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  • Is it bad practice to initialize a variable to a dummy value?

    - by froadie
    This question is a result of the answers to this question that I just asked. It was claimed that this code is "ugly" because it initializes a variable to a value that will never be read: String tempName = null; try{ tempName = buildFileName(); } catch(Exception e){ ... System.exit(1); } FILE_NAME = tempName; Is this indeed bad practice? Should one avoid initializing variables to dummy values that will never actually be used? (EDIT - And what about initializing a String variable to "" before a loop that will concatenate values to the String...? Or is this in a separate category? e.g. String whatever = ""; for(String str : someCollection){ whatever += str; } )

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  • Django store regular expression in DB which then gets evaluated on page

    - by John
    Hi, I want to store a number of url patterns in my django model which a user can provide parameters to which will create a url. For example I might store these 3 urls in my db where %s is the variable parameter provided by the user: www.thisissomewebsite.com?param=%s www.anotherurl/%s/ www.lastexample.co.uk?param1=%s&fixedparam=2 As you can see from these examples the parameter can appear anywhere in the string and not in a fixed position. I have 2 models, one holds the urls and one holds the variables: class URLPatterns(models.Model): pattern = models.CharField(max_length=255) class URLVariables(models.Model): pattern = models.ForeignKey(URLPatterns) param = models.CharField(max_length=255) What would be the best way to generate these urls by replacing the %s with the variable in the database. would it just be a simple replace on the string e.g: urlvariable = URLVariable.objects.get(pk=1) pattern = url.pattern url = pattern.replace("%s", urlvariable.param) or is there a better way? Thanks

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  • How to access function inside PHP OOP

    - by Industrial
    Hi everyone, What do I need to do to call $this-two() from inside my function innerOne? Is that possible with PHP OOP? Here's the error I am recieving: Fatal error: Using $this when not in object context Here's how my code looks: class myClass { function one(){ function innerOne() { // Some code $this->two($var1, $var2); } // Some code innerOne(); } function two($var1, $var2) { // Does magic with passed variables return $var1 . $var2; } } Thanks a lot!

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  • C++ Static Array Initialization - Memory Issue

    - by donalmg
    Hi, I have a header file which contains a member variable declaration of a static char array: class ABC { public: static char newArray[4]; // other variables / functions private: void setArray(int i, char * ptr); } In the CPP file, I have the array initialized to NULL: char ABC::newArray[4] = {0}; In the ABC constructor, I need to overwrite this value with a value constructed at runtime, such as the encoding of an integer: ABC::ABC() { int i; //some int value defined at runtime memset(newArray, 0, 4); // not sure if this is necessary setArray(i,newArray); } ... void setArray(int i, char * value) { // encoding i to set value[0] ... value [3] } When I return from this function, and print the modified newArray value, it prints out many more characters than the 4 specified in the array declaration. Any ideas why this is the case. I just want to set the char array to 4 characters and nothing further. Thanks...

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  • Shared memory of same DLL in different 32 bit processes is sometimes different in a terminal session

    - by KBrusing
    We have an 32 bit application consisting of some processes. They communicate with shared memory of a DLL used by every process. Shared memory is build with global variables in C++ by "#pragma data_seg ("Shared")". When running this application sometime during starting a new process in addition to an existing (first) process we observe that the shared memory of both processes is not the same. All new started processes cannot communicate with the first process. After stopping all of our processes and restarting the application (with some processes) everything works fine. But sometime or other after successfully starting and finishing new processes the problem occurs again. Running on all other Windows versions or terminal sessions on Windows server 2003 our application never got this problem. Is there any new "feature" on Windows server 2008 that might disturb the hamony of our application?

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  • Iterating through a range of dates in Python

    - by ShawnMilo
    This is working fine, but I'm looking for any feedback on how to do it better. Right now I think it's better than nested loops, but it starts to get Perl-one-linerish when you have a generator in a list comprehension. Any suggestions are welcome. day_count = (end_date - start_date).days + 1 for single_date in [d for d in (start_date + timedelta(n) for n in range(day_count)) if d <= end_date]: print strftime("%Y-%m-%d", single_date.timetuple()) Notes: I'm not actually using this to print; that's just for demo purposes. The variables start_date and end_date are datetime.date objects, because I don't need the timestamps (they're going to be used to generate a report). I checked the StackOverflow questions which were similar before posting this, but none were exactly the same. Sample Output (for a start date of 2009-05-30 and an end date of 2009-06-09): 2009-05-30 2009-05-31 2009-06-01 2009-06-02 2009-06-03 2009-06-04 2009-06-05 2009-06-06 2009-06-07 2009-06-08 2009-06-09

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  • How to manage member variable in C++

    - by rhapsodyn
    In brief, my question is about member variables as pointers in unmanaged C++. In java or c#, we have "advanced pointer". In fact, we can't aware the "pointer" in them. We usually initialize the member of a class like this: member = new Member(); or member = null; But in c++, it becomes more confusing. I have seen many styles: using new, or leave the member variable in stack. In my point of view, using boost::shared_ptr seems friendly, but in boost itself source code there are news everywhere. It's the matter of efficiency,isn't it? Is there a guildline like "try your best to avoid new" or something?

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  • looping and arrays

    - by user1838418
    Hi I'm trying to construct a loop to execute 16 states of the 8 4 2 1 code in (C++) while( condition) { double Bubble[16], Bubble1[16]; Bubble[0] = ( a-2 - (b-2) ) + ( c-2 - (d-2)); // represents 0000 Bubble[1] = ( a-2 - (b-2) ) + ( c-2 - (d+2)); // represents 0001 Bubble[2] = ( a-2 - (b-2) ) + ( c+2 - (d-2)); // represents 0010 Bubble[3] = ( a-2 - (b-2) ) + ( c+2 - (d+2)); //represents 0011 ....... Bubble[15] =(a+2 - (b+2) ) + ( c+2 - (d+2)); //represents 1111 } Is there an easy way of coding using for loops? instead of writing bubble[] every time? 0 stands for -2 and 1 stands for +2. So I have 4 variables and each one need to be incremented and/or decremented. Can this be done using for loop? Appreciate your help

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  • Getting a java collection of objects in Alphabetical order

    - by MichaelMcCabe
    I have a question that I dont really know where to start. So I thought i'd ask it here. Basically, I have a drop down with names in it. I want these names to be in alphabetical order. Populating the drop down happens as follows; I query a database and pull down an Id and Name, make a object called "UserList", and set the name and id variables with what I get back. I then add this object to an ArrayList. I do this over and over. I then convert this collection to an array, and pass it to my JSP page using session.setAttribute("userList", UserList); I then populate the drop down as below. <c:forEach items="${usersCompanysList}" var="c" > There probably is a simple answer but how to I sort these names?

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  • javascript function pointer and "this"

    - by Justin808
    I'm passing a method as a variable to be used as a callback. When its called, the "this" is not the object the method is a member of. How do I go about getting access to the method's object instance so I can get access to it variables and other member functions? I have no control over the callback call method, its a separate library. All I do is call the binding from my object init method. I would have expected this inside my _connection method to have been its object. jsPlumb.bind('connection', this._connection);

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  • Capture variable assignments in a Perl eval

    - by Bruce
    I would like to be able to capture variable assignments from a Perl eval. That is, to determine what variable names have been assigned to within the code and extract their value. For example if I run: eval '$foo=42; $bar=3.14;' The result of the eval is 3.14 (the last value evaluated), but I would also like to be able to determine the names "$foo" and "$bar" and their values (without knowing the names in advance). I have read up on a couple of ways of inserting variables into the eval block, through Safe and Eval::Context, but not yet any way of extracting them. I am more familiar with Python's eval/exec which have built in support for this.

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  • Rendering HTML in rails without actually displaying it

    - by Kevin Whitaker
    Hello all, My current project requires me to assemble a .zip file containing HTML and text-only templates for a user to download, for importing into an email marketing program. I've inherited this project, and currently the code uses a "fake" model (that is a model that does not directly correlate to a database table), in which it stores the entire template in a string, using dynamic variables to populate certain areas. The "fake" model then has a method for creating a zip file. It seems to me that there has to be a better way to do this. I was wondering if there was a way to move the template into a .erb/haml file, and then write a method that would populate the file in preparation for being zipped up? Basically, is there a way to render an HTML and text file, without actually having to display them? Thanks for any help.

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  • session_regenerate_id(true) not work

    - by user995789
    I use wampserver2.1 php5.3.3, I found session_regenerate_id(true) not work in my script,document says when I set the parameter 'delete_old_sessions' true, there should be a new sid and all the session variables should be deleted, but the fact is after the function, $_session[abc] is still there. did I misunderstand the function,what is my problem? I appreciate if anyone can help me, <?php session_start(); $_SESSION['abc']=12323; session_regenerate_id(true); echo $_SESSION['abc']; ?> I thought it should display none, but it outputs:12323

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  • Possible to exclude a column from `*` ?

    - by Earlz
    Is it possible to exclude a column from a select * from table statement with SQL Server? I have a need for this and this is my only option other than parsing a raw SQL string to get out the required field names (I really don't want to do that). Just to be bold. When the query is made I do not have access to the list of fields needed from the table but I do know which field I do not need. This is part of a complex multi-part query. Surely there must be some way even if it's "hackish" such as using table variables or views

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  • Getting MATLAB variable (string) from C

    - by Hamming
    Hi! I'm writing a small C application that launchs a Matlab script (.m file). I need to exchange some variables and I don't know how to get an array of chars that exists in Matlab. I'm doing something like this: enter code here result = engGetVariable(ep,"X"); if (!result) { printf ("Error..."); exit -1; } int n = mxGetN(result); char *varx = NULL; memcpy(varx, mxGetData(result),n*sizeof(char)); It doesn't work. Does someone know how to get a Matlab string in C? I've read Matlab documentation about engGetVariable() and the provided example but any of this things clarify me.

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  • Multithreaded SDL error in C++

    - by wyatt
    I'm building a program in C++, using SDL, and am occasionally receiving this error: * glibc detected * ./assistant: double free or corruption (!prev) It's difficult to replicate, so I can't find exactly what's causing it, but I just added a second thread to the program, and neither thread run on its own seems to cause the error. The threads don't share any variables, though they both run the functions SDL_BlitSurface and SDL_Flip. Could running these concurrently throw up such an error, or am I barking up the wrong tree? If this is the cause, should I simply throw a mutex around all SDL calls? Thanks

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  • Drop Columns R Data frame

    - by Btibert3
    I have a number of columns that I would like to drop from a data frame. I know that we can drop them using something like: df$x <- NULL but I was hoping to do this with less commands. Also, I know that I could use this: df[ -c(1,3:6, 12) ] but I am concerned that the relative position of my variables may change. Given how powerful R is, I figured I would ask to see if there is another way beyond dropping each column 1 by 1. Thanks in advance.

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  • Parsing C# Script into Java

    - by pantaryl
    I'm looking for a way to easily read in a C# file and place it into a Java Object for database storage (storing the class name, functions, variables, etc). I'm making a Hierarchical State Machine AI Building Tool for a game I'm creating and need to be able to import an existing C# file and store it in a database for retrieval in the future. Does anyone know of any preexisting libraries for parsing C# files? Something similar to JavaParser? Thanks everyone! EDIT: This needs to be part of my Java Project. I'll be loading in the C# files through my Java Application and saving it into my db4o database.

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  • MySql paging; "Showing result-set" of "total found" help

    - by Camran
    I need a formula for showing results on my classifieds website. I am now done with the paging of records, but this formula for showing results remains. I want it like this: Showing 1-50 of 123 found. Now what is the formula for this? I have these variables which should be enough I think: $results_per_page = 50; //results per page $page = 1; //current page Also a variable called $num_total contains the total nr of hits, in this case 123. Thanks

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  • Call OnDraw in another method, then "refresh" that call in ANOTHER method.

    - by Aidan
    Hey guys, Hopefully this will actually make sense and sorry if its a stupid / obvious question. Basically I'm calling the onDraw method like so... requestWindowFeature(Window.FEATURE_NO_TITLE); Preview mPreview = new Preview(this); DrawOnTop mDraw = new DrawOnTop(this); setContentView(mPreview); addContentView(mDraw, new LayoutParams (LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); You see I'm drawing it on top of a Camera view and the information being drawn is subject to change. I have a listener setup which will update the variables being drawn at the appropriate time but I now want to "refresh" this draw in that listener. How would I do such a thing?

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  • Haskell Weird Kinds

    - by SHiNKiROU
    When I was experimenting with Haskell kinds, and trying to get the kind of ->, and this showed up: $ ghci ... Prelude> :k (->) (->) :: ?? -> ? -> * Prelude> Instead of the expected * -> * -> *. What are the ?? and ? things? Do they mean concrete types or "kind variables"? Or something else?

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  • Counting multiple rows in MySQL in one query

    - by diggersworld
    I currently have a table which stores a load of statistics such as views, downloads, purchases etc. for a multiple number of items. To get a single operation count on each item I can use the following query: SELECT , COUNT() FROM stats WHERE operation = 'view' GROUP BY item_id This gives me all the items and a count of their views. I can then change 'view' to 'purchase' or 'download' for the other variables. However this means three separate calls to the database. Is it possible to get all three in one go?

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  • javascript var declaration within loop

    - by Trouts
    hello, /*Test scope problem*/ for(var i=1; i<3; i++){ //declare variables var no = i; //verify no alert('setting '+no); //timeout to recheck setTimeout(function(){ alert('test '+no); }, 500); } it alerts "setting 1" and "setting 2" as expected, but after the timeout it outputs "test 2" twice - for some reason the variable "no" is not reset after the first loop... i've found only an "ugly" workaround... /*Test scope problem*/ var func=function(no){ //verify no alert('setting '+no); //timeout to recheck setTimeout(function(){ alert('test '+no); }, 500); } for(var i=1; i<3; i++){ func(i); } Any ideas on how to workaround this problem in a more direct way? or is this the only way?

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  • How to restore data on Power Failure using C++ programming on windows.

    - by Tarun
    Hi, In my program I am writing a file of my programs states. I am writing the file many times to the file during the program run, because the program changes some variables that that i need to store very frequently. Now, if , for some reasons my power fails. Then most of the time I loose data in that file. Please, tell me any mechanism which can protect data even if the power fails. (I have written C++ program on windows). Thank you

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  • ADO Execute not reading a line of SQL code?

    - by llaskin
    My code is below: var statement = "test_oracle.sql"; F = aqFile.OpenTextFile(statement, aqFile.faRead, aqFile.ctANSI); F.Cursor = 0; while(! F.IsEndOfFile()){ s = F.ReadLine(); oResult = Project.Variables.oConnection.Execute_(s); CheckResult(oResult, "Unable to run SQL script to add documents"); The first line that "s" reads is: set serverout on size 10000 An error is returned as "ORA-00922: missing or invalid option" Can anyone provide guidance?

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