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• Java Client .class File Protection

  - by Zac

  I am in the requirements phase of building a JEE application that will most likely run on a GlassFish/JBoss backend (doesn't matter for now). I know I shouldn't be thinking about architecture at requirements time, but one can't help but start to imagine how the components would all snap together :-) Here are some hard, non-flexible requirements on the client-side: (1) The client application will be a Swing box (2) The client is free to download, but will use a subscription model (thus requiring a login mechanism with server-side authentication/authorization, etc.) (3) Yes, Java is the best platform solution for the problem at hand for reasons outside the scope of this post (4) The client-side .class files need safeguarding against decompiling That last (4th) requirement is the basis of this post. I'm not really worried about someone actually decompiling and getting at my source code: in the end, it's just Swing controls driven by some lightweight business logic. I'm worried about a scenario where someone decompiles my code, modifies it to exploit/attack the server, re-compiles, and fires it up. I've envisioned all sorts of nasty solutions, but didn't know if this was a common problem with a common solution for JEE developers. Any thoughts? Not interested in "code obfuscation" techniques! Thanks for any input!

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• Multiple Concurrent Postbacks when using UpdatePanels

  - by d4nt

  Here's an example app that I built to demonstrate my problem. A single aspx page with the following on it: <form id="form1" runat="server"> <asp:ScriptManager runat="server" /> <asp:Button runat="server" ID="btnGo" Text="Go" OnClick="btnGo_Click" /> <asp:UpdatePanel runat="server"> <ContentTemplate> <asp:TextBox runat="server" ID="txtVal1" /> </ContentTemplate> </asp:UpdatePanel> </form> Then, in code behind, we have the following: protected void btnGo_Click(object sender, EventArgs e) { Thread.Sleep(5000); Debug.WriteLine(string.Format("{0}: {1}", DateTime.Now.ToString("HH:MM:ss.fffffff"), txtVal1.Text)); txtVal1.Text = ""; } If you run this and click on the "Go" button multiple times you will see multiple debug statements on the "Output" window showing that multiple requests have been processed. This appears to contradict the documented behaviour of update panels (i.e. If you make a request while one is processing, the first requests gets terminated and the current one is processed). Anyway, the point is I want to fix it. The obvious option would be to use Javascript to disable the button after the first press, but that strikes me as hard to maintain, we potentially have the same issue on a lot of screens it could be easily broken if someone renames a button. Do you have any suggestions? Perhaps there is something I could do in BeginRequest in Global.asax to detect a duplicate request? Is there some setting or feature on the UpdatePanel to stop it doing this, or maybe something in the AjaxControlToolkit that will prevent it?

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• How should I generate the partitions / pairs for the Chinese Postman problem?

  - by Simucal

  I'm working on a program for class that involves solving the Chinese Postman problem. Our assignment only requires us to write a program to solve it for a hard-coded graph but I'm attempting to solve it for the general case on my own. The part that is giving me trouble is generating the partitions of pairings for the odd vertices. For example, if I had the following labeled odd verticies in a graph: 1 2 3 4 5 6 I need to find all the possible pairings / partitions I can make with these vertices. I've figured out I'll have i paritions given: n = num of odd verticies k = n / 2 i = ((2k)(2k-1)(2k-2)...(k+1))/2 So, given the 6 odd verticies above, we will know that we need to generate i = 15 partitions. The 15 partions would look like: 1 2 3 4 5 6 1 2 3 5 4 6 1 2 3 6 4 5 ... 1 6 ... Then, for each partition, I take each pair and find the shortest distance between them and sum them for that partition. The partition with the total smallest distance between its pairs is selected, and I then double all the edges between the shortest path between the odd vertices (found in the selected partition). These represent the edges the postman will have to walk twice. At first I thought I had worked out an appropriate algorithm for generating these partitions / pairs but it is flawed. I found it wasn't a simple permutation/combination problem. Does anyone who has studied this problem before have any tips that can help point me in the right direction for generating these partitions?

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• Core principles, rules, and habits for CS students

  - by Asad Butt

  No doubt there is a lot to read on blogs, in books, and on Stack Overflow, but can we identify some guidelines for CS students to use while studying? For me these are: Finish your course books early and read 4-5 times more material relative to your course work. Programming is the one of the fastest evolving professions. Follow the blogs on a daily basis for the latest updates, news, and technologies. Instead of relying on assignments and exams, do at least one extra, non-graded, small to medium-sized project for every programming course. Fight hard for internships or work placements even if they are unpaid, since 3 months of work 1 year at college. Practice everything, every possible and impossible way. Try doing every bit of your assignments project yourself; i.e. fight for every inch. Rely on documentation as the first source for help and samples, Google, and online forums as the last source. Participate often in online communities and forums to learn the best possible approach for every solution to your problem. (After doing your bit.) Make testing one of your habits as it is getting more important everyday in programming. Make writing one of your habits. Write something productive once or twice a week and publish it.

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• Comprehending the Semantic web and it's methods, syntax, vocabularies and languages

  - by DreamCodeR

  Hi. I have just been introduced to the semantic web and it's family of functions but I have a hard time understanding some of it, which I was hoping someone could explain to me. As far as I've understood, RDF can be written in several syntaxes. RDF/XML, Turtle, etc. Now, I understand XML. How it is presented and how it can be parsed. However, some people write in the turtle syntax, but how do they parse that information? I can't seem to find a single library for any language to "extract" the information written in a turtle syntax into another form. The same goes for N3. How can it be used? Executed or else? I seem to be able to understand RDFa. That it is a way to implement RDF into XHTML. For me that is a way to implement RDF into "something". But how can I compare that to turtle, N3, or the like? Thanks in advance.

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• Swig C++ Lua Pass class by reference

  - by Jeremy

  I don't know why I'm having a hard time with this. All I want to do is this: class foo { public: foo(){} ~foo(){} float a,b; }; class foo2 { public: foo2(){} foo2(const foo &f){*this = f;} ~foo2(){} void operator=(const foo& f){ x = f.a; y = f.b; } float x,y; }; /* Usage(cpp): foo f; foo2 f2(f); //or using the = operator f2 = f; */ The problem I'm having is that, after swigging this code, I can't figure out how to make the lua script play nice. /* Usage(lua) f = example.foo() f2 = example.foo2(f) --error */ The error I get is "Wrong arguments for overloaded function 'new_Foo2'": Possible c/c++ prototypes are: foo2() foo2(foo const &) The same thing happens if I try and use do f2 = f. As I understand it everything is stored as a pointer so I did try adding an additional constructor that took a pointer to foo but to no avail.

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• Transitioning from desktop app written in C++ to a web-based app

  - by Karim

  We have a mature Windows desktop application written in C++. The application's GUI sits on top of a windows DLL that does most of the work for the GUI (it's kind of the engine). It, too, is written in C++. We are considering transitioning the Windows app to be a web-based app for various reasons. What I would like to avoid is having to writing the CGI for this web-based app in C++. That is, I would rather have the power of a 4G language like Python or a .NET language for creating the web-based version of this app. So, the question is: given that I need to use a C++ DLL on the backend to do the work of the app what technology stack would you recommend for sitting between the user's browser and are C++ dll? We can assume that the web server will be Windows. Some options: Write a COM layer on top of the windows DLL which can then be access via .NET and use ASP.NET for the UI Access the export DLL interface directly from .NET and use ASP.NET for the UI. Write a custom Python library that wraps the windows DLL so that the rest of the code can be written. Write the CGI using C++ and a C++-based MVC framework like Wt Concerns: I would rather not use C++ for the web framework if it can be avoided - I think languages like Python and C# are simply more powerful and efficient in terms of development time. I'm concerned that my mixing managed and unmanaged code with one of the .NET solutions I'm asking for lots of little problems that are hard to debug (purely anecdotal evidence for that) Same is true for using a Python layer. Anything that's slightly off the beaten path like that worries me in that I don't have much evidence one way or the other if this is a viable long term solution.

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• SVN Serve, Missing a Directory

  - by Ryan Smith

  I'm sure this is an asinine question, and I blame myself for not fully understanding how the SVNSERVE process works. I have an SVN repo, but it needs to be moved to a server within a clients cloud. I did this a while back and ran into the issue of the SVNSERVE.exe process not getting set to the right directory. I have the SVNSERVE.exe process running as a windows service and pointing to the right directory. There are two other repos there that are serving out fine in the same directory. I copied out the new directory just like I did with the others, but I'm getting the error "No repository found". I thought that SVNSERVE just looked at that directory and served out the repositories that were there, but I have had a hard time finding more information about that. I thought it was a Windows permission problem, but I set the whole folder to be full control to EVERYONE, so that's not it. I feel horrible I didn't fully understand this problem the first time I fought it, but it's late on a Sunday night and clients are yelling. Anyone know what I'm missing? Thanks. EDIT: It's specific to the repository. I tested the same process with some of the other repos we have on our server and when I copied them up, they worked just as expected. This bug is breaking me and I wish I could provide more details, but that's all I know. I'm going to try to do an SVN Dump instead of an XCopy and see how that goes. I'll let you know.

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• Intellisense on custom types in Iron Python

  - by Anish Patel

  Hi everybody, I'm just starting to play around with IronPython and am having a hard time using it with custom types created in C#. I can get IronPython to load in assemblies from C# classes, but I'm struggling without the help of intellisense. If I have a class in C# as defined below, how can I make it so that IronPython will be able to see the methods/properties that are available in it? public class Person { public string Name { get; set; } public int Age{ get; set; } public double Weight{ get; set; } public double Height { get; set; } public double CalculateBMI() { return Weight/Math.Pow(Height, 2); } } In Iron python I'd instance a Person object as follows: newPerson = Person() newPerson.Name = 'John' newPerson.Age = 25 newPerson.Weight = 75 newPerson.Height = 1.70 newPerson.CalculateBMI() The thing that is annoying me is that I want to be able to say newPerson = Person() And then be able to see all the methods and properties associated with the person object whenever I type: newPerson. Anyone have any ideas if this can be done?

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• ASP.Net MVC 2 - How to set up a Cancel button with client side navigation

  - by arame3333

  Thanks to a previous question I found a useful link on multiple buttons. http://weblogs.asp.net/dfindley/archive/2009/05/31/asp-net-mvc-multiple-buttons-in-the-same-form.aspx What I want to do is have a cancel button on my page, similar to this; <button name="button" type="button" onclick="document.location.href=$('#cancelUrl').attr('href')">Cancel</button> <a id="cancelUrl" href="<%: Url.Action("Index", "Home") %>" style="display:none;"></a> However although this code works, I really want to go back to the previous page. For Web Forms I could use the javascript Back() or Go(-1) functions, but they relied on postbacks. I could of course hard code the previous page and controller as I have done above. However I am struggling to find links that explain to me how Url.Action works. Because if I do this, I also need to include an index parameter, and I am not clear how the syntax works for that. It seems odd the amount of coding to do this. Out of curiosity, I am also wondering how you TDD client side code like this.

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• Sell me Distributed revision control

  - by ring bearer

  I know 1000s of similar topics floating around. I read at lest 5 threads here in SO But why am I still not convinced about DVCS? I have only following questions (note that I am selfishly worried only about Java projects) What is the advantage or value of committing locally? What? really? All modern IDEs allows you to keep track of your changes? and if required you can restore a particular change. Also, they have a feature to label your changes/versions at IDE level!? what if I crash my hard drive? where did my local repository go? (so how is it cool compared to checking in to a central repo?) Working offline or in an air plane. What is the big deal?In order for me to build a release with my changes, I must eventually connect to the central repository. Till then it does not matter how I track my changes locally. Ok Linus Torvalds gives his life to Git and hates everything else. Is that enough to blindly sing praises? Linus lives in a different world compared to offshore developers in my mid-sized project? Pitch me!

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• Client Web Browser Behavior When Handling 301 Redirect

  - by Jon Swanson

  The RFC seems to suggest that the client should permanently cache the response: http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html 10.3.2 301 Moved Permanently The requested resource has been assigned a new permanent URI and any future references to this resource SHOULD use one of the returned URIs. Clients with link editing capabilities ought to automatically re-link references to the Request-URI to one or more of the new references returned by the server, where possible. This response is cacheable unless indicated otherwise. The new permanent URI SHOULD be given by the Location field in the response. Unless the request method was HEAD, the entity of the response SHOULD contain a short hypertext note with a hyperlink to the new URI(s). If the 301 status code is received in response to a request other than GET or HEAD, the user agent MUST NOT automatically redirect the request unless it can be confirmed by the user, since this might change the conditions under which the request was issued. Note: When automatically redirecting a POST request after receiving a 301 status code, some existing HTTP/1.0 user agents will erroneously change it into a GET request. I'm having a hard time finding concrete browser documentation for any major browser that states how they handle these. I've started digging through the source code of firefox, but quickly got lost. Is the following scenario true for which (if any) browsers, and is there definitive documentation for either Firefox or IE that states as much?: First Time Around: 1.1: User enters link to site A, or clicks on a link directed at Site A 1.2: Browser interprets link at Site A, first time, no cache. Sends GET to Site A. 1.2: Site A responds with 301 Redirect to Site B 1.3: Browser sends GET to Site B. Any Subsequent Times Around: 2.2: User clicks on a link directed at Site A 2.2: Browser sees that, due to a past 301 redirect, Site A should now be Site B. 2.3: Without initiating any request whatsoever at Site A, browser initiates GET at Site B.

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• How can I visualise a "broken" hierarchical dataset?

  I have a reasonably large datatable structured something like this: StaffNo Grade Direct Boss2 Boss3 Boss4 Boss5 Boss6 ------- ----- ----- ----- ----- ----- ----- ----- 10001 1 10002 10002 10057 10094 10043 10099 10002 2 10057 NULL 10057 10094 10043 10099 10003 1 10004 10004 10057 10094 10043 10099 10004 2 10057 NULL 10057 10094 10043 10099 10057 3 10094 NULL NULL 10094 10043 10099 etc.... i.e. a unique id , their level (grade) in the hierarchy, a record of their bosses ID and the IDs of the supervisors above. (The 2,3,4, etc refers to the boss at that particular grade). The system relies on a strict hierarchy - if you are my boss (/parent) then your boss must be my grandparent. Unfortunately this rule is not enforced within the data model and the data ultimately comes from other systems which don't even know about the rule, let alone observe it. So you and I may share the same boss, but our bosses boss won't be the same. note: I cannot change the data model I cannot fix the data at source. So (for the moment) I have to fix the data once it's in place. Once a fortnight someone will do something which breaks the model and I'll need to modify the procs slightly to resolve. Not ideal, but I'm stuck with this for the next six months. Anyway, specific queries are easy to produce but I find it hard to keep track of the bigger picutre. The application which sits on this runs without complaint regardless but navigating around the system becoming extraordinarily confusing. So my question is: Can anyone recommend a tool (or technique) for generating some kind of "broken tree" diagram in this sort of circumstances? I don't want something that will fix things for me, or attempt statistical analysis but at least something that will give a visual indication of how broken it is at any one time. Note : At the moment this is in a SQL Server database but I'm open to ideas utilising C#, Perl or Python.

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• C++ Beginner Delete Question

  - by Pooch

  Hi all, This is my first year learning C++ so bear with me. I am attempting to dynamically allocate memory to the heap and then delete the allocated memory. Below is the code that is giving me a hard time: // String.cpp #include "String.h" String::String() {} String::String(char* source) { this->Size = this->GetSize(source); this->CharArray = new char[this->Size + 1]; int i = 0; for (; i < this->Size; i++) this->CharArray[i] = source[i]; this->CharArray[i] = '\0'; } int String::GetSize(const char * source) { int i = 0; for (; source[i] != '\0'; i++); return i; } String::~String() { delete[] this->CharArray; } Here is the error I get when the compiler tries to delete the CharArray: 0xC0000005: Access violation reading location 0xccccccc0. And here is the last call on the stack: msvcr100d.dll!operator delete(void * pUserData) Line 52 + 0x3 bytes C++ I am fairly certain the error exists within this piece of code but will provide you with any other information needed. Oh yeah, using VS 2010 for XP. Thanks for any and all help!

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• Merge Multple Worksheets From Multple Workbooks

  - by Droter

  Hi, I have found multiple posts on merging data but I am still running into some problems. I have multiple files with multiple sheets. Example 2007-01.xls...2007-12.xls in each of these files are daily data on sheets labeled 01, 02, 03 ..... There are other sheets in the file so I can't just loop through all worksheets. I need to combine the daily data into monthly data, then all of the monthly data points into yearly. On the monthly data I need it to be added to the bottom of the page. I have added the file open changes for Excel 2007 Here is what I have so far: Sub RunCodeOnAllXLSFiles() Dim lCount As Long Dim wbResults As Workbook Dim wbMaster As Workbook Application. ScreenUpdating = False Application.DisplayAlerts = False Application.EnableEvents = False On Error Resume Next Set wbMaster = ThisWorkbook Dim oWbk As Workbook Dim sFil As String Dim sPath As String sPath = "C:\Users\test\" 'location of files ChDir sPath sFil = Dir("*.xls") 'change or add formats Do While sFil <> "" 'will start LOOP until all files in folder sPath have been looped through Set oWbk = Workbooks.Open(sPath & "\" & sFil) 'opens the file Set oWbk = Workbooks.Open(sPath & "\" & sFil) Sheets("01").Select ' HARD CODED FIRST DAY Range("B6:F101").Select 'AREA I NEED TO COPY Range("B6:F101").Copy wbMaster.Activate Workbooks("wbMaster").ActiveSheet.Range("B65536").End(xlUp)(2).PasteSpecial Paste:=xlValues Application.CutCopyMode = False oWbk.Close True 'close the workbook, saving changes sFil = Dir Loop ' End of LOOP On Error Goto 0 Application.ScreenUpdating = True Application.DisplayAlerts = True Application.EnableEvents = True End Sub Right now it can find the files and open them up and get to the right worksheet but when it tries to copy the data nothing is copied over. Thanks for your help, Matt

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• Is it possible to group records belonging to an entity in dbunit?

  - by Joshua

  Our JPA entity model auto-generates primary key identifiers for user, user_address tables. Would it be possible to group these entities given below via dbunit, so that I don't need to provide neither the primary key as well as the foreign key reference from user_address.user_id. It is getting very hard to maintain these keys (i.e. I would prefer to group the primary record 'user' and the child records 'user_address' so that dbunit can group them automatically by looking up the entity metadata). Is it achievable? <user id="1" first_name="Josh" creation_date="2009-07-11 15:45:28"/> <user_address id="1" user_id="1" address="Main St" city="Los Angeles"/> I would prefer something like this <!-- First user --> <user first_name="Josh" creation_date="2009-07-11 15:45:28"/> <user_address address="Main St" city="Los Angeles"/> <!-- Second user --> <user first_name="Mary" creation_date="2009-07-11 15:45:28"/> <user_address address="Taylors St" city="San Jose"/>

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• .NET - Is there a way to programmatically fill all tables in a strongly-typed dataset?

  - by Mike Loux

  Hello, all! I have a SQL Server database for which I have created a strongly-typed DataSet (using the DataSet Designer in Visual Studio 2008), so all the adapters and select commands and whatnot were created for me by the wizard. It's a small database with largely static data, so I would like to pull the contents of this DB in its entirety into my application at startup, and then grab individual pieces of data as needed using LINQ. Rather than hard-code each adapter Fill call, I would like to see if there is a way to automate this (possibly via Reflection). So, instead of: Dim _ds As New dsTest dsTestTableAdapters.Table1TableAdapter.Fill(_ds.Table1) dsTestTableAdapters.Table2TableAdapter.Fill(_ds.Table2) <etc etc etc> I would prefer to do something like: Dim _ds As New dsTest For Each tableName As String In _ds.Tables Dim adapter as Object = <routine to grab adapter associated with the table> adapter.Fill(tableName) Next Is that even remotely doable? I have done a fair amount of searching, and I wouldn't think this would be an uncommon request, but I must be either asking the wrong question, or I'm just weird to want to do this. I will admit that I usually prefer to use unbound controls and not go with strongly-typed datasets (I prefer to write SQL directly), but my company wants to go this route, so I'm researching it. I think the idea is that as tables are added, we can just refresh the DataSet using the Designer in Visual Studio and not have to make too many underlying DB code changes. Any help at all would be most appreciated. Thanks in advance!

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• Python: How can I use Twisted as the transport for SUDS?

  - by jathanism

  I have a project that is based on Twisted used to communicate with network devices and I am adding support for a new vendor (Citrix NetScaler) whose API is SOAP. Unfortunately the support for SOAP in Twisted still relies on SOAPpy, which is badly out of date. In fact as of this question (I just checked), twisted.web.soap itself hasn't even been updated in 21 months! I would like to ask if anyone has any experience they would be willing to share with utilizing Twisted's superb asynchronous transport functionality with SUDS. It seems like plugging in a custom Twisted transport would be a natural fit in SUDS' Client.options.transport, I'm just having a hard time wrapping my head around it. I did come up with a way to call the SOAP method with SUDS asynchronously by utilizing twisted.internet.threads.deferToThread(), but this feels like a hack to me. Here is an example of what I've done, to give you an idea: # netscaler is a module I wrote using suds to interface with NetScaler SOAP # Source: http://bitbucket.org/jathanism/netscaler-api/src import netscaler import os import sys from twisted.internet import reactor, defer, threads # netscaler.API is the class that sets up the suds.client.Client object host = 'netscaler.local' username = password = 'nsroot' wsdl_url = 'file://' + os.path.join(os.getcwd(), 'NSUserAdmin.wsdl') api = netscaler.API(host, username=username, password=password, wsdl_url=wsdl_url) results = [] errors = [] def handleResult(result): print '\tgot result: %s' % (result,) results.append(result) def handleError(err): sys.stderr.write('\tgot failure: %s' % (err,)) errors.append(err) # this converts the api.login() call to a Twisted thread. # api.login() should return True and is is equivalent to: # api.service.login(username=self.username, password=self.password) deferred = threads.deferToThread(api.login) deferred.addCallbacks(handleResult, handleError) reactor.run() This works as expected and defers return of the api.login() call until it is complete, instead of blocking. But as I said, it doesn't feel right. Thanks in advance for any help, guidance, feedback, criticism, insults, or total solutions.

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• Domain model: should things like Logging, Audit, Persistence be in it

  - by hom.tanks

  I'm having a hard time convincing our architect that a Domain model should only have the essential elements of the business domain on it. Things like the fact that a class is persistable, that it needs logging and auditing and that it has a RESTful URI should not drive the domain model. They can be added later on, by using interfaces. Ours is a healthcare information management system. At the very coarse level, its a system where users login and access their healthcare information. They can share this information with others and be custodian for others' information (think Roles). But because of a few sound bytes that caught on early like "Everything should be a REST resource" the model now has a top level class called Resource that every other class extends from. I'm trying to make him see that the domain model should have well defined concepts like User Account, HealthDocument, UserRole etc which are distinct entities of the business , with specific associations between them. Clubbing everything under Resource class lets our model be inflexible besides being potentially incorrect. But he wants me to show him why its a bad idea to do it his way. I don't know how to articulate that properly but all my OO instincts tell me that its just not right. Any thoughts?

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• PostgreSQL, Foreign Keys, Insert speed & Django

  - by Miles

  A few days ago, I ran into an unexpected performance problem with a pretty standard Django setup. For an upcoming feature, we have to regenerate a table hourly, containing about 100k rows of data, 9M on the disk, 10M indexes according to pgAdmin. The problem is that inserting them by whatever method literally takes ages, up to 3 minutes of 100% disk busy time. That's not something you want on a production site. It doesn't matter if the inserts were in a transaction, issued via plain insert, multi-row insert, COPY FROM or even INSERT INTO t1 SELECT * FROM t2. After noticing this isn't Django's fault, I followed a trial and error route, and hey, the problem disappeared after dropping all foreign keys! Instead of 3 minutes, the INSERT INTO SELECT FROM took less than a second to execute, which isn't too surprising for a table <= 20M on the disk. What is weird is that PostgreSQL manages to slow down inserts by 180x just by using 3 foreign keys. Oh, disk activity was pure writing, as everything is cached in RAM; only writes go to the disks. It looks like PostgreSQL is working very hard to touch every row in the referred tables, as 3MB/sec * 180s is way more data than the 20MB this new table takes on disk. No WAL for the 180s case, I was testing in psql directly, in Django, add ~50% overhead for WAL logging. Tried @commit_on_success, same slowness, I had even implemented multi row insert and COPY FROM with psycopg2. That's another weird thing, how can 10M worth of inserts generate 10x 16M log segments? Table layout: id serial primary, a bunch of int32, 3 foreign keys to small table, 198 rows, 16k on disk large table, 1.2M rows, 59 data + 89 index MB on disk large table, 2.2M rows, 198 + 210MB So, am I doomed to either drop the foreign keys manually or use the table in a very un-Django way by defining saving bla_id x3 and skip using models.ForeignKey? I'd love to hear about some magical antidote / pg setting to fix this.

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• Looking for fast, minimal, preferrably free disc cloning software [closed]

  - by Dave

  We have to test our application installation and functionality on many Windows operating system versions and languages (XP, Vista, Win7; English, Spanish, Portuguese, etc; 32-bit & b4-bit.) While we can do much of this in virtual machines, we have noticed that VM's sometimes hide problems, or raise false bugs. So, we need to do "bare metal" OS installation for much of our testing. I have been using Acronis True Image for the past year, and am not impressed. It often gives random errors which require a reboot, and is really slow. For example, when trying to restore an image, it goes through a "Locking partition" cycle about three times (once after you click OK on each step of the wizard), each of which can take 5 minutes to complete. This all happens BEFORE it actually starts the image copy, which is sometimes quick (3-5 minutes), sometimes long (hours). The size of all of our images are roughly the same, so that is not related. So, anyway, I'm looking to switch to something else: I only need very basic functionality--just creating images of entire discs, and then restoring those images onto the exact same hard drive at a later date. That's it. I'm not opposed to paying for a good piece of software, but if there is something free out there that does the job well, that would be a preference. My OS on which the imaging software would run is Windows Vista, but a bootable media (into a Linux flavor) would be fine also, as long as its quick to use and reliable. Recommendations? (Also, moderators, if this should be a CW, I'll be happy to mark it as such; unclear about the rules there.)

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• named_scope + average is causing the table to be specified more then once in the sql query run on po

  - by hadees

  I have a named scopes like so... named_scope :gender, lambda { |gender| { :joins => {:survey_session => :profile }, :conditions => { :survey_sessions => { :profiles => { :gender => gender } } } } } and when I call it everything works fine. I also have this average method I call... Answer.average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") which also works fine if I call it like that. However if I were to call it like so... Answer.gender('m').average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") I get... ActiveRecord::StatementInvalid: PGError: ERROR: table name "profiles" specified more than once : SELECT avg("answers".rating) AS avg_rating, profiles.career AS profiles_career FROM "answers" LEFT OUTER JOIN "survey_sessions" survey_sessions_answers ON "survey_sessions_answers".id = "answers".survey_session_id LEFT OUTER JOIN "profiles" ON "profiles".id = "survey_sessions_answers".profile_id INNER JOIN "survey_sessions" ON "survey_sessions".id = "answers".survey_session_id INNER JOIN "profiles" ON "profiles".id = "survey_sessions".profile_id WHERE ("profiles"."gender" = E'm') GROUP BY profiles.career Which is a little hard to read but says I'm including the table profiles twice. If I were to just remove the include from average it works but it isn't really practical because average is actually being called inside a method which gets passed the scoped. So there is some times gender or average might get called with out each other and if either was missing the profile include it wouldn't work. So either I need to know how to fix this apparent bug in Rails or figure out a way to know what scopes were applied to a ActiveRecord::NamedScope::Scope object so that I could check to see if they have been applied and if not add the include for average.

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• Python: circular imports needed for type checking

  - by phild

  First of all: I do know that there are already many questions and answers to the topic of the circular imports. The answer is more or less: "Design your Module/Class structure properly and you will not need circular imports". That is true. I tried very hard to make a proper design for my current project, I in my opinion I was successful with this. But my specific problem is the following: I need a type check in a module that is already imported by the module containing the class to check against. But this throws an import error. Like so: foo.py: from bar import Bar class Foo(object): def __init__(self): self.__bar = Bar(self) bar.py: from foo import Foo class Bar(object): def __init__(self, arg_instance_of_foo): if not isinstance(arg_instance_of_foo, Foo): raise TypeError() Solution 1: If I modified it to check the type by a string comparison, it will work. But I dont really like this solution (string comparsion is rather expensive for a simple type check, and could get a problem when it comes to refactoring). bar_modified.py: from foo import Foo class Bar(object): def __init__(self, arg_instance_of_foo): if not arg_instance_of_foo.__class__.__name__ == "Foo": raise TypeError() Solution 2: I could also pack the two classes into one module. But my project has lots of different classes like the "Bar" example, and I want to seperate them into different module files. After my own 2 solutions are no option for me: Has anyone a nicer solution for this problem?

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• postgres stored procedure problem

  - by easyrider

  Hi all, Ich have a problem in postgres function: CREATE OR REPLACE FUNCTION getVar(id bigint) RETURNS TABLE (repoid bigint, suf VARCHAR, nam VARCHAR) AS $$ declare rec record; BEGIN FOR rec IN (WITH RECURSIVE children(repoobjectid,variant_of_object_fk, suffix, variantname) AS ( SELECT repoobjectid, variant_of_object_fk, '' as suffix,variantname FROM b2m.repoobject_tab WHERE repoobjectid = id UNION ALL SELECT repo.repoobjectid, repo.variant_of_object_fk, suffix || '..' , repo.variantname FROM b2m.repoobject_tab repo, children WHERE children.repoobjectid = repo.variant_of_object_fk) SELECT repoobjectid,suffix,variantname FROM children) LOOP RETURN next; END LOOP; RETURN; END; It can be compiled, but if y try to call it select * from getVar(18) I got 8 empty rows with 3 columns. If i execute the following part of procedure with hard-coded id parameter: WITH RECURSIVE children(repoobjectid,variant_of_object_fk, suffix, variantname) AS ( SELECT repoobjectid, variant_of_object_fk, '' as suffix,variantname FROM b2m.repoobject_tab WHERE repoobjectid = 18 UNION ALL SELECT repo.repoobjectid, repo.variant_of_object_fk, suffix || '..' , repo.variantname FROM b2m.repoobject_tab repo, children WHERE children.repoobjectid = repo.variant_of_object_fk) SELECT repoobjectid,suffix,variantname FROM children I got exactly, what i need 8 rows with data: repoobjectid suffix variantname 18 19 .. for IPhone 22 .. for Nokia 23 .... OS 1.0 and so on. What is going wrong ? Please help. Thanx in advance

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• How to store an inventory using hashtables?

  - by Harm De Weirdt

  Hello everyone. For an assignment in collego we have to make a script in Perl that allows us to manage an inventory for an e-store. (The example given was Amazon) Users can make orders in a fully text-based environment and the inventory must be updated when an order is completed. Every item in the inventory has 3 to 4 attributes: a product code, a title, a price and for some an amount (MP3's for example do not have this attribute) Since this is my first encounter with Perl, i don't really know how to start. My main problem is how i should "implement" the inventory in the program. One of the functions of the program is searching trough the titles. Another is to make an order, where the user should give a product code. My first idea was a hashtable with the productcode as key. But if i wanted to search in the titles that could be a problem because of this: the hashkey would be something like DVD-123, the information belonging to that key could be "The Green Mask 12" (without the ") where the 12 indicates how many of this DVD are currently in stock. So i'd have to find a way to ignore the 12 in the end. Another solution was to use the title as Hashkey, but that would prove cumbersome too I think. Is there a way to make a hashtable with 2 key's, and when I give only one it returns an array with the other values? (Including the other key and the other information) That way I could use another key depending on what info I need from my inventory. We have to read the default inventory from a txt file looking like this: MP3-72|Lady Gaga - Kiss and Run (Fear of Commitment Monster)|0.99 CD-400|Kings of Leon - Only By The Night|14.50|2 MP3-401|Kings of Leon - Closer|0.85 DVD-144|Live Free or Die Hard|14.99|2 SOFT-864|Windows Vista|49.95 Any help would be appreciated very much :) PS: I am sorry for my bad grammar, English isn't my native language.

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