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• Which MySQL Datatype to use for storing boolean values from/to PHP?

  - by Beat

  Since MySQL doesn't seem to have any 'boolean' datatype, which datatype do you 'abuse' for storing true/false information in MySQL? Especially in the context of writing and reading from/to a PHP-Script. Over time I have used and seen several approaches: tinyint, varchar fields containing the values 0/1, varchar fields containing the strings '0'/'1' or 'true'/'false' and finally enum Fields containing the two options 'true'/'false'. None of the above seems optimal, I tend to prefer the tinyint 0/1 variant, since automatic type conversion in PHP gives me boolean values rather simply. So which datatype do you use, is there a type designed for boolean values which I have overlooked? Do you see any advantages/disadvantages by using one type or another?

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• how to query sqlite for certain rows, i.e. dividing it into pages (perl DBI)

  - by user1380641

  sorry for my noob question, I'm currently writing a perl web application with sqlite database behind it. I would like to be able to show in my app query results which might get thousands of rows - these should be split in pages - routing should be like /webapp/N - where N is the page number. what is the correct way to query the sqlite db using DBI, in order to fetch only the relavent rows. for instance, if I show 25 rows per page so I want to query the db for 1-25 rows in the first page, 26-50 in the second page etc.... Thanks in advanced!

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• The pImpl idiom and Testability

  - by Rimo

  The pImpl idiom in c++ aims to hide the implementation details (=private members) of a class from the users of that class. However it also hides some of the dependencies of that class which is usually regarded bad from a testing point of view. For example if class A hides its implementation details in Class AImpl which is only accessible from A.cpp and AImpl depends on a lot of other classes, it becomes very difficult to unit test class A since the testing framework has no access to the methods of AImpl and also no way to inject dependency into AImpl. This has been a problem for me lately and I am beginning to think that the pImpl idiom and writing testable code don't mix well. Has anyone come across this problem before? and have you found a solution?

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• how to sort an existing table in greasemonkey ?

  - by user570512

  i'm writing a greasemonkey user.js for a page with a table in it. (table is 100 rows by 18 columns.) now what i want to do is to make it sortable on column. and also have it run in both chrome and firefox. all searches for answers sofar resulted in suggestions to use jquery/dojo or something alike. can i be done without any external code? after all it's just a matter of replacing the row's in a different order, right? or is that a silly thing to say? the thing is that i'm already using dojo for some query needs but since i want it to run in both firefox and chrome, i just copy paste the whole dojo thing in my script.. also, most of the solutions i found sofar seem to be more for use when building a table. not for altering an existing one. any help is appreciated.

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• Storing acceleration values in Objective-C/Cocoa?

  - by ASchlaep

  Hi all, I'm writing for the iPhone and I'm trying to measure the time between maximum accelerations. Imagine you've attached your iPhone to an oscillating spring. What I want to do is measure the frequency of the oscillation. The way I am going about doing this is storing a certain number acceleration values (updated 20 times per second) in an NSMutableArray and comparing the current acceleration value with previous acceleration values. How do I add each updated acceleration value to the NSMutableArray and at the same time delete values from the back of the array as I don't need them any more? Thanks in advance!

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• Shall I optimize or let compiler to do that?

  - by Knowing me knowing you

  What is the preferred method of writing loops according to efficiency: Way a) /*here I'm hoping that compiler will optimize this code and won't be calling size every time it iterates through this loop*/ for (unsigned i = firstString.size(); i < anotherString.size(), ++i) { //do something } or maybe should I do it this way: Way b) unsigned first = firstString.size(); unsigned second = anotherString.size(); and now I can write: for (unsigned i = first; i < second, ++i) { //do something } the second way seems to me like worse option for two reasons: scope polluting and verbosity but it has the advantage of being sure that size() will be invoked once for each object. Looking forward to your answers.

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• How to check for a file's authenticity ?

  - by Ale_x

  Let's say I write a game application. I want the level of the player to be stored in an external file. How can I prevent a hacker from writing and modifying the file to put another level ? I want the file to be modified by my application only. I can sign the file's content with a key, but then this key will be stored in the application, therefore it would be possible for a hacker to decompile the binary and find the key. Is there any way to do this ?

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• bash—Better way to store variable between runs?

  - by shardbearer

  I've made a bash script which I run every hour with crontab, and I need to store one variable so that I can access it the next time I run it. The script changes the variable every time it runs, so I can't hardcode it in. Right now I am writing it to a txt file and then reading it back. Is there a better way to do it than this? And the way I am reading the txt file is something I found on here, I don't understand it, and it's kinda clunky. Is there not a built in command for this? Anyway, here's the applicable code, with some of the variables changed to make it easier to read. while read x; do var=$x done < var.txt # Do some stuff, change var to a new value echo $var > var.txt The variable is only a single integer, so the text file feels overkill.

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• what to use for repetitive (daily, weekly, monthly) tasks ? Workflows, Windows Services, something e

  - by mare

  I've been writing Windows Services for a while and they always seem to work fine for things that need to run every day, few times a week, once a month, etc. but I've been lately thinking about going with Windows Workflow Foundation. However, I am unsure how would they run on a server without some container application (for instance SharePoint)? I worked with Sharepoint workflows before and I always had huge problems, at first with the bugs in the workflow architecture implementation (the problems with sleep and delay) and later when they eventually started to work, they were difficult to manage and change. On the other hand Windows Services were always quite easy to implement, easy to create a setup for them and install them and they were always quite resilient (they were often working for months without crashing or something else going wrong). What do you recommend? Please bear in mind we are working in .NET (version is of no problem, if 4.0 brings something new on this subject, we can use it).

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• Why System.String's beahaves like a value type?

  - by Sorush Rabiee

  I want to write a 'Date' class that behaves like a Value Type. for example, Instead of writing a Clone method for setting properties safely, make the Date class to pass by value: public Date Birthday { get { return this.birthday; } set { this.birthday = value.Clone(); } //I want to write this.birthday = value; //without changing external value when this.Birthday changes } I know this is possible because System.String is a class and behaves like a value. for example: String s1 = "Hello"; String s2 = "Hi"; s1 = s2; s2="Hello"; Console.WriteLine(s1); //Prints 'Hi' First I thought writers of this class override '=' operator, but now I know that the '=' operator can not be overridden. so how they write String class?

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• Distribution of many small classes

  - by Moo-Juice

  Hi All, I have a base class called EventArgs. Derived from this are many, many specializations that represent event arguments for a particular kind of event. Consumers of these events may need some, many, or very few of these argument classes. My question is, would you provide a header file for each type (e.g, 50+ header files for the varying ones), would you try to group them in to families and have a 'common' header file for those, or would you throw caution to the window and throw them in to one easy-of-use header file that can just be included? Another approach might be to have 50 header files, and then I could introduce some "family" header files that included particular ones. Not sure about the naming conventions for these kinds of things so it is obvious what is where. I know there may not be a hard and fast rule, but wondering what other developers have done when they find themselves writing many little classes. Thanks in advance.

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• Determining whether a class implements a generic list in a T4 template

  - by James Hollingworth

  I'm writing a T4 template which loads some classes from an assembly, does some analysis of the classes and then generates some code. One particular bit of analysis I need to do is to determine whether the class implements a generic list. I can do this pretty simply in C#, e.g. public class Foo : List<string> { } var t = typeof(Foo); if (t.BaseType != null && t.BaseType.IsGenericType && t.BaseType.GetGenericTypeDefinition() == typeof(List<>))) Console.WriteLine("Win"); However T4 templates use the FXCop introspection engine and so you do not have access to the .net reflection API. I've spent the past couple of hours in Reflector but still can't figure it out. Does anyone have any clues about how to do this?

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• CString a = "Hello " + "World!"; Is it possible?

  - by Sanctus2099

  I'm making my own string class and I was wondering if there's any way to replace the compiler behaviour around " characters. As I said in the title I'd like to make it so that CString a = "Hello " + "World!"; would actually work and not give a compiler error telling that it can't add 2 pointers. My string class automatically converts to char* when needed and thus writing printf(a) would not break the code. I'm sure this is a rather weird question but if it's possible I'd really like to know how to do it. Thank you very much

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• Just how much do I want to make virtual?

  - by Alex

  I am writing an abstract superclass where literally every method is going to be overridden. There is some default functionality I could implement, but most of the time it's enough to leave the implementation to the subclass writer. Since just about every method is going to be overwritten, how much should I make virtual and how much should I just leave as regular methods? In the current incarnation, everything is virtual, but I still haven't let this loose to anyone to use, so the design is flexible. What advantages/disadvantages are there to virtual functions? Links to good reading material about this would be appreciated.

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• Can a parser tell the lexer to ignore a newline?

  - by chollida

  I'm writing a preprocessor for my language. In the preprocessor I've output a line that wasn't in the source file. This causes any error messages that Anltr creates to be incremented by one line. The Lexer handles the line count so I'm wondering if there is a way for the parser to tell the lexer to decrement the line count, or to ignore a specific newline. I'm also open to other suggestions on how to work around this. The only constraint I have is putting the extra line inline with the existing code. I'd prefer to keep it on it's own line to keep my parsing sane.

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• Data access layer design

  - by Sam

  I have a web app and a console application accessing a db. The db has 2 tables (A, B) one of which (A) is specific to the web app. When writing a data access layer, what is the best way to do it? Technically data access layer should provide access to all the data accessible. In doing so, methods to interact with A are exposed to the console application if we have single access layer. Does creating 2 access layers to 2 table in the same database makes any sense? What is a good way to do it?

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• new controller in oo php

  - by pradeep

  Hi , I have a practical doubt , I am using OO php , and i am new to it. I am using zend framework to be clear. I am writing controllers(class) and actions(methods) with in it say PatientMapper.php which has all single mysql table related actions and Patient.php which has all setter and getter functions. I get a doubt that when should i write a new controller. Should i write a controller for all the actions on a single mysql table . or a single controller for all actions related to a module.

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• construct a unique number for a string in java

  - by praveen

  We have a requirement of reading/writing more than 10 million strings into a file. Also we do not want duplicates in the file. Since the strings would be flushed to a file as soon as they are read we are not maintaining it in memory. We cannot use hashcode because of collisions in the hash code due to which we might miss a string as duplicate. Two other approaches i found in my googling: 1.Use a message digest algorithm like MD5 - but it might be too costly to calculate and store. 2.Use a checksum algorithm. [i am not sure if this produces a unique key for a string- can someone please confirm] Is there any other approach avaiable. Thanks.

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• How Can I Run a Regex that Tests Text for Characters in a Particular Alphabet or Script?

  - by Eli

  I'd like to make a regex in Perl that will test a string for a characters in a particular string. This would be something like: $text =~ .*P{'Chinese'}.* Is there a simple way of doing this, for English it's pretty easy by just testing for [a-zA-Z], but for a script like Chinese, or one of the Japanese scripts, I can't figure out any way of doing this short of writing out every character explicitly, which would make for some very ugly code. Ideas? I can't be the first/only person that's wanted to do this.

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• Can EventMachine recognize all threads are completed?

  - by philipjkim

  I'm an EM newbie and writing two codes to compare synchronous and asynchronous IO. I'm using Ruby 1.8.7. The example for sync IO is: def pause_then_print(str) sleep 2 puts str end 5.times { |i| pause_then_print(i) } puts "Done" This works as expected, taking 10+ seconds until termination. On the other hand, the example for async IO is: require 'rubygems' require 'eventmachine' def pause_then_print(str) Thread.new do EM.run do sleep 2 puts str end end end EventMachine.run do EM.add_timer(2.5) do puts "Done" EM.stop_event_loop end EM.defer(proc do 5.times { |i| pause_then_print(i) } end) end 5 numbers are shown in 2.x seconds. Now I explicitly wrote code that EM event loop to be stopped after 2.5 seconds. But what I want is that the program terminates right after printing out 5 numbers. For doing that, I think EventMachine should recognize all 5 threads are done, and then stop the event loop. How can I do that? Also, please correct the async IO example if it can be more natural and expressive. Thanks in advance.

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• Why does php's file_get_contents incorrectly retrieve json files from xkcd?

  - by hally

  In writing a PHP script to download xkcd comics, i incurred errors when trying to get specific comics (as opposed to the latest one). Specifically, pointing file_get_contents at the following url: xkcd.com/$COMIC_NUM/info.0.json inexplicably retrieved the xhtml version of the comic's page on xkcd.com, and not a JSON file. However, if i request the exact same url in my browser, the correct JSON file is downloaded. I'm not sure why this is happening, but i suspect it has something to do with the request headers being sent. Please help! :S

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• How to force calling of QWidget::paintEvent() when its hovered by other window?

  - by Pie_Jesu

  Hi there. I have occured a problem: I'm writing a widget, which displays current date's day number. It's like a button, but it's not derived from QPushButton class. Just from QWidget. So I reimplemented enterEvent(), leaveEvent(), mousePressEvent(), mouseReleaseEvent(). I call update() inside these methods and widget has realistic button behavior (paintEvent() is reimplemented too). But when I change system date and hover that widget with other window, my widget doesn't calls paintEvent() and displays old date. Only when I place mouse over it, widget repaints it's contents. I guess there is an option, which paints old contents on hover event to avoid unnecessary paint events. But I need to disable it. Tried to set many attributes (Qt::WidgetAttribute enum). But it doesn't helps. Please, help me (and sorry for my bad english).

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• How to programatically set a permanent environment variable in Linux?

  - by Richard

  I am writing a little install script for some software. All it does is unpack a target tar, and then i want to permanently set some environment variables - principally the location of the unpacked libs and updating $PATH. Do I need to programmatically edit the .bashrc file, adding the appropriate entries to the end for example, or is there another way? What's standard practice? Edit: The package includes a number of run scripts (20+) that all use these named environment variables, so I need to set them somehow (the variable names have been chosen such that a collision is extremely unlikely)

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• Long list of if statements in Java

  - by steve

  Hi, Sorry I can't find a question answering this, I'm almost certain someone else has raised it before. My problem is that I'm writing some system libraries to run embedded devices. I have commands which can be sent to these devices over radio broadcasts. This can only be done by text. inside the system libraries I have a thread which handles the commands which looks like this if (value.equals("A") { doCommandA() } else if (value.equals"B") { doCommandB() } else if etc. The problem is that there are a lot of commands to it will quickly spiral to something out of control. Horrible to look out, painful to debug and mind boggling to understand in a few months time.

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• Why does this Bash regex match return an Exit Status of "2"?

  - by PreservedMoose

  I'm writing a Bash script that needs to scan for the existence of non-ASCII characters in filenames. I'm using the POSIX bracket regex syntax to match the non-ASCII characters, but for some reason, when I test for the match in an if/then statement, the test always returns an Exit Status of 2, and never matches my test string. Here's the code in question: FILEREQ_SOURCEFILE="Filename–WithNonAScII-Charàcters-05sec_23.98.mov" REGEX_MATCH_NONASCII="[^[:ascii:]]" if [[ $FILEREQ_SOURCEFILE =~ $REGEX_MATCH_NONASCII ]]; then echo "Exit Status: $?" echo "Matched!" else echo "Exit Status: $?" echo "No Match" fi This code always returns: Exit Status: 2 No Match I've read and re-read the bash-hackers.org explanation of how regex matching works, as well as this previous question on SO regarding matching non-ASCII characters, but for the life of me, I can't get this to work. What am I missing here?

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