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• ArchBeat Link-o-Rama Top 10 for November 4-10, 2012

  - by Bob Rhubart

  The Top 10 most popular items shared via the OTN ArchBeat Facebook Page for the week of November 4-10, 2012. OAM/OVD JVM Tuning | @FusionSecExpert Vinay from the Oracle Fusion Middleware Architecture Group (the very prolific A-Team) shares a process for analyzing and improving performance in Oracle Virtual Directory and Oracle Access Manager. Exploring Lambda Expressions for the Java Language and the JVM | Java Magazine In the latest //Java/Architect column in Java Magazine, Ben Evans, Martijn Verburg, and Trisha Gee explain how, "although Lambda expressions might seem unfamiliar to begin with, they're quite easy to pick up, and mastering them will be vital for writing applications that can take full advantage of modern multicore CPUs." SOA Galore: New Books for Technical Eyes Only Shake up up your technical skills with this trio of new technical books from community members covering SOA and BPM. Oracle Solaris 11.1 update focuses on database integration, cloud | Mark Fontecchio TechTarget editor Mark Fontecchio reports on the recent Oracle Solaris 11.1 release, with comments from IDC's Al Gillen. Solving Big Problems in Our 21st Century Information Society | Irving Wladawsky-Berger "I believe that the kind of extensive collaboration between the private sector, academia and government represented by the Internet revolution will be the way we will generally tackle big problems in the 21st century. Just as with the Internet, governments have a major role to play as the catalyst for many of the big projects that the private sector will then take forward and exploit. The need for high bandwidth, robust national broadband infrastructures is but one such example." — Irving Wladawsky-Berger ADF Mobile Custom Javasciprt – iFrame Injection | John Brunswick The ADF Mobile Framework provides a range of out of the box components to add within your AMX pages, according to John Brunswick. But what happens when "an out of the box component does not directly fulfill your development need? What options are available to extend your application interface?" John has an answer. Architects Matter: Making sense of the people who make sense of enterprise IT Why do architects matter? Oracle Enterprise Architect Eric Stephens suggests that you ask yourself this question the next time you take the elevator to the Oracle offices on the 45th floor of the Willis Tower in Chicago, Illinois (or any other skyscraper, for that matter). If you had to take the stairs to get to those offices, who would you blame? "You get the picture," he says. "Architecture is essential for any necessarily complex structure, be it a building or an enterprise." (Read the article...) Converting SSL certificate generated by a 3rd party to an Oracle Wallet | Paulo Albuquerque Oracle Fusion Middleware A-Team member Paulo Albuquerque shares "a workaround to get your private key, certificate and CA trusted certificates chain into Oracle Wallet." How Data and BPM are married to get the right information to the right people at the right time | Leon Smiers "Business Process Management…supports a large group of stakeholders within an organization, all with different needs," says Oracle ACE Leon Smiers. "End-to-end processes typically run across departments, stakeholders and applications, and can often have a long life-span. So how do organizations provide all stakeholders with the information they need?" Leon provides answers in this post. Updated Business Activity Monitoring (BAM) Class | Gary Barg Oracle SOA Team blogger Gary Barg has news for those interested in a skills upgrade. This updated Oracle University course "explains how to use Oracle BAM to monitor enterprise business activities across an enterprise in real time. You can measure your key performance indicators (KPIs), determine whether you are meeting service-level agreements (SLAs), and take corrective action in real time." Thought for the Day "For every complex problem, there is a solution that is simple, neat, and wrong." — H. L. Mencken (September 12, 1880 – January 29, 1956) Source: SoftwareQuotes.com

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• BizTalk Testing Series - The xpath Function

  - by Michael Stephenson

  Background While the xpath function in a BizTalk orchestration is a very powerful feature I have often come across the situation where someone has hard coded an xpath expression in an orchestration. If you have read some of my previous posts about testing I've tried to get across the general theme like test-driven or test-assisted development approaches where the underlying principle is that your building up your solution of small well tested units that are put together and the resulting solution is usually quite robust. You will be finding more bugs within your unit tests and fewer outside of your team. The thing I don't like about the xpath functions usual usage is when you come across an orchestration which has something like the below snippet in an expression or assign shape: string result = xpath(myMessage,"string(//Order/OrderItem/ProductName)"); My main issue with this is that the xpath statement is hard coded in the orchestration and you don't really know it works until you are running the orchestration. Some of the problems I think you end up with are: You waste time with lengthy debugging of the orchestration when your statement isn't working You might not know the function isn't working quite as expected because the testable unit around it is big You are much more open to regression issues if your schema changes     Approach to Testing The technique I usually follow is to hold the xpath statement as a constant in a helper class or to format a constant with a helper function to get the actual xpath statement. It is then used by the orchestration like follows. string result = xpath(myMessage, MyHelperClass.ProductNameXPathStatement); This means that because the xpath statement is available outside of the orchestration it now becomes testable in its own right. This means: I can test it in its own right I'm less likely to waste time tracking down problems caused by an error in the statement I can reduce the risk or regression issuess I'm now able to implement some testing around my xpath statements which usually are something like the following:    The test will use a sample xml file The sample will be validated against the schema The test will execute the xpath statement and then check the results are as expected     Walk-through BizTalk uses the XPathNavigator internally behind the xpath function to implement the queries you will usually use using the navigators select or evaluate functions. In the sample (link at bottom) I have a small solution which contains a schema from which I have generated a sample instance. I will then use this instance as the basis for my tests.     In the below diagram you can see the helper class which I've encapsulated my xpath expressions in, and some helper functions which will format the expression in the case of a repeating node which would want to inject an index into the xpath query.             I have then created a test class which has some functions to execute some queries against my sample xml file. An example of this is below.         In the test class I have a couple of helper functions which will execute the xpath expressions in a similar way to BizTalk. You could have a proper helper class to do this if you wanted.         You can see now in the BizTalk expression editor I can use these functions alongside the xpath function.         Conclusion I hope you can see with very little effort you can make your life much easier by testing xpath statements outside of an orchestration rather than using them directly hard coded into the orchestration.     This can also save you lots of pain longer term because your build should break if your schema changes unexpectedly causing these xpath tests to fail where as your tests around the orchestration will be more difficult to troubleshoot and workout the cause of the problem.     Sample Link The sample is available from the following link: http://code.msdn.microsoft.com/testbtsxpathfunction     Other Tools On the subject of using the xpath function, if you don't already use it the below tool is very useful for creating your xpath statements (thanks BizBert) http://www.bizbert.com/bizbert/2007/11/30/XPath+The+Hidden+Language+Of+BizTalk.aspx

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• Migrating VB6 to HTML5 is not a fiction - Customer success story

  - by Webgui

  All of you VB developers in the present or past would probably find it hard to believe that the old VB code can be migrated and modernized into the latest .NET based HTML5 without having to rewrite the application. But we have been working on such tools for the past couple of years and already have several real world applications that were fully 'transposed' from VB6. The solution is called Instant CloudMove and its main tool is called the TranspositionStudio. It is a unique solution that relies on the concept of transposition. Transposition comes from mathematics and music and refers to exchanging elements while everything else remains the same or moving an element as is from one environment to another. This means that we are taking the source code and put it in a modern technological environment with relatively few adjustments.The concept is based on a set of Mapping Expressions which are basically links between an element in the source environment and one in the target environment that has the same functionality. About 95% of the code is usually mapped out-of-the-box and the rest is handled with easy-to-use mapping tools designed for Visual Studio developers providing them with a familiar environment and concepts for completing the mapping and allowing them to extend and customize existing mapping expressions. The solution is also based on a circular workflow that enables developers to make any changes as required until the result is satisfying.As opposed to existing migration solutions that offer automation are usually a “black box” to the user, the transposition concept enables full visibility, flexibility and control over the code and process at all times allowing to also add/change functionalities or upgrade the UI within the process and tools.This is exactly the case with our customer’s aging VB6 PMS (Property Management System) which needed a technological update as well as a design refresh. The decision was to move the VB6 application which had about 1 million lines of code into the latest web technology. Since the application was initially written 13 years ago and had many upgrades since the code must be very patchy and includes unused sections. As a result, the company Mihshuv Group considered rewriting the entire application in Java since it already had the knowledge. Rewrite would allow starting with a clean slate and designing functionality, database architecture, UI without any constraints. On the other hand, rewrite entitles a long and detailed specification work as well as a thorough QA and this translates into a long project with high risk and costs.So the company looked for a migration solution as an alternative; the research lead to Gizmox and after examining the technology it was decided to perform a hybrid project which would include an automatic transposition of the core of the VB6 application (200,000 lines of code) while they redesigning the UI, adding new functionality, deleting unused code and rewriting about 140 reports with Crystal Reports will be done manually using Visual WebGui development tools.The migration part of the project was completed in 65 days by 3 developers from Mihshuv Group guided by Gizmox migration experts while the rewrite and UI upgrade tasks took about the same. So in only a few months period Mihshuv Group generated an up-to-date product, written in the latest Web technology with modern, friendly UI and improved functionality. Guest selection screen of the original VB6 PMS Guest selection screen on the new web–based PMS Compared to the initial plan to rewrite the entire application in Java, the hybrid migration/rewrite approach taken by Mihshuv Group using Gizmox technology proved as a great decision. In terms of time and cost there were substantial savings; from a project that was priced for at least a year (without taking into account the huge risk and uncertainty) it became a few months project only. More about this and other customer stories can be found here

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• Extending Programming Languages

  - by chpwn

  (Since I just posted this in another question, but my browser had to be annoying and submit it without content first, here it is again:) I'm a fan of clean code. I like my languages to be able to express what I'm trying to do, but I like the syntax to mirror that too. For example, I work on a lot of programs in Objective-C for jailbroken iPhones, which patch other code using the method_setImplementation() function of the runtime. Or, in pyobjc, I have to use the syntax UIView.initWithFrame_(), which is also pretty awful and unreadable with the way the method names are structured. In both cases, the language does not support this in syntax. I've found three basic ways that this is done: Insane macros. Take a look at this "CaptainHook", it does what I'm looking for in a usable way, but it isn't quite clean and is a major hack. There's also "Logos", which implements a very nice syntax, but is written in Perl parsing my code with a ton of regular expressions. This scares me. I like the idea of adding a %hook ClassName, but not by using regular expressions to parse C or Objective-C. Finally, there is Cycript. This is an extension to JavaScript which interfaces with the Objective-C runtime and allows you to use Objective-C style code in your JavaScript, and inject that into other processes. This is likely the cleanest as it actually uses a parser for the JavaScript, but I'm not a huge fan of that language in general. Basically, this is a two part question. Should, and how should, I create an extension to Python and Objective-C to allow me to do this? Is it worth writing a parser for my language to transform the syntax into something nicer, if it is only in a very specialized niche like this? Should I just live with the horrible syntax of the default Objective-C hooking or pyobjc?

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• Extract known pattern substring from NSString (without regex)

  - by d11wtq

  I'm really tempted to drop RegexKit (or my own libpcre wrapper) into my project in order to do this, but before I do that I want to know how Cocoa developers manage to do half of this basic stuff without really convoluted code or without linking with RegexKit or another regular expression library. I find it gobsmacking that Cocoa does not include any regular expression matching features. I've so accustomed to using regular expressions for all kinds of things that I'm lost without them. I can do what I need without them, but the code would be rather convoluted. So, Cocoa devs, I ask you, what's the "Cocoa way" to do this... The problem is an everyday problem in programming as far as I'm concerned. Cocoa must have ways of doing this with the built-in features. Note that the position of the elements I want to match changes, and sometimes "quotes" are present. Whitespace is variable. Take the following strings: Content-Type: application/xml; charset=utf-8 Content-Type: text/html; charset="iso-8859-1" Content-Type: text/plain; charset=us-ascii Content-Type: text/plain; name="example.txt"; charset=utf-8 From all of these strings, how would you go about determining the mime type (e.g. text/plain) and the charset (e.g. utf-8) using just the built-in Cocoa classes? I'd end up performing a series of -rangeOfString: and substring calls, with conditional checks to deal with the optional quotes etc. Is there a way to do this with NSScanner? The NSScanner class seems to have a pretty naive API to me. Something like C's sscanf() that works for NSString objects would be an ideal fit. Most of my string parsing needs are simple such as this example so maybe regular expressions, while I'm accustomed to them, are overkill?

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• Extending Python and Objective-C

  - by chpwn

  I'm a fan of clean code. I like my languages to be able to express what I'm trying to do, but I like the syntax to mirror that too. For example, I work on a lot of programs in Objective-C for jailbroken iPhones, which patch other code using the method_setImplementation() function of the runtime. Or, in PyObjC, I have to use the syntax UIView.initWithFrame_(), which is also pretty awful and unreadable with the way the method names are structured. In both cases, the language does not support this in syntax. I've found three basic ways that this is done: Insane macros. Take a look at this "CaptainHook", it does what I'm looking for in a usable way, but it isn't quite clean and is a major hack. There's also "Logos", which implements a very nice syntax, but is written in Perl parsing my code with a ton of regular expressions. This scares me. I like the idea of adding a %hook ClassName, but not by using regular expressions to parse C or Objective-C. Finally, there is Cycript. This is an extension to JavaScript which interfaces with the Objective-C runtime and allows you to use Objective-C style code in your JavaScript, and inject that into other processes. This is likely the cleanest as it actually uses a parser for the JavaScript, but I'm not a huge fan of that language in general. Should, and how should, I create an extension to Python and Objective-C to allow me to do this? Is it worth writing a parser for my language to transform the syntax into something nicer, if it is only in a very specialized niche like this? Should I just live with the horrible syntax of the default Objective-C hooking or PyObjC?

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• LinqKit System.InvalidCastException When Invoking method-provided expression on member property.

  - by mdworkin

  Given a simple parent/child class structure. I want to use linqkit to apply a child lambda expression on the parent. I also want the Lambda expression to be provided by a utility method. public class Foo { public Bar Bar { get; set; } } public class Bar { public string Value { get; set; } public static Expression<Func<Bar, bool>> GetLambdaX() { return c => c.Value == "A"; } } ... Expression<Func<Foo, bool>> lx = c => Bar.GetLambdaX().Invoke(c.Bar); Console.WriteLine(lx.Expand()); The above code throws System.InvalidCastException: Unable to cast object of type 'System.Linq.Expressions.MethodCallExpression' to type 'System.Linq.Expressions.LambdaExpression'. at LinqKit.ExpressionExpander.VisitMethodCall(MethodCallExpression m) at LinqKit.ExpressionVisitor.Visit(Expression exp) at LinqKit.ExpressionVisitor.VisitLambda(LambdaExpression lambda) at LinqKit.ExpressionVisitor.Visit(Expression exp) at LinqKit.Extensions.Expand<TDelegate>(Expression`1 expr) .... Please help!

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• Having problems with sqlDataReader

  - by Anthony

  I am using a sqlDataReader to get data and set it to session variables. The problem is it doesn't want to work with expressions. I can reference any other column in the table, but not the expressions. The SQL does work. The code is below. Thanks in advance, Anthony Using myConnectionCheck As New SqlConnection(myConnectionString) Dim myCommandCheck As New SqlCommand() myCommandCheck.Connection = myConnectionCheck myCommandCheck.CommandText = "SELECT Projects.Pro_Ver, Projects.Pro_Name, Projects.TL_Num, Projects.LP_Num, Projects.Dev_Num, Projects.Val_Num, Projects.Completed, Flow.Initiate_Date, Flow.Requirements, Flow.Req_Date, Flow.Dev_Review, Flow.Dev_Review_Date, Flow.Interface, Flow.Interface_Date, Flow.Approval, Flow.Approval_Date, Flow.Test_Plan, Flow.Test_Plan_Date, Flow.Dev_Start, Flow.Dev_Start_Date, Flow.Val_Start, Flow.Val_Start_Date, Flow.Val_Complete, Flow.Val_Complete_Date, Flow.Stage_Production, Flow.Stage_Production_Date, Flow.MKS, Flow.MKS_Date, Flow.DIET, Flow.DIET_Date, Flow.Closed, Flow.Closed_Date, Flow.Dev_End, Flow.Dev_End_Date, Users_1.Email AS Expr1, Users_2.Email AS Expr2, Users_3.Email AS Expr3, Users_4.Email AS Expr4, Users_4.FNAME, Users_3.FNAME AS Expr5, Users_2.FNAME AS Expr6, Users_1.FNAME AS Expr7 FROM Projects INNER JOIN Users AS Users_1 ON Projects.TL_Num = Users_1.PIN INNER JOIN Users AS Users_2 ON Projects.LP_Num = Users_2.PIN INNER JOIN Users AS Users_3 ON Projects.Dev_Num = Users_3.PIN INNER JOIN Users AS Users_4 ON Projects.Val_Num = Users_4.PIN INNER JOIN Flow ON Projects.id = Flow.Flow_Pro_Num WHERE id = " myCommandCheck.CommandText += QSid myConnectionCheck.Open() myCommandCheck.ExecuteNonQuery() Dim count As Int16 = myCommandCheck.ExecuteScalar If count = 1 Then Dim myDataReader As SqlDataReader myDataReader = myCommandCheck.ExecuteReader() While myDataReader.Read() Session("TL_email") = myDataReader("Expr1").ToString() Session("PE_email") = myDataReader("Expr2").ToString() Session("DEV_email") = myDataReader("Expr3").ToString() Session("VAL_email") = myDataReader("Expr4").ToString() Session("Project_Name") = myDataReader("Pro_Name").ToString() End While myDataReader.Close() End If End Using

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• Use of const double for intermediate results

  - by Arne

  Hi, I a writing a Simulation program and wondering if the use of const double is of any use when storing intermediate results. Consider this snippet: double DoSomeCalculation(const AcModel &model) { (...) const double V = model.GetVelocity(); const double m = model.GetMass(); const double cos_gamma = cos(model.GetFlightPathAngleRad()); (...) return m*V*cos_gamma*Chi_dot; } Note that the sample is there only to illustrate -- it might not make to much sense from the engineering side of things. The motivation of storing for example cos_gamma in a variable is that this cosine is used many time in other expressions covered by (...) and I feel that the code gets more readable when using cos_gamma rather than cos(model.GetFlightPathAngleRad()) in various expressions. Now the actual is question is this: since I expect the cosine to be the same througout the code section and I actually created the thing only as a placeholder and for convenience I tend to declare it const. Is there a etablished opinion on wether this is good or bad practive or whether it might bite me in the end? Does a compiler make any use of this additional information or am I actually hindering the compiler from performing useful optimizations? Arne

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• Extending EF4 SQL Generation

  - by Basiclife

  Hi, We're using EF4 in a fairly large system and occasionally run into problems due to EF4 being unable to convert certain expressions into SQL. At present, we either need to do some fancy footwork (DB/Code) or just accept the performance hit and allow the query to be executed in-memory. Needless to say neither of these is ideal and the hacks we've sometimes had to use reduce readability / maintainability. What we would ideally like is a way to extend the SQL generation capabilities of the EF4 SQL provider. Obviously there are some things like .Net method calls which will always have to be client-side but some functionality like date comparisons (eg Group by weeks in Linq to Entities ) should be do-able. I've Googled but perhaps I'm using the wrong terminology as all I get is information about the new features of EF4 SQL Generation. For such a flexible and extensible framework, I'd be surprised if this isn't possible. In my head, I'm imagining inheriting from the [SQL 2008] provider and extending it to handle additional expressions / similar in the expression tree it's given to convert to SQL. Any help/pointers appreciated. We're using VS2010 Ultimate, .Net 4 (non-client profile) and EF4. The app is in ASP.Net and is running in a 64-Bit environment in case it makes a difference.

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• Complex derived attributes in Django models

  - by rabidpebble

  What I want to do is implement submission scoring for a site with users voting on the content, much like in e.g. reddit (see the 'hot' function in http://code.reddit.com/browser/sql/functions.sql). My submission model currently keeps track of up and down vote totals. Currently, when a user votes I create and save a related Vote object and then use F() expressions to update the Submission object's voting totals. The problem is that I want to update the score for the submission at the same time, but F() expressions are limited to only simple operations (it's missing support for log(), date_part(), sign() etc.) From my limited experience with Django I can see 4 options here: extend F() somehow (haven't looked at the code yet) to support the missing SQL functions; this is my preferred option and seems to fit within the Django framework the best define a scoring function (much like reddit's 'hot' function) in my database, and have Django use the value of that function for the value of the score field; as far as I can tell, #2 is not possible wrap my two step voting process in a suitably isolated transaction so that I can calculate the voting totals in Python and then update the Submission's voting totals without fear that another vote against the submission could be added/changed in the meantime; I'm hesitant to take this route because it seems overly complex - what is a "suitably isolated transaction" in this case anyway? use raw SQL; I would prefer to avoid this entirely -- what's the point of an ORM if I have to revert to SQL for such a common use case as this! (Note that this coming from somebody who loves sprocs, but is using Django for ease of development.) Before I embark on this mission to extend F() (which I'm not sure is even possible), am I about to reinvent the wheel? Is there a more standard way to do this? It seems like such a common use case and yet in an hour of searching I have yet to find a common solution...

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• Targeted Simplify in Mathematica

  - by Timo

  I generate very long and complex analytic expressions of the general form: (...something not so complex...)(...ditto...)(...ditto...)...lots... When I try to use Simplify, Mathematica grinds to a halt, I am assuming due to the fact that it tries to expand the brackets and or simplify across different brackets. The brackets, while containing long expressions, are easily simplified by Mathematica on their own. Is there some way I can limit the scope of Simplify to a single bracket at a time? Edit: Some additional info and progress. So using the advice from you guys I have now started using something in the vein of In[1]:= trouble = Log[(x + I y) (x - I y) + Sqrt[(a + I b) (a - I b)]]; In[2]:= Replace[trouble, form_ /; (Head[form] == Times) :> Simplify[form],{3}] Out[2]= Log[Sqrt[a^2 + b^2] + (x - I y) (x + I y)] Changing Times to an appropriate head like Plus or Power makes it possible to target the simplification quite accurately. The problem / question that remains, though, is the following: Simplify will still descend deeper than the level specified to Replace, e.g. In[3]:= Replace[trouble, form_ /; (Head[form] == Plus) :> Simplify[form], {1}] Out[3]= Log[Sqrt[a^2 + b^2] + x^2 + y^2] simplifies the square root as well. My plan was to iteratively use Replace from the bottom up one level at a time, but this clearly will result in vast amount of repeated work by Simplify and ultimately result in the exact same bogging down of Mathematica I experienced in the outset. Is there a way to restrict Simplify to a certain level(s)? I realize that this sort of restriction may not produce optimal results, but the idea here is getting something that is "good enough".

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• Exiting from the Middle of an Expression Without Using Exceptions

  - by Jon Purdy

  Is there a way to emulate the use of flow-control constructs in the middle of an expression? Is it possible, in a comma-delimited expression x, y, for y to cause a return? Edit: I'm working on a compiler for something rather similar to a functional language, and the target language is C++. Everything is an expression in the source language, and the sanest, simplest translation to the destination language leaves as many things expressions as possible. Basically, semicolons in the target language become C++ commas. In-language flow-control constructs have presented no problems thus far; it's only return. I just need a way to prematurely exit a comma-delimited expression, and I'd prefer not to use exceptions unless someone can show me that they don't have excessive overhead in this situation. The problem of course is that most flow-control constructs are not legal expressions in C++. The only solution I've found so far is something like this: try { return x(), // x(); (1 ? throw Return(0) : 0); // return 0; } catch (Return& ret) { return ref.value; } The return statement is always there (in the event that a Return construct is not reached), and as such the throw has to be wrapped in ?: to get the compiler to shut up about its void result being used in an expression. I would really like to avoid using exceptions for flow control, unless in this case it can be shown that no particular overhead is incurred; does throwing an exception cause unwinding or anything here? This code needs to run with reasonable efficiency. I just need a function-level equivalent of exit().

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• (x86) Assembler Optimization

  - by Pindatjuh

  I'm building a compiler/assembler/linker in Java for the x86-32 (IA32) processor targeting Windows. High-level concepts of a "language" (in essential a Java API for creating executables) are translated into opcodes, which then are wrapped and outputted to a file. The translation process has several phases, one is the translation between languages: the highest-level code is translated into the medium-level code which is then translated into the lowest-level code (probably more than 3 levels). My problem is the following; if I have higher-level code (X and Y) translated to lower-level code (x, y, U and V), then an example of such a translation is, in pseudo-code: x + U(f) // generated by X + V(f) + y // generated by Y (An easy example) where V is the opposite of U (compare with a stack push as U and a pop as V). This needs to be 'optimized' into: x + y (essentially removing the "useless" code) My idea was to use regular expressions. For the above case, it'll be a regular expression looking like this: x:(U(x)+V(x)):null, meaning for all x find U(x) followed by V(x) and replace by null. Imagine more complex regular expressions, for more complex optimizations. This should work on all levels. What do you suggest? What would be a good approach to optimize in these situations?

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• Javascript string replace with calculations

  - by Chris

  Is there a way to resolve mathematical expressions in strings in javascript? For example, suppose I want to produce the string "Tom has 2 apples, Lucy has 3 apples. Together they have 5 apples" but I want to be able to substitute in the variables. I can do this with a string replacement: string = "Tom has X apples, Lucy has Y apples. Together they have Z apples"; string2 = string.replace(/X/, '2').replace(/Y/, '3').replace(/Z/, '5'); However, it would be better if, instead of having a variable Z, I could use X+Y. Now, I could also do a string replace for X+Y and replace it with the correct value, but that would become messy when trying to deal with all the possible in-string calculations I might want to do. I suppose I'm looking for a way to achieve this: string = "Something [X], something [Y]. Something [(X+Y^2)/5X]"; And for the [_] parts to be understood as expressions to be resolved before substituting back into the string. Thanks for your help.

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• Parsing every part of an HTTP header field-value

  - by brickner

  Hi all. I'm parsing HTTP data directly from packets (either TCP reconstructed or not, you can assume it is). I'm looking for the best way to parse HTTP as accurately as possible. The main issue here is the HTTP header. Looking at the basic RFC of HTTP/1.1, it seems that HTTP header parsing would be complex. The RFC describes very complex regular expressions for different parts of the header. Should I write these regular expressions to parse the different parts of the HTTP header? The basic parsing I've written so far for HTTP header is for the generic HTTP header: message-header = field-name ":" [ field-value ] And I've included replacing inner LWS with SP and repeating headers with the same field-name with comma separated values as described in section 4.2. However, looking at section 14.9 for example would show that in order to parse the different parts of the field-value I need a much more complex parsing scheme. How do you suggest I should handle the complex parts of HTTP parsing (specifically the field-value) assuming I want to give the parser users the full capabilities of HTTP and to parse every part of HTTP? Design suggestions for this would also be appreciated. Thanks.

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• Regular expression, excluding .. in suffix of email addy

  - by user1754700

  This is homework, I've been working on it for a while, I've done lots of reading and feel I have gotten pretty familiar with regex for a beginner. I am trying to find a regular expression for validating/invalidating a list of emails. There are two addresses which are giving me problems, I can't get them both to validate the correct way at the same time. I've gone through a dozen different expressions that work for all the other emails on the list but I can't get those two at the same time. First, the addresses. [email protected] - invalid [email protected] - valid The part of my expression which validates the suffix I originally started with @.+\\.[[a-z]0-9]+ And had a second pattern for checking some more invalid addresses and checked the email against both patterns, one checked for validity the other invalidity but my professor said he wanted it all in on expression. @[[\\w]+\\.[\\w]+]+ or @[\\w]+\\.[\\w]+ I've tried it written many, many different ways but I'm pretty sure I was just using different syntax to express these two expressions. I know what I want it to do, I want it to match a character class of "character+"."character+"+ The plus sign being at least one. It works for the invalid class when I only allow the character class to repeat one time(and obviously the ip doesn't get matched), but when I allow the character class to repeat itself it matches the second period even thought it isn't preceded by a character. I don't understand why.

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• How to make a calculator in PHP?

  - by Giulio Muscarello

  I want to use PHP to calculate simple algebraic expressions like, 8*(5+1), entered via an <input> tag by a normal user (which means, normal notation: no syntax changes like Multiply(8, Add(5, 1))). Also, it has to show all steps, but that's not hard. The problem, right now, is calculating the value of the expressions. Note: this is what I thought so far, which is quite inefficient but it's a provisory solution. Just replace strings where possible: in our example, recognize the string 5+1 and replace it with 6. Then, loop again, replace (6) with 6, loop again, and replace 8*6 with 48. The code for multiplying, for example, should look like this: for ($a=1; $a < 1000; $a++) { for ($b=1; $b < 1000; $b++) { string_replace($a . '*' . $b, $a*$b, $string); } }

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• Howto use predicates in LINQ to Entities for Entity Framework objects

  - by user274947

  I'm using LINQ to Entities for Entity Framework objects in my Data Access Layer. My goal is to filter as much as I can from the database, without applying filtering logic on in-memory results. For that purpose Business Logic Layer passes a predicate to Data Access Layer. I mean Func<MyEntity, bool> So, if I use this predicate directly, like public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.Where(x => isMatched(x)); } I'm getting the exception [System.NotSupportedException] --- {"The LINQ expression node type 'Invoke' is not supported in LINQ to Entities."} Solution in that question suggests to use AsExpandable() method from LINQKit library. But again, using public IQueryable<MyEntity> GetAllMatchedEntities(Func<MyEntity, Boolean> isMatched) { return qry = _Context.MyEntities.AsExpandable().Where(x => isMatched(x)); } I'm getting the exception Unable to cast object of type 'System.Linq.Expressions.FieldExpression' to type 'System.Linq.Expressions.LambdaExpression' Is there way to use predicate in LINQ to Entities query for Entity Framework objects, so that it is correctly transformed it into a SQL statement. Thank you.

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• WHY JSLint complains: "someFunction() was used before it was defined"?

  - by 7hi4g0

  Searching for the JSLint error "was used before it was defined" i've found these: JSLint: Using a function before it's defined error Function was used before it was defined - JSLint JSLint: was used before it was defined jsLint error: “somefunction() was used before it was defined” jslint - Should we tolerate misordered definitions? Problem None of those answers WHY the error is shown. Elaboration According to the ECMA-262 Specification functions are evaluated before execution starts, hence all functions declared using the function keyword are available to all the code idenpendent of the place they were declared (assuming they are acessible on that scope). This is otherwise known as hoisting. Douglas Crockford seems to think it is better to declare every function before the code that uses it regardless of the hoisting effect. According to StackOverflowNewbie in his question, this raises some code organization problems. Not to mention some people, like me, prefer to declare their functions underneath the main/init code. On those questions there are some ways to avoid or fix the error, such as using function expressions vs function declarations. But none of them showed me the reason of the error. Not even Crockford's site. Question(s) Why is it an error to call a function before the declaration, even if it was declared using the function keyword? Is it better to use function expressions instead of function declaration in the JSLint context? If one is preferred, why? Note Not looking for answers like: Crockford is a tyrant Is just Crockford's opinion Thank you :*

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• how to Retrieve the parameters of document.write to detect the creation of dynamic tags

  - by user1335906

  In my Project i am supposed to identify the dynamically created tags which can be done in scripts through document.write("<script src='jquery.js'></script>") For this i used Regular expressions and my code is as follows function find_tag_docwrite(text) { var attrib=new Object; var pat_tag=/<((\S+)\s(.*))>/g; while(t=pat_tag.exec(text) { var tag=RegExp.$1; for(i=0;i<tags.length;i++) { var pat=/(\S+)=((['"]*)(\S+)(['"]*)\3)/g; while(p=pat.exec(f)) { attr=RegExp.$1;val=RegExp.$4; attrib[attr]=val; } } } } in the above function text is parameters of document.write function. Now through this code i am getting the tag names and all the attributes of the tags. But for the below example the above code is not working var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); In such cases Regular expressions does not work so after searching some time where i found hooks on dom methods. so by using this i thought of creating hook for document.write method but i am able to understand how it is done i included the following code in my program but it is not working. function someFunction(text) { console.log(text); } document.write = someFunction; where text is the parameters of document.write. Another problem is After monitoring all the document.write methods using hooks again i have to use regex for finding tag creations. Is there Any alternative

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• OCaml delimiters and scopes

  - by Jack

  Hello! I'm learning OCaml and although I have years of experience with imperative programming languages (C, C++, Java) I'm getting some problems with delimiters between declarations or expressions in OCaml syntax. Basically I understood that I have to use ; to concatenate expressions and the value returned by the sequence will be the one of last expression used, so for example if I have exp1; exp2; exp3 it will be considered as an expression that returns the value of exp3. Starting from this I could use let t = something in exp1; exp2; exp3 and it should be ok, right? When am I supposed to use the double semicol ;;? What does it exactly mean? Are there other delimiters that I must use to avoid syntax errors? I'll give you an example: let rec satisfy dtmc state pformula = match (state, pformula) with (state, `Next sformula) -> let s = satisfy_each dtmc sformula and adder a state = let p = 0.; for i = 0 to dtmc.matrix.rows do p <- p +. get dtmc.matrix i state.index done; a +. p in List.fold_left adder 0. s | _ -> [] It gives me syntax error on | but I don't get why.. what am I missing? This is a problem that occurs often and I have to try many different solutions until it suddently works :/ A side question: declaring with let instead that let .. in will define a var binding that lasts whenever after it has been defined? What I basically ask is: what are the delimiters I have to use and when I have to use them. In addition are there differences I should consider while using the interpreter ocaml instead that the compiler ocamlc? Thanks in advance!

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• Why is Excel's 'Evaluate' method a general expression evaluator?

  - by jtolle

  A few questions have come up recently involving the Application.Evaluate method callable from Excel VBA. The old XLM macro language also exposes an EVALUATE() function. Both can be quite useful. Does anyone know why the evaluator that is exposed can handle general expressions, though? My own hunch is that Excel needed to give people a way to get ranges from string addresses, and to get the value of named formulas, and just opening a portal to the expression evaluator was the easiest way. (The help for the VBA version does say its purpose it to "convert a Microsoft Excel name to an object or a value".) But of course you don't need the ability to evaluate arbitrary expressions just to do that. (That is, Excel could provide a Name.Evaluate method or something instead.) Application.Evaluate seems kind of...unfinished. It's full behavior isn't very well documented, and there are quite a few quirks and limitations (as described by Charles Williams here: http://www.decisionmodels.com/calcsecretsh.htm) with what is exposed. I suppose the answer could be simply "why not expose it?", but I'd be interested to know what design decisions led to this feature taking the form that it does. Failing that, I'd be interested to hear other hunches.

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• Checked and Unchecked operators don't seem to be working when...

  - by flockofcode

  1) Is UNCHECKED operator in effect only when expression inside UNCHECKED context uses an explicit cast ( such as byte b1=unchecked((byte)2000); ) and when conversion to particular type can happen implicitly? I’m assuming this since the following expression throws a compile time error: byte b1=unchecked(2000); //compile time error 2) a) Do CHECKED and UNCHECKED operators work only when resulting value of an expression or conversion is of an integer type? I’m assuming this since in the first example ( where double type is being converted to integer type ) CHECKED operator works as expected: double m = double.MaxValue; b=checked((byte)m); // reports an exception , while in second example ( where double type is being converted to a float type ) CHECKED operator doesn’t seem to be working. since it doesn't throw an exception: double m = double.MaxValue; float f = checked((float)m); // no exception thrown b) Why don’t the two operators also work with expressions where type of a resulting value is of floating-point type? 2) Next quote is from Microsoft’s site: The unchecked keyword is used to control the overflow-checking context for integral-type arithmetic operations and conversions I’m not sure I understand what exactly have expressions and conversions such as unchecked((byte)(100+200)); in common with integrals? Thank you

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• Filtering string in Python

  - by Ecce_Homo

  I am making algorithm for checking the string (e-mail) - like "E-mail addres is valid" but their are rules. First part of e-mail has to be string that has 1-8 characters (can contain alphabet, numbers, underscore [ _ ]...all the parts that e-mail contains) and after @ the second part of e-mail has to have string that has 1-12 characters (also containing all legal expressions) and it has to end with top level domain .com EDIT email = raw_input ("Enter the e-mail address:") length = len (email) if length > 20 print "Address is too long" elif lenght < 5: print "Address is too short" if not email.endswith (".com"): print "Address doesn't contain correct domain ending" first_part = len (splitting[0]) second_part = len(splitting[1]) account = splitting[0] domain = splitting[1] for c in account: if c not in "abcdefghijklmopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.": print "Invalid char", "->", c,"<-", "in account name of e-mail" for c in domain: if c not in "abcdefghijklmopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_.": print "Invalid char", "->", c,"<-", "in domain of e-mail" if first_part == 0: print "You need at least 1 character before the @" elif first_part> 8: print "The first part is too long" if second_part == 4: print "You need at least 1 character after the @" elif second_part> 16: print "The second part is too long" else: # if everything is fine return this print "E-mail addres is valid" EDIT: After reproting what is wrong with our input, now I need to make Python recognize valid address and return ("E-mail adress is valid") This is the best i can do with my knowledge....and we cant use regular expressions, teacher said we are going to learn them later.

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