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  • Integrating a Custom Compiler with the Visual Studio IDE

    - by M.A. Hanin
    Background: I want to create a custom VB compiler, extending the "original" compiler, to handle my custom compile-time attributes. Question: after I've created my custom compiler and I've got an executable file capable of compiling VB code via the standard command-line interface, how do I integrate this compiler with the Visual Studio IDE? (such that pressing "compile" or "build" will make use of my compiler instead of the default compiler). EDIT: (Correct me if i'm wrong) From the reactions here, I see this question is a bit shocking, so I shall further explain my needs and background: .NET provides us with a great mechanism called Attributes. As far as I understand, making attributes apply their intended behavior upon the attributed element (assembly, module, class, method, etc.) - attributes must be reflected upon. So the real trick here is reflecting and applying behavior at the right spot. Lets take Serialization for example: We decorate a class with the Serializable attribute. We then pass an instance of the class to the formatter's Serialize method. The formatter reflects upon the instance, checking if it has the Serializable attribute, and acting accordingly. Now, if we examine the Synchronization, Flags, Obsolete and CLSCompliant attributes, then the real question is: who reflects upon them? At least in some cases, it has to be the compiler (and/or IDE). Therefore, it seems that if I wish to create custom attributes that change an element's behavior regardless of any specific consumer, i must extend the compiler to reflect upon them at compilation. Of course, these are not my personal insights: the book "Applied .NET Attributes" provides a complete example of creating a custom attribute and a custom C# compiler to reflect upon that attribute at compilation (the example is used to implement "java-style checked exceptions").

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  • How to upgrade all dependencies to a specific version

    - by Calm Storm
    Hi, I tried doing a mvn dependency:tree and I get a tree of dependencies. My question is, My project depends on many modules which internally depends on many spring artifacts. There are a few version clashes. I want to upgrade all spring related libraries to say the latest one (2.6.x or above). What is the preferred way to do this? Should I declare all the deps spring-context, spring-support (and 10 other artifacts) in my pom.xml and point them to 2.6.x ? Is there any other better method ? [INFO] +- com.xxxx:yyy-jar:jar:1.0-SNAPSHOT:compile [INFO] | +- com.xxxx:zzz-commons:jar:1.0-SNAPSHOT:compile [INFO] | | +- org.springframework:spring-dao:jar:2.0.7:compile [INFO] | | +- org.springframework:spring-jdbc:jar:2.0.7:compile [INFO] | | +- org.springframework:spring-web:jar:2.0.7:compile [INFO] | | +- org.springframework:spring-support:jar:2.0.7:compile [INFO] | | +- net.sf.ehcache:ehcache:jar:1.2:compile [INFO] | | +- commons-collections:commons-collections:jar:3.2:compile [INFO] | | +- aspectj:aspectjweaver:jar:1.5.3:compile [INFO] | | +- betex-commons:betex-commons:jar:5.5.1-2:compile [INFO] | | \- javax.servlet:servlet-api:jar:2.4:compile [INFO] | +- org.springframework:spring-beans:jar:2.0.7:compile [INFO] | +- org.springframework:spring-jmx:jar:2.0.7:compile [INFO] | +- org.springframework:spring-remoting:jar:2.0.7:compile [INFO] | +- org.apache.cxf:cxf-rt-core:jar:2.0.2-incubator:compile [INFO] | | +- org.apache.cxf:cxf-api:jar:2.0.2-incubator:compile [INFO] | | | +- org.apache.geronimo.specs:geronimo-activation_1.1_spec:jar:1.0-M1:compile [INFO] | | | +- org.codehaus.woodstox:wstx-asl:jar:3.2.1:compile [INFO] | | | +- org.apache.neethi:neethi:jar:2.0.2:compile [INFO] | | | \- org.apache.cxf:cxf-common-schemas:jar:2.0.2-incubator:compile UPDATE : I have removed the extra question about "\-" so my question is now what the subject asks for :)

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  • Regex to check if exact string exists including #

    - by Jayrox
    New question As suggested by Asaph in previous question: Regex to check if exact string exists I am looking for a way to check if an exact string match exists in another string using Regex or any better method suggested. I understand that you tell regex to match a space or any other non-word character at the beginning or end of a string. However, I don't know exactly how to set it up. Search String: #t String 1: Hello World, Nice to see you! #t String 2: Hello World, Nice to see you! String 3: #T Hello World, Nice to see you! I would like to use the search string and compare it to String 1, String 2 and String 3 and only get a positive match from String 1 and String 3 but not from String 2. Requirements: Search String may be at any character position in the Subject. There may or may not be a white-space character before or after it. I do not want it to match if it is part of another string; such as part of a word. For the sake of this question: I think I would do this using this pattern: /\b\#t\b/gi However, this is not returning the results as I would have expected. I am able to find the exact matches for normal strings (strings where # isn't present) using: /\b{$search_string}\b/gi Additional info: this will be used in PHP 5

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  • What are basic programs like, recursion, Fibonacci, small trick programs?

    - by Mike
    This question may seem daft (I'm a new to 'programming' and should probably stop if this is the type of question I'm required to ask)... What are: "basic programs like, recursion, fibonacci, factorial, string manipulation, small trick programs"? I've recently read Coding Horror - the non programmer and followed the links to Kegel and How to get hired. Then I delved through some similar questions here (hence the block quote) and I realised that as a fully fledged non-programmer I probably wouldn't know if I knew recursion (or any of the others) because I wouldn't know what it looked like, or why it was used, and what the results would look like after it was used. I suppose I'm trying to get a picture of "the basics". What the principles are and why we learn them - where they'll be used and what result/s your looking for. If they'll be used as an interview question during my first interview sometime in 2020 I would like to look less ignorant than those 199 out of 200 who just don't know the how, or the why, of programming. As always...I'll get my coat. Thanks Mike

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  • Java: How do you really force a GC using JVMTI's ForceGargabeCollection?

    - by WizardOfOdds
    I'm not looking for the usual "you can only hint the GC in Java using System.gc()" answers, this is not at all what this question is about. My questions is not subjective and is based on a reality: GC can be forced in Java for a fact. A lot of programs that we use daily do it: IntelliJ IDEA, NetBeans, VisualVM. They all can force GC to happen. How is it done? I take it they're all using JVMTI and more specifically the ForceGarbabeCollection (notice the "Force") but how can I try it for myself? http://java.sun.com/javase/6/docs/platform/jvmti/jvmti.html#ForceGarbageCollection Also note that this question is not about "why" I'd want to do this: the "why" may be "curiosity" or "we're writing a program similar to VisualVM", etc. The question is really "how do you force a GC using JVMTI's ForceGarbageCollection"? Does the JVM needs to be launched with any special parameters? Is any JNI required? If so, what code exactly? Does it only work on Sun VMs? Any complete and compilable example would be most welcome.

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  • Questions on usages of sizeof

    - by Appu
    Question 1 I have a struct like, struct foo { int a; char c; }; When I say sizeof(foo), i am getting 8 on my machine. As per my understanding, 4 bytes for int, 1 byte for char and 3 bytes for padding. Is that correct? Given a struct like the above, how will I find out how many bytes will be added as padding? Question 2 I am aware that sizeof can be used to calculate the size of an array. Mostly I have seen the usage like (foos is an array of foo) sizeof(foos)/sizeof(*foos) But I found that the following will also give same result. sizeof(foos) / sizeof(foo) Is there any difference in these two? Which one is preffered? Question 3 Consider the following statement. foo foos[] = {10,20,30}; When I do sizeof(foos) / sizeof(*foos), it gives 2. But the array has 3 elements. If I change the statement to foo foos[] = {{10},{20},{30}}; it gives correct result 3. Why is this happening? Any thoughts..

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  • Using the MVVM Light Toolkit to make Blendable applications

    - by Dave
    A while ago, I posted a question regarding switching between a Blend-authored GUI and a Visual Studio-authored one. I got it to work okay by adding my Blend project to my VS2008 project and then changing the Startup Application and recompiling. This would result in two applications that had completely different GUIs, yet used the exact same ViewModel and Model code. I was pretty happy with that. Now that I've learned about the Laurent Bugnion's MVVM Light Toolkit, I would really like to leverage his efforts to make this process of supporting multiple GUIs for the same backend code possible. The question is, does the toolkit facilate this, or am I stuck doing it my previous way? I've watched his video from MIX10 and have read some of the articles about it online. However, I've yet to see something that indicates that there is a clean way to allow a user to either dynamically switch GUIs on the fly by loading a different DLL. There are MVVM templates for VS2008 and Blend 3, but am I supposed to create both types of projects for my application and then reference specific files from my VS2008 solution? UPDATE I re-read some information on Laurent's site, and seemed to have forgotten that the whole point of the template was to allow the same solution to be opened in VS2008 and Blend. So anyhow, with this new perspective it looks like the templates are actually intended to use a single GUI, most likely designed entirely in Blend (with the convenience of debugging through VS2008), and then be able to use two different ViewModels -- one for design-time, and one for runtime. So it seems to me like the answer to my question is that I want to use a combination of my previous solution, along with the MVVM Light Toolkit. The former will allow me to make multiple, distinct GUIs around my core code, while the latter will make designing fancy GUIs in Blend easier with the usage of a design-time ViewModel. Can anyone comment on this?

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  • vlad the deployer: why do I need a scm folder?

    - by egarcia
    I'm learning to use vlad the deployer and I've got a question. Since I'm still learning I don't know what is pertinent to the question and what isn't, so please bear with me if I'm a little verbose. I've got 2 environments for a new application (test and production) besides my development machine. I've figured out this way to do the initial setup in my vlad.rake: namespace :test task :set set :domain, 'test.myserver.com' end end namespace :production task :set set :domain, 'www.myserver.com' end end This way I can have environment-specific stuff inside the namespaces, and still have shared tasks. For example, this would be the initial setup for test: rake vlad:test:set vlad:setup vlad:update This creates the following folders on my test server: releases/ scm/ shared/ current -> symlink to last release (inside the releases folder) My question is: what's the point of the scm folder? Every time I do vlad:update, the following happens: svn checkout on the scm/ folder above svn export on the /releases/{date} folder update current symlink So scm is a copy of my repository... but then there's an "export" copy of the repository on /releases/{date}. And that is the one used by the application... scm doesn't seem to be used by anyone? Wouldn't I be just fine without the scm folder?

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  • php/mongodb: how does references work in php?

    - by harald
    hello, i asked this in the mongodb user-group, but was not satisfied with the answer, so -- maybe someone at stackoverflow can enlighten me: the question was: $b = array('x' => 1); $ref = &$b; $collection->insert($ref); var_dump($ref); $ref does not contain '_id', because it's a reference to $b, the handbook states. (the code snippet is taken from the php mongo documentation) i should add, that: $b = array('x' => 1); $ref = $b; $collection->insert($ref); var_dump($ref); in this case $ref contains the _id -- for those, who do not know, what the insert method of mongodb-php-driver does -- because $ref is passed by reference (note the $b with and without referencing '&'). on the other hand ... function test(&$data) { $data['_id'] = time(); } $b = array('x' => 1); $ref =& $b; test($ref); var_dump($ref); $ref contains _id, when i call a userland function. my question is: how does the references in these cases differ? my question is probably not mongodb specific -- i thought i would know how references in php work, but apparently i do not: the answer in the mongodb user-group was, that this was the way, how references in php work. so ... how do they work -- explained with these two code-snippets? thanks in advance!!!

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  • Should a Perl constructor return an undef or a "invalid" object?

    - by DVK
    Question: What is considered to be "Best practice" - and why - of handling errors in a constructor?. "Best Practice" can be a quote from Schwartz, or 50% of CPAN modules use it, etc...; but I'm happy with well reasoned opinion from anyone even if it explains why the common best practice is not really the best approach. As far as my own view of the topic (informed by software development in Perl for many years), I have seen three main approaches to error handling in a perl module (listed from best to worst in my opinion): Construct an object, set an invalid flag (usually "is_valid" method). Often coupled with setting error message via your class's error handling. Pros: Allows for standard (compared to other method calls) error handling as it allows to use $obj->errors() type calls after a bad constructor just like after any other method call. Allows for additional info to be passed (e.g. 1 error, warnings, etc...) Allows for lightweight "redo"/"fixme" functionality, In other words, if the object that is constructed is very heavy, with many complex attributes that are 100% always OK, and the only reason it is not valid is because someone entered an incorrect date, you can simply do "$obj->setDate()" instead of the overhead of re-executing entire constructor again. This pattern is not always needed, but can be enormously useful in the right design. Cons: None that I'm aware of. Return "undef". Cons: Can not achieve any of the Pros of the first solution (per-object error messages outside of global variables and lightweight "fixme" capability for heavy objects). Die inside the constructor. Outside of some very narrow edge cases, I personally consider this an awful choice for too many reasons to list on the margins of this question. UPDATE: Just to be clear, I consider the (otherwise very worthy and a great design) solution of having very simple constructor that can't fail at all and a heavy initializer method where all the error checking occurs to be merely a subset of either case #1 (if initializer sets error flags) or case #3 (if initializer dies) for the purposes of this question. Obviously, choosing such a design, you automatically reject option #2.

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  • Weak event handler model for use with lambdas

    - by Benjol
    OK, so this is more of an answer than a question, but after asking this question, and pulling together the various bits from Dustin Campbell, Egor, and also one last tip from the 'IObservable/Rx/Reactive framework', I think I've worked out a workable solution for this particular problem. It may be completely superseded by IObservable/Rx/Reactive framework, but only experience will show that. I've deliberately created a new question, to give me space to explain how I got to this solution, as it may not be immediately obvious. There are many related questions, most telling you you can't use inline lambdas if you want to be able to detach them later: Weak events in .Net? Unhooking events with lambdas in C# Can using lambdas as event handlers cause a memory leak? How to unsubscribe from an event which uses a lambda expression? Unsubscribe anonymous method in C# And it is true that if YOU want to be able to detach them later, you need to keep a reference to your lambda. However, if you just want the event handler to detach itself when your subscriber falls out of scope, this answer is for you.

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  • Subscription Based Billing

    - by regex
    Hello All, I'm putting together a small start up company which will be set up with a subscription based billing model. The bill will go to customers on either a monthly or quarterly basis depending on the end user's preference. My question is two parted: I'm new to online billing and I'm only really aware of Pay Pal when it comes to third party bill payment, but this seems more like a check out system. I'm sure there are better alternatives than PayPal for third party billing processors (I have tried Googling for them, but I'm having trouble finding exactly what I'm looking for). What options (companies) are available for third party payment processing and what types of experiences (good or bad) have you had with them? We would like to give our customers the ability to set up recurring payments. I'd rather not store a customer's credit card number on our database as I imagine there are a plethora of compliance guidelines around this. Is there a third party solution for recurring payment processing? On a side note, this is not necessarily a code related question and is more business focused. I wasn't sure if there was a better route for posting this question, and please commont or modify this if there is another route I should take. Thanks!!

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  • Programmer Puzzle: Encoding a chess board state throughout a game

    - by Andrew Rollings
    Not strictly a question, more of a puzzle... Over the years, I've been involved in a few technical interviews of new employees. Other than asking the standard "do you know X technology" questions, I've also tried to get a feel for how they approach problems. Typically, I'd send them the question by email the day before the interview, and expect them to come up with a solution by the following day. Often the results would be quite interesting - wrong, but interesting - and the person would still get my recommendation if they could explain why they took a particular approach. So I thought I'd throw one of my questions out there for the Stack Overflow audience. Question: What is the most space-efficient way you can think of to encode the state of a chess game (or subset thereof)? That is, given a chess board with the pieces arranged legally, encode both this initial state and all subsequent legal moves taken by the players in the game. No code required for the answer, just a description of the algorithm you would use. EDIT: As one of the posters has pointed out, I didn't consider the time interval between moves. Feel free to account for that too as an optional extra :) EDIT2: Just for additional clarification... Remember, the encoder/decoder is rule-aware. The only things that really need to be stored are the player's choices - anything else can be assumed to be known by the encoder/decoder. EDIT3: It's going to be difficult to pick a winner here :) Lots of great answers!

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  • haskell: a data structure for storing ascending integers with a very fast lookup

    - by valya
    Hello! (This question is related to my previous question, or rather to my answer to it.) I want to store all qubes of natural numbers in a structure and look up specific integers to see if they are perfect cubes. For example, cubes = map (\x -> x*x*x) [1..] is_cube n = n == (head $ dropWhile (<n) cubes) It is much faster than calculating the cube root, but It has complexity of O(n^(1/3)) (am I right?). I think, using a more complex data structure would be better. For example, in C I could store a length of an already generated array (not list - for faster indexing) and do a binary search. It would be O(log n) with lower ?oefficient than in another answer to that question. The problem is, I can't express it in Haskell (and I don't think I should). Or I can use a hash function (like mod). But I think it would be much more memory consuming to have several lists (or a list of lists), and it won't lower the complexity of lookup (still O(n^(1/3))), only a coefficient. I thought about a kind of a tree, but without any clever ideas (sadly I've never studied CS). I think, the fact that all integers are ascending will make my tree ill-balanced for lookups. And I'm pretty sure this fact about ascending integers can be a great advantage for lookups, but I don't know how to use it properly (see my first solution which I can't express in Haskell).

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  • How do I debug a HTTP 502 error?

    - by Bialecki
    I have a Python Tornado server sitting behind a nginx frontend. Every now and then, but not every time, I get a 502 error. I look in the nginx access log and I see this: 127.0.0.1 - - [02/Jun/2010:18:04:02 -0400] "POST /a/question/updates HTTP/1.1" 502 173 "http://localhost/tagged/python" "Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.3) Gecko/20100401 Firefox/3.6.3" and in the error log: 2010/06/02 18:04:02 [error] 14033#0: *1700 connect() failed (111: Connection refused) while connecting to upstream, client: 127.0.0.1, server: _, request: "POST /a/question/updates HTTP/1.1", upstream: "http://127.0.0.1:8888/a/question/updates", host: "localhost", referrer: "http://localhost/tagged/python" I don't think any errors show up in the Tornado log. How would you go about debugging this? Is there something I can put in the Tornado or nginx configuration to help debug this? EDIT: In addition, I get a fair number of 504, gateway timeout errors. Is it possible that the Tornado instance is just busy or something?

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  • Determining failing sectors on portable flash memory

    - by Faxwell Mingleton
    I'm trying to write a program that will detect signs of failure for portable flash memory devices (thumb drives, etc). I have seen tools in the past that are able to detect failing sectors and other kinds of trouble on conventional mechanical hard drives, but I fear that flash memory does not have the same kind of predictable low-level access to the hardware due to the internal workings of the storage. Things like wear-leveling and other block-remapping techniques (to skip over 'dead' sectors?) lead me to believe that determining if a flash drive is failing will be difficult at best, if not impossible (short of having constant read failures and device unmounts). Flash drives at their end-of-life should be easy to detect (constant CRC discrepancies during reads and all-out failure). But what about drives that might be failing early? Are there any tell-tale signs like slower throughput speeds that might indicate a flash drive is going to fail much sooner than normal? Along the lines of detecting potentially bad blocks, I had considered attempting random reads/writes to a file close to or exactly the size of the entire volume, but even then is it possible that the drive might report sizes under its maximum capacity to account for 'dead' blocks? In short, is there any way to circumvent or at least detect (algorithmically or otherwise) the use of block-remapping or other life extension techniques for flash memory? Let me end this question by expressing my uncertainty as to whether or not this belongs on serverfault.com . This is definitely a hardware-related question, but I also desire a software solution - preferably one that I can program myself. If this question is misplaced, I will be happy to migrate it to serverfault - but I do need a programming solution. Please let me know if you need clarification :) Thanks!

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  • How can I stop an auto-generated Linq to SQL class from loading ALL data?

    - by Gary McGill
    I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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  • How can I stop an auto-generated Linq to SQL class from loading ALL data?

    - by Gary McGill
    DUPLICATE of http://stackoverflow.com/questions/2433422/how-can-i-stop-an-auto-generated-linq-to-sql-class-from-loading-all-data post answers there! I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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  • R: convert data.frame columns from factors to characters

    - by Mike Dewar
    Hi, I have a data frame. Let's call him bob: > head(bob) phenotype exclusion GSM399350 3- 4- 8- 25- 44+ 11b- 11c- 19- NK1.1- Gr1- TER119- GSM399351 3- 4- 8- 25- 44+ 11b- 11c- 19- NK1.1- Gr1- TER119- GSM399352 3- 4- 8- 25- 44+ 11b- 11c- 19- NK1.1- Gr1- TER119- GSM399353 3- 4- 8- 25+ 44+ 11b- 11c- 19- NK1.1- Gr1- TER119- GSM399354 3- 4- 8- 25+ 44+ 11b- 11c- 19- NK1.1- Gr1- TER119- GSM399355 3- 4- 8- 25+ 44+ 11b- 11c- 19- NK1.1- Gr1- TER119- I'd like to concatenate the rows of this data frame (this will be another question). But look: > class(bob$phenotype) [1] "factor" Bob's columns are factors. So, for example: > as.character(head(bob)) [1] "c(3, 3, 3, 6, 6, 6)" "c(3, 3, 3, 3, 3, 3)" [3] "c(29, 29, 29, 30, 30, 30)" I don't begin to understand this, but I guess these are indices into the levels of the factors of the columns (of the court of king caractacus) of bob? Not what I need. Strangely I can go through the columns of bob by hand, and do bob$phenotype <- as.character(bob$phenotype) which works fine. And, after some typing, I can get a data.frame whose columns are characters rather than factors. So my question is: how can I do this automatically? How do I convert a data.frame with factor columns into a data.frame with character columns without having to manually go through each column? Bonus question: why does the manual approach work?

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  • Accessing class member variables inside a BackgroundWorker's DoWork event handler, and other Backgro

    - by Justin
    Question 1 In the DoWork event handler of a BackgroundWorker, is it safe to access (for both reading and writing) member variables of the class that contains the BackgroundWorker? Is it safe to access other variables that are not declared inside the DoWork event handler itself? Obviously DoWork should not be accessing any UI objects of, say, a WinForms application, as the UI should only be updated from the UI thread. But what about accessing other (not UI-related) member variables? The reason why I ask is that I've seen the occasional comment come up while Googling saying that accessing member variables is not allowed. The only example I can find at the moment is a comment on this MSDN page, which says: Note, that the BGW can cause exceptions if it attempts to access or modify class level variables. All data must be passed to it by delegates and events. And also: NEVER. NEVER. Never try to reference variables not declared inside of DoWork. It may seem to work at times, but in reality you are just getting lucky. As far as I know, MSDN itself does not document any restrictions of this kind (although if I'm wrong, I'd appreciate a link). But comments like these do seem to pop up every now and again. (Of course if DoWork does access/modify a member variable that could be accessed/modified by the main thread at the same time, it is necessary to synchronise access to that field, eg by using a locking object. But the above quotes seem to require a blanket ban of accessing member variables, rather than just synchronising access!) Question 2 To make this into a more general question, are there any other (not documented?) restrictions that users of the BackgroundWorker should be aware of, aside from the above? Any "best practices", perhaps?

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  • How to get list of files which are currently being diffed in vim

    - by Yogesh Arora
    I am writing a vim plugin in which i need to determine all those files which are currently being diffed. That is the ones for which diff is set. I have been going through the manual but could not find much. Is it possible to do this. This question is actually related to question how-to-detect-the-position-of-window-in-vim. In that question i was trying to get the position of window, so as to detect which one of the diffs is the right one and which is left one. The solution i got was to use winnr() That solution can work only if there are only 2 windows(the ones being diffed). I want to make it generic so that even if multiple windows are open in vim, i can determine which one is on left and which one is right. This is what i was thinking to solve the problem Get a list of all listed buffers For each of this buffers determine if diff is 1 for that If diff is 1 use bufwinnr() to gets it window number. From the window numbers determine which one is left and which one is right. left one will have smaller window number And then determine if current buffer(in which alt-left`alt-right` is pressed) is left or right using winnr of current buffer. Now the pieces that are missing are 1 and 2. For 1 ls can be used but i need to parse its output. Is there a straightfwd way to get list of all listed buffers. And then is there a way to check if for that buffer diff is 1 or not. Any suggestions for a simpler solution are also appreciated.

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  • How to use SQLAlchemy to dump an SQL file from query expressions to bulk-insert into a DBMS?

    - by Mahmoud Abdelkader
    Please bear with me as I explain the problem, how I tried to solve it, and my question on how to improve it is at the end. I have a 100,000 line csv file from an offline batch job and I needed to insert it into the database as its proper models. Ordinarily, if this is a fairly straight-forward load, this can be trivially loaded by just munging the CSV file to fit a schema, but I had to do some external processing that requires querying and it's just much more convenient to use SQLAlchemy to generate the data I want. The data I want here is 3 models that represent 3 pre-exiting tables in the database and each subsequent model depends on the previous model. For example: Model C --> Foreign Key --> Model B --> Foreign Key --> Model A So, the models must be inserted in the order A, B, and C. I came up with a producer/consumer approach: - instantiate a multiprocessing.Process which contains a threadpool of 50 persister threads that have a threadlocal connection to a database - read a line from the file using the csv DictReader - enqueue the dictionary to the process, where each thread creates the appropriate models by querying the right values and each thread persists the models in the appropriate order This was faster than a non-threaded read/persist but it is way slower than bulk-loading a file into the database. The job finished persisting after about 45 minutes. For fun, I decided to write it in SQL statements, it took 5 minutes. Writing the SQL statements took me a couple of hours, though. So my question is, could I have used a faster method to insert rows using SQLAlchemy? As I understand it, SQLAlchemy is not designed for bulk insert operations, so this is less than ideal. This follows to my question, is there a way to generate the SQL statements using SQLAlchemy, throw them in a file, and then just use a bulk-load into the database? I know about str(model_object) but it does not show the interpolated values. I would appreciate any guidance for how to do this faster. Thanks!

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  • Dashcode code translation

    - by Alex Mcp
    Hi, a quick, probably easy question whose answer is probably "best practice" I'm following a tutorial for a custom-template mobile Safari webapp, and to change views around this code is used: function btnSave_ClickHandler(event) { var views = document.getElementById('stackLayout'); var front = document.getElementById('mainScreen'); if (views && views.object && front) { views.object.setCurrentView(front, true); } } My question is just about the if conditional statement. What is this triplet saying, and why do each of those things need to be verified before the view can be changed? Does views.object just test to see if the views variable responds to the object method? Why is this important? EDIT - This is/was the main point of this question, and it regards not Javascript as a language and how if loops work, but rather WHY these 3 things specifically need to be checked: Under what scenarios might views and front not exist? I don't typically write my code so redundantly. If the name of my MySQL table isn't changing, I'll just say UPDATE 'mytable' WHERE... instead of the much more verbose (and in my view, redundant) $mytable = "TheSQLTableName"; if ($mytable == an actual table && $mytable exists && entries can be updated){ UPDATE $mytable; } Whereas if the table's name (or in the JS example, the view's names) ARE NOT "hard coded" but are instead a user input or otherwise mutable, I might right my code as the DashCode example has it. So tell me, can these values "go wrong" anyhow? Thanks!

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  • If I wanted to make a Pac-Man Game?

    - by SoulBeaver
    I am immediately placing this as a community wiki thing. I don't want to ask for help in programming yet or have even a specific question about programming, but rather the process and the resources needed to make such a game. To put it simply: My college friend and I decided to give ourselves a really big challenge to further our skills in programming. In six months time we want to show ourselves a Pac-Man game. Pac-Man will be AI-controlled like the Ghosts and whichever Pac-Man lives the longest after a set of tries wins. This isn't like anything we've done so far. The goal here, for me, isn't to create a perfect game, but to try and complete it, learn a whole bunch in the process. Even if I don't finish in the time, which is a good possibility, I would want to have at least tried this. So my question is this: How should I start preparing myself? I already have started vector math, matrices, all that fun stuff. My desired platform would be DirectX 9.0c; is that advisable? Keep in mind that this is not a preference just for this project, but I wish to have some kind of future in graphics develepment, so I want to pick a platform that is future-safe. As for the game development in general, what should I take into consideration? I have never done a real game before, so any and all advise to development of mid-scale projects( if this would be a mid-scale project ) is greatly appreciated. My main concerns are the pit-falls and demotivators. Sorry if the question is so vague. If it doesn't belong here, then I will remove it. Otherwise, any and all advise regarding making larger projects is greatly appreciated.

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  • Lightweight development web server with support for PHP v2

    - by David
    In line with this question: http://stackoverflow.com/questions/171655/lightweight-web-app-server-for-php The above question has been asked numerous times and answered exactly the same in all the cases I've found using google. My question is similar to a degree but with a different desired goal: On demand development instances. I have come up with a somewhat questionable solution to host arbitrary directories in my user account for the purpose of development testing. I am not interested in custom vhosts but looking to emulate the behaviour I get when using paster or mongrel for Python & Ruby respectively. Ubuntu 9.10 TOXIC@~/ APACHE_RUN_USER=$USER APACHE_RUN_GROUP=www-data apache2 -d ~/Desktop/ -c "Listen 2990" Is there a better solution, could I do something similar with nginix or lighttpd? Note: The above won't work correctly for stock environments without a copied & altered httpd.conf. Update: The ideal goal is to mimic Paster, Webbrick, and Mongrel for rapid local development hosting. For those light weight servers, it takes less then a minute to get a working instance running ( not factoring any DB support ). Apache2 vhost is great but I've been using Apache2 for over ten years and it would be some sort of abomination hack to setup a new entry in /etc/hosts unless you have your own DNS, in which case a wildcard subdomain setup would probably work great. EXCEPT one more problem, it's pretty easy for me to know what is being hosted ( ex. by paster or mongeral ) just doing a sudo netstat -tulpn while there would be a good possibility of confusion in figure out which vhost is what.

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