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  • get random password with puppet function

    - by ninja-2
    I have a function that allow me to generate random password. My function is working well without a puppetmaster. When i tried with a master an error appear when I called the function : Error 400 on SERVER: bad value for range Here is my function module Puppet::Parser::Functions newfunction(:get_random_password, :type => :rvalue, :doc => <<-EOS Returns a random password. EOS ) do |args| raise(Puppet::ParseError, "get_random_password(): Wrong number of arguments " + "given (#{args.size} for 1)") if args.size != 1 specials = ((33..33).to_a + (35..38).to_a + (40..47).to_a + (58..64).to_a + (91..93).to_a + (95..96).to_a + (123..125).to_a).pack('U*').chars.to_a numbers = (0..9).to_a alphal = ('a'..'z').to_a alphau = ('A'..'Z').to_a length = args[0] CHARS = (alphal + specials + numbers + alphau) pwd = CHARS.sort_by { rand }.join[0...length] return pwd end end The function is called in both case with $pwd = get_random_password(10). When I specified the length directly in the function to 10 for example. the password is well generated in master mode. Have you any idea why i can't specify the lentgth value ? Thanks for any help.

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  • C++ Recursive function that reverses the order of an array's indexes between two bounds

    - by CPT Kirk
    I am trying to write a recursive function that has three arguments; an array and two array indexes. The function should reverse the order of the values between the two indexes. I would like to understand what is happening instead of just being told an answer. Here is my code so far: #include <iostream> using namespace std; char switchAroo(char a[], int b1, int b2); int main() { char a[6] {'A', 'B', 'C', 'D', 'E', '\0'}; cout << a; switchAroo(a, 2, 5); return 0; } char switchAroo(char a [], int b1, int b2) { char temp; if (b1 == b2) cout << "The array after switchAroo is " << a << endl; else { temp = a[b1]; a[b1] = a[b2]; a[b2] = temp; b1++; b2--; return switchAroo(a, b1, b2); } } I am getting the following warning code: warning C4715: 'switchAroo' : not all control paths return a value Any help would be greatly appreciated.

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  • Getting memory leak at NSURL connection in Iphone sdk.

    - by monish
    Hi guys, Here Im getting leak at the NSURL connection in my libxml parser can anyone tell how to resolve it. The code where leak generates is: - (BOOL)parseWithLibXML2Parser { BOOL success = NO; ZohoAppDelegate *appDelegate = (ZohoAppDelegate*) [ [UIApplication sharedApplication] delegate]; NSString* curl; if ([cName length] == 0) { curl = @"https://invoice.zoho.com/api/view/settings/currencies?ticket="; curl = [curl stringByAppendingString:appDelegate.ticket]; curl = [curl stringByAppendingString:@"&apikey="]; curl = [curl stringByAppendingString:appDelegate.apiKey]; curl = [curl stringByReplacingOccurrencesOfString:@"\n" withString:@""]; } NSURLRequest *theRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:curl]]; NSLog(@"the request parserWithLibXml2Parser %@",theRequest); NSURLConnection *con = [[[NSURLConnection alloc] initWithRequest:theRequest delegate:self] autorelease];//Memory leak generated here at this line of code. //self.connection = con; //[con release]; // This creates a context for "push" parsing in which chunks of data that are // not "well balanced" can be passed to the context for streaming parsing. // The handler structure defined above will be used for all the parsing. The // second argument, self, will be passed as user data to each of the SAX // handlers. The last three arguments are left blank to avoid creating a tree // in memory. _xmlParserContext = xmlCreatePushParserCtxt(&simpleSAXHandlerStruct, self, NULL, 0, NULL); if(con != nil) { do { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]]; } while (!_done && !self.error); } if(self.error) { //NSLog(@"parsing error"); [self.delegate parser:self encounteredError:nil]; } else { success = YES; } return success; } Anyone's help will be muck appreciated . Thank you, Monish.

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  • C++ Iterator Pipelining Designs

    - by Kirakun
    Suppose we want to apply a series of transformations, int f1(int), int f2(int), int f3(int), to a list of objects. A naive way would be SourceContainer source; TempContainer1 temp1; transform(source.begin(), source.end(), back_inserter(temp1), f1); TempContainer2 temp2; transform(temp1.begin(), temp1.end(), back_inserter(temp2), f2); TargetContainer target; transform(temp2.begin(), temp2.end(), back_inserter(target), f3); This first solution is not optimal because of the extra space requirement with temp1 and temp2. So, let's get smarter with this: int f123(int n) { return f3(f2(f1(n))); } ... SourceContainer source; TargetContainer target; transform(source.begin(), source.end(), back_inserter(target), f123); This second solution is much better because not only the code is simpler but more importantly there is less space requirement without the intermediate calculations. However, the composition f123 must be determined at compile time and thus is fixed at run time. How would I try to do this efficiently if the composition is to be determined at run time? For example, if this code was in a RPC service and the actual composition--which can be any permutation of f1, f2, and f3--is based on arguments from the RPC call.

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  • Complicated .NET factory design

    - by Tom W
    Hello SO; I'm planning to ask a fairly elaborate question that is also something of a musing here, so bear with me... I'm trying to design a factory implementation for a simulation application. The simulation will consist of different sorts of entities i.e. it is not a homogenous simulation in any respect. As a result, there will be numerous very different concrete implementations and only the very general properties will be abstracted at the top level. What I'd like to be able to do is create new simulation entities by calling a method on the model with a series of named arguments representing the parameters of the entity, and have the model infer what type of object is being described by the inbound parameters (from the names of the parameters and potentially the sequence they occur in) and call a factory method on the appropriate derived class. For example, if I pass the model a pair of parameters (Param1=5000, Param2="Bacon") I would like it to infer that the names Param1 and Param2 'belong' to the class "Blob1" and call a shared function "getBlob1" with named parameters Param1:=5000, Param2:="Bacon" whereas if I pass the model (Param1=5000, Param3=50) it would call a similar factory method for Blob2; because Param1 and Param3 in that order 'belong' to Blob2. I foresee several issues to resolve: Whether or not I can reflect on the available types with string parameter names and how to do this if it's possible Whether or not there's a neat way of doing the appropriate constructor inference from the combinatoric properties of the argument list or whether I'm going to have to bodge something to do it 'by hand'. If possible I'd like the model class to be able to accept parameters as parameters rather than as some collection of keys and values, which would require the model to expose a large number of parametrised methods at runtime without me having to code them explicitly - presumably one for every factory method available in the relevant namespace. What I'm really asking is how you'd go about implementing such a system, rather than whether or not it's fundamentally possible. I don't have the foresight or experience with .NET reflection to be able to figure out a way by myself. Hopefully this will prove an informative discussion.

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  • Array indexOf implentation for Internet Explorer

    - by Daemon
    There are plenty of solutions on how to get the indexOf implementation into the Array prototype so that it works under Internet Explorer, however I've stumbled upon an issue that doesn't seem to be addressed anywhere I've looked so far. Using the pretty well agreed upon implementation at MDC, I have the following code that's being problematic now: // indexOf support for IE (from MDC) if (!Array.prototype.indexOf) { Array.prototype.indexOf = function(elt /*, from*/) { var len = this.length >>> 0; var from = Number(arguments[1]) || 0; from = (from < 0) ? Math.ceil(from) : Math.floor(from); if (from < 0) from += len; for (; from < len; from++) { if (from in this && this[from] === elt) return from; } return -1; }; } var i = [1,2,3,4]; for (j in i) { alert(i[j]); } I am expecting to receive 4 alerts, each one containing one of the elements of the array. In Firefox and Chrome, that's exactly what I see, however in IE8 I get an additional alert containing the indexOf function code. What can be done to avoid this?

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  • Error when feeding a mysql db with a python-parsed data

    - by Barnabe
    I use this bit of code to feed some data i have parsed from a web page to a mysql database c=db.cursor() c.executemany( """INSERT INTO data (SID, Time, Value1, Level1, Value2, Level2, Value3, Level3, Value4, Level4, Value5, Level5, ObsDate) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)""", clean_data ) The parsed data looks like this (there are several hundred such lines) clean_data = [(161,00:00:00,8.19,1,4.46,4,7.87,4,6.54,null,4.45,6,2010-04-12),(162,00:00:00,7.55,1,9.52,1,1.90,1,4.76,null,0.14,1,2010-04-12),(164,00:00:00,8.01,1,8.09,1,0,null,8.49,null,0.20,2,2010-04-12),(166,00:00:00,8.30,1,4.77,4,10.99,5,9.11,null,0.36,2,2010-04-12)] if i hard code the data as above mySQL accepts my request (except for some quibbles about formatting) but if the variable clean_data is instead defined as the result of the parsing code, like this: cleaner = [(""" $!!'""", ')]'),(' $!!', ') etc etc] def processThis(str,lst): for find, replace in lst: str = str.replace(find, replace) return str clean_data = processThis(data,cleaner) then i get the dreaded "TypeError: not enough arguments for format string" After playing with formatting options for a few hours (I am very new to this) I am confused... what is the difference between the hard coded data and the result of the processThis function as fas as mySQL is concerned? Any idea greatly appreciated...

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  • Is programming overrated?

    - by aengine
    [Subjective and intended to be a community wiki] I am sorry for such an offensive question: But here are my arguments Most of the progress in "computing" has came from non-programming sources. i.e. People invented faster microprocessors and better routers and novel memory devices. I dont think on average people are writting more efficient programs than those written 10 years ago. And the newer and popular languages are infact slower than C. though speed is one of the lesser criterias. Most of the progress came from novel paradigms. Web, Internet, Cloud computing and Social networking are novel paradigms and did not involve progress in programming as such. Heck even facebook was written in PHP and not some extreme language. Though it did face scalability issues (same with twitter) but i believe money and better programmers (who came in much later) took care of that. Thus ideating capability trumped programming capability/ Even things like Map-Reduce, Column oriented database and Probablistic algorithms (E.g. bloom filters) came from hardcore Algorithms research, rather than some programming convention. Thus my final point is why programming skill is so overstressed? To point a recent example about how only 10% of programmers can "write code" (binary search) without debugging. Isnt it a bit hypocritical, considering your real successs lies in coming up with better algorithm or a novel feature rather than getting right first time???

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  • JavaScript: Is there a better way to retain your array but efficiently concat or replace items?

    - by Michael Mikowski
    I am looking for the best way to replace or add to elements of an array without deleting the original reference. Here is the set up: var a = [], b = [], c, i, obj; for ( i = 0; i < 100000; i++ ) { a[ i ] = i; b[ i ] = 10000 - i; } obj.data_list = a; Now we want to concatenate b INTO a without changing the reference to a, since it is used in obj.data_list. Here is one method: for ( i = 0; i < b.length; i++ ) { a.push( b[ i ] ); } This seems to be a somewhat terser and 8x (on V8) faster method: a.splice.apply( a, [ a.length, 0 ].concat( b ) ); I have found this useful when iterating over an "in-place" array and don't want to touch the elements as I go (a good practice). I start a new array (let's call it keep_list) with the initial arguments and then add the elements I wish to retain. Finally I use this apply method to quickly replace the truncated array: var keep_list = [ 0, 0 ]; for ( i = 0; i < a.length; i++ ){ if ( some_condition ){ keep_list.push( a[ i ] ); } // truncate array a.length = 0; // And replace contents a.splice.apply( a, keep_list ); There are a few problems with this solution: there is a max call stack size limit of around 50k on V8 I have not tested on other JS engines yet. This solution is a bit cryptic Has anyone found a better way?

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  • Can I make a derived class inherit a derived member from its base class in Java?

    - by Eric
    I have code that looks like this: public class A { public void doStuff() { System.out.print("Stuff successfully done"); } } public class B extends A { public void doStuff() { System.out.print("Stuff successfully done, but in a different way"); } public void doMoreStuff() { System.out.print("More advanced stuff successully done"); } } public class AWrapper { public A member; public AWrapper(A member) { this.member = member; } public void doStuffWithMember() { a.doStuff(); } } public class BWrapper extends AWrapper { public B member; public BWrapper(B member) { super(member); //Pointer to member stored in two places: this.member = member; //Not great if one changes, but the other does not } public void doStuffWithMember() { member.doMoreStuff(); } } However, there is a problem with this code. I'm storing a reference to the member in two places, but if one changes and the other does not, there could be trouble. I know that in Java, an inherited method can narrow down its return type (and perhaps arguments, but I'm not certain) to a derived class. Is the same true of fields?

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  • Writing own Unix shell in C - Problems with PATH and execv

    - by user1287523
    I'm writing my own shell in C. It needs to be able to display the users current directory, execute commands based on the full path (must use execv), and allow the user to change the directory with cd. This IS homework. The teacher only gave us a basic primer on C and a very brief skeleton on how the program should work. Since I'm not one to give up easily I've been researching how to do this for three days, but now I'm stumped. This is what I have so far: Displays the user's username, computername, and current directory (defaults to home directory). Prompts the user for input, and gets the input Splits the user's input by " " into an array of arguments Splits the environment variable PATH by ":" into an array of tokens I'm not sure how to proceed from here. I know I've got to use the execv command but in my research on google I haven't really found an example I understand. For instance, if the command is bin/ls, how does execv know the display all files/folders from the home directory? How do I tell the system I changed the directory? I've been using this site a lot which has been helpful: http://linuxgazette.net/111/ramankutty.html but again, I'm stumped. Thanks for your help. Let me know if I should post some of my existing code, I'm wasn't sure if it was necessary though.

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  • Sample twitter App

    - by Jack
    I am now running my code on a web hosting service http://xtreemhost.com/ <?php function updateTwitter($status) { $username = 'xxxxxx'; $password = 'xxxx'; $url = 'http://twitter.com/statuses/update.xml'; $postargs = 'status='.urlencode($status); $responseInfo=array(); $ch = curl_init($url); curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 2); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt ($ch, CURLOPT_POST, true); // Give CURL the arguments in the POST curl_setopt ($ch, CURLOPT_POSTFIELDS, $postargs); // Set the username and password in the CURL call curl_setopt($ch, CURLOPT_USERPWD, $username.':'.$password); // Set some cur flags (not too important) $response = curl_exec($ch); if($response === false) { echo 'Curl error: ' . curl_error($ch); } else { echo 'Operation completed without any errors<br/>'; } // Get information about the response $responseInfo=curl_getinfo($ch); // Close the CURL connection curl_close($ch); // Make sure we received a response from Twitter if(intval($responseInfo['http_code'])==200){ // Display the response from Twitter echo $response; }else{ // Something went wrong echo "Error: " . $responseInfo['http_code']; } curl_close($ch); } updateTwitter("Just finished a sweet tutorial on http://brandontreb.com"); ?> I get the following error now Curl error: Couldn't resolve host 'api.twitter.com' Error: 0 Please somebody solve my problem

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  • Google Anlytics event not firing

    - by yar1
    I am not getting and event data in GA. I installed Google Analytics Debugger Chrome extension and I see nothing happening (same goes when looking at Network panel in developer tools). I Googled it and read many (many) other answers and it looks like I'm doing things right. Page views, etc. are registering correctly... I have this code as the last thing before my closing tag: <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-MYREALCODE', 'mybna.net'); ga('send', 'pageview'); var _gaq = _gaq || []; _gaq.push(['_setAccount', 'UA-MYREALCODE']); _gaq.push(['_trackPageview']); </script> My event handlers are done using jQuery, all inside an external js file, loaded before the closing tag. For example: $(function () { $('#show-less').click(function (e) { pbr.showHideMore(e); _gaq.push(['_trackEvent', 'ShowMore', 'Hide', 'top button']); }); }); Any ideas anyone?

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  • C preprocessor problem in Microsoft Visual Studio 2010

    - by Remo.D
    I've encountered a problem with the new Visual C++ in VS 2010. I've got a header with the following defines: #define STC(y) #y #define STR(y) STC(\y) #define NUM(y) 0##y The intent is that you can have some constant around like #define TOKEN x5A and then you can have the token as a number or as a string: NUM(TOKEN) -> 0x5A STR(TOKEN) -> "\x5A" This is the expected behavior under the the substitution rules of macros arguments and so far it has worked well with gcc, open watcom, pellesC (lcc), Digital Mars C and Visual C++ in VS2008 Express. Today I recompiled the library with VS2010 Express only to discover that it doesn't work anymore! Using the new version I would get: NUM(TOKEN) -> 0x5A STR(TOKEN) -> "\y" It seems that the new preprocessor treats \y as an escape sequence even within a macro body which is a non-sense as escape sequences only have a meaning in literal strings. I suspect this is a gray area of the ANSI standard but even if the original behavior was mandated by the standard, MS VC++ is not exactly famous to be 100% ANSI C compliant so I guess I'll have to live with the new behavior of the MS compiler. Given that, does anybody have a suggestion on how to re-implement the original macros behavior with VS2010?

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  • Are there any other ways to iterate through the attributes of a custom class, excluding the in-built ones?

    - by Ricardo Altamirano
    Is there another way to iterate through only the attributes of a custom class that are not in-built (e.g. __dict__, __module__, etc.)? For example, in this code: class Terrain: WATER = -1 GRASS = 0 HILL = 1 MOUNTAIN = 2 I can iterate through all of these attributes like this: for key, value in Terrain.__dict__.items(): print("{: <11}".format(key), " --> ", value) which outputs: MOUNTAIN --> 2 __module__ --> __main__ WATER --> -1 HILL --> 1 __dict__ --> <attribute '__dict__' of 'Terrain' objects> GRASS --> 0 __weakref__ --> <attribute '__weakref__' of 'Terrain' objects> __doc__ --> None If I just want the integer arguments (a rudimentary version of an enumerated type), I can use this: for key, value in Terrain.__dict__.items(): if type(value) is int: # type(value) == int print("{: <11}".format(key), " --> ", value) this gives the expected result: MOUNTAIN --> 2 WATER --> -1 HILL --> 1 GRASS --> 0 Is it possible to iterate through only the non-in-built attributes of a custom class independent of type, e.g. if the attributes are not all integral. Presumably I could expand the conditional to include more types, but I want to know if there are other ways I'm missing.

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  • Getting rejected value null spring validation

    - by Shabarinath
    Hi in my project when I am trying to validate my form its not showing any error messages even if validation fails (Event Form is not submitted and enters into validation fail block) Here is my code /****************** Post Method *************/ @RequestMapping(value="/property", method = RequestMethod.POST) public String saveOrUpdateProperty(@ModelAttribute("property") Property property, BindingResult result, Model model, HttpServletRequest request) throws Exception { try { if(validateFormData(property, result)) { model.addAttribute("property", new Property()); return "property/postProperty"; } } /********* Validate Block *************/ private boolean validateFormData(Property property, BindingResult result) throws DaoException { if (property.getPropertyType() == null || property.getPropertyType().equals("")) { result.rejectValue("propertyType", "Cannot Be Empty !", "Cannot Be Empty !"); } if (property.getTitle() == null || property.getTitle().equals("")) { result.rejectValue("title", "Cannot Be Empty !", "Cannot Be Empty !"); } return (result.hasFieldErrors() || result.hasErrors()); } But when i debug i can see below one org.springframework.validation.BeanPropertyBindingResult: 1 errors Field error in object 'property' on field 'title': rejected value [null]; codes [Cannot Be Empty !.property.title,Cannot Be Empty !.title,Cannot Be Empty !.java.lang.String,Cannot Be Empty !]; arguments []; default message [Cannot Be Empty !] and this is how i am displaying in jsp file <div class="control-group"> <div class="controls"> <label class="control-label"><span class="required">* </span>Property Type</label> <div class="controls"> <form:input path="title" placeholder="Pin Code" cssClass="form-control border-radius-4 textField"/> <form:errors path="title" style="color:red;"/> </div> </div> </div> Event though when i see the below one when i debug (1 Error its correct) org.springframework.validation.BeanPropertyBindingResult: 1 errors Why it is not displayed in jsp can any one hep me?

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  • (How) Can I approximate a "dynamic" index (key extractor) for Boost MultiIndex?

    - by Sarah
    I have a MultiIndex container of boost::shared_ptrs to members of class Host. These members contain private arrays bool infections[NUM_SEROTYPES] revealing Hosts' infection statuses with respect to each of 1,...,NUM_SEROTYPES serotypes. I want to be able to determine at any time in the simulation the number of people infected with a given serotype, but I'm not sure how: Ideally, Boost MultiIndex would allow me to sort, for example, by Host::isInfected( int s ), where s is the serotype of interest. From what I understand, MultiIndex key extractors aren't allowed to take arguments. An alternative would be to define an index for each serotype, but I don't see how to write the MultiIndex container typedef ... in such an extensible way. I will be changing the number of serotypes between simulations. (Do experienced programmers think this should be possible? I'll attempt it if so.) There are 2^(NUM_SEROTYPES) possible infection statuses. For small numbers of serotypes, I could use a single index based on this number (or a binary string) and come up with some mapping from this key to actual infection status. Counting is still darn slow. I could maintain a separate structure counting the total numbers of infecteds with each serotype. The synchrony is a bit of a pain, but the memory is fine. I would prefer a slicker option, since I would like to do further sorts on other host attributes (e.g., after counting the number infected with serotype s, count the number of those infected who are also in a particular household and have a particular age). Thanks in advance.

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  • Implementing comparision operators via 'tuple' and 'tie', a good idea?

    - by Xeo
    (Note: tuple and tie can be taken from Boost or C++11.) When writing small structs with only two elements, I sometimes tend to choose a std::pair, as all important stuff is already done for that datatype, like operator< for strict-weak-ordering. The downsides though are the pretty much useless variable names. Even if I myself created that typedef, I won't remember 2 days later what first and what second exactly was, especially if they are both of the same type. This gets even worse for more than two members, as nesting pairs pretty much sucks. The other option for that is a tuple, either from Boost or C++11, but that doesn't really look any nicer and clearer. So I go back to writing the structs myself, including any needed comparision operators. Since especially the operator< can be quite cumbersome, I thought of circumventing this whole mess by just relying on the operations defined for tuple: Example of operator<, e.g. for strict-weak-ordering: bool operator<(MyStruct const& lhs, MyStruct const& rhs){ return std::tie(lhs.one_member, lhs.another, lhs.yet_more) < std::tie(rhs.one_member, rhs.another, rhs.yet_more); } (tie makes a tuple of T& references from the passed arguments.) Edit: The suggestion from @DeadMG to privately inherit from tuple isn't a bad one, but it got quite some drawbacks: If the operators are free-standing (possibly friends), I need to inherit publicly With casting, my functions / operators (operator= specifically) can be easily bypassed With the tie solution, I can leave out certain members if they don't matter for the ordering Are there any drawbacks in this implementation that I need to consider?

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  • Why does this Razor syntax gives compilation errors?

    - by dotnetN00b
    I either get a "you need a ; here" or a "best overloaded match has invalid arguments" errors. <tbody> <tr> @for (int i = 0; i < startDay; ++i) { @:<td><span></span><span></span></td> } @for (int j = startDay; j < ((numberOfDays + startDay) - 1); ++j) { <td> <span>@startCount</span> <br /> <span> @{ var todaysEvents = Model.ToList().FindAll(d => d.CalDate.Day == j); foreach(HTMLMVCCalendar.Models.CalendarModel eventsToday in todaysEvents) { foreach(HTMLMVCCalendar.Models.EventModel eventToday in eventsToday.CalEvents) { @eventToday.DayCode.ToString // error here @:<br /> @eventToday.Subject // error here @:<br /> @eventToday.EventDesc //error here } @:<br /> } } </span> </td> if ((j + 1) % 7 == 0) { @:</tr><tr> } @++startCount; } </tr> </tbody>

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  • Unsure how to come up with a good design

    - by Mewzer
    Hello there, I am having trouble coming up with a good design for a group of classes and was hoping that someone could give me some guidance on best practices. I have kept the classes and member functions generic to make the problem simpler. Essentially, I have three classes (lets call them A, B, and C) as follows: class A { ... int GetX( void ) const { return x; }; int GetY( void ) const { return y; }; private: B b; // NOTE: A "has-a" B int x; int y; }; class B { ... void SetZ( int value ) { z = value }; private: int z; C c; // NOTE: B "has-a" C }; class C { private: ... void DoSomething(int x, int y){ ... }; void DoSomethingElse( int z ){ ... }; }; My problem is as follows: Class A uses its member variables "x" and "y" a lot internally. Class B uses its member variable "z" a lot internally. Class B needs to call C::DoSomething(), but C::DoSomething() needs the values of X and Y in class A passed in as arguments. C::DoSomethingElse() is called from say another class (e.g. D), but it needs to invoke SetZ() in class B!. As you can see, it is a bit of a mess as all the classes need information from one another!. Are there any design patterns I can use?. Any ideas would be much appreciated ....

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  • Confused about std::runtime_error vs. std::logic_error

    - by David Gladfelter
    I recently saw that the boost program_options library throws a logic_error if the command-line input was un-parsable. That challenged my assumptions about logic_error vs. runtime_error. I assumed that logic errors (logic_error and its derived classes) were problems that resulted from internal failures to adhere to program invariants, often in the form of illegal arguments to internal API's. In that sense they are largely equivalent to ASSERT's, but meant to be used in released code (unlike ASSERT's which are not usually compiled into released code.) They are useful in situations where it is infeasible to integrate separate software components in debug/test builds or the consequences of a failure are such that it is important to give runtime feedback about the invalid invariant condition to the user. Similarly, I thought that runtime_errors resulted exclusively from runtime conditions outside of the control of the programmer: I/O errors, invalid user input, etc. However, program_options is obviously heavily (primarily?) used as a means of parsing end-user input, so under my mental model it certainly should throw a runtime_error in the case of bad input. Where am I going wrong? Do you agree with the boost model of exception typing?

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  • (Java) Get value of string loaded into dynamic-type object?

    - by Michael
    I'm very new to Java (~10 days), so my code is probably pretty bad, but here's what I've got: ArgsDataHolder argsData = new ArgsDataHolder(); // a class that holds two // ArrayList's where each element // representing key/value args Class thisArgClass; String thisArgString; Object thisArg; for(int i=2; i< argsString.length; i++) { thisToken = argsString[i]; thisArgClassString = getClassStringFromToken(thisToken).toLowerCase(); System.out.println("thisArgClassString: " + thisArgClassString); thisArgClass = getClassFromClassString(thisArgClassString); // find closing tag; concatenate middle Integer j = new Integer(i+1); thisArgString = getArgValue(argsString, j, "</" + thisArgClassString + ">"); thisArg = thisArgClass.newInstance(); thisArg = thisArgClass.valueOf(thisArgString); argsData.append(thisArg, thisArgClass); } The user basically has to input a set of key/value arguments into the command prompt in this format: <class>value</class>, e.g. <int>62</int>. Using this example, thisArgClass would be equal to Integer.class, thisArgString would be a string that read "62", and thisArg would be an instance of Integer that is equal to 62. I tried thisArg.valueOf(thisArgString), but I guess valueOf(<String>) is only a method of certain subclasses of Object. For whatever reason, I can't seem to be able to cast thisArg to thisArgClass (like so: thisArg = (thisArgClass)thisArgClass.newInstance();, at which point valueOf(<String>) should become accessible. There's got to be a nice, clean way of doing this, but it is beyond my abilities at this point. How can I get the value of the string loaded into a dynamically-typed object (Integer, Long, Float, Double, String, Character, Boolean, etc.)? Or am I just overthinking this, and Java will do the conversion for me? :confused:

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  • Passing values for method

    - by Kasun
    I beginner for programming. So can you please show me how to pass values for your compile() method. class CL { private const string clexe = @"cl.exe"; private const string exe = "Test.exe", file = "test.cpp"; private string args; public CL(String[] args) { this.args = String.Join(" ", args); this.args += (args.Length > 0 ? " " : "") + "/Fe" + exe + " " + file; } public Boolean Compile(String content, ref string errors) { //remove any old copies if (File.Exists(exe)) File.Delete(exe); if (File.Exists(file)) File.Delete(file); File.WriteAllText(file, content); Process proc = new Process(); proc.StartInfo.UseShellExecute = false; proc.StartInfo.RedirectStandardOutput = true; proc.StartInfo.RedirectStandardError = true; proc.StartInfo.FileName = clexe; proc.StartInfo.Arguments = this.args; proc.StartInfo.CreateNoWindow = true; proc.Start(); //errors += proc.StandardError.ReadToEnd(); errors += proc.StandardOutput.ReadToEnd(); proc.WaitForExit(); bool success = File.Exists(exe); return success; } }

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  • What is the point of having a key_t if what will be the key to access shared memory is the return value of shmget()?

    - by devoured elysium
    When using shared memory, why should we care about creating a key key_t ftok(const char *path, int id); in the following bit of code? key_t key; int shmid; key = ftok("/home/beej/somefile3", 'R'); shmid = shmget(key, 1024, 0644 | IPC_CREAT); From what I've come to understand, what is needed to access a given shared memory is the shmid, not the key. Or am I wrong? If what we need is the shmid, what is the point in not just creating a random key every time? Edit @link text one can read: What about this key nonsense? How do we create one? Well, since the type key_t is actually just a long, you can use any number you want. But what if you hard-code the number and some other unrelated program hardcodes the same number but wants another queue? The solution is to use the ftok() function which generates a key from two arguments. Reading this, it gives me the impression that what one needs to attach to a shared-memory block is the key. But this isn't true, is it? Thanks

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  • Why can't I pass an object of type T to a method on an object of type <? extends T>?

    - by Matt
    In Java, assume I have the following class Container that contains a list of class Items: public class Container<T> { private List<Item<? extends T>> items; private T value; public Container(T value) { this.value = value; } public void addItem(Item item) { items.add(item); } public void doActions() { for (Item item : items) { item.doAction(value); } } } public abstract class Item<T> { public abstract void doAction(T item); } Eclipse gives the error: The method doAction(capture#1-of ? extends T) in the type Item is not applicable for the arguments (T) I've been reading generics examples and various postings around, but I still can't figure out why this isn't allowed. Eclipse also doesn't give any helpful tips in its proposed fix, either. The variable value is of type T, why wouldn't it be applicable for ? extends T?.

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