digitalmars.D - D Ranges
- Chris (29/29) Sep 13 2013 A short report on component programming and ranges.
- bearophile (5/15) Sep 13 2013 In most cases today you are free to omit those ():
- Dicebot (3/7) Sep 13 2013 ...but you shouldn't if you care about readability (leave at
- Chris (6/15) Sep 13 2013 It also helps other people (and me) to realize that it actually
- Brad Anderson (6/22) Sep 13 2013 Since most ranges in std.algorithm are lazy they are usually not
- Chris (3/28) Sep 13 2013 This reminds me, I have to check whether my ranges are lazy
- deadalnix (2/11) Sep 13 2013 That is my gideline as well. Keep at least the last one.
- Jesse Phillips (34/52) Sep 13 2013 There isn't a guide in the manner you desire.
- Jonathan M Davis (9/14) Sep 13 2013 I find that I use classes very rarely in D. Once in a while, I need
- H. S. Teoh (20/35) Sep 13 2013 [...]
- Jacob Carlborg (5/7) Sep 14 2013 I agree, it seems I most times want a reference type (not talking ranges...
- Chris (30/38) Sep 16 2013 Yes, this occurs sometimes. But I think it's due to my lack of
- Chris (4/46) Sep 16 2013 that do not _have_ to be reinstantiated
- Jonathan M Davis (10/19) Sep 13 2013 In general, if you want to have structs with reference semantics, it's
- monarch_dodra (31/65) Sep 15 2013 I have a few issues with ref counted.
- Jonathan M Davis (8/32) Sep 15 2013 Yeah. RefCounted could/should definitely be improved, but the concept is...
- Paulo Pinto (12/20) Sep 15 2013 Actually, it is much easier to write exception safe code in languages
- Dmitry Olshansky (22/50) Sep 15 2013 Seriously we could do a better job then that.. For instance blit the
- monarch_dodra (13/51) Sep 15 2013 Well, if a struct has no elaborate opAssign, then "=" *is*
- Dmitry Olshansky (16/22) Sep 15 2013 If user don't have the access to the wrapped internal type there should
A short report on component programming and ranges. A lot of my code deals with transforming and reformatting input, e.g. text is split into sentences and words for grammatical parsing (part of speech) and phonetic transcriptions. I'm using D ranges and component programming and I'm quite happy with "one-liners" like foreach (bySentence().byWord().byWhateverFormat().byReformatAgain()) { // Whatever } The code is much easier to maintain, neater and more efficient within each component. Sometimes, however, I wonder how I should design my ranges. It is hard to decide whether to use them as pure pipes or semi-output ranges. "Semi" because they're not sinks as defined by put() but still they can hold data (an array of reformatted strings for example) that could be accessed by using Range.data. I'm not sure as regards "best practice" and whether or not I'm wasting resources by storing data internally. On the other hand, it might be handy to have access to the data stored internally. Does anyone have a rough guide to D ranges? Like Case 1: Use XYZ, Case 2: Use ZYX etc. (I've read this tutorial http://ddili.org/ders/d.en/ranges.html, and I'd like to thank Ali for that! It helped me a lot.) Another issue I've come across is how to integrate CP and ranges into an OO framework. I figure that ranges are good work horses, but it makes sense to keep the overall logic in an OO fashion. Or could it be that D's structs and ranges will replace OOP as we no it (a class-free system).
Sep 13 2013
Chris:A short report on component programming and ranges. A lot of my code deals with transforming and reformatting input, e.g. text is split into sentences and words for grammatical parsing (part of speech) and phonetic transcriptions. I'm using D ranges and component programming and I'm quite happy with "one-liners" like foreach (bySentence().byWord().byWhateverFormat().byReformatAgain()) { // Whatever }In most cases today you are free to omit those (): foreach (bySentence.byWord.byWhateverFormat.byReformatAgain) { Bye, bearophile
Sep 13 2013
On Friday, 13 September 2013 at 13:31:18 UTC, bearophile wrote:In most cases today you are free to omit those (): foreach (bySentence.byWord.byWhateverFormat.byReformatAgain) { Bye, bearophile...but you shouldn't if you care about readability (leave at least the last pair in the line) :P
Sep 13 2013
On Friday, 13 September 2013 at 13:42:07 UTC, Dicebot wrote:On Friday, 13 September 2013 at 13:31:18 UTC, bearophile wrote:It also helps other people (and me) to realize that it actually _does_ something and doesn't just return a value. Often (not always of course), if you omit the brackets it returns a value without doing anything. But that's just a personal convention I might abandon further down the road.In most cases today you are free to omit those (): foreach (bySentence.byWord.byWhateverFormat.byReformatAgain) { Bye, bearophile...but you shouldn't if you care about readability (leave at least the last pair in the line) :P
Sep 13 2013
On Friday, 13 September 2013 at 14:39:29 UTC, Chris wrote:On Friday, 13 September 2013 at 13:42:07 UTC, Dicebot wrote:Since most ranges in std.algorithm are lazy they are usually not doing anything but setting a few members and returning a new range, often without having even touched the input range. Thinking about it I think I may start using () to denote eager versus lazy ranges in my UFCS chains.On Friday, 13 September 2013 at 13:31:18 UTC, bearophile wrote:It also helps other people (and me) to realize that it actually _does_ something and doesn't just return a value. Often (not always of course), if you omit the brackets it returns a value without doing anything. But that's just a personal convention I might abandon further down the road.In most cases today you are free to omit those (): foreach (bySentence.byWord.byWhateverFormat.byReformatAgain) { Bye, bearophile...but you shouldn't if you care about readability (leave at least the last pair in the line) :P
Sep 13 2013
On Friday, 13 September 2013 at 17:35:21 UTC, Brad Anderson wrote:On Friday, 13 September 2013 at 14:39:29 UTC, Chris wrote:This reminds me, I have to check whether my ranges are lazy enough (like myself).On Friday, 13 September 2013 at 13:42:07 UTC, Dicebot wrote:Since most ranges in std.algorithm are lazy they are usually not doing anything but setting a few members and returning a new range, often without having even touched the input range. Thinking about it I think I may start using () to denote eager versus lazy ranges in my UFCS chains.On Friday, 13 September 2013 at 13:31:18 UTC, bearophile wrote:It also helps other people (and me) to realize that it actually _does_ something and doesn't just return a value. Often (not always of course), if you omit the brackets it returns a value without doing anything. But that's just a personal convention I might abandon further down the road.In most cases today you are free to omit those (): foreach (bySentence.byWord.byWhateverFormat.byReformatAgain) { Bye, bearophile...but you shouldn't if you care about readability (leave at least the last pair in the line) :P
Sep 13 2013
On Friday, 13 September 2013 at 13:42:07 UTC, Dicebot wrote:On Friday, 13 September 2013 at 13:31:18 UTC, bearophile wrote:That is my gideline as well. Keep at least the last one.In most cases today you are free to omit those (): foreach (bySentence.byWord.byWhateverFormat.byReformatAgain) { Bye, bearophile...but you shouldn't if you care about readability (leave at least the last pair in the line) :P
Sep 13 2013
On Friday, 13 September 2013 at 11:31:24 UTC, Chris wrote:Sometimes, however, I wonder how I should design my ranges. It is hard to decide whether to use them as pure pipes or semi-output ranges. "Semi" because they're not sinks as defined by put() but still they can hold data (an array of reformatted strings for example) that could be accessed by using Range.data. I'm not sure as regards "best practice" and whether or not I'm wasting resources by storing data internally. On the other hand, it might be handy to have access to the data stored internally. Does anyone have a rough guide to D ranges? Like Case 1: Use XYZ, Case 2: Use ZYX etc. (I've read this tutorial http://ddili.org/ders/d.en/ranges.html, and I'd like to thank Ali for that! It helped me a lot.)There isn't a guide in the manner you desire. In my experience I generally don't hold any more data than the value returned by front (to prevent recalculation). Right now I don't recall what situations I've needed to store the intermediary data, but I know how you feel about having a input rang which is like an output range simply returning a range to provide the chaining ability. I also generally don't find a need to specify output ranges. Output ranges are the end of the line so they kill component programmingAnother issue I've come across is how to integrate CP and ranges into an OO framework. I figure that ranges are good work horses, but it makes sense to keep the overall logic in an OO fashion. Or could it be that D's structs and ranges will replace OOP as we no it (a class-free system).I spent much of my initial time programming in Java, so I have a good grasp of the constructs behind OOP (and a little bit of the prototyping style known to be in Javascript). I also think I have a pretty good grasp on designing for OOP, though I do have a lot I could learn. I hate OOP. I believe it has a place in software design, I just haven't found it yet. Templates cause a lot of problem, though I need to look into using the trick using /final/. Trying to do inheritance when your interface defines that it takes a range or The other issue I have is that OOP is very resistant to change and testing. It is hard enough to get all the data needed for your test cases, then throw in designing mock objects and blah blah, it quickly becomes a mess. And even if you skip all the testing aspects, if you want to make changes there is a giant structure you're making changes for. Yes had I done a better job designing my structure up front to allow for such change I wouldn't be in this mess... Anyway, my recommendation isn't to build up a class structure just because that is what you would do in another language. Figure out if the usability provided by inheritance is what you want, if not struct with helper functions seems to be simplest in development and maintenance. Destroy.
Sep 13 2013
On Saturday, September 14, 2013 04:10:09 Jesse Phillips wrote:Anyway, my recommendation isn't to build up a class structure just because that is what you would do in another language. Figure out if the usability provided by inheritance is what you want, if not struct with helper functions seems to be simplest in development and maintenance. Destroy.I find that I use classes very rarely in D. Once in a while, I need polymorphism, and in that situation, I use classes, but at least in the types of programs that I've usually been writing, polymorphism has rarely made much sense. Structs deal with most everything just fine. Classes definitely have their uses, but IMHO, they should not be the first tool to pull out of your toolbox when writing a D program. Just use them when you actually need them. - Jonathan M Davis
Sep 13 2013
On Fri, Sep 13, 2013 at 10:49:23PM -0400, Jonathan M Davis wrote:On Saturday, September 14, 2013 04:10:09 Jesse Phillips wrote:[...] I've found myself hovering between structs and classes when writing D code. I almost always use structs for ranges, just because value types incur less overhead, which does add up when you use a lot of UFCS chaining. OTOH, I find myself switching to classes just to get the reference semantics in other cases, even if I never actually do any inheritance. Trying to do reference semantics with structs, while certainly possible, is just too error-prone IME. Just a few days ago, I encountered what looked like a nasty functionality bug in my program, only to eventually discover that it was caused by a missing 'ref' in a function's struct parameter, so updates to the struct didn't persist as the code assumed it would. I found myself seriously considering using classes instead, just for the default ref semantics. While D's decision to make structs value-only and classes ref-only is certainly clever, it also introduces some tricky gotchas for the unwary. T -- May you live all the days of your life. -- Jonathan SwiftAnyway, my recommendation isn't to build up a class structure just because that is what you would do in another language. Figure out if the usability provided by inheritance is what you want, if not struct with helper functions seems to be simplest in development and maintenance. Destroy.I find that I use classes very rarely in D. Once in a while, I need polymorphism, and in that situation, I use classes, but at least in the types of programs that I've usually been writing, polymorphism has rarely made much sense. Structs deal with most everything just fine. Classes definitely have their uses, but IMHO, they should not be the first tool to pull out of your toolbox when writing a D program. Just use them when you actually need them.
Sep 13 2013
On 2013-09-14 08:07, H. S. Teoh wrote:OTOH, I find myself switching to classes just to get the reference semantics in other cases, even if I never actually do any inheritance.I agree, it seems I most times want a reference type (not talking ranges here but in general). -- /Jacob Carlborg
Sep 14 2013
On Saturday, 14 September 2013 at 02:10:13 UTC, Jesse Phillips wrote:There isn't a guide in the manner you desire. In my experience I generally don't hold any more data than the value returned by front (to prevent recalculation). Right now I don't recall what situations I've needed to store the intermediary data,but I know how you feel about having a input rang which is like an output range simply returning a range to provide the chaining ability.Yes, this occurs sometimes. But I think it's due to my lack of experience with ranges, that's why I was asking, if there was a rough guide. I don't think I really need to store intermediate data in my components. I'm not sure, however, if I should slowly migrate from OOP to structs. A of now I use them in two scenarios: 1. input / output ranges (flexible and interchangeable "workhorses") 2. storage of user defined data types, e.g. you could have a struct like this for an entry in a dictionary: struct LexEntry { string lemma = "digital"; string transcription = "Some IPA symbols"; string[] definition = ["1. bla bla", "2. bla bla"]; } At the moment, I use a lot of singletons in my program, because a lot of the data and data processing is handled by designated classes that do not to be reinstantiated. They just sit there waiting for input. In fact, without even noticing it, I designed parts of my program in an OO fashion that, in a way, makes OOP superfluous. So I'm beginning to wonder whether classes are really necessary. If I need features like sublcassing, I could just right another input range and add it to the chain. I'm still hesitant because a. if it's not broke, don't fix it and b. there might be some usage scenario when I'll need OO design and that I cannot yet foresee. But I agree that OO design is hard to unittest, it's not easy to single out a component and test it, because it's like a neurological network.
Sep 16 2013
On Monday, 16 September 2013 at 13:05:56 UTC, Chris wrote:On Saturday, 14 September 2013 at 02:10:13 UTC, Jesse Phillips wrote:that do not _have_ to be reinstantiated I could just right <= write (sorry, it's the Monday bug in my head!)There isn't a guide in the manner you desire. In my experience I generally don't hold any more data than the value returned by front (to prevent recalculation). Right now I don't recall what situations I've needed to store the intermediary data,but I know how you feel about having a input rang which is like an output range simply returning a range to provide the chaining ability.Yes, this occurs sometimes. But I think it's due to my lack of experience with ranges, that's why I was asking, if there was a rough guide. I don't think I really need to store intermediate data in my components. I'm not sure, however, if I should slowly migrate from OOP to structs. A of now I use them in two scenarios: 1. input / output ranges (flexible and interchangeable "workhorses") 2. storage of user defined data types, e.g. you could have a struct like this for an entry in a dictionary: struct LexEntry { string lemma = "digital"; string transcription = "Some IPA symbols"; string[] definition = ["1. bla bla", "2. bla bla"]; } At the moment, I use a lot of singletons in my program, because a lot of the data and data processing is handled by designated classes that do not to be reinstantiated. They just sit there waiting for input. In fact, without even noticing it, I designed parts of my program in an OO fashion that, in a way, makes OOP superfluous. So I'm beginning to wonder whether classes are really necessary. If I need features like sublcassing, I could just right another input range and add it to the chain. I'm still hesitant because a. if it's not broke, don't fix it and b. there might be some usage scenario when I'll need OO design and that I cannot yet foresee. But I agree that OO design is hard to unittest, it's not easy to single out a component and test it, because it's like a neurological network.
Sep 16 2013
On Friday, September 13, 2013 23:07:03 H. S. Teoh wrote:OTOH, I find myself switching to classes just to get the reference semantics in other cases, even if I never actually do any inheritance. Trying to do reference semantics with structs, while certainly possible, is just too error-prone IME. Just a few days ago, I encountered what looked like a nasty functionality bug in my program, only to eventually discover that it was caused by a missing 'ref' in a function's struct parameter, so updates to the struct didn't persist as the code assumed it would. I found myself seriously considering using classes instead, just for the default ref semantics.In general, if you want to have structs with reference semantics, it's probably better to just give them reference semantics by making it so that any of their members which are value types are on the heap or by putting all of the struct's guts on the heap. At some point, it becomes debatable as to whether that's better than using a class, but it does have less overhead. There's also RefCounted, which does incur the bookkeeping overhead of the refcounting, but it does make it so that the memory is freed as soon as you don't need the object anymore. - Jonathan M Davis
Sep 13 2013
On Saturday, 14 September 2013 at 06:18:02 UTC, Jonathan M Davis wrote:On Friday, September 13, 2013 23:07:03 H. S. Teoh wrote:I have a few issues with ref counted. First, if you *ever* place one in an array or an AA, then you will leak. It is NOT designed for simply incorporating reference, but for deterministic finalization. Second, it has an elaborate postblit and opAssign. This is not a big issue in itself, but their sole existence does cause dmd to generate code that is sub-optimal. It also means it can't take the "optimal" route in a lot of algorithms (array has to emplace each element individually, for example). Finally, a RefCounted will implicitly cast to its payload. I think this is *horrible*. Before you know it, the Payload will have "jettisoned" its wrapper, and you'll be operating on your value-type payload "raw". For example: void foo(T t); RefCounted!T myRecCounted; foo(myRefCounted); //Passes. Oops! The workaround would be to either require explicit "get" to go from ref counted to payload (breaking existing code), or to entirelly wrap the RefCounted as a member inside the struct (requires boilerplate code). -------- Overall, if I need a reference semantic struct, I find it much simpler for it to just hold a GC pointer to a payload. Though to be honest, as H.S. Teoh, I seriously wonder why I even bother, when I could just use a final class. With proper "private constructors + non-member "make" function", you can make your choice outright transparent to the final user too, meaning you can "fast prototype" with classes, and later change to structs if you think it is worth it.OTOH, I find myself switching to classes just to get the reference semantics in other cases, even if I never actually do any inheritance. Trying to do reference semantics with structs, while certainly possible, is just too error-prone IME. Just a few days ago, I encountered what looked like a nasty functionality bug in my program, only to eventually discover that it was caused by a missing 'ref' in a function's struct parameter, so updates to the struct didn't persist as the code assumed it would. I found myself seriously considering using classes instead, just for the default ref semantics.In general, if you want to have structs with reference semantics, it's probably better to just give them reference semantics by making it so that any of their members which are value types are on the heap or by putting all of the struct's guts on the heap. At some point, it becomes debatable as to whether that's better than using a class, but it does have less overhead. There's also RefCounted, which does incur the bookkeeping overhead of the refcounting, but it does make it so that the memory is freed as soon as you don't need the object anymore. - Jonathan M Davis
Sep 15 2013
On Sunday, September 15, 2013 10:39:40 monarch_dodra wrote:I have a few issues with ref counted. First, if you *ever* place one in an array or an AA, then you will leak. It is NOT designed for simply incorporating reference, but for deterministic finalization. Second, it has an elaborate postblit and opAssign. This is not a big issue in itself, but their sole existence does cause dmd to generate code that is sub-optimal. It also means it can't take the "optimal" route in a lot of algorithms (array has to emplace each element individually, for example). Finally, a RefCounted will implicitly cast to its payload. I think this is *horrible*. Before you know it, the Payload will have "jettisoned" its wrapper, and you'll be operating on your value-type payload "raw". For example: void foo(T t); RefCounted!T myRecCounted; foo(myRefCounted); //Passes. Oops! The workaround would be to either require explicit "get" to go from ref counted to payload (breaking existing code), or to entirelly wrap the RefCounted as a member inside the struct (requires boilerplate code).Yeah. RefCounted could/should definitely be improved, but the concept is essentially the same as smart_ptr in C++11. In many ways, smart pointers are far superior to using the GC, and I really think that we should do a better job of supporting them and promoting them. There are obviously plenty of cases where the GC is better or even necessary, but in many cases - particularly with objects - smart pointers are arguably a much better way to go. - Jonathan M Davis
Sep 15 2013
Am 15.09.2013 10:52, schrieb Jonathan M Davis:... Yeah. RefCounted could/should definitely be improved, but the concept is essentially the same as smart_ptr in C++11. In many ways, smart pointers are far superior to using the GC, and I really think that we should do a better job of supporting them and promoting them. There are obviously plenty of cases where the GC is better or even necessary, but in many cases - particularly with objects - smart pointers are arguably a much better way to go. - Jonathan M DavisActually, it is much easier to write exception safe code in languages with GC. Or in case of ref-counting if the compiler is aware of them. The problems with exception safe code in C++ with memory leaks are related to its C compatibility rules and having to cope to optional exceptions. After watching the Going Native 2013 videos, I really wonder how much of a push C++ will win back from younger developers, outside the game industry and device drivers. Now back to C++ coding. :) -- Paulo
Sep 15 2013
15-Sep-2013 12:39, monarch_dodra пишет:On Saturday, 14 September 2013 at 06:18:02 UTC, Jonathan M Davis wrote: I have a few issues with ref counted. First, if you *ever* place one in an array or an AA, then you will leak. It is NOT designed for simply incorporating reference, but for deterministic finalization.Another problem with built-in AAs...Second, it has an elaborate postblit and opAssign. This is not a big issue in itself, but their sole existence does cause dmd to generate code that is sub-optimal. It also means it can't take the "optimal" route in a lot of algorithms (array has to emplace each element individually, for example).Seriously we could do a better job then that.. For instance blit the whole data, then call postblits on that range. Exception safety would be trickier to achieve. Even better one day I now expect compiler to be able to know that e.g. RefCounted is registered as ARC-capable type then the compiler should elide call to ref-counting.Finally, a RefCounted will implicitly cast to its payload. I think this is *horrible*. Before you know it, the Payload will have "jettisoned" its wrapper, and you'll be operating on your value-type payload "raw". For example: void foo(T t); RefCounted!T myRecCounted; foo(myRefCounted); //Passes. Oops!Well it does a copy. Which is IMO perfectly fine. If you want to prevent that (at least in theory) you should simply mark postblit of T as disabled.The workaround would be to either require explicit "get" to go from ref counted to payload (breaking existing code), or to entirelly wrap the RefCounted as a member inside the struct (requires boilerplate code).There is no need to prevent that in general case. Only RAII kind of things implemented with RefCounted would have problem copying-out the payload but these should have post-blit disabled for their "value" and consequently would not compile.-------- Overall, if I need a reference semantic struct, I find it much simpler for it to just hold a GC pointer to a payload.Ehm.. Isn't finalized class is just that? Plus bit of overhead for monitor.Though to be honest, as H.S. Teoh, I seriously wonder why I even bother, when I could just use a final class. With proper "private constructors + non-member "make" function", you can make your choice outright transparent to the final user too, meaning you can "fast prototype" with classes, and later change to structs if you think it is worth it.This is true. And in fact I would encourage every D programmer to never expose constructors and always provide factory functions. These days constructors are constrained by a set of arcane limitations thusly suck beyond measure in every way possible. But you need them to say initialize immutable members, hence _use_ - but don't _expose_ them. -- Dmitry Olshansky
Sep 15 2013
On Sunday, 15 September 2013 at 12:17:34 UTC, Dmitry Olshansky wrote:15-Sep-2013 12:39, monarch_dodra пишет:Well, if a struct has no elaborate opAssign, then "=" *is* blit+postblit. And it doesn't get much more efficient than that. If not, you have to pull out the memcpy, and things just go downhill from there.On Saturday, 14 September 2013 at 06:18:02 UTC, Jonathan M Davis wrote: I have a few issues with ref counted. First, if you *ever* place one in an array or an AA, then you will leak. It is NOT designed for simply incorporating reference, but for deterministic finalization.Another problem with built-in AAs...Second, it has an elaborate postblit and opAssign. This is not a big issue in itself, but their sole existence does cause dmd to generate code that is sub-optimal. It also means it can't take the "optimal" route in a lot of algorithms (array has to emplace each element individually, for example).Seriously we could do a better job then that.. For instance blit the whole data, then call postblits on that range. Exception safety would be trickier to achieve. Even better one day I now expect compiler to be able to know that e.g. RefCounted is registered as ARC-capable type then the compiler should elide call to ref-counting.It depends how you look at it. If the original intent was to have a type with reference semantics, because your value type was so damn big (eg, PRNG), then that would *not* be OK (and the original point I was making that RefCounted is a bad contender for "just" reference semantics). If you are *trully* using it for deterministic finalization, then yeah, it's OK.Finally, a RefCounted will implicitly cast to its payload. I think this is *horrible*. Before you know it, the Payload will have "jettisoned" its wrapper, and you'll be operating on your value-type payload "raw". For example: void foo(T t); RefCounted!T myRecCounted; foo(myRefCounted); //Passes. Oops!Well it does a copy. Which is IMO perfectly fine. If you want to prevent that (at least in theory) you should simply mark postblit of T as disabled.
Sep 15 2013
15-Sep-2013 17:02, monarch_dodra пишет:It depends how you look at it. If the original intent was to have a type with reference semantics, because your value type was so damn big (eg, PRNG), then that would *not* be OK (and the original point I was making that RefCounted is a bad contender for "just" reference semantics).If user don't have the access to the wrapped internal type there should be no problem. E.g. the wrapped type is private and only usable inside the PRNG's module. Then having public alias for RefCounted!PRNG touted as THE PRNG should suffice. (Truly wicked folks can crack open it with a carefully applied piece of template deduction but each to their own goals). If you are afraid of these dark mages of templates you can do something like: struct RefPRNG{ RefCounted!PRNG payload; mixin ForwardCallsTo!"payload"; } And let them suck it down. IMHO there is no reason to go that far.If you are *trully* using it for deterministic finalization, then yeah, it's OK.See above I don't see the problem. -- Dmitry Olshansky
Sep 15 2013