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• Why is sudo bash different from regular bash

  - by cyberjar09

  Problem description : I am using something called play framework in my development which requires me to make the python script play available in the path. Hence I create a symbolic link in /usr/local/bin ... Now I have written a shell script (call it status.sh) which calls this python script as follows : play status <some values here related to my app> &> /tmp/xyz.txt and this shell script then sends me the file via email. This works perfectly when I execute the script as follows ./script.sh. However when the script is executed as a cron expression everyday I get an output from stderr saying 'play: command not found'. Hence I did some digging on my own and here are my findings : echo $PATH when I am on the shell shows that I have /usr/local/bin available to me hence I can successfully execute the command play status however when I type in sudo bash and then echo $PATH I do not have the path /usr/local/bin anymore. It is a limited set of folders (one of them being /usr/bin). Q : Why this behavior ?! I fail to understand why the path is different. Also as a workaround would you suggest I do : new symbolic link from /usr/bin to /usr/local/bin (what are the side effects of this?) remove /usr/local/bin sym link altogether and only use /usr/bin is there a convention that I am not following here for linking new programs and executing them from $PATH ? Thanks.

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• Any Practical Alternative to the Signals + Slots model for GUI Programming?

  - by IntermediateHacker

  The majority of GUI Toolkits nowadays use the Signals + Slots model. It was Qt and GTK+, if I am not wrong, who pioneered it. You know, the widgets or graphical objects (sometimes even ones that aren't displayed) send signals to the main-loop handler. The main-loop handler then calls the events, callbacks or slots assigned for that widget / graphical object. There are usually default (and in most cases virtual) event-handlers already provided by the toolkit for handling all pre-defined signals, therefore, unlike previous designs where the developer had to write the entire main-loop and handler for each and every message himself (think WINAPI), the developer only has to worry about the signals he needs to implement new functionality on. Now this design is being used in most modern toolkits as far as I know. There are Qt, GTK+, FLTK etc. There is Java Swing. C# even has a language feature for it ( events and delegates ), and Windows Forms has been developed on this design. In fact, over the last decade, this design for GUI programming has become a kind of an unwritten standard. Since it increases productivity and provides greater abstraction. However, my question is: Is there any alternative design, that is parallel or practical for modern GUI programming? i.e Is the Signals + Slots design, the only practical one in town? Is it feasible to do GUI Programming with any other design? Are any modern (preferably successful and popular) GUI toolkits built on an alternative design?

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• Why Use !boolean_variable Over boolean_variable == false

  - by ell

  A comment on this question: Calling A Method that returns a boolean value inside a conditional statement says that you should use !boolean instead of boolean == false when testing conditions. Why? To me boolean == false is much more natural in English and is more explicit. I apologise if this is just a matter of style, but I was wondering if there was some other reason for this preference of !boolean?

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• When does the "Do One Thing" paradigm become harmful?

  - by Petr

  For the sake of argument here's a sample function that prints contents of a given file line-by-line. Version 1: void printFile(const string & filePath) { fstream file(filePath, ios::in); string line; while (file.good()) { getline(file, line); cout << line << endl; } } I know it is recommended that functions do one thing at one level of abstraction. To me, though code above does pretty much one thing and is fairly atomic. Some books (such as Robert C. Martin's Clean Code) seem to suggest breaking the above code into separate functions. Version 2: void printLine(const string & line) { cout << line << endl; } void printLines(fstream & file) { string line; while (file.good()) { getline(file, line); printLine(line); } } void printFile(const string & filePath) { fstream file(filePath, ios::in); printLines(file); } I understand what they want to achieve (open file / read lines / print line), but isn't it a bit of overkill? The original version is simple and in some sense already does one thing - prints a file. The second version will lead to a large number of really small functions which may be far less legible than the first version. Wouldn't it be, in this case, better to have the code at one place? At which point does the "Do One Thing" paradigm become harmful?

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• Origins of code indentation

  - by Daniel Mahler

  I am interested in finding out who introduced code indentation, as well as when and where it was introduced. It seems so critical to code comprehension, but it was not universal. Most Fortran and Basic code was (is?) unindented, and the same goes for Cobol. I am pretty sure I have even seen old Lisp code written as continuous, line-wrapped text. You had to count brackets in your head just to parse it, never mind understanding it. So where did such a huge improvement come from? I have never seen any mention of its origin. Apart from original examples of its use, I am also looking for original discussions of indentation.

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• LINQ Style preference

  - by Erin

  I have come to use LINQ in my every day programming a lot. In fact, I rarely, if ever, use an explicit loop. I have, however, found that I don't use the SQL like syntax anymore. I just use the extension functions. So rather then saying: from x in y select datatransform where filter I use: x.Where(c => filter).Select(c => datatransform) Which style of LINQ do you prefer and what are others on your team are comfortable with?

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• Is '@' Error Suppression a Valid Technique for Testing for an Optional Array Key?

  - by MikeSchinkel

  Rarst and I were debating offline about the use of the '@' error suppression operator in PHP, specifically for use to test for existence of "optional" array keys, i.e. array keys that are being used as a switch here a their lack of existence in the array is functionally equivalent to the array having the key with a value equaling false. Here is pseudo-code for this scenario: function do_something( $args = array() ) { if ( @$args['switch'] ) { // Do something with this switch } // continue on... } vs. this approach: function do_something( $args = array() ) { if ( ! empty( $args['switch'] ) && $args['switch'] ) { // Do something with this switch } // continue on... } Of course in most use-cases, suppressing errors would not be A Good Thing(tm). However in this use-case where an array is passed with an optional element, it seems to me that it is actually a very good technique but I could be wrong and would like to hear other's opinions on the subject before I make up my mind. I do know that there are alleged performance hits for using the former approach but I'd like to know how they compare with the alternative and if they performance hits really matter in real world scenarios? P.S. I decided to post this because, after debating this offline with Rarst, he asked a more general question here on Programmers but didn't actually give a detailed example of the specific use-case we were debating. And since I'm pretty sure he'll want to use the out-of-context answers on that other question as justification for why the above is "bad" I decided I needed to get opinions on this specific use-case.

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• Why write clean, refactored code?

  - by Shamal Karunarathne

  Hi programming lovers, This is a question I've been asking myself for a long time. Thought of throwing out it to you. From my experience of working on several Java based projects, I've seen tons of codes which we call 'dirty'. The unconventional class/method/field naming, wrong way of handling of exceptions, unnecessarily heavy loops and recursion etc. But the code gives the intended results. Though I hate to see dirty code, it's time taking to clean them up and eventually comes the question of "is it worth? it's giving the desired results so what's the point of cleaning?" In team projects, should there be someone specifically to refactor and check for clean code? Or are there situations where the 'dirty' codes fail to give intended results or make the customers unhappy? Do feel free to comment and reply. And tell me if I'm missing something here. Thanks.

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• What are the standard practices for database access in .net?

  - by Gulshan

  I have seen weird database access practices in .net. I have seen stored procedures for every database tasks. I have seen every database property name is preceded by it's table name. I have seen fully separate layer/.dll for very few or no business logic. I have seen along with ORMs, there are separate data access layer playing the same role. And with them, I have always heard- "These are the standards you have to maintain". So, what are the real standards for data access in .net? What are the rules you follow?

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• PHP ORM style of querying

  - by Petah

  Ok so I have made an ORM library for PHP. It uses syntax like so: *(assume that $business_locations is an array)* Business::type(Business:TYPE_AUTOMOTIVE)-> size(Business::SIZE_SMALL)-> left_join(BusinessOwner::table(), BusinessOwner::business_id(), SQL::OP_EQUALS, Business::id())-> left_join(Owner::table(), SQL::OP_EQUALS, Owner::id(), BusinessOwner::owner_id())-> where(Business::location_id(), SQL::in($business_locations))-> group_by(Business::id())-> select(SQL::count(BusinessOwner::id()); Which can also be represented as: $query = new Business(); $query->set_type(Business:TYPE_AUTOMOTIVE); $query->set_size(Business::SIZE_SMALL); $query->left_join(BusinessOwner::table(), BusinessOwner::business_id(), SQL::OP_EQUALS, $query->id()); $query->left_join(Owner::table(), SQL::OP_EQUALS, Owner::id(), BusinessOwner::owner_id()); $query->where(Business::location_id(), SQL::in($business_locations)); $query->group_by(Business::id()); $query->select(SQL::count(BusinessOwner::id()); This would produce a query like: SELECT COUNT(`business_owners`.`id`) FROM `businesses` LEFT JOIN `business_owners` ON `business_owners`.`business_id` = `businesses`.`id` LEFT JOIN `owners` ON `owners`.`id` = `business_owners`.`owner_id` WHERE `businesses`.`type` = 'automotive' AND `businesses`.`size` = 'small' AND `businesses`.`location_id` IN ( 1, 2, 3, 4 ) GROUP BY `businesses`.`id` Please keep in mind that the syntax might not be prefectly correct (I only wrote this off the top of my head) Any way, what do you think of this style of querying? Is the first method or second better/clearer/cleaner/etc? What would you do to improve it?

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• PATH command not found

  - by joslinm

  Hi, I'm not experienced with PATH (Any good reference would be appreciated), but I made a mistake and did PATH=/google_appengine, which I'm assuming completely overrid PATH. Still, I restarted bash and echo'd PATH and found that the folders were back. mark@mark-laptop:~$ echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games However, when I then tried to append to it, I got an error that PATH wasn't found. I've looked around Google and couldn't find a good answer. Any help would be appreciated mark@mark-laptop:~$ PATH = $PATH:/google_appengine PATH: command not found

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• What tools are available for remote communication when working from home or with a distributed team?

  - by Ryan Hayes

  My supervisor is allowing my team to dip our toes in the water of working from home. Considering a recent aquisition of another company is requiring some employees to love this new idea which will hack up to an hour off their commute into work every morning, I really want this to succeed. In order to make it a success, we need good tools to make our lives a lot easier. We currently are set up with OpenVPN, and Team Foundation Server 2010 with SharePoint 2010, and use Live Messenger (for SharePoint integration and easier remote desktop) for IM. These are just what we use (and they are currently working well) , but you can suggest other products. So, what are some great tools that will helps us collaborate, communicate, and generally work together when we're hours apart?

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• How to learn what the industry standards/expectations are, particularly with security?

  - by Aerovistae

  For instance, I was making my first mobile web-application about a year ago, and half-way through, someone pointed me to jQuery Mobile. Obviously this induced a total revolution in my app. Rewrote everything. Now, if you're in the field long enough, maybe that seems like common knowledge, but I was totally new to it. But this set me wondering: there are so many libraries and extensions and frameworks. This seems particularly crucial in the category of security. I'm afraid I'm going to find myself doing something in a professional setting eventually (I'm still a student) and someone's going to walk over and be like, My god, you're trying to secure user data that way? Don't you know about the Gordon-Wokker crypto-magic-hash-algorithms library? Without it you may as well go plaintext. How do you know what the best ways are to maximize security? Especially if you're trying to develop something on your own...

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• Method flags as arguments or as member variables?

  - by Martin

  I think the title "Method flags as arguments or as member variables?" may be suboptimal, but as I'm missing any better terminology atm., here goes: I'm currently trying to get my head around the problem of whether flags for a given class (private) method should be passed as function arguments or via member variable and/or whether there is some pattern or name that covers this aspect and/or whether this hints at some other design problems. By example (language could be C++, Java, C#, doesn't really matter IMHO): class Thingamajig { private ResultType DoInternalStuff(FlagType calcSelect) { ResultType res; for (... some loop condition ...) { ... if (calcSelect == typeA) { ... } else if (calcSelect == typeX) { ... } else if ... } ... return res; } private void InteralStuffInvoker(FlagType calcSelect) { ... DoInternalStuff(calcSelect); ... } public void DoThisStuff() { ... some code ... InternalStuffInvoker(typeA); ... some more code ... } public ResultType DoThatStuff() { ... some code ... ResultType x = DoInternalStuff(typeX); ... some more code ... further process x ... return x; } } What we see above is that the method InternalStuffInvoker takes an argument that is not used inside this function at all but is only forwarded to the other private method DoInternalStuff. (Where DoInternalStuffwill be used privately at other places in this class, e.g. in the DoThatStuff (public) method.) An alternative solution would be to add a member variable that carries this information: class Thingamajig { private ResultType DoInternalStuff() { ResultType res; for (... some loop condition ...) { ... if (m_calcSelect == typeA) { ... } ... } ... return res; } private void InteralStuffInvoker() { ... DoInternalStuff(); ... } public void DoThisStuff() { ... some code ... m_calcSelect = typeA; InternalStuffInvoker(); ... some more code ... } public ResultType DoThatStuff() { ... some code ... m_calcSelect = typeX; ResultType x = DoInternalStuff(); ... some more code ... further process x ... return x; } } Especially for deep call chains where the selector-flag for the inner method is selected outside, using a member variable can make the intermediate functions cleaner, as they don't need to carry a pass-through parameter. On the other hand, this member variable isn't really representing any object state (as it's neither set nor available outside), but is really a hidden additional argument for the "inner" private method. What are the pros and cons of each approach?

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• Eyes easily get dry and itchy [closed]

  - by Lo Wai Lun

  I have currently working as a programmer for half a year Very often, I often looking the monitors with natural contrast and brightness. Still when the weather is getting cold, my eyes feel dry and itchy. Sometimes I can see some red 'tree-roots' (capillaries) near iris. At home, i sometimes use my notebook for 13" or Galaxy Nexus Brightness are also natural contrast and brightness , a bit dim How should we take care of our eyes under this scenario?

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• Best practice in setting return value (use else or?)

  - by Deckard

  Whenever you want to return a value from a method, but whatever you return depends on some other value, you typically use branching: int calculateSomething() { if (a == b) { return x; } else { return y; } } Another way to write this is: int calculateSomething() { if (a == b) { return x; } return y; } Is there any reason to avoid one or the other? Both allow adding "else if"-clauses without problems. Both typically generate compiler errors if you add anything at the bottom. Note: I couldn't find any duplicates, although multiple questions exist about whether the accompanying curly braces should be on their own line. So let's not get into that.

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• How many programmers are female? [closed]

  - by Cawas

  Let's just assume gender and sex do matter and this question isn't so pointless as some may say. I believe gender distribution do say a lot about any given job although I find it very hard to explain why. So, is there any source on the web we can use to have a plain high number referencing female versus male programmers on any given space (country, community, company, etc)? Not asking why nor anything else. Just statistical numbers.

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• Studies on code documentation productivity gains/losses

  - by J T

  Hi everyone, After much searching, I have failed to answer a basic question pertaining to an assumed known in the software development world: WHAT IS KNOWN: Enforcing a strict policy on adequate code documentation (be it Doxygen tags, Javadoc, or simply an abundance of comments) adds over-head to the time required to develop code. BUT: Having thorough documentation (or even an API) brings with it productivity gains (one assumes) in new and seasoned developers when they are adding features, or fixing bugs down the road. THE QUESTION: Is the added development time required to guarantee such documentation offset by the gains in productivity down-the-road (in a strictly economical sense)? I am looking for case studies, or answers that can bring with them objective evidence supporting the conclusions that are drawn. Thanks in advance!

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• Kinect office demo ideas

  - by Tedd Hansen

  I'm thinking of placing a Kinect (connected to a PC) in the office and have something fun on it. Just a small thing people can interact with. Basically I get a depthmap (image) and a color image from the Kinect which I can analyze and do stuff with. My limited imagination came up with: Count people passing by. Measure average width of people passing by. Some ball with physics people can play with. Audible alert when someone is walking too fast. Anyone have any good ideas? :)

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• After how much line of code a function should be break down?

  - by Sumeet

  While working on existing code base, I usually come across procedures that contain Abusive use of IF and Switch statements. The procedures consist of overwhelming code, which I think require re-factoring badly. The situation gets worse when I identify that some of these are recursive as well. But this is always a matter of debate as the code is working fine and no one wants to wake up the dragon. But, everyone accepts it is very expensive code to manage. I am wondering if are any recommendations to determine if a particular Method is a culprit and needs a revisit/rewrite , so that it can broken down or polymophized in an effective manner. Are there any Metrics (like no. of lines in procedure) that can be used to identify such segment of code. The checklist or advice to convince everyone, will be great!

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• Maintainability of Boolean logic - Is nesting if statements needed?

  - by Vaccano

  Which of these is better for maintainability? if (byteArrayVariable != null) if (byteArrayVariable .Length != 0) //Do something with byteArrayVariable OR if ((byteArrayVariable != null) && (byteArrayVariable.Length != 0)) //Do something with byteArrayVariable I prefer reading and writing the second, but I recall reading in code complete that doing things like that is bad for maintainability. This is because you are relying on the language to not evaluate the second part of the if if the first part is false and not all languages do that. (The second part will throw an exception if evaluated with a null byteArrayVariable.) I don't know if that is really something to worry about or not, and I would like general feedback on the question. Thanks.

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• How to use correctly the comments in C/++

  - by Lucio

  I'm learning to program in C and in my stage, the best form to use correctly the comments is writing good comments from the beginning. As the comments are not just for that one understands better the code but others too, I want to know the views of all of you to reach a consensus. So what I want is that the most experienced users edit the following code as you please. (If it's unnecessary, delete it; If it's wrong, correct it; If needed, add more) Thus there'll be multiple answers with different syntax and the responses with the most votes will be taken as referring when commenting. The code to copy, paste and edit to your pleasure is: (And I remark again, just import the comments, not the code) /* This programs find 1 number in 1 file. The file is binary type and has integers in series. The number is integer type and it's entered from the keyboard. When finished the program, a poster will show the results: Saying if the number is in the file or not. */ #include <stdio.h> //FUNCTION 1 //Open file 'path' and closes it. void openf(char path[]) { int num; //Read from Keyboard a Number and it save it into 'num' var printf("Ready for read number.\n\nNumber --> "); fflush(stdin); scanf("%d",&num); //Open file 'path' in READ mode FILE *fvar; fvar=fopen(path,"rb"); //IF error happens when open file, exit of function if (fvar==NULL) { printf("ERROR while open file %s in read mode.",path); exit(1); } /*Verify the result of 'funct' function IF TRUE, 'num' it's in the file*/ if (funct(path,fvar,num)) printf("The number %d it is in the file %s.",num,path); else printf("The number %d it is not in the file %s.",num,path); fclose(fvar); } /*FUNCTION 2 It is a recursive function. Reads number by number until the file is empty or the number is found. Parameters received: 'path' -> Directory file 'fvar' -> Pointer file 'num' -> Number to compare */ int funct(char path[],FILE *fvar,int num) { int compare; //FALSE condition when the pointer reaches the end if (fread(&compare,sizeof(int),1,fvar)>0) /*TRUE condition when the number readed is iqual that 'num' ELSE will go to the function itself*/ if (compare!=num) funct(path,fvar,num); else return 1; else return 0; } int main(int argc, char **argv) { char path[30]="file.bin"; //Direction of the file to process openf(path); //Function with algorithm return 0; }

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• Using prefix incremented loops in C#

  - by KChaloux

  Back when I started programming in college, a friend encouraged me to use the prefix incrementation operator ++i instead of the postfix i++, citing that there was a slight chance of better performance with no real chance of a downside. I realize this is true in C++, and it's become a general habit that I continue to do. I'm led to believe that it makes little to no difference when used in a loop in C#, regardless of data type. Apparently the ++ operator can't be overridden. Nevertheless, I like the appearance more, and don't see a direct downside to it. It did astonish a coworker just a moment ago though, he made the (fairly logical) assumption that my loop would terminate early as a result. He's a self-taught programmer, and apparently never came across the C++ convention. That made me question whether or not the equivalent behavior of pre- and post-fix increment and decrement operators in loops is well known enough. Is it acceptable for me to continue using ++i in looping constructs because of style preference, even though it has no real performance benefit? Or is it likely to cause confusion amongst other programmers? Note: This is assuming the ++i convention is used consistently throughout all code.

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• Intentional misspellings to avoid reserved words

  - by Renesis

  I often see code that include intentional misspellings of common words that for better or worse have become reserved words: klass or clazz for class: Class clazz = ThisClass.class kount for count in SQL: count(*) AS kount Personally I find this decreases readability. In my own practice I haven't found too many cases where a better name couldn't have been used — itemClass or recordTotal. However, it's so common that I can't help but wonder if I'm the only one? Anyone have any advice or even better, quoted recommendations from well-respected programmers on this practice?

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• Script language native extensions - avoiding name collisions and cluttering others' namespace

  - by H2CO3

  I have developed a small scripting language and I've just started writing the very first native library bindings. This is practically the first time I'm writing a native extension to a script language, so I've run into a conceptual issue. I'd like to write glue code for popular libraries so that they can be used from this language, and because of the design of the engine I've written, this is achieved using an array of C structs describing the function name visible by the virtual machine, along with a function pointer. Thus, a native binding is really just a global array variable, and now I must obviously give it a (preferably good) name. In C, it's idiomatic to put one's own functions in a "namespace" by prepending a custom prefix to function names, as in myscript_parse_source() or myscript_run_bytecode(). The custom name shall ideally describe the name of the library which it is part of. Here arises the confusion. Let's say I'm writing a binding for libcURL. In this case, it seems reasonable to call my extension library curl_myscript_binding, like this: MYSCRIPT_API const MyScriptExtFunc curl_myscript_lib[10]; But now this collides with the curl namespace. (I have even thought about calling it curlmyscript_lib but unfortunately, libcURL does not exclusively use the curl_ prefix -- the public APIs contain macros like CURLCODE_* and CURLOPT_*, so I assume this would clutter the namespace as well.) Another option would be to declare it as myscript_curl_lib, but that's good only as long as I'm the only one who writes bindings (since I know what I am doing with my namespace). As soon as other contributors start to add their own native bindings, they now clutter the myscript namespace. (I've done some research, and it seems that for example the Perl cURL binding follows this pattern. Not sure what I should think about that...) So how do you suggest I name my variables? Are there any general guidelines that should be followed?

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