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  • Does the optimizer filter subqueries with outer where clauses

    - by Mongus Pong
    Take the following query: select * from ( select a, b from c UNION select a, b from d ) where a = 'mung' Will the optimizer generally work out that I am filtering a on the value 'mung' and consequently filter mung on each of the queries in the subquery. OR will it run each query within the subquery union and return the results to the outer query for filtering (as the query would perhaps suggest) In which case the following query would perform better : select * from ( select a, b from c where a = 'mung' UNION select a, b from d where a = 'mung' ) Obviously query 1 is best for maintenance, but is it sacrificing much performace for this? Which is best?

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  • Passing arguments and values form HTML to jQuery (events)

    - by Jaroslav Moravec
    What is the practice to pass arguments from HTML to jQuery events function. For example getting id of row from db: <tr class="jq_killMe" id="thisItemId-id"> ... </tr> and jQuery: $(".jq_killMe").click(function () { var tmp = $(this).attr('id).split("-"); var id = tmp[0] // ... } What's the best practise, if I want to pass more than one argument? Is it better not to use jQuery? For example: <tr onclick="killMe('id')"> ... </tr> I didn't find the answer on my question, I will be glad even for links. Thanks.

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  • Rails Full Engine using a Full Engine

    - by SirLenz0rlot
    I've got this full rails engine Foo with functionality X. I want to make another engine, engine Bar, that is pretty much the same, but override funcitonality x with y. (it basically does the same, but a few controller actions and views are differently implemented). (I might split this later in several mountable engines, but for now, this will be the setup: project Baz, using engine Bar, which uses engine Foo) I would like to know if there are any pitfalls. It doesn't seem like a pattern that is often used? Anybody else using this 'some sort of engine inheritance'?

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  • Simplest PHP Routing framework .. ?

    - by David
    I'm looking for the simplest implementation of a routing framework in PHP, in a typical PHP environment (Running on Apache, or maybe nginx) .. It's the implementation itself I'm mostly interested in, and how you'd accomplish it. I'm thinking it should handle URL's, with the minimal rewriting possible, (is it really a good idea, to have the same entrypoint for all dynamic requests?!), and it should not mess with the querystring, so I should still be able to fetch GET params with $_GET['var'] as you'd usually do.. So far I have only come across .htaccess solutions that puts everything through an index.php, which is sort of okay. Not sure if there are other ways of doing it. How would you "attach" what URL's fit to what controllers, and the relation between them? I've seen different styles. One huge array, with regular expressions and other stuff to contain the mapping. The one I think I like the best is where each controller declares what map it has, and thereby, you won't have one huge "global" map, but a lot of small ones, each neatly separated. So you'd have something like: class Root { public $map = array( 'startpage' => 'ControllerStartPage' ); } class ControllerStartPage { public $map = array( 'welcome' => 'WelcomeControllerPage' ); } // Etc ... Where: 'http://myapp/' // maps to the Root class 'http://myapp/startpage' // maps to the ControllerStartPage class 'http://myapp/startpage/welcome' // maps to the WelcomeControllerPage class 'http://myapp/startpage/?hello=world' // Should of course have $_GET['hello'] == 'world' What do you think? Do you use anything yourself, or have any ideas? I'm not interested in huge frameworks already solving this problem, but the smallest possible implementation you could think of. I'm having a hard time coming up with a solution satisfying enough, for my own taste. There must be something pleasing out there that handles a sane bootstrapping process of a PHP application without trying to pull a big magic hat over your head, and force you to use "their way", or the highway! ;)

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  • Guidelines for good webcrawler 'Etiquette'

    - by Harry
    I'm building a search engine (for fun) and it has just struck me that potentially my little project might wreak havok by clicking on ads and all sorts of problems. So what are the guidelines for good webcrawler 'Etiquette'? Things that spring to mind: Observe Robot.txt instructions Limit the number of simultaneous requests to the same domain Don't follow ad links? Stopping the crawler from clicking on ads - This one is particularly on my mind at the moment... how do i stop my bot from 'clicking' on ads? if it is going straight to the url in the ad is it counted as a click?

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  • ASP.Net MVC: Showing the same data using different layouts...

    - by vdh_ant
    Hi guys I'm wanting to create a page that allows the users to select how they would like to view their data - i.e. summary (which supports grouping), grid (which supports grouping), table (which supports grouping), map, time line, xml, json etc. Now each layout would probably have different use a different view model, which inherit from a common base class/view model. The reason being that each layout needs the object structure that it deals with to be different (some need hierarchical others a flatter structure). Each layout would call the same repository method and each layout would support the same functionality, i.e. searching and filtering (hence these controls would be shared between layouts). The main exception to this would be sorting which only grid and table views would need to support. Now my question is given this what do people think is the best approach. Using DisplayFor to handle the rendering of the different types? Also how do I work this with the actions... I would imagine that I would use the one action, and pass in the layout types, but then how does this support the grouping required for the summary, grid and table views. Do i treat each grouping as just a layout type Also how would this work from a URL point of view - what do people think is the template to support this layout functionality Cheers Anthony

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  • Scaffold default files are the best practice?

    - by antpaw
    Hey, i have some experience with MVC. but I'm new to rails. I'm using the scaffold command to generate some default files. The model looks clean and nice, but the controller and the views aren't really dry. The contents of new.html.erb and edit.html.erb are almost the same and the methods new/edit and create/update are doing almost the same thing. In other frameworks i've used only one view for updating and creating new entries and also the same method in my controller by setting the id as an optional parameter. Do they use this structure to keep things RESTful (i have not much of a clue about rest :()? Is it the best practice to use this default stuff for crud?

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  • Singleton Pattern combine with a Decorator

    - by Mike
    Attached is a classic Decorator pattern. My question is how would you modify the below code so that you can wrap zero or one of each topping on to the Pizza Right now I can have a Pepporini - Sausage -- Pepporini -- Pizza class driving the total cost up to $10, charging twice for Pepporini. I don't think I want to use the Chain of Responsibility pattern as order does not matter and not all toppings are used? Thank you namespace PizzaDecorator { public interface IPizza { double CalculateCost(); } public class Pizza: IPizza { public Pizza() { } public double CalculateCost() { return 8.00; } } public abstract class Topping : IPizza { protected IPizza _pizzaItem; public Topping(IPizza pizzaItem) { this._pizzaItem = pizzaItem; } public abstract double CalculateCost(); } public class Pepporini : Topping { public Pepporini(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + 0.50; } } public class Sausage : Topping { public Sausage(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + 1.00; } } public class Onions : Topping { public Onions(IPizza pizzaItem) : base(pizzaItem) { } public override double CalculateCost() { return this._pizzaItem.CalculateCost() + .25; } } }

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  • Why is "copy and paste" of code dangerous?

    - by Yigang Wu
    Sometimes, my boss will complain us why we need so long time to implement a feature. Actually, the feature has been implemented in other AP before, you just need to copy and paste codes from there. The cost should be low. It's really a hard question, because copy and paste codes is not a easy thing from my point. Do you have any good reason to explain your boss who doesn't know technology?

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  • Using a "vo" for joined data?

    - by keithjgrant
    I'm building a small financial system. Because of double-entry accounting, transactions always come in batches of two or more, so I've got a batch table and a transaction table. (The transaction table has batch_id, account_id, and amount fields, and shared data like date and description are relegated to the batch table). I've been using basic vo-type models for each table so far. Because of this table structure structure, though, transactions will almost always be selected with a join on the batch table. So should I take the selected records and splice them into two separate vo objects, or should I create a "shared" vo that contains both batch and transaction data? There are a few cases in which batch records and/or transaction records. Are there possible pitfalls down the road if I have "overlapping" vo classes?

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  • Is it good practice to generally make heavyweight classes non-copyable?

    - by Emile Cormier
    I have a Shape class containing potentially many vertices, and I was contemplating making copy-constructor/copy-assignment private to prevent accidental needless copying of my heavyweight class (for example, passing by value instead of by reference). To make a copy of Shape, one would have to deliberately call a "clone" or "duplicate" method. Is this good practice? I wonder why STL containers don't use this approach, as I rarely want to pass them by value.

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  • IEnumerable and IEnumerator in the same class, bad idea?

    - by David Rutten
    Is this a bad idea? Private Class GH_DataStructureEnumerator(Of Q As Types.IGH_Goo) Implements IEnumerable(Of Q) Implements IEnumerator(Of Q) .... .... 'Current, MoveNext, Reset etc.' .... .... Public Function GetEnumerator_Generic() As IEnumerator(Of Q) _ Implements IEnumerable(Of Q).GetEnumerator Return Me End Function End Class This class is only visible as an IEnumerable(Of T) readonly property, and it saves me an additional class that wraps IEnumerator(Of T). But somehow it just seems wrong. Is there a better way?

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  • Generalized plugable caching pattern?

    - by BCS
    Given that it's one of the hard things in computer science, does anyone know of a way to set up a plugable caching strategy? What I'm thinking of would allow me to write a program with minimal thought as to what needs to be cached (e.i. use some sort of boiler-plate, low/no cost pattern that compiles away to nothing anywhere I might want caching) and then when things are further along and I know where I need caching I can add it in without making invasive code changes. As an idea to the kind of solution I'm looking for; I'm working with the D programing language (but halfway sane C++ would be fine) and I like template.

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  • PDO update query with conditional?

    - by dmontain
    I have a PDO mysql that updates 3 fields. $update = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2, field3=:field3 WHERE key=:key"); But I want field3 to be updated only when $update3 = true; (meaning that the update of field3 is controlled by a conditional statement) Is this possible to accomplish with a single query? I could do it with 2 queries where I update field1 and field2 then check the boolean and update field3 if needed in a separate query. //run this query to update only fields 1 and 2 $update_part1 = $mypdo->prepare("UPDATE tablename SET field1=:field1, field2=:field2 WHERE key=:key"); //if field3 should be update, run a separate query to update it separately if ($update3){ $update_part2 = $mypdo->prepare("UPDATE tablename SET field3=:field3 WHERE key=:key"); } But hopefully there is a way to accomplish this in 1 query?

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  • Best practice for Python Assert

    - by meade
    Is there a performance or code maintenance issue with using assert as part of the standard code instead of using it just for debugging purposes? Is assert x >= 0, 'x is less then zero' and better or worse then if x < 0: raise Exception, 'x is less then zero' Also, is there anyway to set a business rule like if x < 0 raise error that is always checked with out the try, except, finally so, if at anytime throughout the code x is < 0 an error is raised, like if you set assert x < 0 at the start of a function, anywhere within the function where x becomes less then 0 an exception is raised?

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  • Linq to sql Repository pattern , Some doubts

    - by MindlessProgrammer
    I am using repository pattern with linq to sql, I am using a repository class per table. I want to know , am i doing at good/standard way, ContactRepository Contact GetByID() Contact GetAll() COntactTagRepository List<ContactTag> Get(long contactID) List<ContactTag> GetAll() List<ContactTagDetail> GetAllDetails() class ContactTagDetail { public Contact Contact {get;set;} public ContactTag COntactTag {get;set;} } When i need a contact i call method in contactrepository, same for contacttag but when i need contact and tags together i call GetDetais() in ContactTag repository its not returning the COntactTag entity generated by the orm insted its returning ContactTagDetail entity conatining both COntact and COntactTag generated by the orm, i know i can simple call GetAll in COntactTag repository and can access Contact.ContactTag but as its linq to sql it will there is no option to Deferred Load in query level, so whenever i need a entity with a related entity i create a projection class Another doubt is where i really need to right the method i can do it in both contact & ContactTag repostitory like In contact repository GetALlWithTags() or something but i am doing it in in COntactTag repository Whats your suggestions ?

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  • Parent child class relationship design pattern

    - by Jeremy
    I have a class which has a list of child items. Is there a design pattern I can copy that I can apply to these classes so that I can access the parent instance from the child, and it enforces rules such as not being able to add the child to multiple parents, etc?

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  • linux tooling for starting as a net programmer

    - by alfredo dobrekk
    What are the linux developper tools to do the things i do with .NET in my windows environnement : I would like to port my client server application that runs under winform/nhibernate/sql server. Language c# Database SQL server ORM Nhibernate Source control SVN / Tortoise Unit testing Nunit Continuous integration Cruise Control Should i go java and eclipse ? Python and ??? Ruby and ??? Is there some IDE that allow me to manage all these processes under linux ?

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