency Properties ( (alpha) (16) ) ( (beta) (3) ) ( (gamma) (13) ((2) (red)) ) ( (delta) (5) ) ( (epsilon) (13) ((4) (heavy)) ) )

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Re: [boost] Re: ANN: review of FSM library starts
by Augustus Saunders 03 Mar '05

03 Mar '05

First, I appologize for messing up the threading, but I get the digest and so can't respond directly. >Have you ever had a look at other FSM libraries? I think boost::fsm >is less messy than any other library I've seen. Unfortunately, no. My response is based on the fact that 1) I generally think I know what fsm are about, 2) I'm comfortable seeing complex template stuff, yet 3) sample code for simple state machines just didn't click for me. I feel like I'm in the target audience of the library, so I'm looking deeper to see if I can figure out why. >> // I guess there's no way to avoid declaring >> // these ahead of time?? >> class Machine, State1, State2, Event1, Event2; >Actually there is, but I found out about this only recently (Peter > Dimov mentioned this in an unrelated post) and haven't changed the > docs because I feared that this does not work on all compilers: > >Instead of > >struct Greeting; >struct Machine : fsm::state_machine< Machine, Greeting > {}; > >you can write: > >struct Machine : fsm::state_machine< Machine, struct Greeting > {}; Ok, good to know. I'd like to hash out what the "ideal world" would look like and compromise from there, if you know what I mean. >> struct S1Data >> { >> int i; >> S1Data() : i(0) {} >> }; >> >> typedef simple_state< Machine, S1Data, >> BOOST_TYPEOF( cout << constant("Entering State1.") ), >> BOOST_TYPEOF( cout << constant("Exiting State1.") ), >> on_event<Event1, BOOST_TYPEOF( _1->i++ ) >, >> transition<Event1, State2> > >> State1; >> // the "data" member of State1 has type S1Data, and is >> // passed into event handlers >You consider this more readable? Sorry, I have to disagree. For entry > and exit actions and extended state variables I consider my approach > superior, for reaction definition, your approach seems about > equivalent. I think this is how my example would look using the current library, right? struct State1 : simple_state< State1, Machine, custom_reaction< Event1 >, transition< Event1, struct State2 > > { int i; State1() : i(0) { cout << "Entering State1."; } ~State1() { cout << "Exiting State1."; } result react( const Event1 & ) { i++; } }; That's actually not so bad. I've defined both a reaction and a transition on the same event; not sure if you're supposed to do that. Now I'm wondering if there's a way with mpl to determine if a class has a function with a certain signature. Can you eliminate the need for "custom_reaction< Event1 >" and just test whether or not the class implements "result react( const Event1 & )" ? If you could somehow hide the CRT mechanism, and specify children instead of parents, maybe you could boil down to something like so: DEFINE_STATE(State1, transition< Event1, struct State2 >) { int i; State1() : i(0) { cout << "Entering State1."; } ~State1() { cout << "Exiting State1."; } result react( const Event1 & ) { i++; } }; And I think that's about as obvious as you can make it. But that may just be wishful thinking. >I don't understand, you do define states top-down in boost::fsm. Maybe I'm confused, but as best as I can tell, you specify parents instead of specifying children. So, if StateX has StateY and StateZ as inner states, instead of saying StateX : StateY + StateZ, you say StateY -> StateX; StateZ -> StateX. >> it's my impression that with mpl one can iterate >> through the template arguments and figure out if they are events or >> transitions or whatever. So I smushed together the different >One sure can but that would duplicate mpl::list<> functionality to a > certain degree. For "real-world" uses, this seems unimportant. However, for the tutorial and basic examples, I think it would be a good idea if you can silently ignore mpl. Of course those examples should compile and work... I don't have a feel for whether I'm asking for a mountain or a molehill here, so I'll let it be. >Given that the approach you outlined above really works, I think you > can use lambda for transitions without changing a single line of > boost::fsm, you simply define your own reaction that accepts > typeofed lambda expressions instead of function pointers for > transition actions. I'm not so sure whether the same is possible > with entry/exit actions but I'm inclined to think that it > is (that would require deriving your own state class template from > simple_state). I think it would be nice to have a mechanism that accepts lambdas, though I'll concede it is better to avoid it for "average joe" programmer. But since fsm is compile time, an advanced user might use another library/technique to programmatically generate the code she wants as a lambda type. It's always seemed that lambda had great potential as a compile time code generator, and fsm is a place where one might concievably stick it. >Most people get used to the syntax >of boost::fsm quite quickly. Also, I've received feedback that people > really like the fact that they can easily put the bodies of complex > actions in cpp files, I *guess* that would be a little more > difficult with your approach. Now I'm thinking that maybe a macro or two added to what you've got, just to hide some of the machinery, is all that it would take to get what I'm looking for. I'll grant you that I'm struggling to come up with what I think is "ideal." My main goal is boost::fsm using code should be reasonably "guessable" by an educated reader in short order. Basically, my coworkers should be able to look at my code and mostly be able to guess what was going on. [snip] > I'd say it takes one day tops of playing around with boost::fsm to > learn this. My concern is intimidating potential new users more than necessary. Like I said initially, I might have missed a ton of discussion about this from before. If you can point me to a thread where interface issues were hashed out in great detail already, I'll take a look. > I did consider using named template parameters, but > rejected it because it would add to the amount of text you have to > write and would offer a benefit only for beginners. Me, I would probably cater a little more to the beginners, since I think getting more people to use FSM than previously would have to be a good thing. >> tutorial just made my head spin, especially trying to figure out >> how states and machines get tied together (this is still unclear to >> me). > I guess you mean how the implementation ties them toghether? As a > user, why do you need to know that? When I first looked at the sample code, I was hunting high and low, thinking to myself, "Where on earth does it specify which states belong to which?" >As I already mentioned in another post: Targetting every C++ > developer would require an *additional* document at least as thick > as the current tutorial. I think it is reasonable to expect previous > exposure to FSMs. Yes, I do not suggest writing your own guide to FSMs. >> In general, I would drop all mention of UML except for some >> appendix somewhere (and the reference manual too). > >Why? I think it's a distraction. Sure, it's great that you've got this nice correspondance with UML, but that's unimportant *in the tutorial*. Mention it on the about page, have an appendix all about it, go into detail in the references, etc. >> "Getting Started" and >> "Target Audience" should be in a differenct document, and > >Please make a suggestion. Probably just in index.html. >> "How to read this tutorial" should be removed. > >Why? To me, is unnecessary verbiage. It doesn't say anything important. Perhaps you need better headings in the TOC. The ToC is currently broken up by the name of the example; perhaps rather than "StopWatch," say "Simple Finite State Machines - A StopWatch example." >> In general, all of your "remarks" and "comments" need to be in the >> code! > >You're the second person to request that. I personally think it is > better to not clutter code with too many comments. If people think > it is better to have all comments in the code, I'll sure change it. Having it in the code, both in the tutorial and in the example files, would help a lot, IMO. Especially the example files. If you could give me a better overview of the process and hold my hand better about which template parameters are which, I think I would have been much less confused. >> I think the example state machines are basically OK, but I >> think that it is absolutely essential that you include a simple >> example that is alphabet-based. In fact, some helper functions for >> alphabet-based languages are probably a good idea, just to make the >> tutorial easier. > >Why? Well, maybe this isn't the norm, but I was taught FSMs using alphabets-as-events. One of the first things *I* would do with the library is try and implement some examples out of my old college text. I figured most people were taught this way, and so having an example with that would help connect with something familiar. >You mean the mapping between the pressed key and the generated event? > Why? I think it's probably a common thing to want to test your state machine by triggering events from the keyboard in a console app. >> I'm confused about why entering/exiting states causes construction/ >> destruction. It's taken as a given, > >It is not: http://tinyurl.com/5mjra (State-local storage) That's explaining why you offer state-local storage, which I have no qualms with. It doesn't explain why you use the constructor/destructor mechanism, it's just stated that's the way it is. >> but I would tend to assume that >> state-local-storage is maintained throughout unless I explicitly >> reset it. > >Why? Ok, I think I figured something out since I wrote this. You're relying on nesting states to maint data. I think this needs to be explained in big neon signs. I don't think of exiting a state as destroying it, just that it's no longer "active" or whatever. Your model is like a window manager that closes a window every time a different window gets the focus and reopens the first window upon return. Of course, having lost all data imbetween. Maybe hoisting your data up to an enclosing space is a good idea, but I'm not used to working with nested states, so I don't really think that way. I'm willing to be convinced, although I'm suspicious. >> I'm also surprised by the lack of "accept" states. Maybe >> it's not universal, but my theory certainly had them, and it's just >> disconcerting for them not to be there. > >I don't know what accept states are. UML doesn't have them. Now, I'm in no way an academic, so I'm relying on Wikipedia to tell me what's "normal." Since it's in line with my old textbook, I guess it's reasonably standard. Wikipedia tells me that there "acceptor" and "transducer" finite state machines. I've not worked with the "transducer" variety before; my text deals with them only in the exercises. At any rate, with an "acceptor" FSM, if after processing all input you are in an "accept" state, the input was legal, the operation was successful, whatever. Otherwise there was an error. Not that everybody will use them, but it would be nice to be able to mark states as accept-states and ask the machine if the current state is an accept-state. I would certainly recommend adding http://en.wikipedia.org/wiki/Finite_state_machine to your list of links about FSMs. Cheers- Augustus __________________________________ Celebrate Yahoo!'s 10th Birthday! Yahoo! Netrospective: 100 Moments of the Web http://birthday.yahoo.com/netrospective/

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