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• Employee Info Starter Kit: Project Mission

  - by Mohammad Ashraful Alam

  Employee Info Starter Kit is an open source ASP.NET project template that is intended to address different types of real world challenges faced by web application developers when performing common CRUD operations. Using a single database table ‘Employee’, it illustrates how to utilize Microsoft ASP.NET 4.0, Entity Framework 4.0 and Visual Studio 2010 effectively in that context. Employee Info Starter Kit is highly influenced by the concept ‘Pareto Principle’ or 80-20 rule. where it is targeted to enable a web developer to gain 80% productivity with 20% of effort with respect to learning curve and production. User Stories The user end functionalities of this starter kit are pretty simple and straight forward that are focused in to perform CRUD operation on employee records as described below. Creating a new employee record Read existing employee record Update an existing employee record Delete existing employee records Key Technology Areas ASP.NET 4.0 Entity Framework 4.0 T-4 Template Visual Studio 2010 Architectural Objective There is no universal architecture which can be considered as the best for all sorts of applications around the world. Based on requirements, constraints, environment, application architecture can differ from one to another. Trade-off factors are one of the important considerations while deciding a particular architectural solution. Employee Info Starter Kit is highly influenced by the concept ‘Pareto Principle’ or 80-20 rule, where it is targeted to enable a web developer to gain 80% productivity with 20% of effort with respect to learning curve and production. “Productivity” as the architectural objective typically also includes other trade-off factors as well as, such as testability, flexibility, performance etc. Fortunately Microsoft .NET Framework 4.0 and Visual Studio 2010 includes lots of great features that have been implemented cleverly in this project to reduce these trade-off factors in the minimum level. Why Employee Info Starter Kit is Not a Framework? Application frameworks are really great for productivity, some of which are really unavoidable in this modern age. However relying too many frameworks may overkill a project, as frameworks are typically designed to serve wide range of different usage and are less customizable or editable. On the other hand having implementation patterns can be useful for developers, as it enables them to adjust application on demand. Employee Info Starter Kit provides hundreds of “connected” snippets and implementation patterns to demonstrate problem solutions in actual production environment. It also includes Visual Studio T-4 templates that generate thousands lines of data access and business logic layer repetitive codes in literally few seconds on the fly, which are fully mock testable due to language support for partial methods and latest support for mock testing in Entity Framework. Why Employee Info Starter Kit is Different than Other Open-source Web Applications? Software development is one of the rapid growing industries around the globe, where the technology is being updated very frequently to adapt greater challenges over time. There are literally thousands of community web sites, blogs and forums that are dedicated to provide support to adapt new technologies. While some are really great to enable learning new technologies quickly, in most cases they are either too “simple and brief” to be used in real world scenarios or too “complex and detailed” which are typically focused to achieve a product goal (such as CMS, e-Commerce etc) from "end user" perspective and have a long duration learning curve with respect to the corresponding technology. Employee Info Starter Kit, as a web project, is basically "developer" oriented which actually considers a hybrid approach as “simple and detailed”, where a simple domain has been considered to intentionally illustrate most of the architectural and implementation challenges faced by web application developers so that anyone can dive into deep into the corresponding new technology or concept quickly. Roadmap Since its first release by 2008 in MSDN Code Gallery, Employee Info Starter Kit gained a huge popularity in ASP.NET community and had 1, 50,000+ downloads afterwards. Being encouraged with this great response, we have a strong commitment for the community to provide support for it with respect to latest technologies continuously. Currently hosted in Codeplex, this community driven project is planned to have a wide range of individual editions, each of which will be focused on a selected application architecture, framework or platform, such as ASP.NET Webform, ASP.NET Dynamic Data, ASP.NET MVC, jQuery Ajax (RIA), Silverlight (RIA), Azure Service Platform (Cloud), Visual Studio Automated Test etc. See here for full list of current and future editions.

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• C# 4 Named Parameters for Overload Resolution

  - by Steve Michelotti

  C# 4 is getting a new feature called named parameters. Although this is a stand-alone feature, it is often used in conjunction with optional parameters. Last week when I was giving a presentation on C# 4, I got a question on a scenario regarding overload resolution that I had not considered before which yielded interesting results. Before I describe the scenario, a little background first. Named parameters is a well documented feature that works like this: suppose you have a method defined like this: 1: void DoWork(int num, string message = "Hello") 2: { 3: Console.WriteLine("Inside DoWork() - num: {0}, message: {1}", num, message); 4: } This enables you to call the method with any of these: 1: DoWork(21); 2: DoWork(num: 21); 3: DoWork(21, "abc"); 4: DoWork(num: 21, message: "abc"); and the corresponding results will be: Inside DoWork() - num: 21, message: Hello Inside DoWork() - num: 21, message: Hello Inside DoWork() - num: 21, message: abc Inside DoWork() - num: 21, message: abc This is all pretty straight forward and well-documented. What is slightly more interesting is how resolution is handled with method overloads. Suppose we had a second overload for DoWork() that looked like this: 1: void DoWork(object num) 2: { 3: Console.WriteLine("Inside second overload: " + num); 4: } The first rule applied for method overload resolution in this case is that it looks for the most strongly-type match first.  Hence, since the second overload has System.Object as the parameter rather than Int32, this second overload will never be called for any of the 4 method calls above.  But suppose the method overload looked like this: 1: void DoWork(int num) 2: { 3: Console.WriteLine("Inside second overload: " + num); 4: } In this case, both overloads have the first parameter as Int32 so they both fulfill the first rule equally.  In this case the overload with the optional parameters will be ignored if the parameters are not specified. Therefore, the same 4 method calls from above would result in: Inside second overload: 21 Inside second overload: 21 Inside DoWork() - num: 21, message: abc Inside DoWork() - num: 21, message: abc Even all this is pretty well documented. However, we can now consider the very interesting scenario I was presented with. The question was what happens if you change the parameter name in one of the overloads.  For example, what happens if you change the parameter *name* for the second overload like this: 1: void DoWork(int num2) 2: { 3: Console.WriteLine("Inside second overload: " + num2); 4: } In this case, the first 2 method calls will yield *different* results: 1: DoWork(21); 2: DoWork(num: 21); results in: Inside second overload: 21 Inside DoWork() - num: 21, message: Hello We know the first method call will go to the second overload because of normal method overload resolution rules which ignore the optional parameters.  But for the second call, even though all the same rules apply, the compiler will allow you to specify a named parameter which, in effect, overrides the typical rules and directs the call to the first overload. Keep in mind this would only work if the method overloads had different parameter names for the same types (which in itself is weird). But it is a situation I had not considered before and it is one in which you should be aware of the rules that the C# 4 compiler applies.

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• Is inconsistent formatting a sign of a sloppy programmer?

  - by dreza

  I understand that everyone has their own style of programming and that you should be able to read other people's styles and accept it for what it is. However, would one be considered a sloppy programmer if one's style of coding was inconsistent across whatever standard they were working against? Some example of inconsistencies might be: Sometimes naming private variables with _ and sometimes not Sometimes having varying indentations within code blocks Not aligning braces up i.e. same column if using start using new line style Spacing not always consistent around operators i.e. p=p+1, p+=1 vs other times p =p+1 or p = p + 1 etc Is this even something that as a programmer I should be concerned with addressing? Or is it such a minor nit picking thing that at the end of the day I should just not worry about it and worry about what the end user sees and whether the code works rather than how it looks while working? Is it sloppy programming or just over obsessive nit picking? EDIT: After some excellent comments I realized I may have left out some information in my question. This question came about after reviewing another colleagues code check-in and noticing some of these things and then realizing that I've seen these kind of in-consistencies in previous check-ins. It then got me thinking about my code and whether I do the same things and noticed that I typically don't etc I'm not suggesting his technique is either bad or good in this question or whether his way of doing things is right or wrong. EDIT: To answer some queries to some more good feed back. The specific instance this review occurred in was using Visual Studio 2010 and programming in c# so I don't think the editor would cause any issues. In fact it should only help I would hope. Sorry if I left that piece of info out and it effects any current answers. I was trying to be a bit more generic in understanding if this would be considered sloppy etc. And to add an even more specific example of a code piece I saw during reading of the check-in: foreach(var block in Blocks) { // .. some other code in here foreach(var movement in movements) { movement.Moved.Zero(); } // the un-formatted brace } Such a minor thing I know, but many small things add up(???), and I did have to double glance at the code at the time to see where everything lined up I guess. Please note this code was formatted appropriately before this check-in. EDIT: After reading some great answers and varying thoughts, the summary I've taken from this was. It's not necessarily a sign of a sloppy programmer however as programmers we have a duty (to ourselves and other programmers) to make the code as readable as possible to assist in further ongoing development. However it can hint at inadequacies which is something that is only possible to review on a case by case (person by person) basis. There are many reasons why this might occur. They should be taken in context and worked through with the person/people involved if reasonable. We have a duty to try and help all programmers become better programmers! In the good old days when development was done using good old notepad (or other simple text editing tool) this occurred much more frequently. However we have the assistance of modern IDE's now so although we shouldn't necessarily become OTT about this, it should still probably be addressed to some degree. We as programmers vary in our standards, styles and approaches to solutions. However it seems that in general we all take PRIDE in our work and as a trait it is something that can stand programmers apart. Making something to the best of our abilities both internal (code) and external (end user result) goes along way to giving us that big fat pat on the back that we may not go looking for but swells our heart with pride. And finally to quote CrazyEddie from his post below. Don't sweat the small stuff

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• Replicating between Cloud and On-Premises using Oracle GoldenGate

  - by Ananth R. Tiru

  Do you have applications running on the cloud that you need to connect with the on premises systems. The most likely answer to this question is an astounding YES!  If so, then you understand the importance of keep the data fresh at all times across the cloud and on-premises environments. This is also one of the key focus areas for the new GoldenGate 12c release which we announced couple of week ago via a press release. Most enterprises have spent years avoiding the data “silos” that inhibit productivity. For example, an enterprise which has adopted a CRM strategy could be relying on an on-premises based marketing application used for developing and nurturing leads. At the same time it could be using a SaaS based Sales application to create opportunities and quotes. The sales and the marketing teams which use these systems need to be able to access and share the data in a reliable and cohesive way. This example can be extended to other applications areas such as HR, Supply Chain, and Finance and the demands the users place on getting a consistent view of the data. When it comes to moving data in hybrid environments some of the key requirements include minimal latency, reliability and security: Data must remain fresh. As data ages it becomes less relevant and less valuable—day-old data is often insufficient in today’s competitive landscape. Reliability must be guaranteed despite system or connectivity issues that can occur between the cloud and on-premises instances. Security is a key concern when replicating between cloud and on-premises instances. There are several options to consider when replicating between the cloud and on-premises instances. Option 1 – Secured network established between the cloud and on-premises A secured network is established between the cloud and on-premises which enables the applications (including replication software) running on the cloud and on-premises to have seamless connectivity to other applications irrespective of where they are physically located. Option 2 – Restricted network established between the cloud and on-premises A restricted network is established between the cloud and on-premises instances which enable certain ports (required by replication) be opened on both the cloud and on the on-premises instances and white lists the IP addresses of the cloud and on-premises instances. Option 3 – Restricted network access from on-premises and cloud through HTTP proxy This option can be considered when the ports required by the applications (including replication software) are not open and the cloud instance is not white listed on the on-premises instance. This option of tunneling through HTTP proxy may be only considered when proper security exceptions are obtained. Oracle GoldenGate Oracle GoldenGate is used for major Fortune 500 companies and other industry leaders worldwide to support mission-critical systems for data availability and integration. Oracle GoldenGate addresses the requirements for ensuring data consistency between cloud and on-premises instances, thus facilitating the business process to run effectively and reliably. The architecture diagram below illustrates the scenario where the cloud and the on-premises instance are connected using GoldenGate through a secured network In the above scenario, Oracle GoldenGate is installed and configured on both the cloud and the on-premises instances. On the cloud instance Oracle GoldenGate is installed and configured on the machine where the database instance can be accessed. Oracle GoldenGate can be configured for unidirectional or bi-directional replication between the cloud and on premises instances. The specific configuration details of Oracle GoldenGate processes will depend upon the option selected for establishing connectivity between the cloud and on-premises instances. The knowledge article (ID - 1588484.1) titled ' Replicating between Cloud and On-Premises using Oracle GoldenGate' discusses in detail the options for replicating between the cloud and on-premises instances. The article can be found on My Oracle Support. To learn more about Oracle GoldenGate 12c register for our launch webcast where we will go into these new features in more detail.   You may also want to download our white paper "Oracle GoldenGate 12c Release 1 New Features Overview" I would love to hear your requirements for replicating between on-premises and cloud instances, as well as your comments about the strategy discussed in the knowledge article to address your needs. Please post your comments in this blog or in the Oracle GoldenGate public forum - https://forums.oracle.com/community/developer/english/business_intelligence/system_management_and_integration/goldengate

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• Approach for packing 2D shapes while minimizing total enclosing area

  - by Dennis

  Not sure on my tags for this question, but in short .... I need to solve a problem of packing industrial parts into crates while minimizing total containing area. These parts are motors, or pumps, or custom-made components, and they have quite unusual shapes. For some, it may be possible to assume that a part === rectangular cuboid, but some are not so simple, i.e. they assume a shape more of that of a hammer or letter T. With those, (assuming 2D shape), by alternating direction of top & bottom, one can pack more objects into the same space, than if all tops were in the same direction. Crude example below with letter "T"-shaped parts: ***** xxxxx ***** x ***** *** ooo * x vs * x vs * x vs * x o * x * xxxxx * x * x o xxxxx xxx Right now we are solving the problem by something like this: using CAD software, make actual models of how things fit in crate boxes make estimates of actual crate dimensions & write them into Excel file (1) is crazy amount of work and as the result we have just a limited amount of possible entries in (2), the Excel file. The good things is that programming this is relatively easy. Given a combination of products to go into crates, we do a lookup, and if entry exists in the Excel (or Database), we bring it out. If it doesn't, we say "sorry, no data!". I don't necessarily want to go full force on making up some crazy algorithm that given geometrical part description can align, rotate, and figure out best part packing into a crate, given its shape, but maybe I do.. Question Well, here is my question: assuming that I can represent my parts as 2D (to be determined how), and that some parts look like letter T, and some parts look like rectangles, which algorithm can I use to give me a good estimate on the dimensions of the encompassing area, while ensuring that the parts are packed in a minimal possible area, to minimize crating/shipping costs? Are there approximation algorithms? Seeing how this can get complex, is there an existing library I could use? My thought / Approach My naive approach would be to define a way to describe position of parts, and place the first part, compute total enclosing area & dimensions. Then place 2nd part in 0 degree orientation, repeat, place it at 180 degree orientation, repeat (for my case I don't think 90 degree rotations will be meaningful due to long lengths of parts). Proceed using brute force "tacking on" other parts to the enclosing area until all parts are processed. I may have to shift some parts a tad (see 3rd pictorial example above with letters T). This adds a layer of 2D complexity rather than 1D. I am not sure how to approach this. One idea I have is genetic algorithms, but I think those will take up too much processing power and time. I will need to look out for shape collisions, as well as adding extra padding space, since we are talking about real parts with irregularities rather than perfect imaginary blocks. I'm afraid this can get geometrically messy fairly fast, and I'd rather keep things simple, if I can. But what if the best (practical) solution is to pack things into different crate boxes rather than just one? This can get a bit more tricky. There is human element involved as well, i.e. like parts can go into same box and are thus a constraint to be considered. Some parts that are not the same are sometimes grouped together for shipping and can be considered as a common grouped item. Sometimes customers want things shipped their way, which adds human element to constraints. so there will have to be some customization.

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• Representing Mauritius in the 2013 Bench Games

  Only by chance I came across an interesting option for professionals and enthusiasts in IT, and quite honestly I can't even remember where I caught attention of Brainbench and their 2013 Bench Games event. But having access to 600+ free exams in a friendly international intellectual competition doesn't happen to be available every day. So, it was actually a no-brainer to sign up and browse through the various categories. Most interestingly, Brainbench is not only IT-related. They offer a vast variety of fields in their Test Center, like Languages and Communication, Office Skills, Management, Aptitude, etc., and it can be a little bit messy about how things are organised. Anyway, while browsing through their test offers I added a couple of exams to 'My Plan' which I would give a shot afterwards. Self-assessments Actually, I took the tests based on two major aspects: 'Fun Factor' and 'How good would I be in general'... Usually, you have to pay for any kind of exams and given this unique chance by Brainbench to simply train this kind of tests was already worth the time. Frankly speaking, the tests are very close to the ones you would be asked to do at Prometric or Pearson Vue, ie. Microsoft exams, etc. Go through a set of multiple choice questions in a given time frame. Most of the tests I did during the Bench Games were based on 40 questions, each with a maximum of 3 minutes to answer. Ergo, one test in maximum 2 hours - that sounds feasible, doesn't it? The Measure of Achievement While the 2013 Bench Games are considered a worldwide friendly competition of knowledge I was really eager to get other Mauritians attracted. Using various social media networks and community activities it all looked quite well at the beginning. Mauritius was listed on rank #19 of Most Certified Citizens and rank #10 of Most Master Level Certified Nation - not bad, not bad... Until... the next update of the Bench Games Leaderboard. The downwards trend seemed to be unstoppable and I couldn't understand why my results didn't show up on the Individual Leader Board. First of all, I passed exams that were not even listed and second, I had better results on some exams listed. After some further information from the organiser it turned out that my test transcript wasn't available to the public. Only then results are considered and counted in the competition. During that time, I actually managed to hold 3 test results on the Individuals... Other participants were merciless, eh, more successful than me, produced better test results than I did. But still I managed to stay on the final score board: An 'exotic' combination of exam, test result, country and person itself Representing Mauritius and the Visual FoxPro community in that fun event. And although I mainly develop in Visual FoxPro 9.0 SP2 and C# using .NET Framework from 2.0 to 4.5 since a couple of years I still managed to pass on Master Level. Hm, actually my Microsoft Certified Programmer (MCP) exams are dated back in June 2004 - more than 9 years ago... Look who got lucky... As described above I did a couple of exams as time allowed and without any preparations, but still I received the following mail notification: "Thank you for recently participating in our Bench Games event.  We wanted to inform you that you obtained a top score on our test(s) during this event, and as a result, will receive a free annual Brainbench subscription.  Your annual subscription will give you access to all our tests just like Bench Games, but for an entire year plus additional benefits!" -- Leader Board Notification from Brainbench Even fun activities get rewarded sometimes. Thanks to @Brainbench_com for the free annual subscription based on my passed 2013 Bench Games Master Level exam. It would be interesting to know about the total figures, especially to see how many citizens of Mauritius took part in this year's Bench Games. Anyway, I'm looking forward to be able to participate in other challenges like this in the future.

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• Appropriate design / technologies to handle dynamic string formatting?

  - by Mark W

  recently I was tasked with implementing a way of adding support for versioning of hardware packet specifications to one of our libraries. First a bit of information about the project. We have a hardware library which has classes for each of the various commands we support sending to our hardware. These hardware modules are essentially just lights with a few buttons, and a 2 or 4 digit display. The packets typically follow the format {SOH}AADD{ETX}, where AA is our sentinel action code, and DD is the device ID. These packet specs are different from one command to the next obviously, and the different firmware versions we have support different specifications. For example, on version 1 an action code of 14 may have a spec of {SOH}AADDTEXT{ETX} which would be AA = 14 literal, DD = device ID, TEXT = literal text to display on the device. Then we come out with a revision with adds an extended byte(s) onto the end of the packet like this {SOH}AADDTEXTE{ETX}. Assume the TEXT field is fixed width for this example. We have now added a new field onto the end which could be used to say specify the color or flash rate of the text/buttons. Currently this java library only supports one version of the commands, the latest. In our hardware library we would have a class for this command, say a DisplayTextArgs.java. That class would have fields for the device ID, the text, and the extended byte. The command class would expose a method which generates the string ("{SOH}AADDTEXTE{ETX}") using the value from the class. In practice we would create the Args class as needed, populate the fields, call the method to get our packet string, then ship that down across the CAN. Some of our other commands specification can vary for the same command, on the same version, depending on some runtime state. For example, another command for version 1 may be {SOH}AA{ETX}, where this action code clears all of the modules behind a specific controller device of their text. We may overload this packet to have option fields with multiple meanings like {SOH}AAOC{ETX} where OC is literal text, which tells the controller to only clear text on a specific module type, and to leave the others alone, or the spec could also have an option format of {SOH}AADD{ETX} to clear the text off a a specific device. Currently, in the method which generates the packet string, we would evaluate fields on the args class to determine which spec we will be using when formatting the packet. For this example, it would be along the lines of: if m_DeviceID != null then use {SOH}AADD{ETX} else if m_ClearOCs == true then use {SOH}AAOC{EXT} else use {SOH}AA{ETX} I had considered using XML, or a database to store String.format format strings, which were linked to firmware version numbers in some table. We would load them up at startup, and pass in the version number of the hardwares firmware we are currently using (I can query the devices for their firmware version, but the version is not included in all packets as part of the spec). This breaks down pretty quickly because of the dynamic nature of how we select which version of the command to use. I then considered using a rule engine to possibly build out expressions which could be interpreted at runtume, to evaluate the args class's state, and from that select the appropriate format string to use, but my brief look at rule engines for java scared me away with its complexity. While it seems like it might be a viable solution, it seems overly complex. So this is why I am here. I wouldn't say design is my strongest skill, and im having trouble figuring out the best way to approach this problem. I probably wont be able to radically change the args classes, but if the trade off was good enough, I may be able to convince my boss that the change is appropriate. What I would like from the community is some feedback on some best practices / design methodologies / API or other resources which I could use to accomplish: Logic to determine which set of commands to use for a given firmware version Of those command, which version of each command to use (based on the args classes state) Keep the rules logic decoupled from the application so as to avoid needing releases for every firmware version Be simple enough so I don't need weeks of study and trial and error to implement effectively.

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• FindBugs controversial description

  - by Tom Brito

  Am I understanding it wrong, or is the description wrong? Equals checks for noncompatible operand (EQ_CHECK_FOR_OPERAND_NOT_COMPATIBLE_WITH_THIS) This equals method is checking to see if the argument is some incompatible type (i.e., a class that is neither a supertype nor subtype of the class that defines the equals method). For example, the Foo class might have an equals method that looks like: public boolean equals(Object o) { if (o instanceof Foo) return name.equals(((Foo)o).name); else if (o instanceof String) return name.equals(o); else return false; This is considered bad practice, as it makes it very hard to implement an equals method that is symmetric and transitive. Without those properties, very unexpected behavoirs are possible. From: http://findbugs.sourceforge.net/bugDescriptions.html#EQ_CHECK_FOR_OPERAND_NOT_COMPATIBLE_WITH_THIS The description says that the Foo class might have an equals method like that, and after it says that "This is considered bad practice". I'm not getting the "right way".. How should the following method be to be right? @Override public boolean equals(Object obj) { if (obj instanceof DefaultTableModel) return model.equals((DefaultTableModel)obj); else return false; }

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• FindBugs controversal description

  - by Tom Brito

  Am I understanding it wrong, or is the description wrong? Equals checks for noncompatible operand (EQ_CHECK_FOR_OPERAND_NOT_COMPATIBLE_WITH_THIS) This equals method is checking to see if the argument is some incompatible type (i.e., a class that is neither a supertype nor subtype of the class that defines the equals method). For example, the Foo class might have an equals method that looks like: public boolean equals(Object o) { if (o instanceof Foo) return name.equals(((Foo)o).name); else if (o instanceof String) return name.equals(o); else return false; This is considered bad practice, as it makes it very hard to implement an equals method that is symmetric and transitive. Without those properties, very unexpected behavoirs are possible. From: http://findbugs.sourceforge.net/bugDescriptions.html#EQ_CHECK_FOR_OPERAND_NOT_COMPATIBLE_WITH_THIS The description says that the Foo class might have an aquals method like that, and after it says that "This is considered bad practice". I'm not getting the "right way".. How should the following method be to be right? @Override public boolean equals(Object obj) { if (obj instanceof DefaultTableModel) return model.equals((DefaultTableModel)obj); else return false; }

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• Does replace into have a where clause?

  - by Lajos Arpad

  I'm writing an application and I'm using MySQL as DBMS, we are downloading property offers and there were some performance issues. The old architecture looked like this: A property is updated. If the number of affected rows is not 1, then the update is not considered successful, elseway the update query solves our problem. If the update was not successful, and the number of affected rows is more than 1, we have duplicates and we delete all of them. After we deleted duplicates if needed if the update was not successful, an insert happens. This architecture was working well, but there were some speed issues, because properties are deleted if they were not updated for 15 days. Theoretically the main problem is deleting properties, because some properties are alive for months and the indexes are very far from each other (we are talking about 500, 000+ properties). Our host told me to use replace into instead of deleting properties and all deprecated properties should be considered as DEAD. I've done this, but problems started to occur because of syntax error and I couldn't find anywhere an example of replace into with a where clause (I'd like to replace a DEAD property with the new property instead of deleting the old property and insert a new to assure optimization). My query looked like this: replace into table_name(column1, ..., columnn) values(value1, ..., valuen) where ID = idValue Of course, I've calculated idValue and handled everything but I had a syntax error. I would like to know if I'm wrong and there is a where clause for replace into. I've found an alternative solution, which is even better than replace into (using simply an update query) because deletes are happening behind the curtains if I use replace into, but I would like to know if I'm wrong when I say that replace into doesn't have a where clause. For more reference, see this link: http://dev.mysql.com/doc/refman/5.0/en/replace.html Thank you for your answers in advance, Lajos Árpád

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• Best way to close nested streams in Java?

  - by dirtyvagabond

  What is considered the best, most comprehensive way to close nested streams in Java? For example, consider the setup: FileOutputStream fos = new FileOutputStream(...) BufferedOS bos = new BufferedOS(fos); ObjectOutputStream oos = new ObjectOutputStream(bos); I understand the close operation needs to be insured (probably by using a finally clause). What I wonder about is, is it necessary to explicitly make sure the nested streams are closed, or is it enough to just make sure to close the outer stream (oos)? One thing I notice, at least dealing with this specific example, is that the inner streams only seem to throw FileNotFoundExceptions. Which would seem to imply that there's not technically a need to worry about closing them if they fail. Here's what a colleague wrote: Technically, if it were implemented right, closing the outermost stream (oos) should be enough. But the implementation seems flawed. Example: BufferedOutputStream inherits close() from FilterOutputStream, which defines it as: 155 public void close() throws IOException { 156 try { 157 flush(); 158 } catch (IOException ignored) { 159 } 160 out.close(); 161 } However, if flush() throws a runtime exception for some reason, then out.close() will never be called. So it seems "safest" (but ugly) to mostly worry about closing FOS, which is keeping the file open. What is considered to be the hands-down best, when-you-absolutely-need-to-be-sure, approach to closing nested streams? And are there any official Java/Sun docs that deal with this in fine detail?

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• Visual Studio code metrics misreporting lines of code

  - by Ian Newson

  The code metrics analyser in Visual Studio, as well as the code metrics power tool, report the number of lines of code in the TestMethod method of the following code as 8. At the most, I would expect it to report lines of code as 3. [TestClass] public class UnitTest1 { private void Test(out string str) { str = null; } [TestMethod] public void TestMethod() { var mock = new Mock<UnitTest1>(); string str; mock.Verify(m => m.Test(out str)); } } Can anyone explain why this is the case? Further info After a little more digging I've found that removing the out parameter from the Test method and updating the test code causes LOC to be reported as 2, which I believe is correct. The addition of out causes the jump, so it's not because of braces or attributes. Decompiling the DLL with dotPeek reveals a fair amount of additional code generated because of the out parameter which could be considered 8 LOC, but removing the parameter and decompiling also reveals generated code, which could be considered 5 LOC, so it's not simply a matter of VS counting compiler generated code (which I don't believe it should do anyway).

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• Iterator performance contract (and use on non-collections)

  - by polygenelubricants

  If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be iterated in linear time? java.util.Scanner implements Iterator<String>. A Scanner is hardly a data structure (e.g. remove() makes absolutely no sense). Is this considered a design blunder? Is something like PrimeGenerator implements Iterator<Integer> considered bad design, or is this exactly what Iterator is for? (hasNext() always returns true, next() computes the next number on demand, remove() makes no sense). Similarly, would it have made sense for java.util.Random implements Iterator<Double>? Should a type really implement Iterator if it's effectively only using one-third of its API? (i.e. no remove(), always hasNext())

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• Time complexity with bit cost

  - by Keyser

  I think I might have completely misunderstood bit cost analysis. I'm trying to wrap my head around the concept of studying an algorithm's time complexity with respect to bit cost (instead of unit cost) and it seems to be impossible to find anything on the subject. Is this considered to be so trivial that no one ever needs to have it explained to them? Well I do. (Also, there doesn't even seem to be anything on wikipedia which is very unusual). Here's what I have so far: The bit cost of multiplication and division of two numbers with n bits is O(n^2) (in general?) So, for example: int number = 2; for(int i = 0; i < n; i++ ){ number = i*i; } has a time complexity with respect to bit cost of O(n^3), because it does n multiplications (right?) But in a regular scenario we want the time complexity with respect to the input. So, how does that scenario work? The number of bits in i could be considered a constant. Which would make the time complexity the same as with unit cost except with a bigger constant (and both would be linear). Also, I'm guessing addition and subtraction can be done in constant time, O(1). Couldn't find any info on it but it seems reasonable since it's one assembler operation.

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• twisted deferred/callbacks and asynchronous execution

  - by NetSkay

  hey guys, quick question about twisted and python... im trying to figure out how can i make my code more asynchronous using twisted and ive come to sort of a dead end, if a function of mine returns a deferred object, then i add a list of callbacks, the first callback will be called after the deferred function provides some result through deferred_obj.callback, then, in the chain of callbacks, the first callback will do something with the data and call the second callback and etc. however chained callbacks will not be considered asynchronous because they're chained and the event loop will keep firing each one of them concurrently until there is no more, right? however, if i have a deferred object, and i attach as its callback the deferred_obj.callback as in d.addCallback(deferred_obj.callback) then this will be considered asynchronous, because the deferred_obj is waiting for the data, and then the method that will pass the data is waiting on data as well, however once i d.callback 'd' object processes the data then it call deferred_obj.callback however since this object is deferred, unlike the case of chained callbacks, it will execute asynchronously... correct? meaning chained callbacks are NOT asynchronous while chained deferreds are, correct? thank you PS: assuming all of my code is non-blocking

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• What happens to my PriorityQueue if my Comparator throws an exception while it's busy bubbling up or

  - by nieldw

  Hi, I'm trying order pairs of integers ascendantly where a pair is considered less than another pair if both its entries are strictly less than those of the other pair, and larger than the other pair if both its entries are strictly larger than those of the other pair. All other cases are considered incomparable. They way I want to solve this is by defining a Comparator that implements the above, but will throw an exception for incomparable cases, and provide that to a PriorityQueue. Of course, while inserting a pair the priority queue does several comparisons while bubbling the new entry up to its correct position in the heap, and many of these will be comparable. But it may happen during the bubbling process that a pair is encountered with which this new pair is incomparable, and an exception will be thrown. If this happens, what will be the state of the PriorityQueue? Will the pair I was trying to insert sit in the heap at the last position it was in before the exception was thrown? If I use the PriorityQueue's remove(Object o) method, will the PriorityQueue be restored to a consistent state? Thanks

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• GUI toolkit for Unicode text app?

  - by wrp

  In developing a tool for processing text in exotic scripts, I'm having trouble choosing a GUI toolkit. The main part of the interface is to be a text editor, not much more elaborate than Notepad, but with its own input method editor. It is to be extensible in a scripting language so that non-programmers can develop their own input methods and display routines. It will be assumed that all files are UTF-8. More elaborate support like regexes is not needed. The main sticking points are: characters beyond the Basic Multilingual Plane right-to-left and bi-directional text extension in a scripting language cross-platform Linux/Windows/OS X My first choice was Tcl/Tk, but it lacks bidi and going beyond the BMP seems dodgy. At the other extreme, I've considered Qt with embedded ECMAScript, but that might be heavier and less malleable than I would like. I'm even thinking about making it browser based, but I'm concerned that the IM for large scripts would be too heavy for client-side processing. I've also looked at a few similar projects in Java, but the quality of the font rendering in SWING has been unacceptable. What are your experiences in handling Unicode with various toolkits? Are there other serious issues I haven't considered? What would you recommend for doing this in the lightest way?

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• Returning true or error message in Ruby

  - by seaneshbaugh

  I'm wondering if writing functions like this is considered good or bad form. def test(x) if x == 1 return true else return "Error: x is not equal to one." end end And then to use it we do something like this: result = test(1) if result != true puts result end result = test(2) if result != true puts result end Which just displays the error message for the second call to test. I'm considering doing this because in a rails project I'm working on inside my controller code I make calls to a model's instance methods and if something goes wrong I want the model to return the error message to the controller and the controller takes that error message and puts it in the flash and redirects. Kinda like this def create @item = Item.new(params[:item]) if [email protected]? result = @item.save_image(params[:attachment][:file]) if result != true flash[:notice] = result redirect_to(new_item_url) and return end #and so on... That way I'm not constructing the error messages in the controller, merely passing them along, because I really don't want the controller to be concerned with what the save_image method itself does just whether or not it worked. It makes sense to me, but I'm curious as to whether or not this is considered a good or bad way of writing methods. Keep in mind I'm asking this in the most general sense pertaining mostly to ruby, it just happens that I'm doing this in a rails project, the actual logic of the controller really isn't my concern.

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• Is it safe to use random Unicode for complex delimiter sequences in strings?

  - by ccomet

  Question: In terms of program stability and ensuring that the system will actually operate, how safe is it to use chars like ¦, § or ‡ for complex delimiter sequences in strings? Can I reliable believe that I won't run into any issues in a program reading these incorrectly? I am working in a system, using C# code, in which I have to store a fairly complex set of information within a single string. The readability of this string is only necessary on the computer side, end-users should only ever see the information after it has been parsed by the appropriate methods. Because some of the data in these strings will be collections of variable size, I use different delimiters to identify what parts of the string correspond to a certain tier of organization. There are enough cases that the standard sets of ;, |, and similar ilk have been exhausted. I considered two-char delimiters, like ;# or ;|, but I felt that it would be very inefficient. There probably isn't that large of a performance difference in storing with one char versus two chars, but when I have the option of picking the smaller option, it just feels wrong to pick the larger one. So finally, I considered using the set of characters like the double dagger and section. They only take up one char, and they are definitely not going to show up in the actual text that I'll be storing, so they won't be confused for anything. But character encoding is finicky. While the visibility to the end user is meaningless (since they, in fact, won't see it), I became recently concerned about how the programs in the system will read it. The string is stored in one database, while a separate program is responsible for both encoding and decoding the string into different object types for the rest of the application to work with. And if something is expected to be written one way, is possibly written another, then maybe the whole system will fail and I can't really let that happen. So is it safe to use these kind of chars for background delimiters?

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• WYSIWYG in Doxygen

  - by Adam Shiemke

  I'm working on a fairly large project written in C. The idea was to build a library of modular blocks that can be reused across several platforms. Each module is assocaited with a word document in .docx format (huge pain to diff-merge). In these docs, an interface section is specified, listing datatypes and publicly accessable functions. These were often inconsistant with the actual implementation in code, and wading through all this documentation was a pain. I've been working to switch to doxygen to simplify document managemnet. I haven't found a good way to embed the previously written documentation into the doxygen output. I've copy-pasted them into sections and used modules to group the sources together, but the document sections look ugly in the comments (the output is pretty) and since doxygen takes a while to parse through our code (about 30 mins), validating formatting is a pain. Is there some way to WYSIWIG large blocks of documentation into doxygen? I feel this would improve the number of people documenting their code, and the quality of that documentation. I considered linking to html, but that splits out the documentation. I also considered putting them inline in html, but this also seems like a pain and would mean everyone needs a WYSIWIG HTML edditor (or some html skillz). Any ideas on how to make things easier and prettier? Thanks loads.

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• Temporary storage for keeping data between program iterations?

  - by mr.b

  I am working on an application that works like this: It fetches data from many sources, resulting in pool of about 500,000-1,500,000 records (depends on time/day) Data is parsed Part of data is processed in a way to compare it to pre-existing data (read from database), calculations are made, and stored in database. Resulting dataset that has to be stored in database is, however, much smaller in size (compared to original data set), and ranges from 5,000-50,000 records. This process almost always updates existing data, perhaps adds few more records. Then, data from step 2 should be kept somehow, somewhere, so that next time data is fetched, there is a data set which can be used to perform calculations, without touching pre-existing data in database. I should point out that this data can be lost, it's not irreplaceable (key information can be read from database if needed), but it would speed up the process next time. Application components can (and will be) run off different computers (in the same network), so storage has to be reachable from multiple hosts. I have considered using memcached, but I'm not quite sure should I do so, because one record is usually no smaller than 200 bytes, and if I have 1,500,000 records, I guess that it would amount to over 300 MB of memcached cache... But that doesn't seem scalable to me - what if data was 5x that amount? If it were to consume 1-2 GB of cache only to keep data in between iterations (which could easily happen)? So, the question is: which temporary storage mechanism would be most suitable for this kind of processing? I haven't considered using mysql temporary tables, as I'm not sure if they can persist between sessions, and be used by other hosts in network... Any other suggestion? Something I should consider?

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• Extension methods for encapsulation and reusability

  - by tzaman

  In C++ programming, it's generally considered good practice to "prefer non-member non-friend functions" instead of instance methods. This has been recommended by Scott Meyers in this classic Dr. Dobbs article, and repeated by Herb Sutter and Andrei Alexandrescu in C++ Coding Standards (item 44); the general argument being that if a function can do its job solely by relying on the public interface exposed by the class, it actually increases encapsulation to have it be external. While this confuses the "packaging" of the class to some extent, the benefits are generally considered worth it. Now, ever since I've started programming in C#, I've had a feeling that here is the ultimate expression of the concept that they're trying to achieve with "non-member, non-friend functions that are part of a class interface". C# adds two crucial components to the mix - the first being interfaces, and the second extension methods: Interfaces allow a class to formally specify their public contract, the methods and properties that they're exposing to the world. Any other class can choose to implement the same interface and fulfill that same contract. Extension methods can be defined on an interface, providing any functionality that can be implemented via the interface to all implementers automatically. And best of all, because of the "instance syntax" sugar and IDE support, they can be called the same way as any other instance method, eliminating the cognitive overhead! So you get the encapsulation benefits of "non-member, non-friend" functions with the convenience of members. Seems like the best of both worlds to me; the .NET library itself providing a shining example in LINQ. However, everywhere I look I see people warning against extension method overuse; even the MSDN page itself states: In general, we recommend that you implement extension methods sparingly and only when you have to. So what's the verdict? Are extension methods the acme of encapsulation and code reuse, or am I just deluding myself?

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• JavaScript window object element properties

  - by Timothy

  A coworker showed me the following code and asked me why it worked. <span id="myspan">Do you like my hat?</span> <script type="text/javascript"> var spanElement = document.getElementById("myspan"); alert("Here I am! " + spanElement.innerHTML + "\n" + myspan.innerHTML); </script> I explained that a property is attached to the window object with the name of the element's id when the browser parses the document which then contains a reference to the appropriate dom node. It's sort of as if window.myspan = document.getElementById("myspan") is called behind the scenes as the page is being rendered. The ensuing discussion we had raised a few of questions: The window object and most of the DOM are not part of the official JavaScript/ECMA standards, but is the above behavior documented in any other official literature, perhaps browser-related? The above works in a browser (at least the main contenders) because there is a window object, but fails in something like rhino. Is writing code that relys on this considered bad practice because it makes too many assumptions about the execution environment? Are there any browsers in which the above would fail, or is this considered standard behavior across the board? Does anyone here know the answers to those questions and would be willing to enlighten me? I tried a quick internet search, but I admit I'm not sure how to even properly phrase the query. Pointers to references and documentation are welcome.

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• The use of getters and setters for different programming languages [closed]

  - by leonhart88

  So I know there are a lot of questions on getters and setters in general, but I couldn't find something exactly like my question. I was wondering if people change the use of get/set depending on different languages. I started learning with C++ and was taught to use getters and setters. This is what I understand: In C++ (and Java?), a variable can either be public or private, but we cannot have a mix. For example, I can't have a read-only variable that can still be changed inside the class. It's either all public (can read and change it), or all private (can't read and can only change inside the class). Because of this (and possibly other reasons), we use getters and setters. In MATLAB, I can control the "setaccess" and "getaccess" properties of variables, so that I can make things read-only (can directly access the property, but can't overwrite it). In this case, I don't feel like I need a getter because I can just do class.property. Also, in Python it is considered "Pythonic" to not use getters/setters and to only put things into properties if needed. I don't really understand why its OK to have all public variables in Python, because that's opposite of what I learned when I started with C++. I'm just curious what other people's thoughts are on this. Would you use getters and setters for all languages? Would you only use it for C++/Java and do direct access in MATLAB and Python (which is what I am currently doing)? Is the second option considered bad? For my purposes, I am only referring to simple getters and setters (just return/set the value and do not do anything else). Thanks!

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• How to cancel a deeply nested process

  - by Mystere Man

  I have a class that is a "manager" sort of class. One of it's functions is to signal that the long running process of the class should shut down. It does this by setting a boolean called "IsStopping" in class. public class Foo { bool isStoping void DoWork() { while (!isStopping) { // do work... } } } Now, DoWork() was a gigantic function, and I decided to refactor it out and as part of the process broke some of it into other classes. The problem is, Some of these classes also have long running functions that need to check if isStopping is true. public class Foo { bool isStoping void DoWork() { while (!isStopping) { MoreWork mw = new MoreWork() mw.DoMoreWork() // possibly long running // do work... } } } What are my options here? I have considered passing isStopping by reference, which I don't really like because it requires there to be an outside object. I would prefer to make the additional classes as stand alone and dependancy free as possible. I have also considered making isStopping a property, and then then having it call an event that the inner classes could be subscribed to, but this seems overly complex. Another option was to create a "Process Cancelation Token" class, similar to what .net 4 Tasks use, then that token be passed to those classes. How have you handled this situation? EDIT: Also consider that MoreWork might have a EvenMoreWork object that it instantiates and calls a potentially long running method on... and so on. I guess what i'm looking for is a way to be able to signal an arbitrary number of objects down a call tree to tell them to stop what they're doing and clean up and return.

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