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  • constructor should not call methods

    - by Stefano Borini
    I described to a colleague why a constructor calling a method is an antipattern. example (in my rusty C++) class C { public : C(int foo); void setFoo(int foo); private: int foo; } C::C(int foo) { setFoo(foo); } void C::setFoo(int foo) { this->foo = foo } I would like to motivate better this fact through your additional contribute. If you have examples, book references, blog pages, or names of principles, they would be very welcome. Edit: I'm talking in general, but we are coding in python.

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  • designing classes with similar goal but widely different decisional core

    - by Stefano Borini
    I am puzzled on how to model this situation. Suppose you have an algorithm operating in a loop. At every loop, a procedure P must take place, whose role is to modify an input data I into an output data O, such that O = P(I). In reality, there are different flavors of P, say P1, P2, P3 and so on. The choice of which P to run is user dependent, but all P have the same finality, produce O from I. This called well for a base class PBase with a method PBase::apply, with specific reimplementations of P1::apply(I), P2::apply(I), and P3::apply(I). The actual P class gets instantiated in a factory method, and the loop stays simple. Now, I have a case of P4 which follows the same principle, but this time needs additional data from the loop (such as the current iteration, and the average value of O during the previous iterations). How would you redesign for this case?

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  • Is there an excuse for short variable names?

    - by KChaloux
    This has become a large frustration with the codebase I'm currently working in; many of our variable names are short and undescriptive. I'm the only developer left on the project, and there isn't documentation as to what most of them do, so I have to spend extra time tracking down what they represent. For example, I was reading over some code that updates the definition of an optical surface. The variables set at the start were as follows: double dR, dCV, dK, dDin, dDout, dRin, dRout dR = Convert.ToDouble(_tblAsphere.Rows[0].ItemArray.GetValue(1)); dCV = convert.ToDouble(_tblAsphere.Rows[1].ItemArray.GetValue(1)); ... and so on Maybe it's just me, but it told me essentially nothing about what they represented, which made understanding the code further down difficult. All I knew was that it was a variable parsed out specific row from a specific table, somewhere. After some searching, I found out what they meant: dR = radius dCV = curvature dK = conic constant dDin = inner aperture dDout = outer aperture dRin = inner radius dRout = outer radius I renamed them to essentially what I have up there. It lengthens some lines, but I feel like that's a fair trade off. This kind of naming scheme is used throughout a lot of the code however. I'm not sure if it's an artifact from developers who learned by working with older systems, or if there's a deeper reason behind it. Is there a good reason to name variables this way, or am I justified in updating them to more descriptive names as I come across them?

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  • Real-time stock market application

    - by Sam
    I'm an amateur programmer. I'd like to develop a software application (like Tradestation), to analyse real-time market data. Please teach me if the following approach is correct, ie the procedures, knowledge or software needed etc: Use a DB to read the real-time feed from data provider: what should be the right DB to use? I know it should be a time serious one. Can I use SQL, Mysql, or others? What database can receive real-time data feed? Do I need to configure the DB to do this? If the real-time data is in ASCII form, how can it be converted to those that can be read by the DB and my application? Should I have to write codes or just use some add-ins? What kind of add-in are needed? How should I code the program to retrieve the changing data from the DB so that the analysis software screen data can also change asynchronously? (like the RTD in excel) Which aspects of programming do I need to learn to develop the above? Are there web resources/ books I can refer to for more information?

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  • Recommended book on Actors concurrency model (patterns, pitfalls, etc.)?

    - by Larry OBrien
    The Actors concurrency model is clearly gaining favor. Is there a good book that presents the patterns and pitfalls of the model? I am thinking about something that would discuss, for instance, the problems of consistency and correctness in the context of hundreds or thousands of independent Actors. It would be okay if it were associated with a specific language (erlang, I would imagine, since that seems universally regarded as the proven implementation of Actors), but I am hoping for something more than an introductory chapter or two. (FWIW, I'm actually most interested in Actors as they are implemented in Scala.)

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  • Is swing components heavy weight

    - by Pramod PP
    By Adding multiple Panels into a Panel or Dialog, Will it become heavy weight ?. Is there any way to avoid it to make complex views in single panel ? I'm making a java Swing application, there has many controls, I'm placing multiple panel in a single panel and place that panel as the center pane of a dialog. I suspect that the application takes more memory (I don't know it actually takes. Its only a suspect). can anyone please advise on this.

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  • Has any language become greatly popular for something other than its intended purpose?

    - by Jon Purdy
    Take this scenario: A programmer creates a language to solve some problem. He then releases this language to help others solve problems like it. Another programmer discovers it's actually much better for some different category of problems. By virtue of this new application, the language then becomes popular for that application primarily. Are there any instances of this actually occurring? Put another way, does the intended purpose of a language have any bearing on how it's actually used, or whether it becomes popular? Is it even important that a language have an advertised purpose?

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  • Is it important to obfuscate C++ application code?

    - by user827992
    In the Java world, it seems to sometimes be a problem, but, what about C++? Are there different solutions? I was thinking about the fact that someone can replace the C++ library of a specific OS with a different version of the same library, but full of debug symbols to understand what my code does. IS tt a good thing to use standard or popular libraries? This can also happen with some dll library under Windows replaced with the "debug version" of that library. Is it better to prefer static compilation? In commercial applications, I see that for the core of their app they compile everything statically and for the most part the dlls (dynamic libraries in general) are used to offer some third party technologies like anti-piracy solutions (I see this in many games), GUI library (like Qt), OS libraries, etc. Is static compilation the equivalent to obfuscation in the Java world? In better terms, is it the best and most affordable solution to protect your code?

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  • Open Source programs for learning C#

    - by dizzytri99er
    I was wondering if there are any good open source programs out there that are basically 'all-skill' encompassing that i could use to develop my skills Im a strong believer in learning by doing so a nice open source program i could load onto my machine to learn C# would be ideal. I have some knowledge with basic C# and a little more advanced techniques so im not a total beginner i realise similar questions have been asked before but i was just trying no see if there is one definitive one rather than lots of little projects hopefully im not asking too much! haha

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  • Breaking into database administration

    - by user603794
    Hello to all, I am brand new on this site and look forward to interacting with each of you. I am graduating in June with my Bachelors Degree in Computer Information Systems with hopes of become a DBA in the future. I am currently taking a Database class now and studying SQL Server/T-SQL on the side. My experience in IT is limited to managing an Access database at my last employer for two years. What are the chances of landing a junior DBA position after I graduate?

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  • How to increase the bus factor and specialize at the same time?

    - by bizso09
    In agile pair programming it is recommended to switch pairs every now and then so as to increase the bus factor of the team. That means, most people in the team should work on different parts of the system at different times so that everyone has an understanding of it. Now it is impssible that everyone has an expert level of understanding of each part of the system. That's because people are urged to specialize in one area of expertise. If you are an expert database admin, what's the point of working on the user interface of the system when you switch pairs? You will not be able to do such a high quality job as someone who has extensive experience in UI design. How can you increase the bus factor and make sure that you have specialization in your team?

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  • Best Language for the job? Database | C++, .NET, Java

    - by Randy E
    Ok, quick overview. I'm pretty brand new to software design. I have experience reading and editing/customizing PHP things for online scripts/software; Such as CMS, Wordpress, some forum solutions. I'm about to begin my degree in Software Design, the school I'm going to will allow us to kind of focus on an area, C++, Java, or .NET. I've played around a little with VB over the past week, mostly just trying to get a slight feel for it, however nothing extensive. I've been through Herbert Schildt's "C++, A Beginner's Guide." but I was mainly reading it, not doing anything with it beyond a couple basic Console Apps (and getting frustrated with auto-close :/ ). Now, where I decide to focus more in with my degree will depend on what the best language for the job is for my first piece of software I want to develop on my own. Assume I haven't looked at any of the languages at all, please help with the following: My first piece of software will be a database program. Everything has to do with users inputting and retrieving data, and calling that data to help with another function of the software, automatically calculating billing information based on information inputted in the other portion of the program. I won't go into too many details as I'm targeting a niche that doesn't have too much competition, but the competition that is there is established. I want to offer more features, scalable solutions, and the ability to port it to an online version. Ok, basically, it is a complete case management with integrated billing for Private Investigators. I would like the case management to be able to check the Database to see if certain information has been inputted before (such as Names/SSN's), and then the billing will pull hours inputted in the case portion for investigative work, multiplying by an already inputted amount for the fee, and then calculate sales tax. I also want to provide potential clients with an easily scalable solution, that is, a basic option for start ups that costs the least amount, with no additional users, ran on one machine. A middle option with the ability to create users and place them in two groups (User or Admin), as well as adding a few additional features, ran on one machine, but this will allow it to be accessed after being mapped on a network drive. And a third option to allow the placement into 4 different groups (Investigators, Billing, Managers, Admins) and more features. And then, a couple of years after launch, a 4th option that is browser based allowing the same 4 groups to login, as well as clients (view things concerning their case, with some admin customizable objects that can be added for clients view), over the internet. The only licensing security I would like to employ right off the bat will be serial key generated after ordering online (received in an email after the successful purchase). The program will access a database stored on a server periodically to verify license. I would like it to be able to check to make sure it's the most updated version and automatically update if not.

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  • .Net Application & Database Modularity/Reuse

    - by Martaver
    I'm looking for some guidance on how to architect an app with regards to modularity, separation of concerns and re-usability. I'm working on an application (ASP.Net, C#) that has distinctly generic chunks of functionality, that I'd love to be able to lift out, all layers, into re-usable components. This means the module handles the database schema, data access, API, everything so that the next time I want to use it I can just register the module and hook into it. Developing modules of re-usable functionality is a no-brainer, but what is really confusing me is what to do when it comes to handling a core re-usable database schema that serves the module's functionality. In an ideal world, I would register a module and it would ensure that the associated database schema exists in the DB. I would code on the assumption that the tables exist, calling the module's functionality through the DLL, agnostic of the database layer. Kind of like Enterprise Library's Caching/Logging Application Block, which can create a DB schema in the target DB to use as a data store. My Questions is: What do you think is the best way to achieve this, firstly, in terms design architecture, and secondly solution structure. What patterns/frameworks do you know that exist & support this kind of thing? My thoughts so far: I mostly use Entity Framework and SQL Server DB Projects. I thought about a 'black box' approach to modules of functionality. I could use use a code-first approach in EF4, and use the ObjectContext to create a database when the module is initialized. However this means that all of the entities that my module encapsulates would be disconnected from the rest of the application because they belonged to an abstracted ObjectContext. Further - Creating appropriate indexes and references between domain entities and the module's entities would be impossible to do practically. I've thought of adopting Enterprise Library and creating my own Application Blocks. I'm not sure how this would play nice with Entity Framework (if at all) though. I like the idea of building on proven patterns & practices to encapsulate established, reusable functionality. I thought of abandoning Entity Framework for the Module, and just creating a separate DB schema for the module with its own set of stored procedures & ADO.Net. Then deploying the script at run-time if interrogation shows that it doesn't exist. But once again, for application developing outside of the application, I would want to use Entity Framework and I would have to use the module separately, disconnected from the domain ObjectContext. Has anyone had experience developing these sorts of full-stack modules? What advice can you offer? Am I biting off more than I can chew?

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  • Could someone break this nasty habit of mine please?

    - by MimiEAM
    I recently graduated in cs and was mostly unsatisfied since I realized that I received only a basic theoretical approach in a wide range of subjects (which is what college is supposed to do but still...) . Anyway I took the habit of spending a lot of time looking for implementations of concepts and upon finding those I will used them as guides to writing my own implementation of those concepts just for fun. But now I feel like the only way I can fully understand a new concept is by trying to implement from scratch no matter how unoptimized the result may be. Anyway this behavior lead me to choose by default the hard way, that is time consuming instead of using a nicely written library until I hit my head again a huge wall and then try to find a library that works for my purpose.... Does anyone else do that and why? It seems so weird why would anyone (including me) do that ? Is it a bad practice ? and if so how can i stop doing that ?

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  • SpringMvc java.lang.NullPointerException When Posting Form To Server [closed]

    - by dev_darin
    I have a form with a user name field on it when i tab out of the field i use a RESTFUL Web Service that makes a call to a handler method in the controller. The method makes a call to a DAO class that checks the database if the user name exists. This works fine, however when the form is posted to the server i call the same exact function i would call in the handler method however i get a java.lang.NullPointerException when it accesses the class that makes a call to the DAO object. So it does not even access the DAO object the second time. I have exception handlers around the calls in all my classes that makes calls. Any ideas as to whats happening here why i would get the java.lang.NullPointerException the second time the function is called.Does this have anything to do with Spring instantiating DAO classes using a Singleton method or something to that effect? What can be done to resolve this? This is what happens the First Time The Method is called using the Web Service(this is suppose to happen): 13011 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - Inside jdbcOfficersDAO 13031 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL query 13034 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [SELECT userName FROM crimetrack.tblofficers WHERE userName = ?] 13071 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource 13496 [http-8084-2] DEBUG org.springframework.jdbc.core.StatementCreatorUtils - Setting SQL statement parameter value: column index 1, parameter value [adminz], value class [java.lang.String], SQL type unknown 13534 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource 13537 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - No username was found in exception 13537 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz does NOT exist The Second time When The Form Is 'Post' and a validation method handles the form and calls the same method the web service would call: 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - Inside Do UserNameExist about to validate with username : adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz EXCEPTION OCCURED java.lang.NullPointerException ValidateUserNameManager.java public class ValidateUserNameManager implements ValidateUserNameIFace { private OfficersDAO officerDao; private final Logger logger = Logger.getLogger(getClass()); public boolean DoesUserNameExist(String userName) throws Exception { logger.info("Inside Do UserNameExist about to validate with username : " + userName); try{ if(officerDao.OfficerExist(userName) == true){ logger.info("UserName :" + userName + " does exist"); return true; }else{ logger.info("UserName :" + userName + " does NOT exist"); return false; } }catch(Exception e){ logger.info("UserName :" + userName + " EXCEPTION OCCURED " + e.toString()); return false; } } /** * @return the officerDao */ public OfficersDAO getOfficerDao() { return officerDao; } /** * @param officerdao the officerDao to set */ public void setOfficerDao(OfficersDAO officerDao) { this.officerDao = officerDao; } } JdbcOfficersDAO.java public boolean OfficerExist(String userName){ String dbUserName; try{ logger.info("Inside jdbcOfficersDAO"); String sql = "SELECT userName FROM crimetrack.tblofficers WHERE userName = ?"; try{ dbUserName = (String)getJdbcTemplate().queryForObject(sql, new Object[]{userName},String.class); logger.info("Just Returned from database"); }catch(Exception e){ logger.info("No username was found in exception"); return false; } if(dbUserName == null){ logger.info("Database did not find any matching records"); } logger.info("after JdbcTemplate"); if (dbUserName.equals(userName)) { logger.info("User Name Exists"); return true; }else{ logger.info("User Name Does NOT Exists"); return false; } }catch(Exception e){ logger.info("Exception Message in JdbcOfficersDAO is "+e.getMessage()); return false; } } OfficerRegistrationValidation.java public class OfficerRegistrationValidation implements Validator{ private final Logger logger = Logger.getLogger(getClass()); private ValidateUserNameManager validateUserNameManager; public boolean supports(Class<?> clazz) { return Officers.class.equals(clazz); } public void validate(Object target, Errors errors) { Officers officer = (Officers) target; if (officer.getUserName() == null){ errors.rejectValue("userName", "userName.required"); }else{ String userName = officer.getUserName(); logger.info("UserName is not null so going to check if its valid for :" + userName); try { logger.info("User Name in try.....catch block is " + userName); if (validateUserNameManager.DoesUserNameExist(userName)== true){ errors.rejectValue("userName", "userName.exist"); } } catch (Exception e) { logger.info("Error Occured When validating UserName"); errors.rejectValue("userName", "userName.error"); } } if(officer.getPassword()== null){ errors.rejectValue("password", "password.required"); } if(officer.getPassword2()== null){ errors.rejectValue("password2", "password2.required"); } if(officer.getfName() == null){ errors.rejectValue("fName","fName.required"); } if(officer.getlName() == null){ errors.rejectValue("lName", "lName.required"); } if (officer.getoName() == null){ errors.rejectValue("oName", "oName.required"); } if (officer.getEmailAdd() == null){ errors.rejectValue("emailAdd", "emailAdd.required"); } if (officer.getDob() == null){ errors.rejectValue("dob", "dob.required"); } if (officer.getGenderId().equals("A")){ errors.rejectValue("genderId","genderId.required"); } if(officer.getDivisionNo() == 1){ errors.rejectValue("divisionNo", "divisionNo.required"); } if(officer.getPositionId() == 1){ errors.rejectValue("positionId", "positionId.required"); } if (officer.getStartDate() == null){ errors.rejectValue("startDate","startDate.required"); } if(officer.getEndDate() == null){ errors.rejectValue("endDate","endDate.required"); } logger.info("The Gender ID is " + officer.getGenderId().toString()); if(officer.getPhoneNo() == null){ errors.rejectValue("phoneNo", "phoneNo.required"); } } /** * @return the validateUserNameManager */ public ValidateUserNameManager getValidateUserNameManager() { return validateUserNameManager; } /** * @param validateUserNameManager the validateUserNameManager to set */ public void setValidateUserNameManager( ValidateUserNameManager validateUserNameManager) { this.validateUserNameManager = validateUserNameManager; } } Update Error Log using Logger.Error("Message", e): 39024 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 39025 [http-8084-2] ERROR com.crimetrack.service.OfficerRegistrationValidation - Message java.lang.NullPointerException at com.crimetrack.service.OfficerRegistrationValidation.validate(OfficerRegistrationValidation.java:47) at org.springframework.validation.DataBinder.validate(DataBinder.java:725) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:815) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:367) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - Error Occured When validating UserName

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  • About shared (static) Members and its behavior

    - by Allende
    I just realized that I can access shared members from instances of classes (probably this is not correct, but compile and run), and also learn/discover that, I can modify shared members, then create a new instance and access the new value of the shared member. My question is, what happens to the shared members, when it comes back to the "default" value (class declaration), how dangerous is it do this ? is it totally bad ? is it valid in some cases ?. If you want to test my point here is the code (console project vb.net) that I used to test shared members, as you can see/compile/run, the shared member "x" of the class "Hello" has default value string "Default", but at runtime it changes it, and after creating a new object of that class, this object has the new value of the shared member. Module Module1 Public Class hello Public Shared x As String = "Default" Public Sub New() End Sub End Class Sub Main() Console.WriteLine("hello.x=" & hello.x) Dim obj As New hello() Console.WriteLine("obj.x=" & obj.x) obj.x = "Default shared memeber, modified in object" Console.WriteLine("obj.x=" & obj.x) hello.x = "Defaul shared member, modified in class" Console.WriteLine("hello.x=" & hello.x) Dim obj2 As New hello() Console.WriteLine("obj2.x=" & obj2.x) Console.ReadLine() End Sub End Module UPDATE: First at all, thanks to everyone, each answer give feedback, I suppose, by respect I should choose one as "the answer", I don't want to be offensive to anyone, so please don't take it so bad if I didn't choose you answer.

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  • Most effective work habit for coding? [on hold]

    - by Cris
    Working on a big solo project (~15,000 LOC), I am encountering the following phenomenon: I seem to work best when I program in short bursts of 10-15 minutes. Right now I am working on a section which is a complete first time for me architecturally and if I have any architectural issues that emerge when doing the implementation, I seem to be able to best serve these by taking a total break. Then, later, sketching out the ideas on some paper. And when I feel I have sufficient clarity, then going back to code. This iterates until that architectural issue for that section is resolved. This seems quite counter intuitive: that I can progress more quickly by coding less, and taking more breaks. I am nearing the end of the sections which are "first times" for me, and about to dive into stuff which I am much more familiar and am wondering if this counter intuitive efficiency will continue. So my question is: even for regular coding of sections one is familiar with, which don't require constant re-clarification of the best architecture, is more progress to be attained by taking more breaks and coding in bursts?

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  • Techniques and methods to improve and speedup development

    - by Jlouro
    I just got a new project. It’s a WinForm app. And it’s interesting because I will have the possibility to learn how fish farms work and are managed. I will have to develop touch interfaces, and use datasnap to communicate and sync data between farm and office. The development will be done in DELPHI win32, still not sure about the database, but maybe SQLlite. So now comes the difficult part of the project, building it. I am just finishing one. It took me a lot of time to do it and I am a bit “burned out”. I will have time to relax, not much, but a few days. What I am looking is some tips and tricks and possibly tools to be able to speed up the development. It must be up and running in 2 months. So what tricks do you use to speed up things?

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  • How to remove the boundary effects arising due to zero padding in scipy/numpy fft?

    - by Omkar
    I have made a python code to smoothen a given signal using the Weierstrass transform, which is basically the convolution of a normalised gaussian with a signal. The code is as follows: #Importing relevant libraries from __future__ import division from scipy.signal import fftconvolve import numpy as np def smooth_func(sig, x, t= 0.002): N = len(x) x1 = x[-1] x0 = x[0] # defining a new array y which is symmetric around zero, to make the gaussian symmetric. y = np.linspace(-(x1-x0)/2, (x1-x0)/2, N) #gaussian centered around zero. gaus = np.exp(-y**(2)/t) #using fftconvolve to speed up the convolution; gaus.sum() is the normalization constant. return fftconvolve(sig, gaus/gaus.sum(), mode='same') If I run this code for say a step function, it smoothens the corner, but at the boundary it interprets another corner and smoothens that too, as a result giving unnecessary behaviour at the boundary. I explain this with a figure shown in the link below. Boundary effects This problem does not arise if we directly integrate to find convolution. Hence the problem is not in Weierstrass transform, and hence the problem is in the fftconvolve function of scipy. To understand why this problem arises we first need to understand the working of fftconvolve in scipy. The fftconvolve function basically uses the convolution theorem to speed up the computation. In short it says: convolution(int1,int2)=ifft(fft(int1)*fft(int2)) If we directly apply this theorem we dont get the desired result. To get the desired result we need to take the fft on a array double the size of max(int1,int2). But this leads to the undesired boundary effects. This is because in the fft code, if size(int) is greater than the size(over which to take fft) it zero pads the input and then takes the fft. This zero padding is exactly what is responsible for the undesired boundary effects. Can you suggest a way to remove this boundary effects? I have tried to remove it by a simple trick. After smoothening the function I am compairing the value of the smoothened signal with the original signal near the boundaries and if they dont match I replace the value of the smoothened func with the input signal at that point. It is as follows: i = 0 eps=1e-3 while abs(smooth[i]-sig[i])> eps: #compairing the signals on the left boundary smooth[i] = sig[i] i = i + 1 j = -1 while abs(smooth[j]-sig[j])> eps: # compairing on the right boundary. smooth[j] = sig[j] j = j - 1 There is a problem with this method, because of using an epsilon there are small jumps in the smoothened function, as shown below: jumps in the smooth func Can there be any changes made in the above method to solve this boundary problem?

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  • Interview Questions in OOP

    - by Fero
    Hi all, I faced the below interview questions in OOP under PHP language. Kindly clear my clarifications regarding this. I am very confused. As i am a beginner to OOP i got too confused. Could anyone clarify these things clearly? Difference between Abstract class and interface. Interviewer : Let us consider abstract class contains three abstract methods such as a,b,c and interface contains three methods a,b,c. In this case these do the same functionality. Then why are going for abstract and why are we going for interface. Me : ? static keyword. Interviewer: We call static method without creating object by using scope resolution operator in PHP. As well as we can able to call concrete methods also. Then what is need of static keyword there? Me : .... final keyword. Interviewer: Give me any scenario of using final keyword. Me : For db connection related method Interviewer: Other than that? Me: ... Constructor. Interviewer: What is the use of constructor? Me : There is no need for object to access this. It will call automatically when the class calls. Interviewer: Other than that? Me : .... Thanks in advance...

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  • Text comparison algorithm using java-diff-utils

    - by java_mouse
    One of the features in our project is to implement a comparison algorithm between two versions of text and provide a % change between the two versions. While I was researching, I came across google java-diff-utils project. Has anyone used this for comparing text using java-diff-utils ? Using this utility, I can get a list of "delta" which I assume I can use it for the % of difference between two versions of the text? Is this a correct way of doing this? If you have done any text comparison algorithm using Java, could you give me some pointers?

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  • Advice for how to handle company pride

    - by user17971
    We have this "amazing" little product using the latest development methodologies, components with all the bells and whistles. I took over this product maybe 6 months ago and struggled with it from day one. Even though it is supposedly is state of the art because of all its amazing structure, using dependency injections, inversion of control from the unity framework, hibernation and is domain driven in a .net mvvm xaml application to make it streamlined and modular. I knew from the moment I saw the monolith that it was going to be an uphill struggle for me. A lot of little code-bits scattered all around in neatly organized paradigms. Debugging is difficult, tracing the code is difficult, making new code is difficult, although some modifications is surprisinly easy but it doesn't out weight the problems I have with the code by a long shot. When I took over the project I was told that the new management console was ready for delivery and all I had to do was compile it and drop it. This was the beginning of a uphill struggle, our customer didn't agree at all that this was the functionality they had asked for so I had to do modifications to the program to their specifications. Since the project pretty much has been overdue since I took over it it has always been important that we didn't add or change much to the original system. I could modify the existing bits. fast forward until today where I finally completed all their comments and issues with the program but now I think that the users has opened their eyes (even though they saw this program many times) that they will be going backwards with this new system, that it will be much worse than the tool they got today (for a long time due to the fact that I'm the only resource on the project, project manager, tester, developer, integration specialist etc) My problem is that I lost faith in this system quite early due to the nature of the program. Although I made many changes and improvements to the system I wholeheartedly sympathize with the poor users who are going to start using this system. Its not nearly doing all the things it should do. I had this conversation internally with my boss where I told him what I thought about it, that if I were the customer I wouldn't have spent money developing it. So what do I do now? The system in ready, on a staging system and nobody likes it, its too slow and boring and does maybe do 50% of what they need it to do. Despite how much energy and working around the clock I've done to this project: I won't mind scrapping the system but we've spent much money (well my salaries) developing it and my company wants us to be proud of everything we do and advocate it. How will I tackle the contractor when he asks for advice? Surely I can tell him, this is what we agreed upon based on your use case scenarios, and be done with it? How will I inform my boss about this progress? He knows what I feel about it but I always get the feeling he let my criticism pass him by as just hot air, gone tomorrow,.

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  • What are the advantages of mainframes?

    - by Scott Weinstein
    The downsides of Mainframes is well trodden ground; expensive, legacy, dwindling community, etc. I'm not particularly interested in the downsides, but I am curious if there are any benefits to mainframe hardware/software over the current Intel/AMD & Linux/Windows environment. I've been told that MFs are particularly good (and better than current servers) at heavy I/O loads. Is this still true?

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  • What should I do to scale out an high-traffic website?

    - by makerofthings7
    What Best Practices should be undertaken for a Website that needs to "scale out" to handle capacity? This is especially relevant now that people are considering the cloud, but may be missing out on the fundamentals. I'm interested in hearing about anything you consider a best practice from development-level tasks, to infrastructure, to management. Use your best judgement when posting multiple answers, since it may make sense to post them separately for voting purposes. (hint: you'll likely get more reputation points for many small answers than one large answer)

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  • Looking for terminology for the relation of a subject and a predicate

    - by kostja
    While writing some predicates for collection filtering I have stumbled over the choice of the right words for the relation of the subject and the predicate (English is a foreign language for me). What I ended up writing was "Subjects matching this predicate..." This seems to be incorrect, since predicates are functions and not regular expressions. But saying "Subjects for which this predicate returns true..." sounds awkward to me as well.. So what would be the correct term?

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