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  • What are "named tuples" in Python?

    - by Denilson Sá
    Reading the changes in Python 3.1, I found something... unexpected: The sys.version_info tuple is now a named tuple: I never heard about named tuples before, and I thought elements could either be indexed by numbers (like in tuples and lists) or by keys (like in dicts). I never expected they could be indexed both ways. Thus, my questions are: What are named tuples? How to use them? Why/when should I use named tuples instead of normal tuples? Why/when should I use normal tuples instead of named tuples? Is there any kind of "named list" (a mutable version of the named tuple)?

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  • mySQL & Relational databases: How to handle sharding/splitting on application level?

    - by Industrial
    Hi everybody, I have thought a bit about sharding tables, since partitioning cannot be done with foreign keys in a mySQL table. Maybe there's an option to switch to a different relational database that features both, but I don't see that as an option right now. So, the sharding idea seems like a pretty decent thing. But, what's a good approach to do this on a application level? I am guessing that a take-off point would be to prefix tables with a max value for the primary key in each table. Something like products_4000000 , products_8000000 and products_12000000. Then the application would have to check with a simple if-statement the size of the id (PK) that will be requested is smaller then four, eight or twelve million before doing any actual database calls. So, is this a step in the right direction or are we doing something really stupid?

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  • Is memcached a dinosaur in comparison to Redis?

    - by Industrial
    Hi everyone, I have worked quite a bit with memcached the last weeks and just found out about Redis. When I read this part of their readme, I suddenly got a warm, cozy feeling in my stomach: Redis can be used as a memcached on steroids because is as fast as memcached but with a number of features more. Like memcached, Redis also supports setting timeouts to keys so that this key will be automatically removed when a given amount of time passes. This sounds amazing. I'd also found this page with benchmarks: http://www.ruturaj.net/redis-memcached-tokyo-tyrant-mysql-comparison So, honestly - Is memcache really that old dinousaur that is a bad choice from a performance perspective when compared to this newcomer called Redis? I haven't heard lot about Redis previously, thereby the approach for my question!

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  • Eager loading in EF1.0

    - by Dave Swersky
    I have a many-to-many relationship: Application - Applications_Servers - Server This is set up in my Entity Data Model and all is well. My problem is that I'd like to eager-load the whole graph of Applications so that I have an IEnumerable<Applications>, each Application member populated with the Servers collection associated by the many-to-many relationship. Normally this wouldn't be a problem, but according to my research there must be a navigation property between Application and Server. This is not the case for me because my Applications_Servers join table has more in it than just the two keys. Therefore, there is no navigation property directly between Application and Server, and this doesn't work: var apps = (from a in context.Application.Include("Server") select a).ToList(); I get an error saying there is no navigation property on Application called "Server", and that's correct, there is none. How do I write the query to eager-load my Applications with their Servers in this case?

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  • Python - Flatten a dict of lists into unique values?

    - by Jonathan Vanasco
    I have a dict of lists in python: content = {88962: [80, 130], 87484: [64], 53662: [58,80]} I want to turn it into a list of the unique values [58,64,80,130] I wrote a manual solution, but it's a manual solution. I know there are more concise and more elegant way to do this with list comprehensions, map/reduce , itertools , etc. anyone have a clue ? content = {88962: [80, 130], 87484: [64], 53662: [58,80]} result = set({}) for k in content.keys() : for i in content[k]: result.add(i) # and list/sort/print just to compare the output r2 = list( result ) r2.sort() print r2

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  • In a combobox, how do I determine the highlighted item (not selected item)?

    - by Harold Bamford
    First, fair warning: I am a complete newbie with C# and WPF. I have a combobox (editable, searchable) and I would like to be able to intercept the Delete key and remove the currently highlighted item from the list. The behavior I'm looking for is like that of MS Outlook when entering in email addresses. When you give a few characters, a dropdown list of potential matches is displayed. If you move to one of these (with the arrow keys) and hit Delete, that entry is permanently removed. I want to do that with an entry in the combobox. Here is the XAML (simplified): <ComboBox x:Name="Directory" KeyUp="Directory_KeyUp" IsTextSearchEnabled="True" IsEditable="True" Text="{Binding Path=CurrentDirectory, Mode=TwoWay}" ItemsSource="{Binding Source={x:Static self:Properties.Settings.Default}, Path=DirectoryList, Mode=TwoWay}" / The handler is: private void Directory_KeyUp(object sender, KeyEventArgs e) { ComboBox box = sender as ComboBox; if (box.IsDropDownOpen && (e.Key == Key.Delete)) { TrimCombobox("DirectoryList", box.HighlightedItem); // won't compile! } } When using the debugger, I can see box.HighlightedItem has the value I want but when I try and put in that code, it fails to compile with: System.Windows.Controls.ComboBox' does not contain a definition for 'HighlightedItem'... So: how do I access that value? Keep in mind that the item has not been selected. It is merely highlighted as the mouse hovers over it. Thanks for your help.

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  • Does Python Django support custom SQL and denormalized databases with no Foreign Key relationships?

    - by Jay
    I've just started learning Python Django and have a lot of experience building high traffic websites using PHP and MySQL. What worries me so far is Python's overly optimistic approach that you will never need to write custom SQL and that it automatically creates all these Foreign Key relationships in your database. The one thing I've learned in the last few years of building Chess.com is that its impossible to NOT write custom SQL when you're dealing with something like MySQL that frequently needs to be told what indexes it should use (or avoid), and that Foreign Keys are a death sentence. Percona's strongest recommendation was for us to remove all FKs for optimal performance. Is there a way in Django to do this in the models file? create relationships without creating actual DB FKs? Or is there a way to start at the database level, design/create my database, and then have Django reverse engineer the models file?

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  • What's a good way to encrypt data using an asymmetric key, that's available to both java and ruby?

    - by Michael Campbell
    I have a customer that wants to encrypt some data in his database (not passwords; this needs actual encryption, not hashing). The application which will be doing the encrypting/writing is in Java, but the process which will DECRYPT it is behind a secure firewall, and is written in ruby. The idea was to use a public/private key scheme; the java system would encrypt it with the public key, then the process on his local box would use the private key to decrypt it as needed. I'm looking for any experience anyone has doing something like that; my main question is what sorts of libraries on java and ruby can interoperate with the same keys and data.

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  • Doctrine 1.2 Column Naming Conventions for Many To Many Relationships

    - by Alan Storm
    I'm working with an existing database schema, and trying to setup two Doctrine models with a Many to Many relationship, as described in this document When creating tables from scratch, I have no trouble getting this working. However, the existing join tables use a different naming convention that what's described in the Doctrine document. Specifically Table 1 -------------------------------------------------- table_1_id ....other columns.... Table 2 -------------------------------------------------- table_2_id ....other columns.... Join Table -------------------------------------------------- fktable1_id fktable_2_id Basically, the previous developers prefaced all forign keys with an fk. From the examples I've seen and some brief experimenting with code, it appears that Doctrine 1.2 requires that the join table use the same column names as the tables it's joining in Is my assumption correct? If so, has the situation changed in Doctrine 2? If the answers to either of the above are true, how do you configure the models so that all the columns "line up"

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  • Why won't my control accept keyboard input?

    - by Mason Wheeler
    I've built a custom control that I'm trying to send input to. It will accept mouse input and report MouseDown, MouseMove and MouseUp correctly, but for whatever reason, it won't accept keyboard input. When I click on it, it doesn't receive focus, and any keys I press get interpreted by whatever control had the focus already. This is probably something really simple. The first place I thought to look was in the ControlStyle property, but the only thing I can see in the helpfile about keyboard input is csNoStdEvents, which disables it, and my control doesn't have that. So what do I need to do to make it so my control can receive input focus?

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  • Correct association mapping in Entity Framework

    - by Matt Thrower
    Hi, Trying to change two relationships in our entity framework from many-to-one to many-to-many relationships. So I tried the obvious thing: clicked on each association on the diagram, changed the appropriate end of the association accordingly and then changed the name of the navigation property to a plural to reflect the change. This lead to the following build error, or one each for the two changes I've made: Error 3002: Problem in mapping fragments starting at line 1761:Potential runtime violation of table CustomerServices's keys (CustomerServices.Id): Columns (CustomerServices.Id) are mapped to EntitySet CompiledDatabaseCustomerService's properties (CompiledDatabaseCustomerService.CustomerService.Id) on the conceptual side but they do not form the EntitySet's key properties (CompiledDatabaseCustomerService.CompiledDatabase.Id, CompiledDatabaseCustomerService.CustomerService.Id) I'm not entirely sure why this is happening, so unsurprisngly I haven't had much luck fixing it. I've tried fiddling with the mapping details and adding referential constraints to no avail. Anyone point me in the right direction? cheers, Matt

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  • When to define SDD operations System->Actor?

    - by devoured elysium
    I am having some trouble understanding how to make SDDs, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The user tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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  • YUI Datatable Not Taking JSON

    - by Pete Herbert Penito
    I am trying to fill a Datatable with a JSON using YUI, I have this JSON: [{"test":"value1", "test2":"value2", "test3":"value3", "topic_id":"123139007E57", "gmt_timestamp":1553994442, "timestamp_diff":-1292784933382, "status":"images\/statusUp.png", "device_id":"568FDE9CC7275FA"}, .. It continues like this with about 20 different devices, and I close it with a ] I just want to print select keys in the datatable so my Column Definitions look like this: var myColumnDefs = [ {key:"test", sortable:true, resizeable:true}, {key:"test2", sortable:true, resizeable:true}, {key:"topic_id", sortable:true, resizeable:true}, {key:"status", sortable:true, resizeable:true}, {key:"device_id", sortable:true, resizeable:true}, ]; var myDataSource = new YAHOO.util.DataSource(bookorders); myDataSource.responseType = YAHOO.util.DataSource.TYPE_JSARRAY; myDataSource.responseSchema = { fields: ["test","test2","topic_id","status","device_id"] }; var myDataTable = new YAHOO.widget.DataTable("basic", myColumnDefs, myDataSource); It's print Data Error for some reason, what am I doing wrong? Thanks! I have tested the validity of the JSON at JSONLint and it says it is valid.

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  • User Defined Class as a Template Parameter

    - by isurulucky
    Hi, I' m implementing a custom STL map. I need to make sure that any data type (basic or user defined) key will work with it. I declared the Map class as a template which has two parameters for the key and the value. My question is if I need to use a string as the key type, how can I overload the < and operators for string type keys only?? In template specialization we have to specialize the whole class with the type we need as I understand it. Is there any way I can do this in a better way?? What if I add a separate Key class and use it as the template type for Key? Thank You!!

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  • How to launch a Windows process as 64-bit from 32-bit code?

    - by Jonas
    To pop up the UAC dialog in Vista when writing to the HKLM registry hive, we opt to not use the Win32 Registry API, as when Vista permissions are lacking, we'd need to relaunch our entire application with administrator rights. Instead, we do this trick: ShellExecute(hWnd, "runas" /* display UAC prompt on Vista */, windir + "\\Reg", "add HKLM\\Software\\Company\\KeyName /v valueName /t REG_MULTI_TZ /d ValueData", NULL, SW_HIDE); This solution works fine, besides that our application is a 32-bit one, and it runs the REG.EXE command as it would be a 32-bit app using the WOW compatibility layer! :( If REG.EXE is ran from the command line, it's properly ran in 64-bit mode. This matters, because if it's ran as a 32-bit app, the registry keys will end up in the wrong place due to registry reflection. So is there any way to launch a 64-bit app programmatically from a 32-bit app and not have it run using the WOW64 subsystem like its parent 32-bit process (i.e. a "*" suffix in the Task Manager)?

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  • help regarding PERL program

    - by riya
    Could someone write simple PERL programs for the following scenarios: 1) convert a list from {1,2,3,4,5,7,9,10,11,12,34} to {1-5,7,9-12,34} 2) to sort a list of negative numbers 3) to insert values to hash array 4) there is a file with content: C1 c2 c3 c4 r1 r2 r3 r4 put it into an hash array where keys = {c1,c2,c3,c4} and values = {r1,r2,r3,r4} 5) There are testcases running each testcase runs as a process and has a process ID. The logs are logged in a logfile process ID appended to each line. Prog to find out if the test case has passed or failed. The program shoud be running till the processes are running and display output.

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  • Outlook Macro to Search

    - by Corpa Loom
    What's the best way to automate this function? I want to be able to do this in Outlook 2010, (1)select a specific mail account (2)Key in a folder that I am looking for (3)Then have the macro/program fire off an "*" asterisk (4)Then insert the text that I keyed in step one. I am trying to automate the search for a folder hot-keys that already exist. My problem is that I can't type the folder that I am looking for fast enough and all the search programs that I have used are far too slow. The hot-key search is awesome and super fast, I just can't type the folder that I am looking for fast enough. Can this process be automated? And I can't use this code, it is far too slow: http://www.vboffice.net/sample.html?mnu=2&smp=82&cmd=showitem&lang=en

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  • How can this be done with (N)Hibernate?

    - by Vilx-
    I'm creating a windows forms application with NHibernate. It's an MDI application, so there is no limit to how many forms the user can have open at the same time (probably many). For most forms I want to have an "OK" and a "Cancel" button. Both close the form, but "OK" also saves the modified data to the DB. The forms can be pretty complex, and the modifications are likely to touch a whole graph of objects, adding some, deleting some, and changing some more. It would be good if the changes could be automatically detected and persisted as needed, without the need to manually keep track of each of them. What would be a good way to do this? Extra information: I can make whatever DB schema I want. I'm using MSSQL 2008 and currently have decided for GUID primary keys (with guid.comb generator) and a TIMESTAMP column for optimistic concurrency. I tried to simply set FlushMode of a NHibernate ISession to Never, doing all modifications as needed, and then calling Flush() if the user clicked OK. But that didn't work.

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  • CSS to create curved corner between two elements?

    - by Tauren
    My UI has an unordered list on the left. When a list item is selected, a div appears on the right of it. I'd like to have a curved outer corner where the <li> and the <div> meet. See the white arrow in the image below. To extend the blue <li> to the edge of the <ul>, I'm planning to do something like this: li { right-margin: 2em; border-radius: 8px; } li.active { right-margin: 0; border-bottom-right-radius: 0; border-top-right-radius: 0; } Is there a better way to extend the <li> to the edge of the <ul>? Obviously, I'll include the webkit and mozilla border radius CSS as well. The main thing I'm unsure about is that outer corner underneath the bottom right corner of the active <li>. I have some ideas, but they seem like hacks. Any suggestions? NOTE that the <ul> is indicated in grey, but it would be white in the real design. Also, I'm planning to use Javascript to position the <div> correctly when an <li> is selected.

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  • Visual Studio Error: An item with the same key has already been added

    - by PaN1C_Showt1Me
    When I'm trying to change the default Image of a Control on Windows Forms in Form Designer (no matter where on which control) I get this error: Error message: An item with the same key has already been added I tried to delete and recreate the Resources.resx file.. I assured that only 1 resx file with these keys exist.. (in fact that's my only resource file) but it still does not work. I have som strings in it and some images. That's all. Any idea?

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  • App Engine: how would you... snapshotting entities

    - by Andrew B.
    Let's say you have two kinds, Message and Contact, related by a db.ListProperty of keys on Message. A user creates a message, adds some contacts as recipients, and emails the message. Later, the user deletes one of the contact entities that was a recipient of the message. Our application should delete the appropriate Contact entity, but we want to preserve the original recipient list for the message that was sent for the user's records. In essence, we want a snapshot of the message entity at the time it was sent. If we naively delete the contact entity, though, we lose snapshot integrity; if not, we are left with an invalid key. How would you handle this situation, either in controller logic or model changes? class User(db.Model): email = db.EmailProperty(required=True) class Contact(db.Model): email = db.EmailProperty(required=True) user = db.ReferenceProperty(User, collection_name='contacts') class Message(db.Model): recipients = db.ListProperty(db.Key) # contacts sender = db.ReferenceProperty(User, collection_name='messages') body = db.TextProperty() is_emailed = db.BooleanProperty(default=False)

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  • Just an experiment changing the application data path

    - by Arthur
    When I change the Appication Data path in windows xp registry to a network folder I get this error message on the next system startup: "windows cannot load the user's profile but has logged you with the default profile system" The registry keys are: "[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders]" "[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\User Shell Folders]" under the names "AppData" and "Local AppData" I dont care if "Windows logins you with the default profile system" but is there a way to disable that message, or change the message timeout form 30 seconds to 0?,or maybe create an script that changes the Application Data path every system startup? P.S. The computer with the shared folder is always on.

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  • How to make flyspell bypass some words by context?

    - by manu
    Hi, I use Emacs for writing most of my writings. I write using reStructuredText, and then transform them to LaTeX after some preprocessing since I write my citations á-la LaTeX. This is an excerpt of one of my texts (in Spanish): En \cite[pp.~XXVIII--XXIX]{Crnkovic2002} se brindan algunos riesgos que se pueden asumir con el desarrollo basado en componentes, los This text is processed by some custom scripts that deals with the \cite part so rst2latex can do its job. When I activate flyspell-mode it signals most of the citation keys as spelling errors. How can I tell flyspell not to spellcheck things within \cite commands. Furthermore, how can I combine rst-mode and flyspell, so that rst-mode would keep flyspell from spellchecking the following? reST comments reST code literal reST directive parameters and arguments reST raw directive contents Any ideas?

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  • Multiple key map in c++

    - by Morgan
    Hi, I'm wondering if any of you know of a c++ associative map container type which I can perform multiple key lookups on. The map needs to have constant time lookups but I don't care if it's ordered or unordered. It just needs to be fast. For example, I want to store a bunch of std::vector objects in a map with an integer and a void* as the lookup keys. Both the int and the void* must match for my vector to be retrieved. Does anything like this exist already? Or am I going to have to roll my own. If so, any suggestions? I've been trying to store a boost::unordered_map inside another boost::unordered_map, but I have not had any success with this method yet. Maybe I will continue Pershing this method if there is no simpler way. Thanks!

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  • Python: Data Object or class

    - by arg20
    I enjoy all the python libraries for scraping websites and I am experimenting with BeautifulSoup and IMDB just for fun. As I come from Java, I have some Java-practices incorporated into my programming styles. I am trying to get the info of a certain movie, I can either create a Movie class or just use a dictionary with keys for the attributes. My question is, should I just use dictionaries when a class will only contain data and perhaps almost no behaviour? In other languages creating a type will help you enforce certain restrictions and because of type checks the IDE will help you program, this is not always the case in python, so what should I do? Should I resort to creating a class only when there's both, behaviour and data? Or create a movie class even though it'll probably be just a data container? This all depends on your model, in this particular case either one is fine but I'm wondering about what's a good practice.

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