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  • Most readable way to write simple conditional check

    - by JRL
    What would be the most readable/best way to write a multiple conditional check such as shown below? Two possibilities that I could think of (this is Java but the language really doesn't matter here): Option 1: boolean c1 = passwordField.getPassword().length > 0; boolean c2 = !stationIDTextField.getText().trim().isEmpty(); boolean c3 = !userNameTextField.getText().trim().isEmpty(); if (c1 && c2 && c3) { okButton.setEnabled(true); } Option 2: if (passwordField.getPassword().length > 0 && !stationIDTextField.getText().trim().isEmpty() && !userNameTextField.getText().trim().isEmpty() { okButton.setEnabled(true); } What I don't like about option 2 is that the line wraps and then indentation becomes a pain. What I don't like about option 1 is that it creates variables for nothing and requires looking at two places. So what do you think? Any other options?

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  • Omit return type in C++0x

    - by Clinton
    I've recently found myself using the following macro with gcc 4.5 in C++0x mode: #define RETURN(x) -> decltype(x) { return x; } And writing functions like this: template <class T> auto f(T&& x) RETURN (( g(h(std::forward<T>(x))) )) I've been doing this to avoid the inconvenience having to effectively write the function body twice, and having keep changes in the body and the return type in sync (which in my opinion is a disaster waiting to happen). The problem is that this technique only works on one line functions. So when I have something like this (convoluted example): template <class T> auto f(T&& x) -> ... { auto y1 = f(x); auto y2 = h(y1, g1(x)); auto y3 = h(y1, g2(x)); if (y1) { ++y3; } return h2(y2, y3); } Then I have to put something horrible in the return type. Furthermore, whenever I update the function, I'll need to change the return type, and if I don't change it correctly, I'll get a compile error if I'm lucky, or a runtime bug in the worse case. Having to copy and paste changes to two locations and keep them in sync I feel is not good practice. And I can't think of a situation where I'd want an implicit cast on return instead of an explicit cast. Surely there is a way to ask the compiler to deduce this information. What is the point of the compiler keeping it a secret? I thought C++0x was designed so such duplication would not be required.

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  • Use of 'super' keyword when accessing non-overridden superclass methods

    - by jonny
    I'm trying to get the hang of inheritance in Java and have learnt that when overriding methods (and hiding fields) in sub classes, they can still be accessed from the super class by using the 'super' keyword. What I want to know is, should the 'super' keyword be used for non-overridden methods? Is there any difference (for non-overridden methods / non-hidden fields)? I've put together an example below. public class Vehicle { public int tyreCost; public Vehicle(int tyreCost) { this.tyreCost = tyreCost; } public int getTyreCost() { return tyreCost; } } and public class Car extends Vehicle { public int wheelCount; public Vehicle(int tyreCost, int wheelCount) { super(tyreCost); this.wheelCount = wheelCount; } public int getTotalTyreReplacementCost() { return getTyreCost() * wheelCount; } } Specifically, given that getTyreCost() hasn't been overridden, should getTotalTyreReplacementCost() use getTyreCost(), or super.getTyreCost() ? I'm wondering whether super should be used in all instances where fields or methods of the superclass are accessed (to show in the code that you are accessing the superclass), or only in the overridden/hidden ones (so they stand out).

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  • C++ class initialisation containing class variable initialization

    - by Phil Hannent
    I noticed some code of a colleague today that initialized class variables in the initialization. However it was causing a warning, he says because of the order they are in. My question is why is it better to do variable initialization where it currently is and not within the curly brackets? DiagramScene::DiagramScene( int slideNo, QRectF screenRect, MainWindow* parent ) : QGraphicsScene( screenRect, parent ), myParent( parent ), slideUndoImageCurrentIndex(-1), nextGroupID(0), m_undoInProgress(false), m_deleteItemOnNextUndo(0) line(0), path(0) { /* Setup default brush for background */ scDetail->bgBrush.setStyle(Qt::SolidPattern); scDetail->bgBrush.setColor(Qt::white); setBackgroundBrush(scDetail->bgBrush); }

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  • Microsoft C++ Language Reference

    - by eSKay
    Whenever any question is asked, and a reference text is needed, I never see MSDN C++ Language Reference being referred. I was browsing through it and I personally feel that it is extremely well written. Is there some specific reason it is not used as often as a standard? Is it because it contains some VC++ specific features?

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  • Is there a downside to adding an anonymous empty delegate on event declaration?

    - by serg10
    I have seen a few mentions of this idiom (including on SO): // Deliberately empty subscriber public event EventHandler AskQuestion = delegate {}; The upside is clear - it avoids the need to check for null before raising the event. However, I am keen to understand if there are any downsides. For example, is it something that is in widespread use and is transparent enough that it won't cause a maintenance headache? Is there any appreciable performance hit of the empty event subscriber call?

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  • How does the verbosity of identifiers affect the performance of a programmer?

    - by DR
    I always wondered: Are there any hard facts which would indicate that either shorter or longer identifiers are better? Example: clrscr() opposed to ClearScreen() Short identifiers should be faster to read because there are fewer characters but longer identifiers often better resemble natural language and therefore also should be faster to read. Are there other aspects which suggest either a short or a verbose style? EDIT: Just to clarify: I didn't ask: "What would you do in this case?". I asked for reasons to prefer one over the other, i.e. this is not a poll question. Please, if you can, add some reason on why one would prefer one style over the other.

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  • Adding the sum of numbers using a loop statement

    - by Deonna
    I need serious help dividing the positive numbers and the negative numbers. I am to accumulate the total of the negative values and separately accumulate the total of the positive values. After the loop, you are then to display the sum of the negative values and the sum of the positive values. The data is suppose to look like this: -2.3 -1.9 -1.5 -1.1 -0.7 -0.3 0.1 0.5 0.9 1.3 1.7 2.1 2.5 2.9 Sum of negative values: -7.8 Sum of positive values: 12 So far I have this: int main () { int num, num2, num3, num4, num5, sum, count, sum1; int tempVariable = 0; int numCount = 100; int newlineCount = 0, newlineCount1 = 0; float numCount1 = -2.3; while (numCount <= 150) { cout << numCount << " "; numCount += 2; newlineCount ++; if(newlineCount == 6) { cout<< " " << endl; newlineCount = 0; } } **cout << "" << endl; while (numCount1 <=2.9 ) { cout << numCount1 << " "; numCount1 += 0.4; newlineCount1 ++; } while ( newlineCount1 <= 0 && newlineCount >= -2.3 ); cout << "The sum is " << newlineCount1 << endl;** return 0; }

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  • What is the best way to return two values from a method?

    - by Edward Tanguay
    When I have to write methods which return two values, I usually go about it as in the following code which returns a List<string>. Or if I have to return e.g. a id and string, then I return a List<object> and then pick them out with index number and recast the values. This recasting and referencing by index seems inelegant so I want to develop a new habit for methods that return two values. What is the best pattern for this? using System; using System.Collections.Generic; using System.Linq; namespace MultipleReturns { class Program { static void Main(string[] args) { string extension = "txt"; { List<string> entries = GetIdCodeAndFileName("first.txt", extension); Console.WriteLine("{0}, {1}", entries[0], entries[1]); } { List<string> entries = GetIdCodeAndFileName("first", extension); Console.WriteLine("{0}, {1}", entries[0], entries[1]); } Console.ReadLine(); } /// <summary> /// gets "first.txt", "txt" and returns "first", "first.txt" /// gets "first", "txt" and returns "first", "first.txt" /// it is assumed that extensions will always match /// </summary> /// <param name="line"></param> public static List<string> GetIdCodeAndFileName(string line, string extension) { if (line.Contains(".")) { List<string> parts = line.BreakIntoParts("."); List<string> returnItems = new List<string>(); returnItems.Add(parts[0]); returnItems.Add(line); return returnItems; } else { List<string> returnItems = new List<string>(); returnItems.Add(line); returnItems.Add(line + "." + extension); return returnItems; } } } public static class StringHelpers { public static List<string> BreakIntoParts(this string line, string separator) { if (String.IsNullOrEmpty(line)) return null; else { return line.Split(new string[] { separator }, StringSplitOptions.None).Select(p => p.Trim()).ToList(); } } } }

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  • Developing a jQuery plugin that returns a given object, instead of jQuery object itself!

    - by mehdi5275
    Hi, Consider the following base code: (function($) { $.fn.myPlugin = function(settings) { return this.each(function() { //whatever }); }; }); The plugin returns a jQuery object. The question is how am I supposed to write a plugin that returns a custom object so that I can do something like this: var api = $('div.myelement').myPlugin(); api.onMyEventName(function(e, whateverParam) { //whatever }); It'd be highly appreciated if you could write some lines of code that describes me how to do that, how to call the onMyEventName function on a custom api object... Thanks.

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  • What's Your favorite f# use? where does f# makes life (a lot) easier (compared to c#)?

    - by luckyluke
    I've skimmed the stack and did not get the overflow as there is probably no such question. I'm just learning f# and I am A seasoned c# and .net dev. I am into financial apps and currently F# helps me a lot with maths calcs like zero finding or minimum finding (although I still want some good maths library there). I see that processing multiple items (files or smth) tends to be easier, but my GUI (web, win) are still c# based. I am in the team of 5 devs and we know that the new tool is out, we are learning it after hours (to pimp ourselves up) but maybe we shouldn't bash the door somebody already opened. So in business apps, whats Your first killer part of soft You would code in F# (if You could and would know IT would be easier, faster, more testable, easier to maintain etc.? Business rules? ImageProcessing? Data processing? hope it's not to subjective. luke

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  • Using typedefs (or #defines) on built in types - any sensible reason?

    - by jb
    Well I'm doing some Java - C integration, and throught C library werid type mappings are used (theres more of them;)): #define CHAR char /* 8 bit signed int */ #define SHORT short /* 16 bit signed int */ #define INT int /* "natural" length signed int */ #define LONG long /* 32 bit signed int */ typedef unsigned char BYTE; /* 8 bit unsigned int */ typedef unsigned char UCHAR; /* 8 bit unsigned int */ typedef unsigned short USHORT; /* 16 bit unsigned int */ typedef unsigned int UINT; /* "natural" length unsigned int*/ Is there any legitimate reason not to use them? It's not like char is going to be redefined anytime soon. I can think of: Writing platform/compiler portable code (size of type is underspecified in C/C++) Saving space and time on embedded systems - if you loop over array shorter than 255 on 8bit microprocessor writing: for(uint8_t ii = 0; ii < len; ii++) will give meaureable speedup.

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  • PHP if statement - select two different get variables?

    - by arsoneffect
    Below is my example script: <li><a <?php if ($_GET['page']=='photos' && $_GET['view']!=="projects"||!=="forsale") { echo ("href=\"#\" class=\"active\""); } else { echo ("href=\"/?page=photos\""); } ?>>Photos</a></li> <li><a <?php if ($_GET['view']=='projects') { echo ("href=\"#\" class=\"active\""); } else { echo ("href=\"/?page=photos&view=projects\""); } ?>>Projects</a></li> <li><a <?php if ($_GET['view']=='forsale') { echo ("href=\"#\" class=\"active\""); } else { echo ("href=\"/?page=photos&view=forsale\""); } ?>>For Sale</a></li> I want the PHP to echo the "href="#" class="active" only when it is not on the two pages: ?page=photos&view=forsale or ?page=photos&view=projects

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  • How does CouchDB perform for a regularly updated dataset?

    - by Ritesh M Nayak
    I am planning on using CouchDB on a project. But as the querying mechanism involves writing views (which are a lot like indexes on regular RDMBMS's) I was wondering, if the document database keeps getting updated a lot ( a write heavy database) would CouchDB perform well compared to a regular RDBMS? Or do we have to compact/re-index the system occasionally to make it perform faster?

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  • multiple return values from PHP with jQuery AJAX

    - by benhowdle89
    I'm using this jQuery code: $.ajax ({ type: "POST", url: "customerfilter.php", data: dataString, cache: false, success: function(html) { $(".custName").html(html); } }); How can i do something like this: $(".projDesc").html(html1); So i can split the returned results into two html elements? echo "<p>" .$row['cust_name']. "</p>"; thats the PHP i'm using and i want to echo another statement which i can put into another HTML element Does this make sense?

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  • Which style of return is "better" for a method that might return None?

    - by Daenyth
    I have a method that will either return an object or None if the lookup fails. Which style of the following is better? def get_foo(needle): haystack = object_dict() if needle not in haystack: return None return haystack[needle] or, def get_foo(needle): haystack = object_dict() try: return haystack[needle] except KeyError: # Needle not found return None I'm undecided as to which is more more desirable myself. Another choice would be return haystack[needle] if needle in haystack else None, but I'm not sure that's any better.

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  • Is GOTO really as evil as we are led to believe?

    - by RoboShop
    I'm a young programmer, so all my working life I've been told GOTO is evil, don't use it, if you do, your first born son will die. Recently, I've realized that GOTO actually still exists in .NET and I was wondering, is GOTO really as bad as they say, or is it just because everyone says you shouldn't use it, so that's why you don't. I know GOTO can be used badly, but are there any legit situations where you may possibly use it. The only thing I can think of is maybe to use GOTO to break out of a bunch of nested loops. I reckon that might be better then having to "break" out of each of them but because GOTO is supposedly always bad, I would never use it and it would probably never pass a peer review. What are your views? Is GOTO always bad? Can it sometimes be good? Has anyone here actually been gutsy enough to use GOTO for a real life system?

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  • Resharper: how to force introducing new private fields at the bottom of the class?

    - by Igor Brejc
    Resharper offers a very useful introduce and initialize field xxx action when you specify a new parameter in a constructor like: Constructor (int parameter) The only (minor) nuisance is that it puts the new field at the beginning of the class - and I'm a fan of putting private parts as far away as possible from the prying eyes of strangers ;). If, however, you already have some private fields in the class, Resharper will put the new field "correctly" (note the quotes, I don't want to start a flame war over this issue) next to those, even if they are at the end of the class. Is there a way to force Resharper to always put new fields at the end of the class? UPDATE: OK, I forgot to mention I know about the "Type Members Layout in Options" feature, but some concrete help on how to modify the template to achieve fields placement would be nice.

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