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• Named previously unnamed branch

  - by Jab

  It seems naming a previously unnamed branch doesn't really work out. It creates a nasty multiple heads problem that I can't find a solution for. Here is the workflow... UserA starts working on feature that they expect to be small, so they just start working(off the default branch). The change turns out to be a large project and will need multiple contributors. So UserA issues... hg branch "Feature1" and continues working, committing locally s needed. UserA then pulls down the changes from the central repo so he can push. At this point, why does hg heads return 3 heads? It shows 2 for default and 1 for Feature1. The first head for default is the latest change by another user on the branch(irrelevant). The second default head is the commit prior to the hg branch "Feature1" commit. The central repository has rules enforced so that only 1 head per branch is allowed, so forcing a push isn't an option. The repo doesn't want multiple heads on the default branch. UserA should be able to push these changes so that other users can see the Feature1 branch and help out. I can't seem to find a way to "correct" this. I don't think I can re-write the branch of the initial commits for the feature, before it was a named branch. I know the initial changes before the named branch are technically on the default branch, but does that mean they will be heads until that Feature1 branch is merged?

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• C# - Advantages/Disadvantages of different implementations for Comparing Objects

  - by Kevin Crowell

  This questions involves 2 different implementations of essentially the same code. First, using delegate to create a Comparison method that can be used as a parameter when sorting a collection of objects: class Foo { public static Comparison<Foo> BarComparison = delegate(Foo foo1, Foo foo2) { return foo1.Bar.CompareTo(foo2.Bar); }; } I use the above when I want to have a way of sorting a collection of Foo objects in a different way than my CompareTo function offers. For example: List<Foo> fooList = new List<Foo>(); fooList.Sort(BarComparison); Second, using IComparer: public class BarComparer : IComparer<Foo> { public int Compare(Foo foo1, Foo foo2) { return foo1.Bar.CompareTo(foo2.Bar); } } I use the above when I want to do a binary search for a Foo object in a collection of Foo objects. For example: BarComparer comparer = new BarComparer(); List<Foo> fooList = new List<Foo>(); Foo foo = new Foo(); int index = fooList.BinarySearch(foo, comparer); My questions are: What are the advantages and disadvantages of each of these implementations? What are some more ways to take advantage of each of these implementations? Is there a way to combine these implementations in such a way that I do not need to duplicate the code? Can I achieve both a binary search and an alternative collection sort using only 1 of these methods?

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• MySQL managing catalogue views

  - by Mark Lawrence

  A friend of mine has a catalogue that currently holds about 500 rows or 500 items. We are looking at ways that we can provide reports on the catalogue inclduing the number of times an item was viewed, and dates for when its viewed. His site is averaging around 25,000 page impressions per month and if we assumed for a minute that half of these were catalogue items then we'd assume roughly 12,000 catalogue items viewed each month. My question is the best way to manage item views in the database. First option is to insert the catalogue ID into a table and then increment the number of times its viewed. The advantage of this is its compact nature. There will only ever be as many rows in the table as there are catalogue items. `catalogue_id`, `views` The disadvantage is that no date information is being held, short of maintaining the last time an item was viewed. The second option is to insert a new row each time an item is viewed. `catalogue_id`, `timestamp` If we continue with the assumed figure of 12,000 item views that means adding 12,000 rows to the table each month, or 144,000 rows each year. The advantage of this is we know the number of times the item is viewed, and also the dates for when its viewed. The disadvantage is the size of the table. Is a table with 144,000 rows becoming too large for MySQL? Interested to hear any thoughts or suggestions on how to achieve this. Thanks.

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• C++ Check Substring of a String

  - by user69514

  I'm trying to check whether or not the second argument in my program is a substring of the first argument. The problem is that it only work if the substring starts with the same letter of the string. .i.e Michigan - Mich (this works) Michigan - Mi (this works) Michigan - igan (this doesn't work) #include <stdio.h> #include <string.h> #include <string> using namespace std; bool my_strstr( string str, string sub ) { bool flag = true; int startPosition = -1; char subStart = str.at(0); char strStart; //find starting position for(int i=0; i<str.length(); i++){ if(str.at(i) == subStart){ startPosition = i; break; } } for(int i=0; i<sub.size(); i++){ if(sub.at(i) != str.at(startPosition)){ flag = false; break; } startPosition++; } return flag; } int main(int argc, char **argv){ if (argc != 3) { printf ("Usage: check <string one> <string two>\n"); } string str1 = argv[1]; string str2 = argv[2]; bool result = my_strstr(str1, str2); if(result == 1){ printf("%s is a substring of %s\n", argv[2], argv[1]); } else{ printf("%s is not a substring of %s\n", argv[2], argv[1]); } return 0; }

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• Linked List push()

  - by JKid314159

  The stack is initialized with a int MaxSize =3. Then I push one int onto the list. " Pushed:" is returned to the console. Program crashes here. I think my logic is flawed but unsure. Maybe an infinite loop or unmet condition? Thanks for your help. I'm trying to traverse the list to the last node in the second part of the full() method. I implemented this stack as array based so must implement this method full() as this method is inside of main class. while(!stacker.full()) { cout << "Enter number = "; cin >> intIn; stacker.push(intIn); cout << "Pushed: " << intIn << endl; }//while Call to LinkListStack.cpp to class LinkList full(). int LinkList::full() { if(head == NULL) { top = 0; } else { LinkNode * tmp1; LinkNode * tmp2; tmp1 = head; while(top != MaxSize) { if(tmp1->next != NULL){ tmp2 = tmp1->next; tmp1 = tmp2; ++top; }//if }//while }//else return (top + 1 == MaxSize); }

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• Why should I override hashCode() when I override equals() method?

  - by Bragaadeesh

  Ok, I have heard from many places and sources that whenever I override the equals() method, I need to override the hashCode() method as well. But consider the following piece of code package test; public class MyCustomObject { int intVal1; int intVal2; public MyCustomObject(int val1, int val2){ intVal1 = val1; intVal2 = val2; } public boolean equals(Object obj){ return (((MyCustomObject)obj).intVal1 == this.intVal1) && (((MyCustomObject)obj).intVal2 == this.intVal2); } public static void main(String a[]){ MyCustomObject m1 = new MyCustomObject(3,5); MyCustomObject m2 = new MyCustomObject(3,5); MyCustomObject m3 = new MyCustomObject(4,5); System.out.println(m1.equals(m2)); System.out.println(m1.equals(m3)); } } Here the output is true, false exactly the way I want it to be and I dont care of overriding the hashCode() method at all. This means that hashCode() overriding is an option rather being a mandatory one as everyone says. I want a second confirmation.

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• Windows loader problem - turn on verbose mode

  - by doobop

  Hi, I'm in the process of reorganizing some of the legacy libraries in our application which has unmanaged code calling into libraries of managed code. While I have the code reorganized, it produces the following loader error: ... 'app.exe': Loaded 'C:\WINDOWS\system32\CsDisp.dll' 'app.exe': Loaded 'C:\WINDOWS\system32\psapi.dll' 'app.exe': Loaded 'C:\WINDOWS\system32\shell32.dll' 'app.exe': Loaded 'C:\appCode\Debug\daq206_32.dll', Binary was not built with debug information. 'app.exe': Loaded 'C:\appCode\Debug\SiUSBXp.dll', Binary was not built with debug information. 'app.exe': Loaded 'C:\appCode\Debug\AdlinkDAQ.dll', Symbols loaded. 'app.exe': Loaded 'C:\WINDOWS\system32\P9842.dll', Binary was not built with debug information. LDR: LdrRelocateImageWithBias() failed 0xc0000018 LDR: OldBase : 10000000 LDR: NewBase : 00A80000 LDR: Diff : 0x7c90d6fa0012f6cc LDR: NextOffset : 00000000 LDR: *NextOffset : 0x0 LDR: SizeOfBlock : 0xa80000 Debugger:: An unhandled non-continuable exception was thrown during process load I believe 0xc0000018 error is an overlapping address range. So, I have two questions. First, what linker options may cause this error? I'm currently linking with /DYNAMICBASE:NO and /FIXED:No as this was how some of the previous libraries were set up. Second, is there a way to turn on verbose mode for the loader so I can see what exactly it's trying to load? P9842 is a third party library so I imagine it is getting to one of my libraries after P9842 and failing on that one. Can I narrow it down? Thanks.

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• How to paginate Django with other get variables?

  - by vagabond

  I am having problems using pagination in Django. Take the URL below as an example: http://127.0.0.1:8000/users/?sort=first_name On this page I sort a list of users by their first_name. Without a sort GET variable it defaults to sort by id. Now if I click the next link I expect the following URL: http://127.0.0.1:8000/users/?sort=first_name&page=2 Instead I lose all get variables and end up with http://127.0.0.1:8000/users/?page=2 This is a problem because the second page is sorted by id instead of first_name. If I use request.get_full_path I will eventually end up with an ugly URL: http://127.0.0.1:8000/users/?sort=first_name&page=2&page=3&page=4 What is the solution? Is there a way to access the GET variables on the template and replace the value for the page? I am using pagination as described in Django's documentation and my preference is to keep using it. The template code I am using is similar to this: {% if contacts.has_next %} <a href="?page={{ contacts.next_page_number }}">next</a> {% endif %}

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• Why are compilers so stupid?

  - by martinus

  I always wonder why compilers can't figure out simple things that are obvious to the human eye. They do lots of simple optimizations, but never something even a little bit complex. For example, this code takes about 6 seconds on my computer to print the value zero (using java 1.6): int x = 0; for (int i = 0; i < 100 * 1000 * 1000 * 1000; ++i) { x += x + x + x + x + x; } System.out.println(x); It is totally obvious that x is never changed so no matter how often you add 0 to itself it stays zero. So the compiler could in theory replace this with System.out.println(0). Or even better, this takes 23 seconds: public int slow() { String s = "x"; for (int i = 0; i < 100000; ++i) { s += "x"; } return 10; } First the compiler could notice that I am actually creating a string s of 100000 "x" so it could automatically use s StringBuilder instead, or even better directly replace it with the resulting string as it is always the same. Second, It does not recognize that I do not actually use the string at all, so the whole loop could be discarded! Why, after so much manpower is going into fast compilers, are they still so relatively dumb? EDIT: Of course these are stupid examples that should never be used anywhere. But whenever I have to rewrite a beautiful and very readable code into something unreadable so that the compiler is happy and produces fast code, I wonder why compilers or some other automated tool can't do this work for me.

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• How can I determine PerlLogHandler performance impact?

  - by Timmy

  I want to create a custom Apache2 log handler, and the template that is found on the apache site is: #file:MyApache2/LogPerUser.pm #--------------------------- package MyApache2::LogPerUser; use strict; use warnings; use Apache2::RequestRec (); use Apache2::Connection (); use Fcntl qw(:flock); use File::Spec::Functions qw(catfile); use Apache2::Const -compile => qw(OK DECLINED); sub handler { my $r = shift; my ($username) = $r->uri =~ m|^/~([^/]+)|; return Apache2::Const::DECLINED unless defined $username; my $entry = sprintf qq(%s [%s] "%s" %d %d\n), $r->connection->remote_ip, scalar(localtime), $r->uri, $r->status, $r->bytes_sent; my $log_path = catfile Apache2::ServerUtil::server_root, "logs", "$username.log"; open my $fh, ">>$log_path" or die "can't open $log_path: $!"; flock $fh, LOCK_EX; print $fh $entry; close $fh; return Apache2::Const::OK; } 1; What is the performance cost of the flocks? Is this logging process done in parallel, or in serial with the HTTP request? In parallel the performance would not matter as much, but I wouldn't want the user to wait another split second to add something like this.

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• How to use AFIncrementalStore to binding with a NSManagedObject

  - by Matrosov Alexander

  I am searching for more information on how to use AFIncrementalStore. I need to know how to implement it step by step. Please don't down vote it, because of many resources, I really need help with this. If I understood right AFIncrementalStore it is a layer for fetching data from the server and for the mapping data model. Am I right? So I have few URL that I need to mapping into my local model. All of them use GET requests. For example base_url/api/categories I get this string in response: [{"category":{"name":"3d max","id":"1111001","users":[]}}, {"category":{"name":"photoshop","id":"1111002","users":[]}}, {"category":{"name":"auto cad","id":"1111003","users":[]}}] So I have a question how I can binding my local db with this data using AFIncrementalStore. Also if you can see there are relationships in the response string that are connected to uses. The array for users will contain id that is correspond to concert users. So I think second question is how to point that model has to have relationship.

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• Truncating a string while storing it in an array in c

  - by Nick

  I am trying to create an array of 20 character strings with a maximum of 17 characters that are obtained from a file named "words.dat". After that the program should truncate the string only showing the first 17 characters and completely ignore the rest of that string. However My question is: I am not quite sure how to accomplish this, can anyone give me some insight on how to accomplish this task? Here is my current code as is: #include <stdio.h> #include <stdlib.h> #define WORDS 20 #define LENGTH 18 char function1(char[WORDS][LENGTH]); int main( void ) { char word_array [WORDS] [LENGTH]; function1(word_array); return ( 0 ) ; } char function1(char word_array[WORDS][LENGTH]) { FILE *wordsfile = fopen("words.dat", "r"); int i = 0; if (wordsfile == NULL) printf("\nwords.dat was not properly opened.\n"); else { for (i = 0; i < WORDS; i++) { fscanf(wordsfile, "%17s", word_array[i]); printf ("%s \n", word_array[i]); } fclose(wordsfile); } return (word_array[WORDS][LENGTH]); } words.dat file: Ninja DragonsFury failninja dragonsrage leagueoflegendssurfgthyjnu white black red green yellow green leagueoflegendssughjkuj dragonsfury Sword sodas tiger snakes Swords Snakes sage Sample output: blahblah@fang:~>a.out Ninja DragonsFury failninja dragonsrage leagueoflegendssu rfgthyjnu white black red green yellow green leagueoflegendssu ghjkuj dragonsfury Sword sodas tiger snakes Swords blahblah@fang:~> What will be accomplished afterwards with this program is: After function1 works properly I will then create a second function name "function2" that will look throughout the array for matching pairs of words that match "EXACTLY" including case . After I will create a third function that displays the 20 character strings from the words.dat file that I previously created and the matching words.

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• Trie Backtracking in Recursion

  - by Darksky

  I am building a tree for a spell checker with suggestions. Each node contains a key (a letter) and a value (array of letters down that path). So assume the following sub-trie in my big trie: W / \ a e | | k k | | is word--> e e | ... This is just a subpath of a sub-trie. W is a node and a and e are two nodes in its value array etc... At each node, I check if the next letter in the word is a value of the node. I am trying to support mistyped vowels for now. So 'weke' will yield 'wake' as a suggestion. Here's my searchWord function in my trie: def searchWord(self, word, path=""): if len(word) > 0: key = word[0] word = word[1:] if self.values.has_key(key): path = path + key nextNode = self.values[key] return nextNode.searchWord(word, path) else: # check here if key is a vowel. If it is, check for other vowel substitutes else: if self.isWord: return path # this is the word found else: return None Given 'weke', at the end when word is of length zero and path is 'weke', my code will hit the second big else block. weke is not marked as a word and so it will return with None. This will return out of searchWord with None. To avoid this, at each stack unwind or recursion backtrack, I need to check if a letter is a vowel and if it is, do the checking again. I changed the if self.values.has_key(key) loop to the following: if self.values.has_key(key): path = path + key nextNode = self.values[key] ret = nextNode.searchWord(word, path) if ret == None: # check if key == vowel and replace path # return nextNode.searchWord(... return ret What am I doing wrong here? What can I do when backtracking to achieve what I'm trying to do?

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• Boost Asio UDP retrieve last packet in socket buffer

  - by Alberto Toglia

  I have been messing around Boost Asio for some days now but I got stuck with this weird behavior. Please let me explain. Computer A is sending continuos udp packets every 500 ms to computer B, computer B desires to read A's packets with it own velocity but only wants A's last packet, obviously the most updated one. It has come to my attention that when I do a: mSocket.receive_from(boost::asio::buffer(mBuffer), mEndPoint); I can get OLD packets that were not processed (almost everytime). Does this make any sense? A friend of mine told me that sockets maintain a buffer of packets and therefore If I read with a lower frequency than the sender this could happen. ¡? So, the first question is how is it possible to receive the last packet and discard the ones I missed? Later I tried using the async example of the Boost documentation but found it did not do what I wanted. http://www.boost.org/doc/libs/1_36_0/doc/html/boost_asio/tutorial/tutdaytime6.html From what I could tell the async_receive_from should call the method "handle_receive" when a packet arrives, and that works for the first packet after the service was "run". If I wanted to keep listening the port I should call the async_receive_from again in the handle code. right? BUT what I found is that I start an infinite loop, it doesn't wait till the next packet, it just enters "handle_receive" again and again. I'm not doing a server application, a lot of things are going on (its a game), so my second question is, do I have to use threads to use the async receive method properly, is there some example with threads and async receive? Thanks for you attention.

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• How can I have sub-elements of a complex/mixed type with unrestricted order and count?

  - by mbmcavoy

  I am working with XML where some elements will contain text with additional markup. This is similar to this example at W3Schools. However, I need the markup tags to be able to appear in any order and possibly more than once. To modify their example for illustration: <letter> Dear Mr.<name>John Smith</name>. Your order <orderid>1032</orderid> will be shipped on <shipdate>2001-07-13</shipdate>. Thank you, <name>Bob Adams</name> </letter> None of the options presented by W3Schools (on the page following the linked example) allow this XML due to the second <name> element. Their explanation of the "indicators" and my testing are consistent. <xs:sequence> - violates the element order <xs:choice> - more than one kind of element is used. <xs:all> - maxOccurs is restricted to "1". This seems like it should be basic, after all, XHTML allows such things. How do I define my schema to allow this?

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• Java Executor: Small tasks or big ones?

  - by Arash Shahkar

  Consider one big task which could be broken into hundreds of small, independently-runnable tasks. To be more specific, each small task is to send a light network request and decide upon the answer received from the server. These small tasks are not expected to take longer than a second, and involve a few servers in total. I have in mind two approaches to implement this using the Executor framework, and I want to know which one's better and why. Create a few, say 5 to 10 tasks each involving doing a bunch of send and receives. Create a single task (Callable or Runnable) for each send & receive and schedule all of them (hundreds) to be run by the executor. I'm sorry if my question shows that I'm lazy to test these and see for myself what's better (at least performance-wise). My question, while looking after an answer to this specific case, has a more general aspect. In situations like these when you want to use an executor to do all the scheduling and other stuff, is it better to create lots of small tasks or to group those into a less number of bigger tasks?

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• Recursive QuickSort suffering a StackOverflowException -- Need fresh eyes

  - by jon

  I am working on a Recursive QuickSort method implementation in a GenericList Class. I will have a second method that accepts a compareDelegate to compare different types, but for development purposes I'm sorting a GenericList<int I am recieving stackoverflow areas in different places depending on the list size. I've been staring at and tracing through this code for hours and probably just need a fresh pair of (more experienced)eyes. Definitely wanting to learn why it is broken, not just how to fix it. public void QuickSort() { int i, j, lowPos, highPos, pivot; GenericList<T> leftList = new GenericList<T>(); GenericList<T> rightList = new GenericList<T>(); GenericList<T> tempList = new GenericList<T>(); lowPos = 1; highPos = this.Count; if (lowPos < highPos) { pivot = (lowPos + highPos) / 2; for (i = 1; i <= highPos; i++) { if (this[i].CompareTo(this[pivot]) <= 0) leftList.Add(this[i]); else rightList.Add(this[i]); } leftList.QuickSort(); rightList.QuickSort(); for(i=1;i<=leftList.Count;i++) tempList.Add(leftList[i]); for(i=1;i<=rightList.Count;i++) tempList.Add(rightList[i]); this.items = tempList.items; this.count = tempList.count; } }

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• How to declare JavaScript and CSS XHTML-compatible?

  - by joyce

  Hi! I'm wondering how to declare JavaScript code within a CDATA section so that it is compatible with XHTML. Which method is correct/recommended? Method 1: <script type="text/javascript"> // <![CDATA[ CODE // ]]> </script> Method 2: <script type="text/javascript"> /* <![CDATA[ */ CODE /* ]]> */ </script> Is the second one also suitable for inline CSS? And, is it possible/does it make sense to add some encoding declaration here like <script type="text/javascript" charset="utf-8"> ... <style type="text/css" media="screen" charset="utf-8"> ... or <script type="text/javascript"> @charset "utf-8"; ... <style type="text/css" media="screen"> @charset "utf-8"; ...

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• algorithim for simple colision detection in Java

  - by Bob Twinkles

  I'm not very experienced with Java, just started a couple weeks ago, but I have a simple applet that has two user controlled balls, drawn through java.awt and I need a way to detect a collision with between them. I have an algorithm for detecting collision with the walls: while (true){ if (xPositon > (300 - radius)){ xSpeed = -xSpeed; } else if (xPositon < radius){ xSpeed = -xSpeed; } else if (yPositon > (300 - radius)) { ySpeed = -ySpeed; } else if (yPositon < radius){ ySpeed = -ySpeed; } xPositon += xSpeed; yPositon += ySpeed; and for the second ball if (xPositon2 > (300 - radius)){ xSpeed2 = -xSpeed2; } else if (xPositon2 < radius){ xSpeed2 = -xSpeed2; } else if (yPositon2 > (300 - radius)) { ySpeed2 = -ySpeed2; } else if (yPositon2 < radius){ ySpeed2 = -ySpeed2; } xPositon2 += xSpeed2; yPositon2 += ySpeed2; the applet is 300 pixels by 300 pixels radius stores the radius of the circles xPositon and xPositon2 store the x cordanents for the two balls yPositon and yPositon store the y cordanents for the two balls xSpeed and xSpeed2 store the x velocities for the two balls ySpeed and ySpeed2 store the y velocities for the two balls I've only taken algebra 1 so please no advanced math or physics.

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• jQuery: one-liner for removing all children but one

  - by user1352530

  HTML code is: <li> <a href="#" /> <ul> <li> <a href="#"/> </li> </ul> </li> I want to delete any node under $(this) = li that is not a link. If there are more than one link, just the first one is saved, and if there are links inside the ul tag, they are not included because they are descendants and no childrens. Something like this (I am cloning and outputting html): $(this).clone().remove('not(a:first)').html(); //Assuming remove looks for "a" as a first child Does not work, so I try with this: $(this).clone().children().remove('not(a:first)').parent().html(); Does not work so I try with this: $(this).clone().remove('not(>a:first)').html(); I need the original element as a reference after removal for chaining more operations EDIT: Ok! Second one works with a little syntax correction as some appointed (:not( instead of not() but I would like to know if there is any other solution similar to the third line so I don't have to do children().remove().parent(). Thank you!

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• How to handle management trying to interfere with the project (including architecture decision)

  - by Zwei Steinen

  I feel this is not a very good question to post on SO, but I need some advice from experienced developers... (I'm a second year developer) I guess this is a problem to many, many projects, but in our case, it is getting intense. There were so much interference from people that don't know a bit about software development, that our development came to an almost complete stop. We had to literary escape to another location to get any useful job done. Now we were happily producing results, but then I get a request for a "meeting" and it's them again. I have a friendly relationship with them, but I feel very daunted at the thought of talking about non-sense all over again. Should I be firm and tell them to shut up and wait for our results? Or should I be diplomatic and create an illusion they are making a positive contribution or something?? My current urge is to be unfriendly and murmur some stuff so they will give up or something. What would you do if you were in this situation?

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• How do I find all paths through a set of given nodes in a DAG?

  - by Hanno Fietz

  I have a list of items (blue nodes below) which are categorized by the users of my application. The categories themselves can be grouped and categorized themselves. The resulting structure can be represented as a Directed Acyclic Graph (DAG) where the items are sinks at the bottom of the graph's topology and the top categories are sources. Note that while some of the categories might be well defined, a lot is going to be user defined and might be very messy. Example: On that structure, I want to perform the following operations: find all items (sinks) below a particular node (all items in Europe) find all paths (if any) that pass through all of a set of n nodes (all items sent via SMTP from example.com) find all nodes that lie below all of a set of nodes (intersection: goyish brown foods) The first seems quite straightforward: start at the node, follow all possible paths to the bottom and collect the items there. However, is there a faster approach? Remembering the nodes I already passed through probably helps avoiding unnecessary repetition, but are there more optimizations? How do I go about the second one? It seems that the first step would be to determine the height of each node in the set, as to determine at which one(s) to start and then find all paths below that which include the rest of the set. But is this the best (or even a good) approach? The graph traversal algorithms listed at Wikipedia all seem to be concerned with either finding a particular node or the shortest or otherwise most effective route between two nodes. I think both is not what I want, or did I just fail to see how this applies to my problem? Where else should I read?

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• Why is this linq extension method hit the database twice?

  - by Pure.Krome

  Hi folks, I have an extension method called ToListIfNotNullOrEmpty(), which is hitting the DB twice, instead of once. The first time it returns one result, the second time it returns all the correct results. I'm pretty sure the first time it hits the database, is when the .Any() method is getting called. here's the code. public static IList<T> ToListIfNotNullOrEmpty<T>(this IEnumerable<T> value) { if (value.IsNullOrEmpty()) { return null; } if (value is IList<T>) { return (value as IList<T>); } return new List<T>(value); } public static bool IsNullOrEmpty<T>(this IEnumerable<T> value) { if (value != null) { return !value.Any(); } return true; } I'm hoping to refactor it so that, before the .Any() method is called, it actually enumerates through the entire list. If i do the following, only one DB call is made, because the list is already enumerated. var pewPew = (from x in whatever select x) .ToList() // This enumerates. .ToListIsNotNullOrEmpty(); // This checks the enumerated result. I sorta don't really want to call ToList() then my extension method. Any ideas, folks?

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• PDO using singleton stored as class properity

  - by Misiur

  Hi again. OOP drives me crazy. I can't move PDO to work. Here's my DB class: class DB extends PDO { public function &instance($dsn, $username = null, $password = null, $driver_options = array()) { static $instance = null; if($instance === null) { try { $instance = new self($dsn, $username, $password, $driver_options); } catch(PDOException $e) { throw new DBException($e->getMessage()); } } return $instance; } } It's okay when i do something like this: try { $db = new DB(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } But this: try { $db = DB::instance(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } catch(DBException $e) { echo $e->getMessage(); } Does nothing. I mean, even when I use wrong password/username, I don't get any exception. Second thing - I have class which is "heart" of my site: class Core { static private $instance; public $db; public function __construct() { if(!self::$instance) { $this->db = DB::instance(DB_TYPE.':hpost='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASS); } return self::$instance; } private function __clone() { } } I've tried to use "new DB" inside class, but this: $r = $core->db->query("SELECT * FROM me_config"); print_r($r->fetch()); Return nothing. $sql = "SELECT * FROM me_config"; print_r($core->db->query($sql)); I get: PDOStatement Object ( [queryString] => SELECT * FROM me_config ) I'm really confused, what am I doing wrong?

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• Practice of checking 'trueness' or 'equality' in conditional statements - does it really make sense?

  - by Senthil

  I remember many years back, when I was in school, one of my computer science teachers taught us that it was better to check for 'trueness' or 'equality' of a condition and not the negative stuff like 'inequality'. Let me elaborate - If a piece of conditional code can be written by checking whether an expression is true or false, we should check the 'trueness'. Example: Finding out whether a number is odd - it can be done in two ways: if ( num % 2 != 0 ) { // Number is odd } or if ( num % 2 == 1 ) { // Number is odd } When I was beginning to code, I knew that num % 2 == 0 implies the number is even, so I just put a ! there to check if it is odd. But he was like 'Don't check NOT conditions. Have the practice of checking the 'trueness' or 'equality' of conditions whenever possible.' And he recommended that I use the second piece of code. I am not for or against either but I just wanted to know - what difference does it make? Please don't reply 'Technically the output will be the same' - we ALL know that. Is it a general programming practice or is it his own programming practice that he is preaching to others?

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