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  • Tutorials and Introductions to C++ Expression Templates

    - by grrussel
    What are good introductions to the creation of C++ expression template systems? I would like to express arithmetic on user defined types while avoiding temporary values (which may be large), and to learn how to do this directly rather than applying an existing library. I have found Todd Veldhuizen's original paper and an example from the Josuttis C++ Templates book, and an article by Kreft & Langer. I am looking for simple, clear expositions.

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  • Rails: three most recent comments with unique users

    - by Dennis Collective
    what would I put in the named scope :by_unique_users so that I can do Comment.recent.by_unique_users.limit(3), and only get one comment per user? class User has_many :comments end class Comment belongs_to :user named_scope :recent, :order => 'comments.created_at DESC' named_scope :limit, lambda { |limit| {:limit => limit}} named_scope :by_unique_users end on sqlite named_scope :by_unique_user, :group = "user_id" works, but makes it freak out on postgres, which is deployed on production PGError: ERROR: column "comments.id" must appear in the GROUP BY clause or be used in an aggregate function

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  • SQLAlchemy - select for update example

    - by Mark
    I'm looking for a complete example of using select for update in SQLAlchemy, but haven't found one googling. I need to lock a single row and update a column, the following code doesn't work (blocks forever): s = table.select(table.c.user=="test",for_update=True) u = table.update().where(table.c.user=="test") u.execute(email="foo") Do I need a commit? How do I do that? As far as I know you need to: begin transaction select ... for update update commit

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  • Strange behavior of move with strings

    - by Umair Ahmed
    I am testing some enhanced string related functions with which I am trying to use move as a way to copy strings around for faster, more efficient use without delving into pointers. While testing a function for making a delimited string from a TStringList, I encountered a strange issue. The compiler referenced the bytes contained through the index when it was empty and when a string was added to it through move, index referenced the characters contained. Here is a small downsized barebone code sample:- unit UI; interface uses System.SysUtils, System.Types, System.UITypes, System.Rtti, System.Classes, System.Variants, FMX.Types, FMX.Controls, FMX.Forms, FMX.Dialogs, FMX.Layouts, FMX.Memo; type TForm1 = class(TForm) Results: TMemo; procedure FormCreate(Sender: TObject); end; var Form1: TForm1; implementation {$R *.fmx} function StringListToDelimitedString ( const AStringList: TStringList; const ADelimiter: String ): String; var Str : String; Temp1 : NativeInt; Temp2 : NativeInt; DelimiterSize : Byte; begin Result := ' '; Temp1 := 0; DelimiterSize := Length ( ADelimiter ) * 2; for Str in AStringList do Temp1 := Temp1 + Length ( Str ); SetLength ( Result, Temp1 ); Temp1 := 1; for Str in AStringList do begin Temp2 := Length ( Str ) * 2; // Here Index references bytes in Result Move ( Str [1], Result [Temp1], Temp2 ); // From here the index seems to address characters instead of bytes in Result Temp1 := Temp1 + Temp2; Move ( ADelimiter [1], Result [Temp1], DelimiterSize ); Temp1 := Temp1 + DelimiterSize; end; end; procedure TForm1.FormCreate(Sender: TObject); var StrList : TStringList; Str : String; begin // Test 1 : StringListToDelimitedString StrList := TStringList.Create; Str := ''; StrList.Add ( 'Hello1' ); StrList.Add ( 'Hello2' ); StrList.Add ( 'Hello3' ); StrList.Add ( 'Hello4' ); Str := StringListToDelimitedString ( StrList, ';' ); Results.Lines.Add ( Str ); StrList.Free; end; end. Please devise a solution and if possible, some explanation. Alternatives are welcome too.

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  • some troubles with WPF and Windows XP

    - by Sorush Rabiee
    is .net framework 3 compatible with xp? i install visual studio 9.0 (.net 3.5) on win XP. when i compile a WPF project and try to run it, this error occurs: cannot initialize application ...... at address 0x<some digits> (antivirus protection is off) after first fail of wpf, all other project types (windows application, console &...) after compiling don't run. where is problem?

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  • SQL to join to the best matching row

    - by williamjones
    I have a wiki system where there is a central table, Article, that has many Revisions in their own table. The Revisions each contain a created_at time and date column. I want to update the Articles to contain a denormalized field sort_name from the most recent Revision's name field. What SQL command can I issue to fill in each Article's sort_name field with its most recent Revision's name field? For what it's worth, I'm on PostgreSQL.

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  • query to get part of a string

    - by tri
    column1 \\abc\tri\eds\rf1\edr\4ed \\f.d\tri\ef\poe \\ghi0j\tri\gf\rf\k\hg\ose ' ' ' i got some rows like that in a column now i want to get the result set like \\abc\tri\eds \\f.d\tri\ef\ \\ghij\tri\gf simply from first '\' to end of 4th '\'

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  • Qt QTableView and horizontalHeader()->restoreState()

    - by cheez
    I can't narrow down this bug, however I seem to have the following problem: - saveState() of a horizontalHeader() - restart app - Modify model so that it has one less column - restoreState() - Now, for some reason, the state of the headerview is totally messed up. I cannot show or hide any new columns, nor can I ever get a reasonable state back I know, this is not very descriptive but I'm hoping others have had this problem before.

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  • Hibernate can't load Custom SQL collection

    - by Geln Yang
    Hi, There is a table Item like, code,name 01,parent1 02,parent2 0101,child11 0102,child12 0201,child21 0202,child22 Create a java object and hbm xml to map the table.The Item.parent is a Item whose code is equal to the first two characters of its code : class Item{ String code; String name; Item parent; List<Item> children; .... setter/getter.... } <hibernate-mapping> <class name="Item" table="Item"> <id name="code" length="4" type="string"> <generator class="assigned" /> </id> <property name="name" column="name" length="50" not-null="true" /> <many-to-one name="parent" class="Item" not-found="ignore"> <formula> <![CDATA[ (select i.code,r.name from Item i where (case length(code) when 4 then i.code=SUBSTRING(code,1,2) else false end)) ]]> </formula> </many-to-one> <bag name="children"></bag> </class> </hibernate-mapping> I try to use formula to define the many-to-one relationship,but it doesn't work!Is there something wrong?Or is there other method? Thanks! ps,I use mysql database. add 2010/05/23 Pascal's answer is right,but the "false" value must be replaced with other expression,like "1=2".Because the "false" value would be considered to be a column of the table. select i.code from Item i where ( case length(code) when 4 then i.code=SUBSTRING(code,1,2) else 1=2 end) And I have another question about the children "bag" mapping.There isn't formula configuration option for "bag",but we can use "loader" to load a sql-query.I configure the "bag" as following.But it get a list whose size is 0.What's wrong with it? <class> ... ... <bag name="children"> <key /> <one-to-many class="Item"></one-to-many> <loader query-ref="getChildren"></loader> </bag> </class> <sql-query name="getChildren"> <load-collection alias="r" role="Item.children" /> <![CDATA[(select {r.*} from Item r join Item o where o.code=:code and ( case length(o.code) when 2 then (length(r.code)=4 and SUBSTRING(r.code,1,2)=o.code) else 1=2 end ))]]> </sql-query>

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  • Insert into Table from #tempTable fails

    - by AJ
    I am simply taking the data from a Table and insert it into #tempTable then delete the data, and insert it back to the table. I get "Insert Error: Column name or number of supplied values does not match table definition." Error. Here are the lines I am running. SELECT * INTO #tempTable FROM dbo.ProductSales SELECT * FROM #tempTable DELETE FROM dbo.ProductSales INSERT INTO dbo.ProductSales SELECT * FROM #tempTable Any Idea?

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  • Reducing size of a character array in Numpy

    - by Morgoth
    Given a character array: In [21]: x = np.array(['a ','bb ','cccc ']) One can remove the whitespace using: In [22]: np.char.strip(x) Out[22]: array(['a', 'bb', 'cccc'], dtype='|S8') but is there a way to also shrink the width of the column to the minimum required size, in the above case |S4?

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  • iPhone plotting / charting libraries

    - by sashaeve
    I am looking for good plotting library (line, pie, column charts) which allows to interact with user touches something like in Stocks app. I found a core-plot library but seems like that interaction logic is not well-covered. Please suggest what libraries can be used?

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  • AD-DirectoryServices: .NET2.0 - Speaking architecture, approach and best practices... Suggestions?

    - by Will Marcouiller
    I've been mandated to write an application to migrate the Active Directory access models to another environment. Here's the context: I'm stuck with VB.NET 2005 and .NET Framework 2.0; The application must use the Windows authenticated user to manage AD; The objects I have to handle are Groups, Users and OrganizationalUnits; I intend to use the Façade design pattern to provider ease of use and a fully reusable code; I plan to write a factory for each of the objects managed (group, ou, user); The use of Attributes should be useful here, I guess; As everything is about the DirectoryEntry class when accessing the AD, it seems a good candidate for generic types. Obligatory features: User creates new OUs manually; User creates new group manually; User creates new user (these users are services accounts) manually; Application reads an XML file which contains the OUs, groups and users to create; Application informs the user about the OUs, groups and users that shall be created; User specifies the domain environment where to migrate the XML input file designated objects; User makes changes if needed, and launches the task operations; Application performs required by the XML input file operations against the underlying AD as specified by the user; Application informs the user upon completion. Linear features: User fetches OUs, groups, users; User changes OUs, groups, users; User deletes OUs, groups, users; The application logs AD entries and operations performed, plus errors and exceptions; Nice-to-have features: Application rollbacks operations on error or exception. I've been working for weeks now to get acquainted with the AD and the System.DirectoryServices assembly. But I don't seem to find a way to be fully satisfied with what I'm doing and always looking for better. I have studied Bret de Smet's Linq to AD on CodePlex, but then again, I can't use it as I'm stuck with .NET 2.0, so no Linq! But I've learned about Attributes, and seen that he's working with generic types as he codes a DirectorySource class to perform the operations for OUs, groups and users. I have been able to add groups to the AD; I have been able to add users to the AD; The created user is automatically disabled? I seem to get confused with the use of a LDAP path to add objects. For instance, one needs two instances of a System.DirectoryServices.DirectoryEntry class to add a group, for instance. Why this? Any suggestions? Thanks for any help, code sample, ideas, architural solution, everything!

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  • dual map structure implementation?

    - by Danra
    Hey, I'm looking for a standard dual-map structure - is there one implemented in std/boost/another standard C++ library? When I say "dual-map" I mean a map which can be indexed efficiently both by the key and the "value" (it actually has two key types instead of one key type and one value type). for example: dualmap<int,string> m; m[1] = "foo"; m["bar"] = 2 int a = m["bar"]; // a = 2 Thanks, Dan

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  • Cannot create the Silverlight ASP.NET website in Visual Studio 2008 Web Developer edition

    - by BALAMURUGAN
    I need to create a ASp.net website with silverlight controls. I am having only express editions of 2008 (Web developer edition and C# express editions). I have created the WPF application sing C# expression and create the new XAML files. Then I have created asp.net website in web developer edition and linked the xaml files with the . But nothing works. Note: I have not silverlight application project types and templates in Visual Studio 2008 web developer edition.

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  • Accessing ItemRenderer in AdvancedDataGrid Flex / AS3?

    - by Muhammad Husnain Ashfaq
    i have XMLList data which is used for advanceddatagird dataprovide(by converting it to hierarchal data ), the advanceddatagrid consist of 2 columns,i want to access the ItemRenderer of 2nd colomn (customized item rendrer) by giving the item. i can get the itemRendrer bu using var Obj:Object = itemToItemRenderer(item); i cant understand that obj is IListItemRendrer, but in 2nd colomn i have used the renderer named "ProcessFLowRendrer"? can you tell me how i can access the rendrer of 2nd column, by item not by index ?

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  • Float: left not showing up after a certain point.

    - by Bobby K
    http://test.jptgraphics.com/products?cat=APPAREL This works fine in Safari but shows incorrectly in the latest version of Firefox ( was fine in 3.5) and in some versions of IE. In the middle column the product thumbnails drop down below when the 'float: left;' parameter is used. It is as if it is being escaped by a tag from that point forward no 'float: left's work and all the items are centered moving forward.

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  • nhibernate fluent bool to smallint mapping

    - by Raul
    In my application I have a bool property named DisplayIndicator. In the database (DB2) it's correspondence is DISPL_IND column of type smallint. The correspondence is the following: [DisplayINdicator=True, DISPL_IND=1] and [DisplayINdicator=False, DISPL_IND=0] Is it possible to map using nhibernate fluence the bool property to smallint?

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