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• Python: Beginning problems

  - by Blogger

  ok so basically i very new to programming and have no idea how to go about these problems help if you will ^^ Numerologists claim to be able to determine a person’s character traits based on the “numeric value” of a name. The value of a name is determined by summing up the values of the letters of the name, where ‘a’ is 1, ‘b’ is 2, ‘c’ is 3 etc., up to ‘z’ being 26. For example, the name “Zelle” would have the value 26 + 5 + 12 + 12 + 5 = 60 (which happens to be a very suspicious number, by the way). Write a program that calculates the numeric value of a single name provided as input. Word count. A common utility on Unix/Linux systems is a small program called “wc”. This program counts the number of lines, words (strings of characters separated by blanks, tabs, or new lines), and characters in a file. Write your own version of this program. The program should accept a file name as input and then print three numbers showing the count of lines, words, and characters in the file.

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• Truncate portions of a string to limit the whole string's length in Ruby

  - by Horace Loeb

  Suppose you want to generate dynamic page titles that look like this: "It was all a dream, I used to read word up magazine" from "Juicy" by The Notorious B.I.G I.e., "LYRICS" from "SONG_NAME" by ARTIST However, your title can only be 69 characters total and this template will sometimes generate titles that are longer. One strategy for solving this problem is to truncate the entire string to 69 characters. However, a better approach is to truncate the less important parts of the string first. I.e., your algorithm might look something like this: Truncate the lyrics until the entire string is <= 69 characters If you still need to truncate, truncate the artist name until the entire string is <= 69 characters If you still need to truncate, truncate the song name until the entire string is <= 69 characters If all else fails, truncate the entire string to 69 characters Ideally the algorithm would also limit the amount each part of the string could be truncated. E.g., step 1 would really be "Truncate the lyrics to a minimum of 10 characters until the entire string is <= 69 characters" Since this is such a common situation, I was wondering if someone has a library or code snippet that can take care of it.

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• How would you mask data returned in a Dynamic Data for Entities website?

  - by David Stratton

  I'm doing this in Visual Studio 2008, not 2010, in case there is a relevant difference between the two versions of the Dynamic Data websites. How would I mask data in the automatically generated tables in a Dynamic Data for Entities website? The scenario is we have one table where we want to allow users to ENTER sensitive data, but not VIEW sensitive data, so... (In the list below, I'm using "template" to mean "The web page generated automatically based on the schema and action. I'm sure that's the wrong terminology, but the meaning should be clear.) The "Insert" template should have the field's textbox available for the user to type a value in. The "Edit" template should have the field's textbox blanked out (empty string) regardless of what was in the field in the database in the first place, but the user should be able to type in new data and have it save The "View" template should either have the data for this field masked, or non-visible. The auto-generated table showing the list of records should also have this field masked or non-visible. I can do this easily with standard Web Forms, but I'm having a hard time figuring this out in the Dynamic Data site I'm working on. Masking data is such a common task, I have to believe Microsoft thought of this and provided a way to do it...

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• ASP.NET MVC Authorize by Group

  - by Jimmo

  I have what seems like a common issue with SaaS applications, but have not seen this question on here anywhere. I am using ASP.NET MVC with Forms Authentication. I have implemented a custom membership provider to handle logic, but have one issue (perhaps the issue is in my mental picture of the system). As with many SaaS apps, Customers create accounts and use the app in a way that looks like they are the only ones present (they only see their items, users, etc.) In reality, there are generic controllers and views presenting data depending on their account. When calling something like ValidateUser, I have access to their affiliation in the User object - what I don't have is the context of the request to which to compare it. As an example, One company called ABC goes to abc.mysite.com Another company called XYZ goes to xyz.mysite.com When an ABC user calls http://abc.mysite.com/product/edit/12 I have an [Authorize] attribute on the Edit method in the ProductController to make sure he is signed in and has sufficient permission to do so. If that same ABC user tried to access http://xyz.mysite.com/product/edit/12 I would not want to validate him in the context of that call. In the ValidateUser of the MembershipProvider, I have the information about the user, but not about the request. I can tell that the user is from ABC, but I cannot tell that the request is for XYZ at that point in the code. How should I resolve this?

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• Moving .NET assemblies away from the application base directory?

  - by RasmusKL

  I have a WinForms application with a bunch of third party references. This makes the output folder quite messy. I'd like to place the compiled / referenced dlls into a common subdirectory in the output folder, bin / lib - whatever - and just have the executables (+ needed configs etc) reside in the output folder. After some searching I ran into assembly probing (http://msdn.microsoft.com/en-us/library/4191fzwb.aspx) - and verified that if I set this up and manually move the assemblies my application will still work if they are stored in the designated subdirectory like so: <configuration> <runtime> <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1"> <probing privatePath="bin" /> </assemblyBinding> </runtime> </configuration> However, this doesn't solve the build part - is there any way to specify where referenced assemblies and compiled library assemblies go? Only solutions I can think of off the top of my head is either post-build actions or dropping the idea and using ILMerge or something. There has got to be a better way of defining the structure :-)

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• recommended format to save time with MJD + BCD format in database

  - by pierr

  Hi, There is a time represented in MJD and BCD format with 5 bytes .I am wondering what is the recommended format to save this date-time in the sqlite database so that user can search against it ? My first attempt is to save it just as it is, that is a 5 bytes string. The user will use the same format to search and the result will be converted to unix time by the user with following code. However, later, I was suggested to save the time in the integer - the UTC time, for example. But I can not find a standard way to do the conversion. I feel this is a common issue and would like to hear your comments. time_t sidate_to_unixtime(unsigned char sidate[]) { int k = 0; struct tm tm; double mjd; /* check for the undefined value */ if ((sidate[0] == 0xff) && (sidate[1] == 0xff) && (sidate[2] == 0xff) && (sidate[3] == 0xff) && (sidate[4] == 0xff)) { return -1; } memset(&tm, 0, sizeof(tm)); mjd = (sidate[0] << 8) | sidate[1]; tm.tm_year = (int) ((mjd - 15078.2) / 365.25); tm.tm_mon = (int) (((mjd - 14956.1) - (int) (tm.tm_year * 365.25)) / 30.6001); tm.tm_mday = (int) mjd - 14956 - (int) (tm.tm_year * 365.25) - (int) (tm.tm_mon * 30.6001); if ((tm.tm_mon == 14) || (tm.tm_mon == 15)) k = 1; tm.tm_year += k; tm.tm_mon = tm.tm_mon - 2 - k * 12; tm.tm_sec = bcd_to_integer(sidate[4]); tm.tm_min = bcd_to_integer(sidate[3]); tm.tm_hour = bcd_to_integer(sidate[2]); return mktime(&tm); }

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• How do I launch background jobs w/ paramiko?

  - by sophacles

  Here is my scenario: I am trying to automate some tasks using Paramiko. The tasks need to be started in this order (using the notation (host, task)): (A, 1), (B, 2), (C, 2), (A,3), (B,3) -- essentially starting servers and clients for some testing in the correct order. Further, because in the tests networking may get mucked up, and because I need some of the output from the tests, I would like to just redirect output to a file. In similar scenarios the common response is to use 'screen -m -d' or to use 'nohup'. However with paramiko's exec_cmd, nohup doesn't actually exit. Using: bash -c -l nohup test_cmd & doesnt work either, exec_cmd still blocks to process end. In the screen case, output redirection doesn't work very well, (actually, doesnt work at all the best I can figure out). So, after all that explanation, my question is: is there an easy elegant way to detach processes and capture output in such a way as to end paramiko's exec_cmd blocking? Update The dtach command works nicely for this!

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• CALayer and Off-Screen Rendering

  - by Luke Mcneice

  I have a Paging UIScrollView with a contentSize large enough to hold a number of small UIScrollViews for zooming, The viewForZoomingInScrollView is a viewController that holds a CALayer for drawing a PDF page onto. This allows me to navigate through a PDF much like the ibooks PDF reader. The code that draws the PDF (Tiled Layers) is located in: - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx; And simply adding a 'page' to the visible screen calls this method automatically. When I change page there is some delay before all the tiles are drawn, even though the object (page) has already been created. What i want to be able to do is render the next page before the user scrolls to it, thus preventing the visible tiling effect. However, i have found that if the layer is located offscreen adding it to the scrollview doesn't call the drawLayer. Any Ideas/common gotchas here? I have tried: [viewController.view.layer setNeedsLayout]; [viewController.view.layer setNeedsDisplay]; NB: The fact that this is replicating the ibooks functionally is irrelevant within the context of the full app.

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• Java application design question

  - by ring bearer

  I have a hobby project, which is basically to maintain 'todo' tasks in the way I like. One task can be described as: public class TodoItem { private String subject; private Date dueBy; private Date startBy; private Priority priority; private String category; private Status status; private String notes; } As you can imagine I would have 1000s of todo items at a given time. What is the best strategy to store a todo item? (currently on an XML file) such that all the items are loaded quickly up on app start up(the application shows kind of a dashboard of all the items at start up)? What is the best way to design its back-end so that it can be ported to Android/or a J2ME based phone? Currently this is done using Java Swing. What should I concentrate on so that it works efficiently on a device where memory is limited? The application throws open a form to enter new todo task. For now, I would like to save the newly added task to my-todos.xml once the user presses "save" button. What are the common ways to append such a change to an existing XML file?(note that I don't want to read the whole file again and then persist)

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• Adding Mysql Columns in Rails Rake

  - by Gigg

  I have a rake file that does a series of calculations on a database. Basically it adds usage on equipment regularly. At the end of the day it needs to add that days total to a monthly total table and update that same table. i use the following simple concepts: To get data from the database is pretty simple: @usages = Usage.find(:all) time = Time.new for usage in @usages sql = ActiveRecord::Base.connection To insert it into the database: sql.execute "INSERT (or UPDATE) into usages ## add values and options as per MySQL But how do I: take a column from a database, add all of its values together that have a common value in another column, (i.e. if column x == value y) and then insert it into another column in another table, say dailyusages? I have tried these options: task (:monthly => :environment) do @dailyusages = Dailyusage.find(:all) for dailyusage in @dailyusages sql = ActiveRecord::Base.connection time = Time.new device = monthlyusages.device month = time.month if device == dailyusages.device ##&& month == dailyusages.month total = (dailyusage.total.sum.to_i) @monthlyusages = Monthlyusage.find(:all) for monthlyusage in @monthlyusages sql = ActiveRecord::Base.connection old_total = monthlyusage.total.to_i new_total = (old_total + total) sql.execute "UPDATE monthlyusages ( year, month, total, device ) values('#{time.year}', '#{time.month}', '#{total}', '#{dailyusage.device}' )" end I obviously have uncommented options and tried all sorts of things. Any help would really save me a load of trouble. Thanks in advance. (** BTW - I am new to rails, so go easy on me **)

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• ASP.Net MVC: Showing the same data using different layouts...

  - by vdh_ant

  Hi guys I'm wanting to create a page that allows the users to select how they would like to view their data - i.e. summary (which supports grouping), grid (which supports grouping), table (which supports grouping), map, time line, xml, json etc. Now each layout would probably have different use a different view model, which inherit from a common base class/view model. The reason being that each layout needs the object structure that it deals with to be different (some need hierarchical others a flatter structure). Each layout would call the same repository method and each layout would support the same functionality, i.e. searching and filtering (hence these controls would be shared between layouts). The main exception to this would be sorting which only grid and table views would need to support. Now my question is given this what do people think is the best approach. Using DisplayFor to handle the rendering of the different types? Also how do I work this with the actions... I would imagine that I would use the one action, and pass in the layout types, but then how does this support the grouping required for the summary, grid and table views. Do i treat each grouping as just a layout type Also how would this work from a URL point of view - what do people think is the template to support this layout functionality Cheers Anthony

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• Java SSH2 libraries in depth: Trilead/Ganymed/Orion [/other?]

  - by Bernd Haug

  I have been searching for a pure Java SSH library to use for a project. The single most important needed feature is that it has to be able to work with command-line git, but remote-controlling command-line tools is also important. A pretty common choice, e.g. used in the IntelliJ IDEA git integration (which works very well), seems to be Trilead SSH2. Looking at their website, it's not being maintained any more. Trilead seems to have been a fork of Ganymed SSH2, which was a ETH Zurich project that didn't see releases for a while, but had a recent release by its new owner, Christian Plattner. There is another actively maintained fork from that code base, Orion SSH, that saw an even more recent release, but which seems to get mentioned online much less than the other 2 forks. Has anybody here worked with any of (or, if possible, both) of Ganymed and Orion and could kindly describe the development experience with either/both? Accuracy of documentation [existence of documentation?], stability, buggyness... - all of these would be highly interesting to me. Performance is not so important for my current project. If there is another pure-Java SSH implementation that should be used instead, please feel free to mention it, but please don't just mention a name...describe your judgment from actual experience. Sorry if this question may seem a bit "do my homework"-y, but I've really searched for reviews. Everything out there seems to be either a listing of implementations or short "use this! it's great!" snippets.

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• Binary Search Tree for specific intent

  - by Luís Guilherme

  We all know there are plenty of self-balancing binary search trees (BST), being the most famous the Red-Black and the AVL. It might be useful to take a look at AA-trees and scapegoat trees too. I want to do deletions insertions and searches, like any other BST. However, it will be common to delete all values in a given range, or deleting whole subtrees. So: I want to insert, search, remove values in O(log n) (balanced tree). I would like to delete a subtree, keeping the whole tree balanced, in O(log n) (worst-case or amortized) It might be useful to delete several values in a row, before balancing the tree I will most often insert 2 values at once, however this is not a rule (just a tip in case there is a tree data structure that takes this into account) Is there a variant of AVL or RB that helps me on this? Scapegoat-trees look more like this, but would also need some changes, anyone who has got experience on them can share some thougts? More precisely, which balancing procedure and/or removal procedure would help me keep this actions time-efficient?

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• Have I found a security problem in an API or do I just not understand SSL?

  - by jamieb

  I'm working on building a set of Python bindings around an XML-based API provided by a vendor. The vendor requires that all transactions be conducted over SSL. Using a Linux box, I created a key file and a CSR for my application. Using their self-service web portal, I then generate a certificate using that CSR. Both the key file and the certificate are used when making the SSL request to the API. I'm now working on designing exception classes to make error messages more verbose (and, hopefully, more useful to developers using my bindings). Part of my testing has included altering the key file: transpose a couple characters here, replace 4 or 5 with random characters there, etc. To my surprise, altering the key file had no effect! As long as I didn't change the total length of it, the API didn't complain about a bad key file. The only way I was able to throw an error was by swapping in a completely different key from another application. At that point, the API complained about the Common Name not matching. Is this normal behavior or has the vendor not properly implemented SSL?

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• Testing for interface implementation in WCF/SOA

  - by rabidpebble

  I have a reporting service that implements a number of reports. Each report requires certain parameters. Groups of logically related parameters are placed in an interface, which the report then implements: [ServiceContract] [ServiceKnownType(typeof(ExampleReport))] public interface IService1 { [OperationContract] void Process(IReport report); } public interface IReport { string PrintedBy { get; set; } } public interface IApplicableDateRangeParameter { DateTime StartDate { get; set; } DateTime EndDate { get; set; } } [DataContract] public abstract class Report : IReport { [DataMember] public string PrintedBy { get; set; } } [DataContract] public class ExampleReport : Report, IApplicableDateRangeParameter { [DataMember] public DateTime StartDate { get; set; } [DataMember] public DateTime EndDate { get; set; } } The problem is that the WCF DataContractSerializer does not expose these interfaces in my client library, thus I can't write the generic report generating front-end that I plan to. Can WCF expose these interfaces, or is this a limitation of the serializer? If the latter case, then what is the canonical approach to this OO pattern? I've looked into NetDataContractSerializer but it doesn't seem to be an officially supported implementation (which means it's not an option in my project). Currently I've resigned myself to including the interfaces in a library that is common between the service and the client application, but this seems like an unnecessary extra dependency to me. Surely there is a more straightforward way to do this? I was under the impression that WCF was supposed to replace .NET remoting; checking if an object implements an interface seems to be one of the most basic features required of a remoting interface?

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• Refactoring exercise with generics

  - by Berryl

  I have a variation on a Quantity (Fowler) class that is designed to facilitate conversion between units. The type is declared as: public class QuantityConvertibleUnits<TFactory> where TFactory : ConvertableUnitFactory, new() { ... } In order to do math operations between dissimilar units, I convert the right hand side of the operation to the equivalent Quantity of whatever unit the left hand side is in, and do the math on the amount (which is a double) before creating a new Quantity. Inside the generic Quantity class, I have the following: protected static TQuantity _Add<TQuantity>(TQuantity lhs, TQuantity rhs) where TQuantity : QuantityConvertibleUnits<TFactory>, new() { var toUnit = lhs.ConvertableUnit; var equivalentRhs = _Convert<TQuantity>(rhs.Quantity, toUnit); var newAmount = lhs.Quantity.Amount + equivalentRhs.Quantity.Amount; return _Convert<TQuantity>(new Quantity(newAmount, toUnit.Unit), toUnit); } protected static TQuantity _Subtract<TQuantity>(TQuantity lhs, TQuantity rhs) where TQuantity : QuantityConvertibleUnits<TFactory>, new() { var toUnit = lhs.ConvertableUnit; var equivalentRhs = _Convert<TQuantity>(rhs.Quantity, toUnit); var newAmount = lhs.Quantity.Amount - equivalentRhs.Quantity.Amount; return _Convert<TQuantity>(new Quantity(newAmount, toUnit.Unit), toUnit); } ... same for multiply and also divide I need to get the typing right for a concrete Quantity, so an example of an add op looks like: public static ImperialLengthQuantity operator +(ImperialLengthQuantity lhs, ImperialLengthQuantity rhs) { return _Add(lhs, rhs); } The question is those verbose methods in the Quantity class. The only change between the code is the math operator (+, -, *, etc.) so it seems that there should be a way to refactor them into a common method, but I am just not seeing it. How can I refactor that code? Cheers, Berryl

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• Is it possible from Spring to inject the result of calling a method on a ref bean?

  - by Alex Worden

  Hi, Is it possible from Spring to inject the result of calling a method on a ref bean? I'm trying to refactor some cut/pasted code from two separate projects into a common class. In one of the projects, the code lives in a class I'll call "MyClient" that is being instantiated from Spring. It is injected with another spring-instantiated class "MyRegistry", then the MyClient class uses that class to look up an endpoint. All I really need is the endpoint String in my refactored class, which can be initialized via a Setter. I really cannot have a dependency on MyRegistry from MyClient in the refactored code. So, my question is this... is there a way I can inject the endpoint String from spring that was looked up in the MyRegistry class. So, I currently have: <bean id="registryService" class="foo.MyRegistry"> ...properties set etc... </bean> <bean id="MyClient" class="foo.MyClient"> <property name="registry" ref="registryService"/> </bean> But I'd like to have (and I know this is imaginary Spring syntax) <bean id="MyClient" class="foo.MyClient"> <property name="endPoint" value="registryService.getEndPoint('bar')"/> </bean> where MyRegistry will have a method getEndPoint(Stirng endPointName) Hope that makes sense from a the standpoint of what I'm trying to achieve. Please let me know if something like this is possible in Spring!

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• Scrollbars in ScrollView not showing after custom child view changes size

  - by Ted Hopp

  I have a ScrollView containing a client that is a vertical LinearLayout. The client, in turn, contains custom views that change height dynamically as a background thread does some work. The problem I'm having is that the ScrollView's vertical scroll bar is not updating correctly in Android 1.5. The most common problem occurs when the initial total height of the client is less than the viewport and grows. Initially there is no scroll bar, and it does not show up when the client grows until I actually scroll the window with a touch gesture or other UI action. After that, the scroll bar shows up. However, the thumb does not update as the height continues to change from the background thread. If I scroll the view again through the UI, the thumb immediately corrects itself. My code for updating the height from the background thread is: post(mLayoutRequestor); postInvalidate(); (mLayoutRequestor is a Runnable that just calls requestLayout().) This is done after I've recorded the new height in a variable mHeight. My onMeasure() method calls setMeasuredDimension with a height computed like this: private int measureHeight(int measureSpec) { int result; int specMode = MeasureSpec.getMode(measureSpec); int specSize = MeasureSpec.getSize(measureSpec); if (specMode == MeasureSpec.EXACTLY) { result = specSize; } else { result = mHeight; if (specMode == MeasureSpec.AT_MOST && result > specSize) result = specSize; } return result; } Am I supposed to be calling something else besides requestLayout() to get the scroll bar to update correctly?

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• .NET Web Service hydrate custom class

  - by row1

  I am consuming an external C# Web Service method which returns a simple calculation result object like this: [Serializable] public class CalculationResult { public string Name { get; set; } public string Unit { get; set; } public decimal? Value { get; set; } } When I add a Web Reference to this service in my ASP .NET project Visual Studio is kind enough to generate a matching class so I can easily consume and work with it. I am using Castle Windsor and I may want to plug in other method of getting a calculation result object, so I want a common class CalculationResult (or ICalculationResult) in my solution which all my objects can work with, this will always match the object returned from the external Web Service 1:1. Is there anyway I can tell my Web Service client to hydrate a particular class instead of its generated one? I would rather not do it manually: foreach(var fromService in calcuationResultsFromService) { ICalculationResult calculationResult = new CalculationResult() { Name = fromService.Name }; yield return calculationResult; } Edit: I am happy to use a Service Reference type instead of the older Web Reference.

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• SQLAlchemy - relationship limited on more than just the foreign key

  - by Marian

  I have a wiki db layout with Page and Revisions. Each Revision has a page_id referencing the Page, a page relationship to the referenced page; each Page has a all_revisions relationship to all its revisions. So far so common. But I want to implement different epochs for the pages: If a page was deleted and is recreated, the new revisions have a new epoch. To help find the correct revisions, each page has a current_epoch field. Now I want to provide a revisions relation on the page that only contains its revisions, but only those where the epochs match. This is what I've tried: revisions = relationship('Revision', primaryjoin = and_( 'Page.id == Revision.page_id', 'Page.current_epoch == Revision.epoch', ), foreign_keys=['Page.id', 'Page.current_epoch'] ) Full code (you may run that as it is) However this always raises ArgumentError: Could not determine relationship direction for primaryjoin condition ...`, I've tried all I had come to mind, it didn't work. What am I doing wrong? Is this a bad approach for doing this, how could it be done other than with a relationship?

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• sql-server performance optimization by removing print statements

  - by AG

  We're going through a round of sql-server stored procedure optimizations. The one recommendation we've found that clearly applies for us is 'SET NOCOUNT ON' at the top of each procedure. (Yes, I've seen the posts that point out issues with this depending on what client objects you run the stored procedures from but these are not issues for us.) So now I'm just trying to add in a bit of common sense. If the benefit of SET NOCOUNT ON is simply to reduce network traffic by some small amount every time, wouldn't it also make sense to turn off all the PRINT statements we have in the stored procedures that we only use for debugging? I can't see how it can hurt performance. OTOH, it's a bit of a hassle to implement due to the fact that some of the print statements are the only thing within else clauses, so you can't just always comment out the one line and be done. The change carries some amount of risk so I don't want to do it if it isn't going to actually help. But I don't see eliminating print statements mentioned anywhere in articles on optimization. Is that because it is so obvious no one bothers to mention it?

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• What techniques can be used to detect so called "black holes" (a spider trap) when creating a web crawler?

  - by Tom

  When creating a web crawler, you have to design somekind of system that gathers links and add them to a queue. Some, if not most, of these links will be dynamic, which appear to be different, but do not add any value as they are specifically created to fool crawlers. An example: We tell our crawler to crawl the domain evil.com by entering an initial lookup URL. Lets assume we let it crawl the front page initially, evil.com/index The returned HTML will contain several "unique" links: evil.com/somePageOne evil.com/somePageTwo evil.com/somePageThree The crawler will add these to the buffer of uncrawled URLs. When somePageOne is being crawled, the crawler receives more URLs: evil.com/someSubPageOne evil.com/someSubPageTwo These appear to be unique, and so they are. They are unique in the sense that the returned content is different from previous pages and that the URL is new to the crawler, however it appears that this is only because the developer has made a "loop trap" or "black hole". The crawler will add this new sub page, and the sub page will have another sub page, which will also be added. This process can go on infinitely. The content of each page is unique, but totally useless (it is randomly generated text, or text pulled from a random source). Our crawler will keep finding new pages, which we actually are not interested in. These loop traps are very difficult to find, and if your crawler does not have anything to prevent them in place, it will get stuck on a certain domain for infinity. My question is, what techniques can be used to detect so called black holes? One of the most common answers I have heard is the introduction of a limit on the amount of pages to be crawled. However, I cannot see how this can be a reliable technique when you do not know what kind of site is to be crawled. A legit site, like Wikipedia, can have hundreds of thousands of pages. Such limit could return a false positive for these kind of sites. Any feedback is appreciated. Thanks.

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• How to calculate this string-dissimilarity function efficiently?

  - by ybungalobill

  Hello, I was looking for a string metric that have the property that moving around large blocks in a string won't affect the distance so much. So "helloworld" is close to "worldhello". Obviously Levenshtein distance and Longest common subsequence don't fulfill this requirement. Using Jaccard distance on the set of n-grams gives good results but has other drawbacks (it's a pseudometric and higher n results in higher penalty for changing single character). [original research] As I thought about it, what I'm looking for is a function f(A,B) such that f(A,B)+1 equals the minimum number of blocks that one have to divide A into (A1 ... An), apply a permutation on the blocks and get B: f("hello", "hello") = 0 f("helloworld", "worldhello") = 1 // hello world -> world hello f("abba", "baba") = 2 // ab b a -> b ab a f("computer", "copmuter") = 3 // co m p uter -> co p m uter This can be extended for A and B that aren't necessarily permutations of each other: any additional character that can't be matched is considered as one additional block. f("computer", "combuter") = 3 // com uter -> com uter, unmatched: p and b. Observing that instead of counting blocks we can count the number of pairs of indices that are taken apart by a permutation, we can write f(A,B) formally as: f(A,B) = min { C(P) | P:|A|?|B|, P is bijective, ?i?dom(P) A[P(i)]=B[P(i)] } C(P) = |A| + |B| - |dom(P)| - |{ i | i,i+1?dom(P) and P(i)+1=P(i+1) }| - 1 The problem is... guess what... ... that I'm not able to calculate this in polynomial time. Can someone suggest a way to do this efficiently? Or perhaps point me to already known metric that exhibits similar properties?

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• Cookie not working after mod rewrite rule

  - by moonwalker

  Hi all, I have a simple Cookie to set the chosen language: $lang = $_GET['lang']; $myLang = $_COOKIE["myLang"]; if (!isset($_COOKIE["myLang"])){ setcookie("myLang", "en", $expire); include "languages/en.php"; $myLang = "en"; }else{ include "languages/$myLang.php"; } // One year to expire $expire = time()+60*60*24*30*365; // Put $languages in a common header file. $languages = array('en' => 1, 'fr' => 2, 'nl' => 3); if (array_key_exists($lang, $languages)) { include "languages/{$lang}.php"; setcookie("myLang", $lang, $expire); $myLang = $lang; } After using some rewrite rules, it just doesn't work anymore. I tried the following: setcookie("myLang", "en", $expire, "/" , false); No luck at all. This is my .htaccess file: <IfModule mod_rewrite.c> Options +FollowSymLinks Options +Indexes RewriteEngine On RewriteBase / RewriteRule ^sort/([^/]*)/([^/]*)$ /3arsi2/sort.php?mode=$1&cat=$2 [L] RewriteRule ^category/([^/]*)$ /3arsi2/category.php?cat=$1 [L] RewriteRule ^category/([^/]*)/([^/]*)$ /3arsi2/category.php?cat=$1&lang=$2 [L] RewriteRule ^search/([^/]*)$ /3arsi2/search.php?mode=$1 [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^u/([^/]+)/?$ 3arsi2/user.php?user=$1 [NC,L] RewriteRule ^u/([^/]+)/(images|videos|music)/?$ 3arsi2/user.php?user=$1&page=$2 [NC,L] RewriteRule ^([^\.]+)$ 3arsi2/$1.php [NC,L] </IfModule> Any idea how to solve this? I'm still new to the mod rewrite thing, so I still don't really understand the logic behind it all. Thanks for any help you can provide.

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• what are all the Optimize tricks that you know for asp.net code ?

  - by Aristos

  After some time of many code programming on asp.net, I discover the very big speed different between string and StringBuilder. I know that is very common and known but I just mention it for start. The second think that I have found to speed up the code, is to use the const, and not the static, for declare my configuration constants value (especial the strings). With the const, the compiler not create new object, but just place the value, on the point that you have ask it, but with the static declaration, is create a new memory object and keep its on the memory. My third trick, is when I search for string, I use hash values, and not the string itself. For example, if I need a List<string SomeValues, and place inside strings that I need to search them, I prefer to use List<int SomeHashValue, and I use the hash value to locate the strings. My forth thought that I was wandering, is if is better to place big strings in one line, or separate them in different lines with the + symbol to be more easy to read out. I make some tests and see that the compiler make a good job is some split the string, in many lines, using the + symbol. What other tricks/tips do you know and use on your programming to make it run faster, and maybe use less memory. Well I know, that some times, to make something run faster, you need more memory, more cache. My priority is on speed. Because Speed Counts.

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