文件列表:

Fear and loathing.txt (6004, 2017-04-11)
使用说明.txt (1685, 2017-04-11)
Declarations.bas (777, 2017-04-11)
PathFGlobal.bas (136, 2017-04-11)
Xtimers.bas (8189, 2017-04-11)
CoOrdinate.cls (395, 2017-04-11)
Heap.cls (17230, 2017-04-11)
HeapNode.cls (1841, 2017-04-11)
MapNode.cls (386, 2017-04-11)
Path.cls (1995, 2017-04-11)
PathFinder.cls (12742, 2017-04-11)
PathFinderTracker.cls (1845, 2017-04-11)
v84AStarNode.cls (420, 2017-04-11)
Xtimer.cls (6664, 2017-04-11)
Helga.frm (17284, 2017-04-11)
Helga.frx (7550, 2017-04-11)
『源码天空』.url (164, 2017-04-11)
PathFind2.vbp (875, 2017-04-11)
PathFinding.vbp (981, 2017-04-11)
TCAStarBaseClasses.vbp (811, 2017-04-11)
Xtimers.vbp (995, 2017-04-11)
PathFind2.vbw (133, 2017-04-11)
PathFinding.vbw (103, 2017-04-11)
W0bAStarBaseClasses.vbw (149, 2017-04-11)
Xtimers.vbw (68, 2017-04-11)

Multithreading in VB Ok, before you can even start this project you'll have to compile them In order, open, and compile the following projects to DLLs. 1) AstarBaseClasses.vbp 2) Xtimers.vbp 3) PathFinding.vbp Don't worry too much if you have an error like "Unable to set version compatible component". Then, open PathFind2.vbp and run it, making sure you have the correct references. You must have the Enterprise edition of Visual Basic (5 or 6) for this to work correctly. This project is NOT for newbies to Visual Basic!!!!!!!!!! Credits: All the multithreading parts are adapted from Microsoft's multi-threaded Coffee example, supplied with Visual Basic, and much puzzling over what the manual has to say about it. ================ I'm attempting this project 'cos I'm sick of using DoEvents and having applications freeze and hang because a task takes a little longer than expected. I also want to do more than one thing at once. I'm also tired of seeing multithreading in VB never attempted, or if it is, done badly using API calls. VB is not guaranteed thread-safe (parts of it are), so I don't see why I should deliberately try to break it. Instead, let's do it the way MS recommends. Which is not easy...sigh This will have to be made up of 3 layers (4 if you count Xtimers): /------------------------\ | Main Program | |------------------------| | Multi-Threaded Pieces | |------------------------| | Base Classes & Types | \------------------------/ Why do it like this? Erm, because the multi-threaded pieces must relate to the main program. The "Base Classes & Types" will work sort of like a C header file and sort of like a Windows type library. Because of the need to pass objects between the main program & the multithreaded pieces, I'll need to have the base classes as a completely seperate DLL. Please note that VB is NOT the first computer language I've learnt. I moved from Modula-2 (a sort of Pascal-like language where you _have_ to follow the rules of "good programming"), Unix C-Programming, Informix-4gl, and finally Visual Basic. I love this entry about Basic from the jargon file, and I can't resist quoting it here: ---- BASIC /bay'-sic/ n. A programming language, originally designed for Dartmouth's experimental timesharing system in the early 1960s, which for many years was the leading cause of brain damage in proto-hackers. Edsger W. Dijkstra observed in "Selected Writings on Computing: A Personal Perspective" that "It is practically impossible to teach good programming style to students that have had prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration." This is another case (like Pascal) of the cascading lossage that happens when a language deliberately designed as an educational toy gets taken too seriously. A novice can write short BASIC programs (on the order of 10-20 lines) very easily; writing anything longer (a) is very painful, and (b) encourages bad habits that will make it harder to use more powerful languages well. This wouldn't be so bad if historical accidents hadn't made BASIC so common on low-end micros in the 1***0s. As it is, it probably ruined tens of thousands of potential wizards. [1995: Some languages called `BASIC' aren't quite this nasty any more, having acquired Pascal- and C-like procedures and control structures and shed their line numbers. --ESR] Note: the name is commonly parsed as Beginner's All-purpose Symbolic Instruction Code, but this is a backronym. BASIC was originally named Basic, simply because it was a simple and basic programming language. Because most programming language names were in fact acronyms, BASIC was often capitalized just out of habit or to be silly. No acronym for BASIC originally existed or was intended (as one can verify by reading texts through the early 1970s). Later, around the mid-1970s, people began to make up backronyms for BASIC because they weren't sure. Beginner's All-purpose Symbolic Instruction Code is the one that caught on. -------------------------------------------------------------------------------- Before even attempting multithreading you must a) Disown Visual Basic. Curse it. Learn to despise its' intricacies and magic way of doing things. A quote from Bruce McKinley sums VB up nicely: ---- While later versions of Visual Basic (4 through 6) had some object-oriented features, the language itself was not based on these features. It was based on magic. Something happened to make all those controls appear on forms and interact with your code. But you couldn't really tell what it was. And you certainly couldn't mess with it. That was the appeal of the language. It just worked. You could produce amazingly powerful applications in a short time using techniques that felt just right, even though they didn't make sense if you looked at them too closely. Now it's true that at some point you ran out of magic. The more complicated your application, the more likely you were to hit inconsistencies and incompleteness. Features added in the later versions of VB didn't quite fit the original plan. ---- When you do multithreading, you are completely out of magic. Learn to praise Java where multithreading is so intrinsic to the language that it becomes easy. Kneel at the altar of C++ and swear that as soon as you can convince your boss, you will stop using Visual Basic. Praise Dennis Ritchie, and sacrifice a virgin at midnight (I didn't say it was going to be all bad now did I)... b) Understand threading - Read up on it - this will help you achieve the first goal! c) Write your code DEFENSIVELY. Error traps are essential. d) Work out how you handle errors (I still haven't figured this one out yet - events are probably the best way). e) Test test test test test test test. f) Did I mention you need to test it rigorously?

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