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• Do variable references (alias) incure runtime costs in c++?

  - by cheshirekow

  Maybe this is a compiler specific thing. If so, how about for gcc (g++)? If you use a variable reference/alias like this: int x = 5; int& y = x; y += 10; Does it actually require more cycles than if we didn't use the reference. int x = 5; x += 10; In other words, does the machine code change, or does the "alias" happen only at the compiler level? This may seem like a dumb question, but I am curious. Especially in the case where maybe it would be convenient to temporarily rename some member variables just so that the math code is a little easier to read. Sure, we're not exactly talking about a bottleneck here... but it's something that I'm doing and so I'm just wondering if there is any 'actual' difference... or if it's only cosmetic.

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• Concurrent Programming:Should I write a sequential program first, then add thread safety?

  - by evthim

  I'm working on a project where we have to create a number of threads(actual number will be inputted in by testers (TA's)). I'm having trouble not only with the programming but also with the design, I can't wrap my head around all of the threads that will be invoked and where I might cause errors. The project is due soon so I don't want to waste time on this if it'll actually set me back, but I was wondering if I should write the program like only one thread will be running and everything should be sequential and then later go back and try to add the thread safety parts of the code? Would that take twice the original amount of time? Project Description: Note:I'm going to be as vague as possible so I don't violate any honor codes, sorry :( your program should accept n number of objectA threads, m number of objectB threads, and r number of objectC objectB threads interact with code in objectA. objectA threads interact with code in objectB and objectC objectB and objectC don't directly interact, but do so indirectly through objectA -ex: objectB needs something from objectA. objectA gets the result for that something by calling objectC my confusion stems mostly from the fact that all of this interactions will be done by m+n threads and there are various restrictions throughout the descriptions, like objectB can request something from objectA, and objectA has to wait for objectC to finish that something before returning it to objectB. Also each objectA thread can only work on one instruction from objectB at a time, etc. etc. I just want to know if I write the code so that there is only 1 objectA, 1 objectB and 1 object C, can I go back and easily modify it so that those 1's can be changed to m, n and r? Sorry again, if my description is a little bit confusing.

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• Clarification of atomic memory access for different OSs

  - by murrekatt

  I'm currently porting a Windows C++ library to MacOS as a hobby project as a learning experience. I stumbled across some code using the Win Interlocked* functions and thus I've been trying to read up on the subject in general. Reading related questions here in SO, I understand there are different ways to do these operations depending on the OS. Interlocked* in Windows, OSAtomic* in MacOS and I also found that compilers have builtin (intrinsic) operations for this. After reading gcc builtin atomic memory access, I'm left wondering what is the difference between intrinsic and the OSAtomic* or Interlocked* ones? I mean, can I not choose between OSAtomic* or gcc builtin if I'm on MacOS when I use gcc? The same if I'd be on Windows using gcc. I also read that on Windows Interlocked* come as both inline and intrinsic versions. What to consider when choosing between intrinsic or inline? In general, are there multiple options on OSs what to use? Or is this again "it depends"? If so, what does it depend on? Thanks!

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• How do people handle foreign keys on clients when synchronizing to master db

  - by excsm

  Hi, I'm writing an application with offline support. i.e. browser/mobile clients sync commands to the master db every so often. I'm using uuid's on both client and server-side. When synching up to the server, the servre will return a map of local uuids (luid) to server uuids (suid). Upon receiving this map, clients updated their records suid attributes with the appropriate values. However, say a client record, e.g. a todo, has an attribute 'list_id' which holds the foreign key to the todos' list record. I use luids in foreign_keys on clients. However, when that attribute is sent over to the server, it would dirty the server db with luids rather than the suid the server is using. My current solution, is for the master server to keep a record of the mappings of luids to suids (per client id) and for each foreign key in a command, look up the suid for that particular client and use the suid instead. I'm wondering wether others have come across thus problem and if so how they have solved it? Is there a more efficient, simpler way? I took a look at this question "Synchronizing one or more databases with a master database - Foreign keys (5)" and someone seemed to suggest my current solution as one option, composite keys using suids and autoincrementing sequences and another option using -ve ids for client ids and then updating all negative ids with the suids. Both of these other options seem like a lot more work. Thanks, Saimon

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• c# Sending emails with authentication. standard approach not working

  - by Ready Cent

  I am trying to send an email using the following very standard code. However, I get the error that follow... MailMessage message = new MailMessage(); message.Sender = new MailAddress("[email protected]"); message.To.Add("[email protected]"); message.Subject = "test subject"; message.Body = "test body"; SmtpClient client = new SmtpClient(); client.Host = "mail.myhost.com"; //client.Port = 587; NetworkCredential cred = new NetworkCredential(); cred.UserName = "[email protected]"; cred.Password = "correct password"; cred.Domain = "mail.myhost.com"; client.Credentials = cred; client.UseDefaultCredentials = false; client.Send(message); Mailbox unavailable. The server response was: No such user here. This recipient email address definitely works. To make this account work I had to do some special steps in outlook. Specifically, I had to do change account settings - more settings - outgoing server - my outgoing server requires authentication & use same settings. I am wondering if there is some other strategy. I think the key here is that my host is Server Intellect and I know that some people on here use them so hopefully someone else has been able to get through this. I did talk to support but they said with coding issues I am on my own :o

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• What's a good way to make a Flex component with placeholders in it?

  - by Daniel Brockman

  I want to create a component that has a couple of "holes" that are to be filled in differently on each use. Currently, I'm doing it like this (using the Flex 4 framework in this example --- it would look almost the same for Flex 3): public var fooComponent : IVisualElement; public var barComponent : IVisualElement; override protected function createChildren() : void { super.createChildren(); fooContainer.addElement(fooComponent); barContainer.addElement(barComponent); } <Group id="fooContainer"/> <!-- ... other components ... --> <Group id="barContainer"/> This works well, but it's kind of a lot of code to write for something so simple. What I'd like is something like this: [Bindable] public var fooComponent : IVisualElement; [Bindable] public var barComponent : IVisualElement; <Placeholder content="{fooComponent}"/> <!-- ... other components ... --> <Placeholder content="{barComponent}"/> Now, I could implement the Placeholder component myself, but I can't help wondering if there isn't a better way to do this using the existing tools in the Flex framework. Theoretically, with the proper compiler support, it could even be boiled down to something like this: <Placeholder id="fooComponent"/> <!-- ... other components ... --> <Placeholder id="barComponent"/>

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• Best way to unit test Collection?

  - by limc

  I'm just wondering how folks unit test and assert that the "expected" collection is the same/similar as the "actual" collection (order is not important). To perform this assertion, I wrote my simple assert API:- public void assertCollection(Collection<?> expectedCollection, Collection<?> actualCollection) { assertNotNull(expectedCollection); assertNotNull(actualCollection); assertEquals(expectedCollection.size(), actualCollection.size()); assertTrue(expectedCollection.containsAll(actualCollection)); assertTrue(actualCollection.containsAll(expectedCollection)); } Well, it works. It's pretty simple if I'm asserting just bunch of Integers or Strings. It can also be pretty painful if I'm trying to assert a collection of Hibernate domains, say for example. The collection.containsAll(..) relies on the equals(..) to perform the check, but I always override the equals(..) in my Hibernate domains to check only the business keys (which is the best practice stated in the Hibernate website) and not all the fields of that domain. Sure, it makes sense to check just against the business keys, but there are times I really want to make sure all the fields are correct, not just the business keys (for example, new data entry record). So, in this case, I can't mess around with the domain.equals(..) and it almost seems like I need to implement some comparators for just unit testing purposes instead of relying on collection.containsAll(..). Are there some testing libraries I could leverage here? How do you test your collection? Thanks.

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• Android Remote Video with Titanium

  - by Tim

  Greetings all! I'm trying to play a video that is hosted on our webserver on an android phone. I've already built this for iPhone and it works great. Droid, however is a different issue. Instead of getting video, I'm just getting a black screen, no error or anything. The code I am using is: activeContent = Titanium.Media.createVideoPlayer({ contentURL: content, backgroundColor:'#111', movieControlMode:Titanium.Media.VIDEO_CONTROL_DEFAULT }); win.add(activeContent); activeContent.play(); The video I'm downloading does play on the droid when not using Titanium, so I know its not a format issue. (its an .MP4 incase anyone is wondering.) I've used Titanium SDK's 1.5.1 and am on the continuous build of 1.6.0 from earlier today. using the 2.2 Droid SDK, and Titanium Developer 1.2.2 Does anyone have any thoughts on this? One of the big selling points for android is its ability to pull media from the net, and I'm honestly a little concerned about this shortcoming if its an issue with Titanium.

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• Design question for windows application, best approach?

  - by Jamie Keeling

  Hello, I am in the process of designing an application that will allow you to find pictures (screen shots) made from certain programs. I will provide the locations of a few of the program in the application itself to get the user started. I was wondering how I should go about adding new locations as the time goes on, my first thought was simply hard coding it into the application but this will mean the user has to reinstall it to make the changes take affect. My second idea was to use an XML file to contain all the locations as well as other data, such as the name of the application. This also means the user can add their own locations if they wish as well as sharing them over the internet. The second option seemed the best approach but then I had to think how would it be managed on the users computer. Ideally I'd like just a single .exe without the reliance on any external files such as the XML but this would bring me back to point one. Would it be best to simply use the ClickOnce deployment to create an entry in the start menu and create a folder containing the .exe and the file names? Thanks for the feedback, I don't want to start implementing the application until the design is nailed.

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• php class scope when calling a non-method function not accessing all class members

  - by Aglystas

  So I'm using a stand alone function from within a class that that uses the class it's being called from. Here's the function function catalogProductLink($product_id,$product_name,$categories=true) { //This is the class that the function is called from global $STATE; if ($categories) { //The $STATE->category_id is the property I want to access, which I can't if (is_array($STATE->category_id)) { foreach($STATE->category_id as $cat_id) { if ($cat_id == 0) continue; $str .= "c$cat_id/"; } } } $str .= catalogUrlKeywords($product_name).'-p'.$product_id.'.html'; return $str; } And here's the function call, which is being made from within the $STATE class. $redirect = catalogProductLink($this->product_id, $tempProd->product_name, true, false); The object that I need access to is the $STATE object that has been declared global. Prior to this function call there are lots of public properties populated, but when I look at the $STATE object within the function scope it loses all the properties but one, product_id. The property that matters for this function is the category_id property, which is an array of category id's. I'm wondering why I don't have access to all the public properties of the $STATE object and how I can get access to them.

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• Haskell Cons Operator (:)

  - by Carson Myers

  I am really new to Haskell (Actually I saw "Real World Haskell" from O'Reilly and thought "hmm, I think I'll learn functional programming" yesterday) and I am wondering: I can use the construct operator to add an item to the beginning of a list: 1 : [2,3] [1,2,3] I tried making an example data type I found in the book and then playing with it: --in a file data BillingInfo = CreditCard Int String String | CashOnDelivery | Invoice Int deriving (Show) --in ghci $ let order_list = [Invoice 2345] $ order_list [Invoice 2345] $ let order_list = CashOnDelivery : order_list $ order_list [CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, CashOnDelivery, ...- etc... it just repeats forever, is this because it uses lazy evaluation? -- EDIT -- okay, so it is being pounded into my head that let order_list = CashOnDelivery:order_list doesn't add CashOnDelivery to the original order_list and then set the result to order_list, but instead is recursive and creates an infinite list, forever adding CashOnDelivery to the beginning of itself. Of course now I remember that Haskell is a functional language and I can't change the value of the original order_list, so what should I do for a simple "tack this on to the end (or beginning, whatever) of this list?" Make a function which takes a list and BillingInfo as arguments, and then return a list? -- EDIT 2 -- well, based on all the answers I'm getting and the lack of being able to pass an object by reference and mutate variables (such as I'm used to)... I think that I have just asked this question prematurely and that I really need to delve further into the functional paradigm before I can expect to really understand the answers to my questions... I guess what i was looking for was how to write a function or something, taking a list and an item, and returning a list under the same name so the function could be called more than once, without changing the name every time (as if it was actually a program which would add actual orders to an order list, and the user wouldn't have to think of a new name for the list each time, but rather append an item to the same list).

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• Select statement with multiple 'where' fields using same value without duplicating text

  - by kdbdallas

  I will start by saying that I don't think what I want can be done, but that said, I am hoping I am wrong and someone knows more than me. So here is your chance... Prove you are smarter than me :) I want to do a search against a SQLite table looking for any records that "are similar" without having to write out the query in long hand. To clarify this is how I know I can write the query: select * from Articles where title like '%Bla%' or category like '%Bla%' or post like '%Bla%' This works and is not a huge deal if you are only checking against a couple of columns, but if you need to check against a bunch then your query can get really long and nasty looking really fast, not to mention the chance for typos. (ie: 'Bla%' instead of '%Bla%') What I am wondering is if there is a short hand way to do this? *This next code does not work the way I want, but just shows kind of what I am looking for select * from Articles where title or category or post like '%Bla%' Anyone know if there is a way to specify that multiple 'where' columns should use the same search value without listing that same search value for every column? Thanks in advance!

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• C# / Silverlight / WPF / Fast rendering lots of circles

  - by Walt W

  I want to render a lot of circles or small graphics within either silverlight or wpf (around 1000-10000) as fast and as frequently as possible. If I have to go to DX or OGL, that's fine, but I'm wondering about doing this within either of those two frameworks first (read: it's OK if an answer is WPF-only or Silverlight-only). Also, if there is a way to access DX through WPF and render on a surface that way, I would be interested in that as well. So, what's the fastest way to draw a load of circles? They can be as plain as necessary, but they do need to have a radius. Currently I'm using DrawingVisual and a DrawingContext.DrawEllipse() command for each circle, then rendering the visual to a RenderTargetBItmap, but it becomes very slow as the number of circles rises. By the way, these circles move every frame, so caching isn't really an option unless you're going to suggest caching the individual circles . . . But their sizes are dynamic, so I'm not sure that's a great approach.

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• Creating a complex tree model in Qt

  - by Zeke

  I'm writing an IRC Client (yes another one). Long story short. I'm writing a Server dialogue that keeps a list of this: Identity Networks Channels Addresses I have 3 different list views that will be for the Networks, Channels and Addresses. When the user changes the Identity (combo box). The network listview will lookup all the networks for that specific Identity. After it loads up the Networks it will automatically select the first network and then load all the channels and addresses for that specific network. The problem is I want to have 3 views for 1 model, to minimise all the memory and the loading of data. So that it makes it much easier to manage and not do a bunch of work. If you'd look at QColumnView it's the same exact thing. But I don't need it to be on one exact page since the views are on entirely different tabs to make it easier to go through the Server dialogue. I'm wondering what will be the best way to go about handling this complexity. The information is stored in a SQLite database. I already have the classes written to extract and store it. Just the modelling is the painful part of this solution.

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• [OT a bit] Flex+JEE what is it good for?

  - by Zenzen

  Ok so sorry for being, I guess, a bit off topic but still I think this is the best place to ask. My new semester just started (don't worry I won't ask you to do my homework) and this time we have a rather cool subject about www programming in general where we have to do a web service, web abb - whatever as long as it's "web". Here's the problem though, my team and I want to do it with Flex and JEE but we don't have much experience about what are they actually used for. I mean we know you can do virtually anything with it, but we don't really want to lose time on doing something useless. My first idea was to do a "brainstorming" 3D room/service - a place where people could log in have a video conference, a whiteboard, a place to upload pictures everyone could see, some toolbars for google, youtube etc. plus some other features which would make real-time brainstorming easy when you can't get everyone in one place. But is Flex+JEE really suitable? I mean I'm 99% sure it's doable but is it really worth doing it in Flex+JEE or was the whole purpose of JEE completely different? @EDIT: well this was only one of our ideas obviously. I do know the basics of JSP, Servlets, JPA etc. of course but yeah the main goal of this project is to get some actual experience. The problem is we don't really know is it worth doing something like let's say a social network (something like extended facebook) for gamers (doesn't really matter if it already exists) in JEE or would it only look ridiculous (because PHP or whatever would be a far better choice)? Bottom line is that we are wondering are only large scale applications (for banks etc.) written in JEE or is it good for anything (even the smaller projects)?

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• Performance of Multiple Joins

  - by geeko

  Greetings Overflowers, I need to query against objects with many/complex spacial conditions. In relational databases that is translated to many joins (possibly 10+). I'm new to this business and wondering whether to go with MS SQL Server 2008 R2 or Oracle 11g or document-based solutions such as RavenDB or simply go with some spacial database (GIS)... Any thoughts ? Regards UPDATE: Thank you all for your answers. Would anybody opt for document/spatial databases ? My database would consist of tens of millions to few billion records. Mostly read-only. Almost no updates unless in case of mistakes in input. Overnight inserts and not that frequent. The join tables are predicted beforehand but the number of self joins (tables joining themselves multiple times) is not. Small pages of results from such queries are going to be viewed on an highly interactive website so response time is critical. Any predictions on how this can perform on MS SQL Server 2008 R2 or Oracle 11g ? I'm also concerned about boosting performance by adding more servers, which one scales better ? How about PostgresQL ?

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• How to use named_scope to incrementally construct a complex query?

  - by wbharding

  I want to use Rails named_scope to incrementally build complex queries that are returned from external methods. I believe I can get the behavior I want with anonymous scopes like so: def filter_turkeys Farm.scoped(:conditions => {:animal => 'turkey'}) end def filter_tasty Farm.scoped(:conditions => {:tasty => true}) end turkeys = filter_turkeys is_tasty = filter_tasty tasty_turkeys = filter_turkeys.filter_tasty But say that I already have a named_scope that does what these anonymous scopes do, can I just use that, rather than having to declare anonymous scopes? Obviously one solution would be to pass my growing query to each of the filter methods, a la def filter_turkey(existing_query) existing_query.turkey # turkey is a named_scoped that filters for turkey end But that feels like an un-DRY way to solve the problem. Oh, and if you're wondering why I would want to return named_scope pieces from methods, rather than just build all the named scopes I need and concatenate them together, it's because my queries are too complex to be nicely handled with named_scopes themselves, and the queries get used in multiple places, so I don't want to manually build the same big hairy concatenation multiple times.

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• Patterns / Solutions to complicated Feature Management

  - by yclian

  Hi all, My company develops CDN / Web-Hosting solution. We have a middleware that's served as a business logic layer and exposes web service for the front-end. I would like to seek for a clean solution to feature management - there're uncertainties and ugly workarounds/solutions in the software that the dev would say "when it happens or is broken, we will fix it". For example, here're the following features that a web publisher can have: Sites limit Bandwidth limit SSL feature + SSL configuration per site If we downgrade a web publisher, when he's having 10 sites, down to 5 sites, we can choose not to suspend the rest of the 5 sites, or we shall prompt for suspension before the downgrade. For the case of bandwidth limit, the downgrade is easy, when the bandwidth check happens, if the publisher has it exceeded, then we will suspend his account. For the case of SSL feature. Every SSL configuration is tied to a site, what shall happen to these configuration object when the SSL feature is downgraded from enabled to disabled? So as you can see, there're many different situations and there are different ways of handling it. I can make a system that examines the impacts and prompts the user to make changes before the downgrade/upgrade. Or a system that ignores the impacts and just upgrade/downgrade. Bad. Or a system designed in a way that the client code need to be aware of the complex feature matrix (or I can expose a helper to the client code to check if a feature is not DEFUNCT) There can be many ways that I am still thinking but puzzled. I am wondering, how would you tackle this issue and is there any recommended patterns or books or software that you think I can refer to? Appreciate your help.

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• Ruby Alias and module_function

  - by Jesse J

  I'm trying to debug someone else's code and having trouble figuring out what's wrong. When I run rake, one of the errors I get is: 2) Error: test_math(TestRubyUnits): NoMethodError: undefined method `unit_sin' for CMath:Module /home/user/ruby-units/lib/ruby_units/math.rb:21:in `sin' This is the function that calls the method: assert_equal Math.sin(pi), Math.sin("180 deg".unit) And this is what the class looks like: module Math alias unit_sin sin def sin(n) Unit === n ? unit_sin(n.to('radian').scalar) : unit_sin(n) end alias unit_cos cos def cos(n) Unit === n ? unit_cos(n.to('radian').scalar) : unit_cos(n) end ... module_function :unit_sin module_function :sin module_function :unit_cos module_function :cos ... end (The ellipsis means "more of the same"). As far as I can see, this is valid Ruby code. Is there something I'm missing here that's causing the error, or could the error be coming from something else? Update: I'm wondering if the problem has to do with namespaces. This code is attempting to extend CMath, so perhaps the alias and/or module_function isn't actually getting into CMath, or something like that....

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• Is it possible to replace values in a queryset before sending it to your template?

  - by Issy

  Hi Guys, Wondering if it's possible to change a value returned from a queryset before sending it off to the template. Say for example you have a bunch of records Date | Time | Description 10/05/2010 | 13:30 | Testing... etc... However, based on the day of the week the time may change. However this is static. For example on a monday the time is ALWAYS 15:00. Now you could add another table to configure special cases but to me it seems overkill, as this is a rule. How would you replace that value before sending it to the template? I thought about using the new if tags (if day=1), but this is more of business logic rather then presentation. Tested this in a custom template tag def render(self, context): result = self.model._default_manager.filter(from_date__lte=self.now).filter(to_date__gte=self.now) if self.day == 4: result = result.exclude(type__exact=2).order_by('time') else: result = result.order_by('type') result[0].time = '23:23:23' context[self.varname] = result return '' However it still displays the results from the DB, is this some how related to 'lazy' evaluation of templates? Thanks! Update Responding to comments below: It's not stored wrong in the DB, its stored Correctly However there is a small side case where the value needs to change. So for example I have a From Date & To date, my query checks if todays date is between those. Now with this they could setup a from date - to date for an entire year, and the special cases (like mondays as an example) is taken care off. However if you want to store in the DB you would have to capture several more records to cater for the side case. I.e you would be capturing the same information just to cater for that 1 day when the time changes. (And the time always changes on the same day, and is always the same)

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• Address String Split in javscript

  - by Arasoi

  Ok folks I have bombed around for a few days trying to find a good solution for this one. What I have is two possible address formats. 28 Main St Somecity, NY 12345-6789 or Main St Somecity, Ny 12345-6789 What I need to do Is split both strings down into an array structured as such address[0] = HousNumber address[1] = Street address[2] = City address[3] = State address[4] = ZipCode My major problem is how to account for the lack of a house number. with out having the whole array shift the data up one. address[0] = Street address[1] = City address[2] = State address[3] = ZipCode [Edit] For those that are wondering this is what i am doing atm . (cleaner version) place = response.Placemark[0]; point = new GLatLng(place.Point.coordinates[1],place.Point.coordinates[0]); FCmap.setCenter(point,12); var a = place.address.split(','); var e = a[2].split(" "); var x = a[0].split(" "); var hn = x.filter(function(item,index){ return index == 0; }); var st = x.filter(function(item,index){ return index != 0; }); var street = ''; st.each(function(item,index){street += item + ' ';}); results[0] = new Hash({ FullAddie: place.address, HouseNum: hn[0], Dir: '', Street: street, City: a[1], State: e[1], ZipCode: e[2], GPoint: new GMarker(point), Lat: place.Point.coordinates[1], Lng: place.Point.coordinates[0] }); // End Address Splitting

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• For business people to manage, keep binary images in MySQL or just the urls?

  - by Michael Mao

  Hello everyone: I am working on a task to enable image uploading and auto-scaling(from full sized to thumbnail) by jQuery & PHP. I can naturally come up with two approaches : First, store both images as binary objects directly into MySQL; Second, store only urls to the images and keep the images somewhere on server. The images are for everyone to view, so there are no security restrictions, as far as I know. Personally I don't have any preference, however, at the end of the day, it is the business people that are going to manage the images as part of the system(CRUD). So I am wondering which seems to be a bit better for them? Of course I am building a easy-to-use, visualize web interface for the staff to control the process, but I am not sure if that is enough. Lessons told me that if I don't think for the future and seek the most flexible approach, the I will probably screw myself sooner or later. PS. The following link is what I've found so far, which is pretty cool, no flash involved :) Andrew Valum's ajax image upload jQuery plugin

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• Which fieldtype is best for storing PRICE values?

  - by BerggreenDK

  Hi there I am wondering whats the best "price field" in MSSQL for a shoplike structure? Looking at this overview: http://www.teratrax.com/sql_guide/data_types/sql_server_data_types.html We have datatypes called money, smallmoney, then we have decimal/numeric and lastly float and real Name, memory/disk-usage and value ranges: Money: 8 bytes (values: -922,337,203,685,477.5808 to +922,337,203,685,477.5807) Smallmoney: 4 bytes (values: -214,748.3648 to +214,748.3647) Decimal: 9 [default, min. 5] bytes (values: -10^38 +1 to 10^38 -1 ) Float: 8 bytes (values: -1.79E+308 to 1.79E+308 ) Real: 4 bytes (values: -3.40E+38 to 3.40E+38 ) My question is: is it really wise to store pricevalues in those types? what about eg. INT? Int: 4 bytes (values: -2,147,483,648 to 2,147,483,647) Lets say a shop uses dollars, they have cents, but I dont see prices being $49.2142342 so the use of a lot of decimals showing cents seems waste of SQL bandwidth. Secondly, most shops wouldn't show any prices near 200.000.000 (not in normal webshops at least... unless someone is trying to sell me a famous tower in Paris) So why not go for an int? An int is fast, its only 4 bytes and you can easily make decimals, by saving values in cents instead of dollars and then divide when you present the values. The other approach would be to use smallmoney which is 4 bytes too, but this will require the math part of the CPU to do the calc, where as Int is integer power... on the downside you will need to divide every single outcome. Are there any "currency" related problems with regionalsettings when using smallmoney/money fields? what will these transfer too in C#/.NET ? Any pros/cons? Go for integer prices or smallmoney or some other? Whats does your experience tell?

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• Is there an equivalent for ActiveRecord#find_by equivalent for C#?

  - by Benjamin Manns

  I'm originally a C# developer (as a hobby), but as of late I have been digging into Ruby on Rails and I am really enjoying it. Right now I am building an application in C# and I was wondering if there is any collection implementation for C# that could match (or "semi-match") the find_by method of ActiveRecord. What I am essentially looking for is a list that would hold Rectangles: class Rectangle { public int Width { get; set; } public int Height { get; set; } public String Name { get; set; } } Where I could query this list and find all entries with Height = 10, Width = 20, or name = "Block". This was done with ActiveRecord by doing a call similar to Rectangle.find_by_name('Block'). The only way I can think of doing this in C# is to create my own list implementation and iterate through each item manually checking each item against the criteria. I fear I would be reinventing the wheel (and one of poorer quality). Any input or suggestions is much appreciated.

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• Java website protection solutions (especially XSS)

  - by Mark

  I'm developing a web application, and facing some security problems. In my app users can send messages and see other's (a bulletin board like app). I'm validating all the form fields that users can send to my app. There are some very easy fields, like "nick name", that can be 6-10 alpabetical characters, or message sending time, which is sended to the users as a string, and then (when users ask for messages, that are "younger" or "older" than a date) I parse this with SimpleDateFormat (I'm developing in java, but my question is not related to only java). The big problem is the message field. I can't restrict it to only alphabetical characters (upper or lowercase), because I have to deal with some often use characters like ",',/,{,} etc... (users would not be satisfied if the system didn't allow them to use these stuff) According to this http://ha.ckers.org/xss.html, there are a lot of ways people can "hack" my site. But I'm wondering, is there any way I can do to prevent that? Not all, because there is no 100% protection, but I'd like a solution that can protect my site. I'm using servlets on the server side, and jQuery, on the client side. My app is "full" AJAX, so users open 1 JSP, then all the data is downloaded and rendered by jQuery using JSON. (yeah, I know it's not "users-without-javascript" friendly, but it's 2010, right? :-) ) I know front end validation is not enough. I'd like to use 3 layer validation: - 1. front end, javascript validate the data, then send to the server - 2. server side, the same validation, if there is anything, that shouldn't be there (because of client side javascript), I BAN the user - 3. if there is anything that I wasn't able to catch earlier, the rendering process handle and render appropriately Is there any "out of the box" solution, especially for java? Or other solution that I can use?

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