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• Acceptable name for extension method that accept null

  - by GaryX

  Hi, I really don't like to call String.IsNullOrEmpty(str). That makes me need to think "String" class first, then call it on the object "str". I like to call str.IsNullOrEmpty(), which doesn't need me to think "String" class. The problem is that extension method accept null instance to call on, which is not the usual case when you call a normal method. My question what do you think will be a convetion name for extension methods that accept null? For string, that is easy, "IsNullOrEmpty()" (anything that contains "IsNull") sounds good for me. For others, like GetDisplayName(), do we name it as "NullOrGetDisplayName" ?

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• Why is this Python class copying another class contents?

  - by fjfnaranjo

  Hello guys. I'm trying to understand an estrange behavior in Python. I have the next python code: class IntContainer: listOfInts = [] def __init__(self, initListOfInts): for i in initListOfInts: self.listOfInts.append(i) def printInts(self): print self.listOfInts if __name__ == "__main__": intsGroup1 = [1,2,3,4] intsGroup2 = [4,5,6,7] intsGroups = [intsGroup1,intsGroup2] intsContainers = [] for ig in intsGroups: newIntContainer = IntContainer(ig) intsContainers.append(newIntContainer) for ic in intsContainers: print ic.listOfInts I expect to get something like: [1, 2, 3, 4] [4, 5, 6, 7] But i get: [1, 2, 3, 4, 4, 5, 6, 7] [1, 2, 3, 4, 4, 5, 6, 7] I have check the next question: http://stackoverflow.com/questions/1876905/why-is-python-reusing-a-class-instance-inside-in-function And a lot of Python reference, but I can not understand what is happening. I think is related with the newIntContainer identifier reutilization, but I do not understand it deeply. Why Python appears to reused the last reference for the new object, even if I have added it to a permanent list? What can I do to resolve this behavior? Thanks ;)

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• Continuously reading from a stream in C#?

  - by Damien Wildfire

  I have a Stream object that occasionally gets some data on it, but at unpredictable intervals. Messages that appear on the Stream are well-defined and declare the size of their payload in advance (the size is a 16-bit integer contained in the first two bytes of each message). I'd like to have a StreamWatcher class which detects when the Stream has some data on it. Once it does, I'd like an event to be raised so that a subscribed StreamProcessor instance can process the new message. Can this be done with C# events without using Threads directly? It seems like it should be straightforward, but I can't get quite get my head around the right way to design this.

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• Iphone UI Size / Layout Resource?

  - by blindJesse

  Is anyone aware of a website or download to reference for the size of UI elements or standard iphone interface stuff? What I mean is something that gives the height of elements like the status bar, tab bar, navigation bar, default tableviewcell height (and such things as width of accessory view, indentation, etc), default icon sizes, default font sizes for UI elements (if they need to be mimicked, for instance), etc etc etc. It's amazing how many times I have to go back to find a reference or estimate the size and position of a standard element. It seems like it would be an invaluable resource that could fit on a printed page or two.

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• Different RegisterWindowMessage() names appear the same

  - by Mike Trader

  Using the C/C++ Windows API RegisterWindowMessage() I am using the name of the application as the message name. Next I call CreatMutex() using the same name so that I can tell if it already exists. If it does, I know this application is already running and not to launch a second instance of it. THis is the operation of my function Running() My confusion is over the message name. It seems that "AutoConvert.exe" and "AutoAppend.exe" are interpreted as the same name. Why?

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• Force memcached to write to all servers in pool

  - by Industrial

  Hi everyone, I have thought a bit on how to make sure that a particular key is distributed to ALL memcached servers in a pool. My current, untested solution is to make another instance of memcached, something like this: $cluster['local'] = array('host' => '192.168.1.1', 'port' => '11211', 'weight' => 50); foreach ($this->cluster() as $cluster) { @$this->tempMemcache = new Memcache; @$this->tempMemcache->connect($cluster['host'], $cluster['port']); @$this->tempMemcache->set($key, $value, $this->compress, $expireTime); @$this->tempMemcache->close(); } What is common sense to do in this case, when certain keys need to be stored on ALL servers for reliability?

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• need a virtual template member workaround

  - by yurib

  Hello, I need to write a program implementing the visitor design pattern. The problem is that the base visitor class is a template class. This means that BaseVisited::accept() takes a template class as a parameter and since it uses 'this' and i need 'this' to point to the correct runtime instance of the object, it also needs to be virtual. I'd like to know if there's any way around this problem. template <typename T> class BaseVisitor { public: BaseVisitor(); T visit(BaseVisited *visited); virtual ~BaseVisitor(); } class BaseVisited { BaseVisited(); template <typename T> virtual void accept(BaseVisitor<T> *visitor) { visitor->visit(this); }; // problem virtual ~BaseVisited(); }

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• C++ function object terminology functor, deltor, comparitor, etc..

  - by Robert S. Barnes

  Is there a commonly accepted terminology for various types for common functors? For instance I found myself naturally using comparitor for comparison functors like this: struct ciLessLibC : public std::binary_function<std::string, std::string, bool> { bool operator()(const std::string &lhs, const std::string &rhs) const { return strcasecmp(lhs.c_str(), rhs.c_str()) < 0 ? 1 : 0; } }; Or using the term deltor for something like this: struct DeleteAddrInfo { void operator()(const addr_map_t::value_type &pr) const { freeaddrinfo(pr.second); } }; If using these kinds of shorthand terms is common, it there some dictionary of them all someplace?

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• MySQL returns fewer rows with GROUP BY statement

  - by bschaeffer

  I've got a MySQL database that stores image information. Right now it only has three rows stored in the database, and each row is associated with something like, for instance, a unique blog post via a key column. As of right now, one "blog post key" has one image, and one has two images in the database. When I run this query, MySQL returns all three rows. SELECT `id`, `key`, `url` FROM (`images`) WHERE `key` = 'TpaS4G5h' OR `key` = '78855e44' However, when i add the GROUP BY statement I only get two rows... one for each key. SELECT `id`, `key`, `url` FROM (`images`) WHERE `key` = 'TpaS4G5h' OR `key` = '78855e44' GROUP BY `key` I'm sure there is a simple solution, but I don't know what it is... so any help would be really appreciated. Thanks in advance!

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• rails respond_to and various forms of html responses

  - by lukewendling

  I often use respond_to do |format| ... end in Rails for my Restful actions, but I don't know what the ideal solution is for handling various forms of, say, html responses. For instance, view1 that calls action A might expect back html with a list of widgets wrapped in a UL tag, while view2 expects the same list of widgets wrapped in a table. How does one Restfully express that not only do I want back an html formatted response, but I want it wrapped in a table, or in a UL, OL, options, or some other common list-oriented html tag?

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• get foreign key objects in a single query - Django

  - by John

  Hi I have 2 models in my django code: class ModelA(models.Model): name = models.CharField(max_length=255) description = models.CharField(max_length=255) created_by = models.ForeignKey(User) class ModelB(models.Model): category = models.CharField(max_length=255) modela_link = models.ForeignKey(ModelA, 'modelb_link') functions = models.CharField(max_length=255) created_by = models.ForeignKey(User) Say ModelA has 100 records, all of which may or may not have links to ModelB Now say I want to get a list of every ModelA record along with the data from ModelB I would do: list_a = ModelA.objects.all() Then to get the data for ModelB I would have to do for i in list_a: i.additional_data = i.modelb_link.all() However this runs a query on every instance of i. Thus making 101 queries to run. Is there any way of running this all in just 1 query. Or at least less than the 101 queries. I've tried putting in ModelA.objects.select_related().all() but this didn't seem to have any effect. Thanks

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• In few words, what can be said about Func<>

  - by Richard77

  Hello, I've been seing Func< for sometime now, and I've manage to avoid it (for now). But, now it looks like I can't dodge it forever. For instance, I tried Dynamic Linq, but almost everything was in terms of Func<. I've tried one of my book (C# 2008/Deitel&Deitel) and also MSDN but I'm not getting it yet. They all jump straight in the subject. What can be said (in few words) about Func< Can I get some links on the web that can get me started on that matter? Thanks for helping

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• OneToMany association updates instead of insert

  - by Shvalb

  I have an entity with one-to-many association to child entity. The child entity has 2 columns as PK and one of the column is FK to the parent table. mapping looks like this: @OneToMany(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER ) @JoinColumn(name="USER_RESULT_SEQUENCES.USER_RESULT_ID", referencedColumnName="USER_RESULT_ID", unique=true, insertable=true, updatable=false) private List<UserResultSequence> sequences; I create an instance of parent and add children instances to list and then try to save it to DB. If child table is empty it inserts all children and it works perfectly. if the child table is not empty it updates existing rows! I don't know why it updates instead of inserts, any ideas why this might happen?? Thank you!

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• C# class code loaded in RAM ?

  - by Spi1988

  hi, I would like to know whether the actual code of a C# class gets loaded in RAM when you instantiate the class? So for example if I have 2 Classes CLASS A , CLASS B, where class A has 10000 lines of code but just 1 field, an int. And class B has 10 lines of code and also 1 field an int as well. If I instantiate Class A will it take more RAM than Class B due to its lines of code ? A supplementary question, If the lines of code are loaded in memory together with the class, will they be loaded for every instance of the class? or just once for all the instances? Thanks in advance.

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• Iterating over a large data set in long running Python process - memory issues?

  - by user1094786

  I am working on a long running Python program (a part of it is a Flask API, and the other realtime data fetcher). Both my long running processes iterate, quite often (the API one might even do so hundreds of times a second) over large data sets (second by second observations of certain economic series, for example 1-5MB worth of data or even more). They also interpolate, compare and do calculations between series etc. What techniques, for the sake of keeping my processes alive, can I practice when iterating / passing as parameters / processing these large data sets? For instance, should I use the gc module and collect manually? Any advice would be appreciated. Thanks!

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• Override decimal ToString() method

  - by Jimbo

  I have a decimal datatype with a precision of (18, 8) in my database and even if its value is simply 14.765 it will still get displayed as 14.76500000 when I use Response.Write to return its value into a webpage. Is it possible to override its default ToString method to return the number in the format #,###,##0.######## so that it only displays relevant decimal places? UPDATE I'm assuming that when one outputs number on a page like <%= item.price %> (where item.price is a number) that the number's ToString method is being called? I'm trying to avoid having to change every instance where the value is displayed by defaulting the ToString() format somehow.

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• How to authenticate a user using SQL

  - by Tom

  I have an DLL which is constantly connected to a SQL Server instance. The server itself is connected with "admin" permissions, but "normal" users should be able to access the server with their own username and password. The server would still be connected a "admin". I just want to check if the user can access the database. Is there a way to authenticate the user using a SQL query? It would of course be possible to add a encrypted "password" column to a database table for users, but I would prefer not having to do that.

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• How can I parse free text (Twitter tweets) against a large database of values?

  - by user136416

  Hi there Suppose I have a database containing 500,000 records, each representing, say, an animal. What would be the best approach for parsing 140 character tweets to identify matching records by animal name? For instance, in this string... "I went down to the woods to day and couldn't believe my eyes: I saw a bear having a picnic with a squirrel." ... I would like to flag up the words "bear" and "squirrel", as they appear in my database. This strikes me as a problem that has probably been solved many times, but from where I'm sitting it looks prohibitively intensive - iterating over every db record checking for a match in the string is surely a crazy way to do it. Can anyone with a comp sci degree put me out of my misery? I'm working in C# if that makes any difference. Cheers!

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• Password Hash Implementation

  - by oyerli

  I am developing a new application using Symfony. I want to store the passwords hashed, so I overridded the save method in my User model: public function save(Doctrine_Connection $conn = null) { $this->setUserPassword( md5($this->getUserPassword()) ); return parent::save($conn); } This works good when a new user created. However, this causes problems when we edit a user without changing his password. This causes Doctrine to hash the already hashed password. So, I need to check that whether the UserPassword is modified in this DoctrineRecord instance. How can I manage to do that?

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• Ubuntu Wired network(ethernet does not work)

  - by badnaam

  It was working just fine, until the other day I yanked it out. The wireless works just fine on the same router. If I login to a windows 7 instance on this dual boot laptop then the ehternet works just fine. So it's not a hardware, cable or router issue. The card even gets an ip, but I can't connect to the internet. Here are the details from route, iptables, ifconfig, ping etc. Any ideas? I have been struggling with this for day, none seems to have an answer. http://pastie.org/954816

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• PHP find if file data is an image

  - by Christian Sciberras

  Imagine I have some file data in a variable $data. I need to determine whether it is an image or not. No need for details such as corrupt images etc. Firs thought would be getting the file mime type by looking at the magic number and then see whether "image" is in the mime type. No such luck, even if I have a "file extension to mime type" script, I don't have a reliable way to get mime from magic number. My next option was to have a reasonable list of image file magic numbers and consult them. However, it relatively difficult to find such magic numbers (gif for instance has different magic numbers, some of which could pretty rare - if memory serves me right). A better idea would be some linux program which can do this kind of thing. Any ideas? I'm running RHEL and PHP 5.3. I've got root access - ie able to install stuff if needed. - Chris.

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

  - by user1380641

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

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• PHP-friendly NoSQL solutions

  - by mattbasta

  I'm looking to use a NoSQL solution for my next project, which will be written in PHP. What choices do I have in terms of NoSQL solutions that can easily interfaced via PHP? I haven't done much thinking about the architecture yet, so I'm not sure what my needs will be; I'd simply like to know what my choices are so I don't build something I can't reasonably implement. For instance, I know Cassandra has Pandra, but that's just a PHP library. MongoDB has a native PECL extension.

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• asp.net mvc - limit access to web pages

  - by niao

  Greetings, in my asp.net mvc application what i would like to do is to enable access to some pages only after user was successfully authorized. I have already created custom membership provider and that works fine. How can I, in web config create such rule - for instance for all pages in ~Admin/ folder? I don't want to create on every controller's action the validation code. For now i have in my web.config the following statement: <location path="~/Admin"> <system.web> <authorization> <deny users="?"/> </authorization> </system.web> but it doesn't work.

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• problem with exporting a customized form from dll

  - by mavric

  I'm working on an application so i have write an dll which contain a form with some additional work and methods. so in the beginning of my program the thread launch this form (from my dll) to get some informations and then hide it and initialize some components and the application form and then show it. when the thread come the line where it define new instance of the exported form "MyForm inputform = new MyForm();" it throw an Exception called "Top-level control cannot be added to a control." so i don't know what to do ?!!. i tried to take the code of the form from the dll source code and put it in the main program and it works.... .but still i want to know what happen and what impede my application from run that form from my dll. thanks.

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