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  • PHP Sort Array based on values in another.....

    - by Fearghal
    Need some help regarding array sorting.... I have two arrays. The main one (where the key is the user id) : $user[31] = 'Tom' $user[43] = 'Jane' and another array with the order they should be displayed (where key is the order and value is the user id) : $order[1] = 43 $order[2] = 31 How can I apply the ordering to the main array using the ordering one? Thanks guys!

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  • How to order actions in menus in Eclipse RCP

    - by Marcos Scriven
    If I add action within an extension point thus: <action class="com.mycompany.MyAction" id="mycompany.myaction.MyAction" menubarPath="actions" /> How can I control its ordering programatically? It looks like they are simply ordered alphabetically according to their ID. I don't want to have to give them names such as '001-z', '002-a', just to get 'z' to appear before 'a'. It would also be a nightmare re-ordering them later.

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  • Is stack address shared by Heap addresses ??

    - by numerical25
    I read On most operating systems, the addresses in memory starts from highest to lowest. So I am wondering if the heap, stack, and global memory all fall under the same ordering..? If I created... pointerType* pointer = new pointerType //creates memory address 0xffffff And then created a local varible on the stack localObject object would localObjects address be 0xfffffe Or is heap and stack ordering completely different.

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  • Help needed to construct a SQL query

    - by song202y
    Need your help to get the list of suggested friends (who aren't friends of the current user but are friends of 2 or more of the current user's friends). The primary ordering should put people at the same school at the top, and the secondary ordering should put people with more common friends (that is, the number of people who are friends of that person and the current user) near the top. Users: user_id PK, user_name Profiles: user_id PK, school_name, ... Friendships: id PK, user_id FK, friend_id FK Thank you in advance. Joe

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  • Sell good Dumps, track 1&2, CVV, Paypal, WU TRANSFER Service

    - by gOOD dUMPS cvv
    my products for sale: Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers I am here to sell, supply good and quality CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... In last 5 years my Job Is This. PRESTIGE is my first motto. Not easy to build the good PRESTIGE. My motto is Always make customers satisfied & happy ! I have unlocked many softwares make good money, example: -Software to make the bug and crack MTCN of the Western Union. Version : 2.0.1.1 ( new update ) -Software to open balance in PayPal and Bank Login -Software hacking credit card, debit card Version 1.0 **I only sell it for my good customers, and my familiarity ***I update more than 200 CC + CVV everyday. Fresh + good valid + Strong,private + high balance with best price Our products are checked by a partner who works in a bank. Our products are better than 5-7 days after they are dead. They are raised mainly for money atm. Can be used in most countries. ** If you are a serious buyer, let contact via : Yahoo ID: goodcvv_dumps Mail: [email protected] ICQ: 667686221 * Sell CVV; Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers. CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... I promise CC of mine are good,high balance and fresh all with good price. PRESTIGE is my first motto. I sure u will be happy All I need is good & serious buyer to business for a long time * SELL GOOD CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;...!IF NOT GOOD, WILL CHANGE IMMEDIATELY * Contact me to negotiate about the price if buying bulk. I really need more serious buyers to do long business. You will be given many endow when we have long time business,you do good for me, I do good for u too. Long & good business.This is all I need :) - US (vis,mas)= $3/CC; US (amex,dis)= $5/CC; US BIN; US fullz; USA Visa VBV info for sale. - UK (vis,mas)= $8/CC; UK (amex,dis)= $20/CC; UK BIN; UK DOB; UK with Postcode; UK fullz; UK pass VBV - EU (vis,mas)= $20/CC; EU Amex = $30/CC; EU DOB; EU fullz; EU pass VBV. Include: Italy CVV; Spain CVV; France CVV; Sweden CVV; Denmark CVV; Slovakia CVV; Portugal CVV; Norway CVV; Belgium CVV Greece CVV; Germany CVV; Ireland CVV; Newzealand CVV; Switzerland CVV; Finland CVV; Turkey CVV; Netherland CVV - CA (vis,mas)= $8/CC; CA BIN; CA GOLD; CA Amex; CA Fullz; CA pass VBV - AU (vis,mas)= $10/CC; AU BIN; AU Amex; AU DOB; AU fullz; AU pass VBV - Brazil random = $15/CC; Brazil BIN - Middle East: UAE = $15/CC; Qatar= $10/CC; Saudi Arabia;... - ASIA ( Malay; Indo; Japan;China; Hongkong; Singapore...) = $10/CC - South Africa = $10/CC - And All CC; CC pass VBV; CVV pass VBV; CCN SSN- INTER ( BIN,DOB,SSN,FULLZ) of another Countries. Good CC, CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... [Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers] [Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers] ------------------------------ CONTACT via Y!H: goodcvv_dumps or ICQ: 667686221 or Mail: [email protected] ------------------------------------ * WARNING!!! BEFORE MAKE BUSINESS or add my ID, let read carefull my rule because i really hate Spammers,Rippers and Scammers - Dont trust, dont talk more - Don't Spamm And Don't Scam! I very hate do spam or rip and I don't want who spam me. - All my CVV are tested before sell, that's sure - I accept LR; WU or MoneyGram. - I only work with reliable buyers. Need good & serious buyer to business for a long time - I work with only one slogan: prestige and quality to satisfy my clients !!! - I was so happy to see you actually make more big money from the business with me Once you trust me, work with me. And if not trust,dont contact me, dont waste time! --------------------------THANKS, LOOK FORWARD TO WORKING WITH ALL of YOU !!!---------------------------- * Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts,Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers. CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... [Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts,Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers] * Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected] ===================== WESTERN UNION TRANSFER SERVICE ======================= We are Very PROFESSIONAL in WESTION UNION. Our Special Job Is this We Have big Western Union Service for everywhere and every when for you. We transfer money to all country in world. We can transfer big amount. And you can receive this money from your country. Our service accept payment 15% of transfer amount for small transfer . And 10% of big transfer. For large transfer . We make is very safe. And this service is very fast. We start to run software to make transfer to your WU info very fast,without delay and immediately. We give you MTCN and sender info and all cashout info, 15 mins after your payment complete. CONTACT US via Y!H: goodcvv_dumps or ICQ: 667686221 or Mail: [email protected] to know more info, price list of WU TRANSFER SERVICE ====================== Verified Paypal Accounts for sale ======================== If u are interested in it, contact me to know the price list & have the Tips for using above accounts safely,not be suspended when using accounts. I will not responsible if you get suspended. ===================== Dumps, Track1&2 with PIN & without PIN for ATM Cashout ======================= - Tracks 1&2 US;Tracks 1&2 UK;Tracks 1&2 CA,AU; Tracks 1&2 EU, with PIN and without PIN. - Dumps US; Dumps CA; Dumps EU; Dumps ASIA; Dumps AU, Brazil with good quality & price. Update Types of Dumps having now: Mix; Debit Classic; MC Standard;MC World; Gold; Platinum; Business/Corporate; Purchasing/Signature; Infinite - Contact me via Y!H: goodcvv_dumps (ICQ: 667686221) to know more info & price list of dumps, tracks ! ======================== Bank Logins Account (US UK CA AU EU) ======================== Sell Bank acc: Bank BOA, Bank HSBC USA, HSBC UK, Chase,Washovia, Halifax, Barclays, Abbey,... I make sure that my BANK LOGIN are security & easily to use. If u are interested in this, contact me to know more info about balance, price list,...! ================= Top-up Prepaid Cards, Debit Cards ========================= - If you hold any prepaid cards, debit cards, any country or any company. - I can top you funds into your prepaid cards, debit cards or any virtual cards. - top up your debit cards with hacked credit cards - top up your prepaid card with bank account login - top up you card with paypal account or any other - Have all tools to top your cards account - Top up does not take more then 10 minutes - Payoneer Cards top up available at cheap ================= Service: Provide Ebay - Apple - Amazon - Itunes GIFT CARD & Game Card with best price ===================== Contact me to negotiate about the price if buying bulk - PlayStation® Network Card - Xbox LIVE 12 Month Gold Membership = 30$ Xbox LIVE 4000 Microsoft Points = 30$ Zynga $50 Game Card (World Wide) = 30$ Ultimate game card 50$ = 30$ Ultimate game card 20$ = 10$ Key Diablo 3 = 25$ ITUNES GIFT CARD AMAZON GIFT CARD Ebay gift card Visa gift card ---------------- Our products are checked by a partner who works in a bank -------------------- Our products are better than 5-7 days after they are dead. They are raised mainly for money atm. Can be used in most countries. ---------------- Contact Via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected] ------------------------ Need good & serious buyer to business for a long time [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]]

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  • Sell good CVV, Dumps track 1&2, Paypal, WU TRANSFER

    - by Good Dumps CVV for sale
    My products for sale: Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers I am here to sell, supply good and quality CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... In last 5 years my Job Is This. PRESTIGE is my first motto. Not easy to build the good PRESTIGE. My motto is Always make customers satisfied & happy ! I have unlocked many softwares make good money, example: -Software to make the bug and crack MTCN of the Western Union. Version : 2.0.1.1 ( new update ) -Software to open balance in PayPal and Bank Login -Software hacking credit card, debit card Version 1.0 **I only sell it for my good customers, and my familiarity ***I update more than 200 CC + CVV everyday. Fresh + good valid + Strong,private + high balance with best price Our products are checked by a partner who works in a bank. Our products are better than 5-7 days after they are dead. They are raised mainly for money atm. Can be used in most countries. ** If you are a serious buyer, let contact via : Yahoo ID: goodcvv_dumps Mail: [email protected] ICQ: 667686221 * Sell CVV; Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers. CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... I promise CC of mine are good,high balance and fresh all with good price. PRESTIGE is my first motto. I sure u will be happy All I need is good & serious buyer to business for a long time * SELL GOOD CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;...!IF NOT GOOD, WILL CHANGE IMMEDIATELY * Contact me to negotiate about the price if buying bulk. I really need more serious buyers to do long business. You will be given many endow when we have long time business,you do good for me, I do good for u too. Long & good business.This is all I need :) - US (vis,mas)= $3/CC; US (amex,dis)= $5/CC; US BIN; US fullz; USA Visa VBV info for sale. - UK (vis,mas)= $8/CC; UK (amex,dis)= $20/CC; UK BIN; UK DOB; UK with Postcode; UK fullz; UK pass VBV - EU (vis,mas)= $20/CC; EU Amex = $30/CC; EU DOB; EU fullz; EU pass VBV. Include: Italy CVV; Spain CVV; France CVV; Sweden CVV; Denmark CVV; Slovakia CVV; Portugal CVV; Norway CVV; Belgium CVV Greece CVV; Germany CVV; Ireland CVV; Newzealand CVV; Switzerland CVV; Finland CVV; Turkey CVV; Netherland CVV - CA (vis,mas)= $8/CC; CA BIN; CA GOLD; CA Amex; CA Fullz; CA pass VBV - AU (vis,mas)= $10/CC; AU BIN; AU Amex; AU DOB; AU fullz; AU pass VBV - Brazil random = $15/CC; Brazil BIN - Middle East: UAE = $15/CC; Qatar= $10/CC; Saudi Arabia;... - ASIA ( Malay; Indo; Japan;China; Hongkong; Singapore...) = $10/CC - South Africa = $10/CC - And All CC; CC pass VBV; CVV pass VBV; CCN SSN- INTER ( BIN,DOB,SSN,FULLZ) of another Countries. Good CC, CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... [Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers] [Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts;Ebay Accounts Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers] ------------------------------ CONTACT via Y!H: goodcvv_dumps or ICQ: 667686221 or Mail: [email protected] ------------------------------------ * WARNING!!! BEFORE MAKE BUSINESS or add my ID, let read carefull my rule because i really hate Spammers,Rippers and Scammers - Dont trust, dont talk more - Don't Spamm And Don't Scam! I very hate do spam or rip and I don't want who spam me. - All my CVV are tested before sell, that's sure - I accept LR; WU or MoneyGram. - I only work with reliable buyers. Need good & serious buyer to business for a long time - I work with only one slogan: prestige and quality to satisfy my clients !!! - I was so happy to see you actually make more big money from the business with me Once you trust me, work with me. And if not trust,dont contact me, dont waste time! --------------------------THANKS, LOOK FORWARD TO WORKING WITH ALL of YOU !!!---------------------------- * Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts,Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers. CVV for shipping;booking airline ticket;shopping online;ordering Laptop,Iphone;... [Sell CVV; Dumps, track1&2; Bank logins; Paypal Accounts,Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Cards, ATM Card; MSR, ATM SKIMMERS. Do WU Transfers and Bank Transfers] * Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected] ===================== WESTERN UNION TRANSFER SERVICE ======================= We are Very PROFESSIONAL in WESTION UNION. Our Special Job Is this We Have big Western Union Service for everywhere and every when for you. We transfer money to all country in world. We can transfer big amount. And you can receive this money from your country. Our service accept payment 15% of transfer amount for small transfer . And 10% of big transfer. For large transfer . We make is very safe. And this service is very fast. We start to run software to make transfer to your WU info very fast,without delay and immediately. We give you MTCN and sender info and all cashout info, 15 mins after your payment complete. CONTACT US via Y!H: goodcvv_dumps or ICQ: 667686221 or Mail: [email protected] to know more info, price list of WU TRANSFER SERVICE ====================== Verified Paypal Accounts for sale ======================== If u are interested in it, contact me to know the price list & have the Tips for using above accounts safely,not be suspended when using accounts. I will not responsible if you get suspended. ===================== Dumps, Track1&2 with PIN & without PIN for ATM Cashout ======================= - Tracks 1&2 US;Tracks 1&2 UK;Tracks 1&2 CA,AU; Tracks 1&2 EU, with PIN and without PIN. - Dumps US; Dumps CA; Dumps EU; Dumps ASIA; Dumps AU, Brazil with good quality & price. Update Types of Dumps having now: Mix; Debit Classic; MC Standard;MC World; Gold; Platinum; Business/Corporate; Purchasing/Signature; Infinite - Contact me via Y!H: goodcvv_dumps (ICQ: 667686221) to know more info & price list of dumps, tracks ! ======================== Bank Logins Account (US UK CA AU EU) ======================== Sell Bank acc: Bank BOA, Bank HSBC USA, HSBC UK, Chase,Washovia, Halifax, Barclays, Abbey,... I make sure that my BANK LOGIN are security & easily to use. If u are interested in this, contact me to know more info about balance, price list,...! ================= Top-up Prepaid Cards, Debit Cards ========================= - If you hold any prepaid cards, debit cards, any country or any company. - I can top you funds into your prepaid cards, debit cards or any virtual cards. - top up your debit cards with hacked credit cards - top up your prepaid card with bank account login - top up you card with paypal account or any other - Have all tools to top your cards account - Top up does not take more then 10 minutes - Payoneer Cards top up available at cheap ================= Service: Provide Ebay - Apple - Amazon - Itunes GIFT CARD & Game Card with best price ===================== Contact me to negotiate about the price if buying bulk - PlayStation® Network Card - Xbox LIVE 12 Month Gold Membership = 30$ Xbox LIVE 4000 Microsoft Points = 30$ Zynga $50 Game Card (World Wide) = 30$ Ultimate game card 50$ = 30$ Ultimate game card 20$ = 10$ Key Diablo 3 = 25$ ITUNES GIFT CARD AMAZON GIFT CARD Ebay gift card Visa gift card ---------------- Our products are checked by a partner who works in a bank -------------------- Our products are better than 5-7 days after they are dead. They are raised mainly for money atm. Can be used in most countries. ---------------- Contact Via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected] ------------------------ Need good & serious buyer to business for a long time [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]] [Sell CVV, Dumps,track1&2; Bank logins; Paypal Accounts;Ebay Accounts; Mailpass; SMTP;RDP;VPS;CCN;SSN; Sell Amazon gift card & itunes gift card; Game Card, ATM Card, MSR, ATM SKIMMERS. Do WU Transfer and Bank Transfers....Contact via Y!H: goodcvv_dumps or ICQ: 667686221. Mail: [email protected]]

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  • Inappropriate Updates?

    - by Tony Davis
    A recent Simple-talk article by Kathi Kellenberger dissected the fastest SQL solution, submitted by Peter Larsson as part of Phil Factor's SQL Speed Phreak challenge, to the classic "running total" problem. In its analysis of the code, the article re-ignited a heated debate regarding the techniques that should, and should not, be deemed acceptable in your search for fast SQL code. Peter's code for running total calculation uses a variation of a somewhat contentious technique, sometimes referred to as a "quirky update": SET @Subscribers = Subscribers = @Subscribers + PeopleJoined - PeopleLeft This form of the UPDATE statement, @variable = column = expression, is documented and it allows you to set a variable to the value returned by the expression. Microsoft does not guarantee the order in which rows are updated in this technique because, in relational theory, a table doesn’t have a natural order to its rows and the UPDATE statement has no means of specifying the order. Traditionally, in cases where a specific order is requires, such as for running aggregate calculations, programmers who used the technique have relied on the fact that the UPDATE statement, without the WHERE clause, is executed in the order imposed by the clustered index, or in heap order, if there isn’t one. Peter wasn’t satisfied with this, and so used the ingenious device of assuring the order of the UPDATE by the use of an "ordered CTE", based on an underlying temporary staging table (a heap). However, in either case, the ordering is still not guaranteed and, in addition, would be broken under conditions of parallelism, or partitioning. Many argue, with validity, that this reliance on a given order where none can ever be guaranteed is an abuse of basic relational principles, and so is a bad practice; perhaps even irresponsible. More importantly, Microsoft doesn't wish to support the technique and offers no guarantee that it will always work. If you put it into production and it breaks in a later version, you can't file a bug. As such, many believe that the technique should never be tolerated in a production system, under any circumstances. Is this attitude justified? After all, both forms of the technique, using a clustered index to guarantee the order or using an ordered CTE, have been tested rigorously and are proven to be robust; although not guaranteed by Microsoft, the ordering is reliable, provided none of the conditions that are known to break it are violated. In Peter's particular case, the technique is being applied to a temporary table, where the developer has full control of the data ordering, and indexing, and knows that the table will never be subject to parallelism or partitioning. It might be argued that, in such circumstances, the technique is not really "quirky" at all and to ban it from your systems would server no real purpose other than to deprive yourself of a reliable technique that has uses that extend well beyond the running total calculations. Of course, it is doubly important that such a technique, including its unsupported status and the assumptions that underpin its success, is fully and clearly documented, preferably even when posting it online in a competition or forum post. Ultimately, however, this technique has been available to programmers throughout the time Sybase and SQL Server has existed, and so cannot be lightly cast aside, even if one sympathises with Microsoft for the awkwardness of maintaining an archaic way of doing updates. After all, a Table hint could easily be devised that, if specified in the WITH (<Table_Hint_Limited>) clause, could be used to request the database engine to do the update in the conventional order. Then perhaps everyone would be satisfied. Cheers, Tony.

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  • Delphi Exception handling problem with multiple Exception handling blocks

    - by Robert Oschler
    I'm using Delphi Pro 6 on Windows XP with FastMM 4.92 and the JEDI JVCL 3.0. Given the code below, I'm having the following problem: only the first exception handling block gets a valid instance of E. The other blocks match properly with the class of the Exception being raised, but E is unassigned (nil). For example, given the current order of the exception handling blocks when I raise an E1 the block for E1 matches and E is a valid object instance. However, if I try to raise an E2, that block does match, but E is unassigned (nil). If I move the E2 catching block to the top of the ordering and raise an E1, then when the E1 block matches E is is now unassigned. With this new ordering if I raise an E2, E is properly assigned when it wasn't when the E2 block was not the first block in the ordering. Note I tried this case with a bare-bones project consisting of just a single Delphi form. Am I doing something really silly here or is something really wrong? Thanks, Robert type E1 = class(EAbort) end; E2 = class(EAbort) end; procedure TForm1.Button1Click(Sender: TObject); begin try raise E1.Create('hello'); except On E: E1 do begin OutputDebugString('E1'); end; On E: E2 do begin OutputDebugString('E2'); end; On E: Exception do begin OutputDebugString('E(all)'); end; end; // try() end;

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  • Delph Exception handling problem with multiple Exception handling blocks

    - by Robert Oschler
    I'm using Delphi Pro 6 on Windows XP with FastMM 4.92 and the JEDI JVCL 3.0. Given the code below, I'm having the following problem: only the first exception handling block gets a valid instance of E. The other blocks match properly with the class of the Exception being raised, but E is unassigned (nil). For example, given the current order of the exception handling blocks when I raise an E1 the block for E1 matches and E is a valid object instance. However, if I try to raise an E2, that block does match, but E is unassigned (nil). If I move the E2 catching block to the top of the ordering and raise an E1, then when the E1 block matches E is is now unassigned. With this new ordering if I raise an E2, E is properly assigned when it wasn't when the E2 block was not the first block in the ordering. Note I tried this case with a bare-bones project consisting of just a single Delphi form. Am I doing something really silly here or is something really wrong? Thanks, Robert type E1 = class(EAbort) end; E2 = class(EAbort) end; procedure TForm1.Button1Click(Sender: TObject); begin try raise E1.Create('hello'); except On E: E1 do begin OutputDebugString('E1'); end; On E: E2 do begin OutputDebugString('E2'); end; On E: Exception do begin OutputDebugString('E(all)'); end; end; // try() end;

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  • How to approach parallel processing of messages?

    - by Dan
    I am redesigning the messaging system for my app to use intel threading building blocks and am stumped trying to decide between two possible approaches. Basically, I have a sequence of message objects and for each message type, a sequence of handlers. For each message object, I apply each handler registered for that message objects type. The sequential version would be something like this (pseudocode): for each message in message_sequence <- SEQUENTIAL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The first approach which I am considering processes the message objects in turn (sequentially) and applies the handlers concurrently. Pros: predictable ordering of messages (ie, we are guaranteed a FIFO processing order) (potentially) lower latency of processing each message Cons: more processing resources available than handlers for a single message type (bad parallelization) bad use of processor cache since message objects need to be copied for each handler to use large overhead for small handlers The pseudocode of this approach would be as follows: for each message in message_sequence <- SEQUENTIAL parallel_for each handler in (handler_table for message.type) apply handler to message <- PARALLEL The second approach is to process the messages in parallel and apply the handlers to each message sequentially. Pros: better use of processor cache (keeps the message object local to all handlers which will use it) small handlers don't impose as much overhead (as long as there are other handlers also to be run) more messages are expected than there are handlers, so the potential for parallelism is greater Cons: Unpredictable ordering - if message A is sent before message B, they may both be processed at the same time, or B may finish processing before all of A's handlers are finished (order is non-deterministic) The pseudocode is as follows: parallel_for each message in message_sequence <- PARALLEL for each handler in (handler_table for message.type) apply handler to message <- SEQUENTIAL The second approach has more advantages than the first, but non-deterministic ordering is a big disadvantage.. Which approach would you choose and why? Are there any other approaches I should consider (besides the obvious third approach: parallel messages and parallel handlers, which has the disadvantages of both and no real redeeming factors as far as I can tell)? Thanks!

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

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

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  • Thoughts on my new template language?

    - by Ralph
    Let's start with an example: using "html5" using "extratags" html { head { title "Ordering Notice" jsinclude "jquery.js" } body { h1 "Ordering Notice" p "Dear @name," p "Thanks for placing your order with @company. It's scheduled to ship on {@ship_date|dateformat}." p "Here are the items you've ordered:" table { tr { th "name" th "price" } for(@item in @item_list) { tr { td @item.name td @item.price } } } if(@ordered_warranty) p "Your warranty information will be included in the packaging." p(class="footer") { "Sincerely," br @company } } } The "using" keyword indicates which tags to use. "html5" might include all the html5 standard tags, but your tags names wouldn't have to be based on their HTML counter-parts at all if you didn't want to. The "extratags" library for example might add an extra tag, called "jsinclude" which gets replaced with something like <script type="text/javascript" src="@content"></script> Tags can be optionally be followed by an opening brace. They will automatically be closed as the closing brace. If no brace is used, they will be closed after taking on element. Variables are prefixed with the @ symbol. They may be used inside double-quoted strings. I think I'll use single-quotes to indicate "no variable substitution" like PHP does. Filter functions can be applied to variables like @variable|filter. Arguments can be passed to the filter @variable|filter:@arg1,arg2="y" Attributes can be passed to tags by including them in (), like p(class="classname"). Some questions: Which symbol should I use to prefix variables? @ (like Razor), $ (like PHP), or something else? Should the @ symbol be necessary in "for" and "if" statements? It's kind of implied that those are variables. Tags and controls (like if,for) presently have the exact same syntax. Should I do something to differentiate the two? If so, what? Do you like the attribute syntax? (round brackets) I'll add more questions in a few minutes, once I get some feedback.

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  • C#/.NET Little Wonders: The Predicate, Comparison, and Converter Generic Delegates

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. In the last three weeks, we examined the Action family of delegates (and delegates in general), the Func family of delegates, and the EventHandler family of delegates and how they can be used to support generic, reusable algorithms and classes. This week I will be completing my series on the generic delegates in the .NET Framework with a discussion of three more, somewhat less used, generic delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>. These are older generic delegates that were introduced in .NET 2.0, mostly for use in the Array and List<T> classes.  Though older, it’s good to have an understanding of them and their intended purpose.  In addition, you can feel free to use them yourself, though obviously you can also use the equivalents from the Func family of delegates instead. Predicate<T> – delegate for determining matches The Predicate<T> delegate was a very early delegate developed in the .NET 2.0 Framework to determine if an item was a match for some condition in a List<T> or T[].  The methods that tend to use the Predicate<T> include: Find(), FindAll(), FindLast() Uses the Predicate<T> delegate to finds items, in a list/array of type T, that matches the given predicate. FindIndex(), FindLastIndex() Uses the Predicate<T> delegate to find the index of an item, of in a list/array of type T, that matches the given predicate. The signature of the Predicate<T> delegate (ignoring variance for the moment) is: 1: public delegate bool Predicate<T>(T obj); So, this is a delegate type that supports any method taking an item of type T and returning bool.  In addition, there is a semantic understanding that this predicate is supposed to be examining the item supplied to see if it matches a given criteria. 1: // finds first even number (2) 2: var firstEven = Array.Find(numbers, n => (n % 2) == 0); 3:  4: // finds all odd numbers (1, 3, 5, 7, 9) 5: var allEvens = Array.FindAll(numbers, n => (n % 2) == 1); 6:  7: // find index of first multiple of 5 (4) 8: var firstFiveMultiplePos = Array.FindIndex(numbers, n => (n % 5) == 0); This delegate has typically been succeeded in LINQ by the more general Func family, so that Predicate<T> and Func<T, bool> are logically identical.  Strictly speaking, though, they are different types, so a delegate reference of type Predicate<T> cannot be directly assigned to a delegate reference of type Func<T, bool>, though the same method can be assigned to both. 1: // SUCCESS: the same lambda can be assigned to either 2: Predicate<DateTime> isSameDayPred = dt => dt.Date == DateTime.Today; 3: Func<DateTime, bool> isSameDayFunc = dt => dt.Date == DateTime.Today; 4:  5: // ERROR: once they are assigned to a delegate type, they are strongly 6: // typed and cannot be directly assigned to other delegate types. 7: isSameDayPred = isSameDayFunc; When you assign a method to a delegate, all that is required is that the signature matches.  This is why the same method can be assigned to either delegate type since their signatures are the same.  However, once the method has been assigned to a delegate type, it is now a strongly-typed reference to that delegate type, and it cannot be assigned to a different delegate type (beyond the bounds of variance depending on Framework version, of course). Comparison<T> – delegate for determining order Just as the Predicate<T> generic delegate was birthed to give Array and List<T> the ability to perform type-safe matching, the Comparison<T> was birthed to give them the ability to perform type-safe ordering. The Comparison<T> is used in Array and List<T> for: Sort() A form of the Sort() method that takes a comparison delegate; this is an alternate way to custom sort a list/array from having to define custom IComparer<T> classes. The signature for the Comparison<T> delegate looks like (without variance): 1: public delegate int Comparison<T>(T lhs, T rhs); The goal of this delegate is to compare the left-hand-side to the right-hand-side and return a negative number if the lhs < rhs, zero if they are equal, and a positive number if the lhs > rhs.  Generally speaking, null is considered to be the smallest value of any reference type, so null should always be less than non-null, and two null values should be considered equal. In most sort/ordering methods, you must specify an IComparer<T> if you want to do custom sorting/ordering.  The Array and List<T> types, however, also allow for an alternative Comparison<T> delegate to be used instead, essentially, this lets you perform the custom sort without having to have the custom IComparer<T> class defined. It should be noted, however, that the LINQ OrderBy(), and ThenBy() family of methods do not support the Comparison<T> delegate (though one could easily add their own extension methods to create one, or create an IComparer() factory class that generates one from a Comparison<T>). So, given this delegate, we could use it to perform easy sorts on an Array or List<T> based on custom fields.  Say for example we have a data class called Employee with some basic employee information: 1: public sealed class Employee 2: { 3: public string Name { get; set; } 4: public int Id { get; set; } 5: public double Salary { get; set; } 6: } And say we had a List<Employee> that contained data, such as: 1: var employees = new List<Employee> 2: { 3: new Employee { Name = "John Smith", Id = 2, Salary = 37000.0 }, 4: new Employee { Name = "Jane Doe", Id = 1, Salary = 57000.0 }, 5: new Employee { Name = "John Doe", Id = 5, Salary = 60000.0 }, 6: new Employee { Name = "Jane Smith", Id = 3, Salary = 59000.0 } 7: }; Now, using the Comparison<T> delegate form of Sort() on the List<Employee>, we can sort our list many ways: 1: // sort based on employee ID 2: employees.Sort((lhs, rhs) => Comparer<int>.Default.Compare(lhs.Id, rhs.Id)); 3:  4: // sort based on employee name 5: employees.Sort((lhs, rhs) => string.Compare(lhs.Name, rhs.Name)); 6:  7: // sort based on salary, descending (note switched lhs/rhs order for descending) 8: employees.Sort((lhs, rhs) => Comparer<double>.Default.Compare(rhs.Salary, lhs.Salary)); So again, you could use this older delegate, which has a lot of logical meaning to it’s name, or use a generic delegate such as Func<T, T, int> to implement the same sort of behavior.  All this said, one of the reasons, in my opinion, that Comparison<T> isn’t used too often is that it tends to need complex lambdas, and the LINQ ability to order based on projections is much easier to use, though the Array and List<T> sorts tend to be more efficient if you want to perform in-place ordering. Converter<TInput, TOutput> – delegate to convert elements The Converter<TInput, TOutput> delegate is used by the Array and List<T> delegate to specify how to convert elements from an array/list of one type (TInput) to another type (TOutput).  It is used in an array/list for: ConvertAll() Converts all elements from a List<TInput> / TInput[] to a new List<TOutput> / TOutput[]. The delegate signature for Converter<TInput, TOutput> is very straightforward (ignoring variance): 1: public delegate TOutput Converter<TInput, TOutput>(TInput input); So, this delegate’s job is to taken an input item (of type TInput) and convert it to a return result (of type TOutput).  Again, this is logically equivalent to a newer Func delegate with a signature of Func<TInput, TOutput>.  In fact, the latter is how the LINQ conversion methods are defined. So, we could use the ConvertAll() syntax to convert a List<T> or T[] to different types, such as: 1: // get a list of just employee IDs 2: var empIds = employees.ConvertAll(emp => emp.Id); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.ConvertAll(emp => (int)emp.Salary); Note that the expressions above are logically equivalent to using LINQ’s Select() method, which gives you a lot more power: 1: // get a list of just employee IDs 2: var empIds = employees.Select(emp => emp.Id).ToList(); 3:  4: // get a list of all emp salaries, as int instead of double: 5: var empSalaries = employees.Select(emp => (int)emp.Salary).ToList(); The only difference with using LINQ is that many of the methods (including Select()) are deferred execution, which means that often times they will not perform the conversion for an item until it is requested.  This has both pros and cons in that you gain the benefit of not performing work until it is actually needed, but on the flip side if you want the results now, there is overhead in the behind-the-scenes work that support deferred execution (it’s supported by the yield return / yield break keywords in C# which define iterators that maintain current state information). In general, the new LINQ syntax is preferred, but the older Array and List<T> ConvertAll() methods are still around, as is the Converter<TInput, TOutput> delegate. Sidebar: Variance support update in .NET 4.0 Just like our descriptions of Func and Action, these three early generic delegates also support more variance in assignment as of .NET 4.0.  Their new signatures are: 1: // comparison is contravariant on type being compared 2: public delegate int Comparison<in T>(T lhs, T rhs); 3:  4: // converter is contravariant on input and covariant on output 5: public delegate TOutput Contravariant<in TInput, out TOutput>(TInput input); 6:  7: // predicate is contravariant on input 8: public delegate bool Predicate<in T>(T obj); Thus these delegates can now be assigned to delegates allowing for contravariance (going to a more derived type) or covariance (going to a less derived type) based on whether the parameters are input or output, respectively. Summary Today, we wrapped up our generic delegates discussion by looking at three lesser-used delegates: Predicate<T>, Comparison<T>, and Converter<TInput, TOutput>.  All three of these tend to be replaced by their more generic Func equivalents in LINQ, but that doesn’t mean you shouldn’t understand what they do or can’t use them for your own code, as they do contain semantic meanings in their names that sometimes get lost in the more generic Func name.   Tweet Technorati Tags: C#,CSharp,.NET,Little Wonders,delegates,generics,Predicate,Converter,Comparison

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  • C#/.NET Little Wonders: Tuples and Tuple Factory Methods

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can really help improve your code by making it easier to write and maintain.  This week, we look at the System.Tuple class and the handy factory methods for creating a Tuple by inferring the types. What is a Tuple? The System.Tuple is a class that tends to inspire a reaction in one of two ways: love or hate.  Simply put, a Tuple is a data structure that holds a specific number of items of a specific type in a specific order.  That is, a Tuple<int, string, int> is a tuple that contains exactly three items: an int, followed by a string, followed by an int.  The sequence is important not only to distinguish between two members of the tuple with the same type, but also for comparisons between tuples.  Some people tend to love tuples because they give you a quick way to combine multiple values into one result.  This can be handy for returning more than one value from a method (without using out or ref parameters), or for creating a compound key to a Dictionary, or any other purpose you can think of.  They can be especially handy when passing a series of items into a call that only takes one object parameter, such as passing an argument to a thread's startup routine.  In these cases, you do not need to define a class, simply create a tuple containing the types you wish to return, and you are ready to go? On the other hand, there are some people who see tuples as a crutch in object-oriented design.  They may view the tuple as a very watered down class with very little inherent semantic meaning.  As an example, what if you saw this in a piece of code: 1: var x = new Tuple<int, int>(2, 5); What are the contents of this tuple?  If the tuple isn't named appropriately, and if the contents of each member are not self evident from the type this can be a confusing question.  The people who tend to be against tuples would rather you explicitly code a class to contain the values, such as: 1: public sealed class RetrySettings 2: { 3: public int TimeoutSeconds { get; set; } 4: public int MaxRetries { get; set; } 5: } Here, the meaning of each int in the class is much more clear, but it's a bit more work to create the class and can clutter a solution with extra classes. So, what's the correct way to go?  That's a tough call.  You will have people who will argue quite well for one or the other.  For me, I consider the Tuple to be a tool to make it easy to collect values together easily.  There are times when I just need to combine items for a key or a result, in which case the tuple is short lived and so the meaning isn't easily lost and I feel this is a good compromise.  If the scope of the collection of items, though, is more application-wide I tend to favor creating a full class. Finally, it should be noted that tuples are immutable.  That means they are assigned a value at construction, and that value cannot be changed.  Now, of course if the tuple contains an item of a reference type, this means that the reference is immutable and not the item referred to. Tuples from 1 to N Tuples come in all sizes, you can have as few as one element in your tuple, or as many as you like.  However, since C# generics can't have an infinite generic type parameter list, any items after 7 have to be collapsed into another tuple, as we'll show shortly. So when you declare your tuple from sizes 1 (a 1-tuple or singleton) to 7 (a 7-tuple or septuple), simply include the appropriate number of type arguments: 1: // a singleton tuple of integer 2: Tuple<int> x; 3:  4: // or more 5: Tuple<int, double> y; 6:  7: // up to seven 8: Tuple<int, double, char, double, int, string, uint> z; Anything eight and above, and we have to nest tuples inside of tuples.  The last element of the 8-tuple is the generic type parameter Rest, this is special in that the Tuple checks to make sure at runtime that the type is a Tuple.  This means that a simple 8-tuple must nest a singleton tuple (one of the good uses for a singleton tuple, by the way) for the Rest property. 1: // an 8-tuple 2: Tuple<int, int, int, int, int, double, char, Tuple<string>> t8; 3:  4: // an 9-tuple 5: Tuple<int, int, int, int, double, int, char, Tuple<string, DateTime>> t9; 6:  7: // a 16-tuple 8: Tuple<int, int, int, int, int, int, int, Tuple<int, int, int, int, int, int, int, Tuple<int,int>>> t14; Notice that on the 14-tuple we had to have a nested tuple in the nested tuple.  Since the tuple can only support up to seven items, and then a rest element, that means that if the nested tuple needs more than seven items you must nest in it as well.  Constructing tuples Constructing tuples is just as straightforward as declaring them.  That said, you have two distinct ways to do it.  The first is to construct the tuple explicitly yourself: 1: var t3 = new Tuple<int, string, double>(1, "Hello", 3.1415927); This creates a triple that has an int, string, and double and assigns the values 1, "Hello", and 3.1415927 respectively.  Make sure the order of the arguments supplied matches the order of the types!  Also notice that we can't half-assign a tuple or create a default tuple.  Tuples are immutable (you can't change the values once constructed), so thus you must provide all values at construction time. Another way to easily create tuples is to do it implicitly using the System.Tuple static class's Create() factory methods.  These methods (much like C++'s std::make_pair method) will infer the types from the method call so you don't have to type them in.  This can dramatically reduce the amount of typing required especially for complex tuples! 1: // this 4-tuple is typed Tuple<int, double, string, char> 2: var t4 = Tuple.Create(42, 3.1415927, "Love", 'X'); Notice how much easier it is to use the factory methods and infer the types?  This can cut down on typing quite a bit when constructing tuples.  The Create() factory method can construct from a 1-tuple (singleton) to an 8-tuple (octuple), which of course will be a octuple where the last item is a singleton as we described before in nested tuples. Accessing tuple members Accessing a tuple's members is simplicity itself… mostly.  The properties for accessing up to the first seven items are Item1, Item2, …, Item7.  If you have an octuple or beyond, the final property is Rest which will give you the nested tuple which you can then access in a similar matter.  Once again, keep in mind that these are read-only properties and cannot be changed. 1: // for septuples and below, use the Item properties 2: var t1 = Tuple.Create(42, 3.14); 3:  4: Console.WriteLine("First item is {0} and second is {1}", 5: t1.Item1, t1.Item2); 6:  7: // for octuples and above, use Rest to retrieve nested tuple 8: var t9 = new Tuple<int, int, int, int, int, int, int, 9: Tuple<int, int>>(1,2,3,4,5,6,7,Tuple.Create(8,9)); 10:  11: Console.WriteLine("The 8th item is {0}", t9.Rest.Item1); Tuples are IStructuralComparable and IStructuralEquatable Most of you know about IComparable and IEquatable, what you may not know is that there are two sister interfaces to these that were added in .NET 4.0 to help support tuples.  These IStructuralComparable and IStructuralEquatable make it easy to compare two tuples for equality and ordering.  This is invaluable for sorting, and makes it easy to use tuples as a compound-key to a dictionary (one of my favorite uses)! Why is this so important?  Remember when we said that some folks think tuples are too generic and you should define a custom class?  This is all well and good, but if you want to design a custom class that can automatically order itself based on its members and build a hash code for itself based on its members, it is no longer a trivial task!  Thankfully the tuple does this all for you through the explicit implementations of these interfaces. For equality, two tuples are equal if all elements are equal between the two tuples, that is if t1.Item1 == t2.Item1 and t1.Item2 == t2.Item2, and so on.  For ordering, it's a little more complex in that it compares the two tuples one at a time starting at Item1, and sees which one has a smaller Item1.  If one has a smaller Item1, it is the smaller tuple.  However if both Item1 are the same, it compares Item2 and so on. For example: 1: var t1 = Tuple.Create(1, 3.14, "Hi"); 2: var t2 = Tuple.Create(1, 3.14, "Hi"); 3: var t3 = Tuple.Create(2, 2.72, "Bye"); 4:  5: // true, t1 == t2 because all items are == 6: Console.WriteLine("t1 == t2 : " + t1.Equals(t2)); 7:  8: // false, t1 != t2 because at least one item different 9: Console.WriteLine("t2 == t2 : " + t2.Equals(t3)); The actual implementation of IComparable, IEquatable, IStructuralComparable, and IStructuralEquatable is explicit, so if you want to invoke the methods defined there you'll have to manually cast to the appropriate interface: 1: // true because t1.Item1 < t3.Item1, if had been same would check Item2 and so on 2: Console.WriteLine("t1 < t3 : " + (((IComparable)t1).CompareTo(t3) < 0)); So, as I mentioned, the fact that tuples are automatically equatable and comparable (provided the types you use define equality and comparability as needed) means that we can use tuples for compound keys in hashing and ordering containers like Dictionary and SortedList: 1: var tupleDict = new Dictionary<Tuple<int, double, string>, string>(); 2:  3: tupleDict.Add(t1, "First tuple"); 4: tupleDict.Add(t2, "Second tuple"); 5: tupleDict.Add(t3, "Third tuple"); Because IEquatable defines GetHashCode(), and Tuple's IStructuralEquatable implementation creates this hash code by combining the hash codes of the members, this makes using the tuple as a complex key quite easy!  For example, let's say you are creating account charts for a financial application, and you want to cache those charts in a Dictionary based on the account number and the number of days of chart data (for example, a 1 day chart, 1 week chart, etc): 1: // the account number (string) and number of days (int) are key to get cached chart 2: var chartCache = new Dictionary<Tuple<string, int>, IChart>(); Summary The System.Tuple, like any tool, is best used where it will achieve a greater benefit.  I wouldn't advise overusing them, on objects with a large scope or it can become difficult to maintain.  However, when used properly in a well defined scope they can make your code cleaner and easier to maintain by removing the need for extraneous POCOs and custom property hashing and ordering. They are especially useful in defining compound keys to IDictionary implementations and for returning multiple values from methods, or passing multiple values to a single object parameter. Tweet Technorati Tags: C#,.NET,Tuple,Little Wonders

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  • Searching integer sequences

    - by David Gibson
    I have a fairly complex search problem that I've managed to reduce to the following description. I've been googling but haven't been able to find an algorithm that seems to fit my problem cleanly. In particular the need to skip arbitrary integers. Maybe someone here can point me to something? Take a sequence of integers A, for example (1 2 3 4) Take various sequences of integers and test if any of them match A such that. A contains all of the integers in the tested sequence The ordering of the integers in the tested sequence are the same in A We don't care about any integers in A that are not in the test sequence We want all matching test sequences, not just the first. An example A = (1 2 3 4) B = (1 3) C = (1 3 4) D = (3 1) E = (1 2 5) B matches A C matches A D does not match A as the ordering is different E does not match A as it contains an integer not in A I hope that this explanation is clear enough. The best I've managed to do is to contruct a tree of the test sequences and iterate over A. The need to be able to skip integers leads to a lot of unsuccessful search paths. Thanks Reading some suggestions I feel that I have to clarify a couple of points that I left too vague. Repeated numbers are allowed, in fact this is quite important as it allows a single test sequence to match A is multiple ways A = (1234356), B = (236), matches could be either -23---6 or -2--3-6 I expect there to be a very large number of test sequences, in the thousands at least and sequence A will tend to have a max length of maybe 20. Thus simply trying to match each test sequence one by one by iterating becomes extremely inefficient. Sorry if this wasn't clear.

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  • Learning Electronics & the Arduino Microcontroller

    - by Chris Williams
    Lately, I've had a growing interest in Electronics & Microcontrollers. I'm a loyal reader of Make Magazine and thoroughly enjoy seeing all the various projects in each issue, even though I rarely try to make any of them. I've been reading and watching videos about the Arduino, which is an open source Microcontroller and software project that the people at Make (and a lot of other folks) are pretty hot about. Even the prebuilt hardware is remarkably inexpensive , although there are kits available to build one from the base components. (Full disclosure: I bought my first soldering iron... EVER... just last week, so I fully acknowledge the likelihood of making some mistakes. That's why I'm not trying to do the "build it yourself" kit just yet. It's also another reason to be happy the hardware is so cheap.) There are a number of different Arduino boards available, but the two that have really piqued my interest are the Arduino UNO and the NETduino. The UNO is a very popular board, with a number of features and is under $35 which means I won't hurl myself off a bridge when I inevitably destroy it. The NETduino is very similar to the Arduino UNO and has the added advantage of being programmable with... you guessed it... C#. I'm actually ordering both boards and some miscellaneous other doodads to go with them.  There are a few good websites for this sort of thing, including www.makershed.com and www.adafruit.com. The price difference is negligible, so in my case, I'm ordering from Maker Shed (the Make Magazine people) because I want to support them. :) I've also picked up a few O'Reilly books on the subject which I am looking forward to reading & reviewing: Make: Electronics, Arduino: A Quick Start Guide and Getting Started With Arduino (all three of which arrived on my doorstep today.) This ties in with my "learn more about robotics" goals as well, since I'll need a good understanding of Electronics if I want to move past Lego Mindstorms eventually.

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  • Messages do not always appear in [catalog].[event_messages] in the order that they occur [SSIS]

    - by jamiet
    This is a simple heads up for anyone doing SQL Server Integration Services (SSIS) development using SSIS 2012. Be aware that messages do not always appear in [catalog].[event_messages] in the order that they occur, observe… In the following query I am looking at a subset of messages in [catalog].[event_messages] and ordering them by [event_message_id]: SELECT [event_message_id],[event_name],[message_time],[message_source_name]FROM   [catalog].[event_messages] emWHERE  [event_message_id] BETWEEN 290972 AND 290982ORDER  BY [event_message_id] ASC--ORDER BY [message_time] ASC Take a look at the two rows that I have highlighted, note how the OnPostExecute event for “Utility GetTargetLoadDatesPerETLIfcName” appears after the OnPreExecute event for “FELC Loop over TargetLoadDates”, I happen to know that this is incorrect because “Utility GetTargetLoadDatesPerETLIfcName” is a package that gets executed by an Execute Package Task prior to the For Each Loop “FELC Loop over TargetLoadDates”: If we order instead by [message_time] then we see something that makes more sense: SELECT [event_message_id],[event_name],[message_time],[message_source_name]FROM   [catalog].[event_messages] emWHERE  [event_message_id] BETWEEN 290972 AND 290982--ORDER BY [event_message_id] ASCORDER  BY [message_time] ASC We can see that the OnPostExecute for “Utility GetTargetLoadDatesPerETLIfcName” did indeed occur before the OnPreExecute event for “FELC Loop over TargetLoadDates”, they just did not get assigned an [event_message_id] in chronological order. We can speculate as to why that might be (I suspect the explanation is something to do with the two executables appearing in different packages) but the reason is not the important thing here, just be aware that you should be ordering by [message_time] rather than [event_message_id] if you want to get 100% accurate insights into your executions. @Jamiet

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  • How do I fix the display of Windows 7's Control Panel?

    - by kez
    This has really bugged me since I took the plunge and upgraded to Windows 7. I think everything is great on the whole apart from the Control Panel. Instead of ordering from top to bottom like in normal folders, it is ordered from left to right. Whenever I go to find something in Control Panel it takes 3 times as long because I expect to find Programs and Features below Power Options yet it is to the right. This is a screenshot to demonstrate - note the ordering goes across instead of down. My question - does anyone have a cunning fix to display the Control Panel ordered in the same way that normal folders are displayed?

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  • Deal Registration is moving to OPS– Guest Post

    - by Kristin Rose
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif";} We have listened to, contemplated around, and agreed with your feedback when it comes to our current deal registration system, and now we are proud to announce that deal registration is moving to the Oracle Partner Store! If you missed the live announcement at Oracle OpenWorld, watch below as Titina Ott, VP of  Worldwide Alliances & Channels, presents on this upcoming and exciting functionality. Some benefits of this move include: Simplified Registration Form Easier and Faster Product Selection Expanded Browser Support Shared Registration Visibility Between VAD and VAR Downloadable tracking and reporting Shared Customer Selection From Partner Ordering Functions As you may already be aware, the Oracle Partner Store is a very popular, feature rich application for partners like you, that handles software and hardware ordering, including configurations, additional discount requests and product and price information. This big move is set to go live November 19th 2012, but don’t wait until then! If you don’t already have an Oracle Partner Store account, register today  and get ready for the big move! Best Regards, Simon Davis Senior Director Ww A&C Quote To Order

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  • Is there a piece of software which lets you turn "anything" into a dynamic reorderable list?

    - by Robin Green
    I could write this myself, but I want to know if it already exists. Basically, it must fulfill these criteria: To reorder items, the user must never have to manually renumber them. That would be annoying, and it doesn't scale. Can read from a range of data sources (e.g. a database, a directory on the file system, a text file, another list) When the original data source changes, the list must automatically change with it (possibly with confirmation, e.g. if a list item would be deleted) Ability to persist the list ordering in some fashion Graphical display of list items (so that they can include e.g. images) Optional extras: Ability to modify data and write back to the data source (other than the ordering information)

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  • Which order to define getters and setters in? [closed]

    - by N.N.
    Is there a best practice for the order to define getters and setters in? There seems to be two practices: getter/setter pairs first getters, then setters (or the other way around) To illuminate the difference here is a Java example of getter/setter pairs: public class Foo { private int var1, var2, var3; public int getVar1() { return var1; } public void setVar1(int var1) { this.var1 = var1; } public int getVar2() { return var2; } public void setVar2(int var2) { this.var2 = var2; } public int getVar3() { return var3; } public void setVar3(int var3) { this.var3 = var3; } } And here is a Java example of first getters, then setters: public class Foo { private int var1, var2, var3; public int getVar1() { return var1; } public int getVar2() { return var2; } public int getVar3() { return var3; } public void setVar1(int var1) { this.var1 = var1; } public void setVar2(int var2) { this.var2 = var2; } public void setVar3(int var3) { this.var3 = var3; } } I think the latter type of ordering is clearer both in code and in class diagrams but I do not know if that is enough to rule out the other type of ordering.

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  • "didChangeSection:" NSfetchedResultsController delegate method not being called

    - by robenk
    I have a standard split view controller, with a detail view and a table view. Pressing a button in the detail view can cause the an object to change its placement in the table view's ordering. This works fine, as long as the resulting ordering change doesn't result in a section being added or removed. I.e. an object can change it's ordering in a section or switch from one section to another. Those ordering changes work correctly without problems. But, if the object tries to move to a section that doesn't exist yet, or is the last object to leave a section (therefore requiring the section its leaving to be removed), then the application crashes. NSFetchedResultsControllerDelegate has methods to handle sections being added and removed that should be called in those cases. But those delegate methods aren't being called for some reason. The code in question, is boilerplate: - (void)controllerWillChangeContent:(NSFetchedResultsController *)controller { NSLog(@"willChangeContent"); [self.tableView beginUpdates]; } - (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type { NSLog(@"didChangeSection"); switch(type) { case NSFetchedResultsChangeInsert: [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath { NSLog(@"didChangeObject"); UITableView *tableView = self.tableView; switch(type) { case NSFetchedResultsChangeInsert: [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; case NSFetchedResultsChangeUpdate: [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath]; break; case NSFetchedResultsChangeMove: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]withRowAnimation:UITableViewRowAnimationFade]; break; } } - (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { NSLog(@"didChangeContent"); [self.tableView endUpdates]; [detailViewController.reminderView update]; } Starting the application, and then causing the last object to leave a section results in the following output: 2011-01-08 23:40:18.910 Reminders[54647:207] willChangeContent 2011-01-08 23:40:18.912 Reminders[54647:207] didChangeObject 2011-01-08 23:40:18.914 Reminders[54647:207] didChangeContent 2011-01-08 23:40:18.915 Reminders[54647:207] *** Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit_Sim/UIKit-1145.66/UITableView.m:825 2011-01-08 23:40:18.917 Reminders[54647:207] Serious application error. Exception was caught during Core Data change processing: Invalid update: invalid number of sections. The number of sections contained in the table view after the update (5) must be equal to the number of sections contained in the table view before the update (6), plus or minus the number of sections inserted or deleted (0 inserted, 0 deleted). with userInfo (null) As you can see, "willChangeContent", "didChangeObject" (moving the object in question), and "didChangeContent" were all called properly. Based on the Apple's NSFetchedResultsControllerDelegate documentation "didChangeSection" should have been called before "didChangeObject", which would have prevented the exception causing the crash. So I guess the question is how do I assure that didChangeSection gets called? Thanks in advance for any help!

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  • Parallelism in .NET – Part 12, More on Task Decomposition

    - by Reed
    Many tasks can be decomposed using a Data Decomposition approach, but often, this is not appropriate.  Frequently, decomposing the problem into distinctive tasks that must be performed is a more natural abstraction. However, as I mentioned in Part 1, Task Decomposition tends to be a bit more difficult than data decomposition, and can require a bit more effort.  Before we being parallelizing our algorithm based on the tasks being performed, we need to decompose our problem, and take special care of certain considerations such as ordering and grouping of tasks. Up to this point in this series, I’ve focused on parallelization techniques which are most appropriate when a problem space can be decomposed by data.  Using PLINQ and the Parallel class, I’ve shown how problem spaces where there is a collection of data, and each element needs to be processed, can potentially be parallelized. However, there are many other routines where this is not appropriate.  Often, instead of working on a collection of data, there is a single piece of data which must be processed using an algorithm or series of algorithms.  Here, there is no collection of data, but there may still be opportunities for parallelism. As I mentioned before, in cases like this, the approach is to look at your overall routine, and decompose your problem space based on tasks.  The idea here is to look for discrete “tasks,” individual pieces of work which can be conceptually thought of as a single operation. Let’s revisit the example I used in Part 1, an application startup path.  Say we want our program, at startup, to do a bunch of individual actions, or “tasks”.  The following is our list of duties we must perform right at startup: Display a splash screen Request a license from our license manager Check for an update to the software from our web server If an update is available, download it Setup our menu structure based on our current license Open and display our main, welcome Window Hide the splash screen The first step in Task Decomposition is breaking up the problem space into discrete tasks. This, naturally, can be abstracted as seven discrete tasks.  In the serial version of our program, if we were to diagram this, the general process would appear as: These tasks, obviously, provide some opportunities for parallelism.  Before we can parallelize this routine, we need to analyze these tasks, and find any dependencies between tasks.  In this case, our dependencies include: The splash screen must be displayed first, and as quickly as possible. We can’t download an update before we see whether one exists. Our menu structure depends on our license, so we must check for the license before setting up the menus. Since our welcome screen will notify the user of an update, we can’t show it until we’ve downloaded the update. Since our welcome screen includes menus that are customized based off the licensing, we can’t display it until we’ve received a license. We can’t hide the splash until our welcome screen is displayed. By listing our dependencies, we start to see the natural ordering that must occur for the tasks to be processed correctly. The second step in Task Decomposition is determining the dependencies between tasks, and ordering tasks based on their dependencies. Looking at these tasks, and looking at all the dependencies, we quickly see that even a simple decomposition such as this one can get quite complicated.  In order to simplify the problem of defining the dependencies, it’s often a useful practice to group our tasks into larger, discrete tasks.  The goal when grouping tasks is that you want to make each task “group” have as few dependencies as possible to other tasks or groups, and then work out the dependencies within that group.  Typically, this works best when any external dependency is based on the “last” task within the group when it’s ordered, although that is not a firm requirement.  This process is often called Grouping Tasks.  In our case, we can easily group together tasks, effectively turning this into four discrete task groups: 1. Show our splash screen – This needs to be left as its own task.  First, multiple things depend on this task, mainly because we want this to start before any other action, and start as quickly as possible. 2. Check for Update and Download the Update if it Exists - These two tasks logically group together.  We know we only download an update if the update exists, so that naturally follows.  This task has one dependency as an input, and other tasks only rely on the final task within this group. 3. Request a License, and then Setup the Menus – Here, we can group these two tasks together.  Although we mentioned that our welcome screen depends on the license returned, it also depends on setting up the menu, which is the final task here.  Setting up our menus cannot happen until after our license is requested.  By grouping these together, we further reduce our problem space. 4. Display welcome and hide splash - Finally, we can display our welcome window and hide our splash screen.  This task group depends on all three previous task groups – it cannot happen until all three of the previous groups have completed. By grouping the tasks together, we reduce our problem space, and can naturally see a pattern for how this process can be parallelized.  The diagram below shows one approach: The orange boxes show each task group, with each task represented within.  We can, now, effectively take these tasks, and run a large portion of this process in parallel, including the portions which may be the most time consuming.  We’ve now created two parallel paths which our process execution can follow, hopefully speeding up the application startup time dramatically. The main point to remember here is that, when decomposing your problem space by tasks, you need to: Define each discrete action as an individual Task Discover dependencies between your tasks Group tasks based on their dependencies Order the tasks and groups of tasks

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