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  • does a switch idiom make sense in this case?

    - by the ungoverned
    I'm writing a parser/handler for a network protocol; the protocol is predefined and I am writing an adapter, in python. In the process of decoding the incoming messages, I've been considering using the idiom I've seen suggested elsewhere for "switch" in python: use a hash table whose keys are the field you want to match on (a string in this case) and whose values are callable expressions: self.switchTab = { 'N': self.handleN, 'M': self.handleM, ... } Where self.handleN, etc., are methods on the current class. The actual switch looks like this: self.switchTab[selector]() According to some profiling I've done with cProfile (and Python 2.5.2) this is actually a little bit faster than a chain of if..elif... statements. My question is, do folks think this is a reasonable choice? I can't imagine that re-framing this in terms of objects and polymorphism would be as fast, and I think the code looks reasonably clear to a reader.

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  • Using IF in T-SQL weakens or breaks execution plan caching?

    - by AnthonyWJones
    It has been suggest to me that the use of IF statements in t-SQL batches is detrimental to performance. I'm trying to find some confirmation of this assertion. I'm using SQL Server 2005 and 2008. The assertion is that with the following batch:- IF @parameter = 0 BEGIN SELECT ... something END ELSE BEGIN SELECT ... something else END SQL Server cannot re-use the execution plan generated because the next execution may need a different branch. This implies that SQL Server will eliminate one branch entirely from execution plan on the basis that for the current execution it can already determine which branch is needed. Is this really true? In addition what happens in this case:- IF EXISTS (SELECT ....) BEGIN SELECT ... something END ELSE BEGIN SELECT ... something else END where it's not possible to determine in advance which branch will be executed?

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  • Database Abstraction & Factory Methods

    - by pws5068
    I'm interested in learning more about design practices in PHP for Database Abstraction & Factory methods. For background, my site is a common-interest social networking community currently in beta mode. Currently, I've started moving my old code for object retrieval to factory methods. However, I do feel like I'm limiting myself by keeping a lot of SQL table names and structure separated in each function/method. Questions: Is there a reason to use PEAR (or similar) if I dont anticipate switching databases? Can PEAR interface with the MySqli prepared statements I currently use? Will it help me separate table names from each method? (If no, what other design patterns might I want to research?) Will it slow down my site once I have a significantly large member base?

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  • Foolproof way to check for nonzero (error) return code in windows batch file

    - by Pat
    Intro There's a lot of advice out there for dealing with return codes in batch files (using the ERROLEVEL mechanism), e.g. Get error code from within a batch file ERRORLEVEL inside IF Some of the advice is to do if errorlevel 1 goto somethingbad, while others recommend using the %ERRORLEVEL% variable and using ==, EQU, LSS, etc. There seem to be issues within IF statements and such, so then delayedexpansion is encouraged, but it seems to come with quirks of its own. Question What is a foolproof (i.e. robust, so it will work on nearly any system with nearly any return code) way to know if a bad (nonzero) code has been returned? My attempt For basic usage, the following seems to work ok to catch any nonzero return code: if not errorlevel 0 ( echo error level was nonzero )

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  • How to quickly check if two columns in Excel are equivalent in value?

    - by mindless.panda
    I am interested in taking two columns and getting a quick answer on whether they are equivalent in value or not. Let me show you what I mean: So its trivial to make another column (EQUAL) that does a simple compare for each pair of cells in the two columns. It's also trivial to use conditional formatting on one of the two, checking its value against the other. The problem is both of these methods require scanning the third column or the color of one of the columns. Often I am doing this for columns that are very, very long, and visual verification would take too long and neither do I trust my eyes. I could use a pivot table to summarize the EQUAL column and see if any FALSE entries occur. I could also enable filtering and click on the filter on EQUAL and see what entries are shown. Again, all of these methods are time consuming for what seems to be such a simple computational task. What I'm interested in finding out is if there is a single cell formula that answers the question. I attempted one above in the screenshot, but clearly it doesn't do what I expected, since A10 does not equal B10. Anyone know of one that works or some other method that accomplishes this?

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  • How to call constructor of the current class and parent class at the same time?

    - by Siegfried
    public class A{ public A(int a, int b) {...} } public class B : A{ List a; List b; public B(){...} //constructor1 public B(int a, int b) : base(a,b){...} //constructor2 } My question is I need to initialize both list a and b in class B. If I put them in the constructor1, how can I call constructor1 in constructor2? I don't want to rewrite the initialization statements in constructor2 again. Thanks!

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  • Java library to partially export a database while respecting referential integrity constraints

    - by Mwanji Ezana
    My production database is several GB's uncompressed and it's getting to be a pain to download and run locally when trying to reproduce a bug or test a feature with real data. I would like to be able to select the specific records that interest me, then have the library figure out what other records are necessary to produce a dataset that respects the databases integrity constraints and finally print it out as a list of insert statements or dump that I can restore. For example: given Author, Blog and Comment tables when I select comments posted after a certain date I should get inserts for the Blog records the comments have foreign keys to and the Author records those Blogs have foreign keys to.

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  • Using using to dispose of nested objects

    - by TooFat
    If I have code with nested objects like this do I need to use the nested using statements to make sure that both the SQLCommand and the SQLConnection objects are disposed of properly like shown below or am I ok if the code that instantiates the SQLCommand is within the outer using statement. using (SqlConnection conn = new SqlConnection(sqlConnString)) { using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand()) { cmd.CommandType = CommandType.Text; cmd.CommandText = cmdTextHere; conn.Open(); cmd.Connection = conn; rowsAffected = cmd.ExecuteNonQuery(); } }

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  • Best way to gather, then import data into drupal?

    - by Frank
    I am building my first database driven website with Drupal and I have a few questions. I am currently populating a google docs excel spreadsheet with all of the data I want to eventually be able to query from the website (after it's imported). Is this the best way to start? If this is not the best way to start what would you recommend? My plan is to populate the spreadsheet then import it as a csv into the mysql db via the CCK Node. I've seen two ways to do this. http://drupal.org/node/133705 (importing data into CCK nodes) http://drupal.org/node/237574 (Inserting data using spreadsheet/csv instead of SQL insert statements) Basically my question(s) is what is the best way to gather, then import data into drupal? Thanks in advance for any help, suggestions.

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  • Java/MySQL: Working with data in classes

    - by skiwi
    What is the best way to deal with accessing/modifying tables in a database? I have read about the Data Access Object approach, but none of the resources I have found so far indicate a clear implementation of it. So assume you have a database with a table called accounts that has columns id, name, password and email. How would you properly access it within Java? I mean most people know how to do SQL statements, but that is not really the point. I hope people here can be of help. Regards.

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  • How to enable reading non-ascii characters in Servlets

    - by Daziplqa
    How to make the servlet accept non-ascii (Arabian, chines, etc) characters passed from JSPs? I've tried to add the following to top of JSPs: <%@page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> And to add the following in each post/get method in the servlet: request.setCharacterEncoding("UTF-8"); response.setCharacterEncoding("UTF-8"); I've tried to add a Filter that executes the above two statements instead of in the servlet. To be quite honest, these was working in the past, but now it doesn't work anymore. I am using tomcat 5.0.28/6.x.x on JDK1.6 on both Win & Linux boxes.

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  • move vim cursor after a function

    - by emergence
    I'm using both the supertab and snipmate plugins. Let's say I'm using snipmate to create an if statement structure. Once I'm done adding statements inside the if-statement, how can I quickly move the cursor after the if-statement. For example: if [ $a = "b" ]; then bla; fi If my cursor is right on the semicolon and I'm in insert mode. What is the fewest number of actions I can take to move the cursor to the line after the 'fi'? If I press tab, supertab just open an autocomplete window. Thanks

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  • Handling user security scope with nHibernate or other ORM

    - by Schotime
    How should one handle the situation where you may need to filter by a group of users. Here is the scenario. I have an administrator role in my company. I should be able to see all the data belonging to me plus all the other users who I have control over. A plain old user however should only be able to access their own data. If you are writing regular sql statements then you can have a security table with every user and who they have access too but i'm not sure how to handle this situation in the OO and ORM world. Any one dealt with this scenario in a web application using an ORM? Would love to hear your thoughts!

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  • How to deal with the limited Linq Support of OData (Open Data Protocol)

    - by user341127
    I have a software, which uses a lot of Linq to SQL. Recently, I want to immigrate to OData (or WCF Data Service) architecture. But I met too many problems in Linq for the Linq support of OData is so limited. I have to modify most of my Linq statements and test them thoroughly again. I am wondering whether there is a system way to solve such a problem instead of my manual work. For example, by an external package. BTW, now I have no confidence to use OData as a kind of architecture. You are appreciated to share your ideas. Thank you in advance, Ying

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  • Better way to write this Java code?

    - by Macha
    public void handleParsedCommand(String[] commandArr) { if(commandArr[0].equalsIgnoreCase("message")) { int target = Integer.parseInt(commandArr[1]); String message = commandArr[2]; MachatServer.sendMessage(target, this.conId, message); } else if(commandArr[0].equalsIgnoreCase("quit")) { // Tell the server to disconnect us. MachatServer.disconnect(conId); } else if(commandArr[0].equalsIgnoreCase("confirmconnect")) { // Blah blah and so on for another 10 types of command } else { try { out.write("Unknown: " + commandArr[0] + "\n"); } catch (IOException e) { System.out.println("Failed output warning of unknown command."); } } } I have this part of my server code for handling the types of messages. Each message contains the type in commandArr[0] and the parameters in the rest of commandArr[]. However, this current code, while working seems very unelegant. Is there a better way to handle it? (To the best of my knowledge, String values can't be used in switch statements, and even then, a switch statement would only be a small improvement.

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  • nHibernate Linq Projection

    - by Craig
    I am using the version 1.0 release of Linq for nHibernate. When I run the following linq statements I receive the error not a single-length projection: Surname I can find very few references to this on the web and looking into the source it says it should never occur! ClientID is a Int type and Surname is a string. When I comment out all the string fields in the projection and just leave ClientID it runs ok, but as soon as I add surname back it errors. var context = m_ClientRepository.Linq; var result = (from client in context from address in client.Addresses from contact in client.Contacts where client.Surname.StartsWith(surname) && client.GivenName.StartsWith(givenName) && contact.Value.StartsWith(phoneNumber) group client by new { client.ClientID, client.Surname, client.GivenName } into clientGroup select new ClientSearchDTO() { ClientID = clientGroup.Key.ClientID, Surname = clientGroup.Key.Surname, GivenName = clientGroup.Key.GivenName, Address = clientGroup.Max(x => x.Addresses.FirstOrDefault().Address), PhoneNumber = clientGroup.Max(x => x.Contacts.FirstOrDefault().Value) }) .Skip(Paging.FirstRecord(pageNumber)) .Take(5);

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  • MySQL Many to Many with Unique keys and Update/Select if Exists otherwise Insert

    - by Jayrox
    In my goal to have a Many-to-Many relationship in my MySQL database I have arrived at another bridge to build. Current Tables: Users (id, name) Tags (id, name) User_Tags (user_id, tag_id) Here is the goal: I would like to have the ability to take a tag i.e: #fb and insert it into my Tags database which has a unique constraint on name and if the tag exists I would like to return it's id I would like to insert the tag.id and the current user's user.id into User_Tags. I do not have any unique constraints on the User_Tags table because I would like to be able to track the user's most commonly used tags and present them in a list ordered by frequency of use. I am currently developing this project in PHP using prepared statements. Additionally, performance is not currently an issue as my user count is still fairly small, but it is steadily growing and may be an issue in the future.

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  • Equivalent of Switch Statement in MySql 5

    - by Robert Gowland
    Using MySql 5, I have a task where I need to update one table based on the contents of another table. For example, I need to add 'A1' to table 'A' if table 'B' contains 'B1'. I need to add 'A2a' and 'A2b' to table 'A' if table 'B' contains 'B2', etc.. In our case, the value in table 'B' we're interested is an enum. Right now I have a stored procedure containing a series of statements like: INSERT INTO A SELECT 'A1' FROM B WHERE B.Value = 'B1'; --Repeat for 'B2' -> 'A2a', 'A2b'; 'B3' -> 'A3', etc... Is there a nicer more DRY way of accomplishing this?

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  • Sharing some info with all DLLs pulled into a process

    - by JBRWilkinson
    Hi all, We've got an Enterprise system which has many processes (EXEs, services, DCOM servers, COM+ apps, ISAPI, MMC snapins) all of which make use of many COM components. We've recently seen failures in some of the customer deployments, but are finding it hard to troubleshoot the cause. In order to track down the problem, we've augmented the entire source with logging statements where errors occur. In order to identify which logs came from what processes, the C++ logging code (compiled into all components) uses the EXE name to name the log. This is good for some cases, but not all - COM+ apps, ISAPI and MMC snapins all have system EXE names and the logs end up interleaved. I saw this post about shared data sections which might help, but what I don't understand is who decides what goes in the shared section. Is there any way I can guarantee that a particular piece of code writes into the shared section before anyone else reads it? Or is there a better solution to this problem?

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  • How to call/execute another ASP.net page from the parent ASP.Net page without disrupting the flow of

    - by NJTechGuy
    When a button/link is clicked, I want this URL to be called followed by the execution of the following statements. The ASP.Net page is in C# btw. Function A statement A call abc.apsx statement B abc.aspx is a silent page, doesn't display anything on the page but creates an output.txt file. So when abc.aspx is called, output.txt file is created and Statement B is executed seamlessly. Hope I made sense. I have no .Net programming knowledge. Please help me. Thank you..

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  • Implementation code for GetDateFormat Win32 function

    - by morpheous
    I am porting some legacy code from windows to Linux (Ubuntu Karmic to be precise). I have come across a Win32 function GetDateFormat(). The statements I need to port over are called like this: GetDateFormat(LOCALE_USER_DEFAULT, 0, &datetime, "MMMM", 'January', 31); OR GetDateFormat(LOCALE_USER_DEFAULT, 0, &datetime, "MMMM", 'May', 30); Where datetime is a SYSTEMTIME struct. Does anyone know where I can get the code for the function - or failing that, tips on how to "roll my own" equivalent function?

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  • Convert this VB code to C#?

    - by Róisín Kerr Lautman
    I was wondering if anyone would be able to help me convert the below code to c#? From what I have read it seems to be similar however I am not sure if my 'case' statements are still able to be used? Public Class Form1 Dim dteStart As Date Dim dteFinish As Date Dim span As TimeSpan Public Sub KeyDown(ByVal Sender As System.Object, ByVal e As _ System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyDown Select Case e.KeyCode Case Keys.Q Label1.BackColor = Color.Green dteStart = Now() Case Keys.W Label2.BackColor = Color.Green Case Keys.E Label3.BackColor = Color.Green Case Keys.R Label4.BackColor = Color.Green dteFinish = Now() span = dteFinish.Subtract(dteStart) Label5.Text = span.ToString End Select End Sub Public Sub KeyUp(ByVal Sender As System.Object, ByVal e As _ System.Windows.Forms.KeyEventArgs) Handles MyBase.KeyUp Select Case e.KeyCode Case Keys.Q Label1.BackColor = Color.Red Case Keys.W Label2.BackColor = Color.Red Case Keys.E Label3.BackColor = Color.Red Case Keys.R Label4.BackColor = Color.Red End Select End Sub End Class

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  • Java, how to trace functions called

    - by user435657
    Hi all, I want to trace the beginning [& ending] of functions called in Java, like the following code: public void foo() { System.out.println("begin of foo()"); ... System.out.println("e-n-d of foo()"); } But maintaining of the dump code System.out.println is something tedious and error-prone, for there may be tens of thounds of function in an class. Any good idea can ease this work? I don't want dump statements all over the file. Implementation of both or one of the beginning & ending traces is perferd. But, if impossible, recordings of that the function has been called is also helpful. I mean not care the exact beginnig and ending, just tell that the function has been called.

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  • How come (a_method || :other) returns :other only when assigning to a var called a_method?

    - by Paul Annesley
    Given the following method: def some_method :value end The following statements work as I would expect: some_method || :other # => :value x = some_method || :other # => :value But the behaviour of the following statement perplexes me: some_method = some_method || :other # => :other It creates a local variable called some_method as expected, and subsequent calls to some_method return the value of that local variable. But why does it assign :other rather than :value? I understand that it's probably not a smart thing to do, and can see how it might be ambiguous, but I thought the right-hand-side of the assignment should be evaluated prior to the assignment being considered... I've tested this in Ruby 1.8.7 and Ruby 1.9.2 with identical results. Cheers! Paul

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  • INSERT INTO statement that copies rows and auto-increments non-identity key ID column

    - by AmoebaMan17
    Given a table that has three columns ID (Primary Key, not-autoincrementing) GroupID SomeValue I am trying to write a single SQL INSERT INTO statement that will make a copy of every row that has one GroupID into a new GroupID. Example beginning table: ID | GroupID | SomeValue ------------------------ 1 | 1 | a 2 | 1 | b Goal after I run a simple INSERT INTO statement: ID | GroupID | SomeValue ------------------------ 1 | 1 | a 2 | 1 | b 3 | 2 | a 4 | 2 | b I thought I could do something like: INSERT INTO MyTable ( [ID] ,[GroupID] ,[SomeValue] ) ( SELECT (SELECT MAX(ID) + 1 FROM MyTable) ,@NewGroupID ,[SomeValue] FROM MyTable WHERE ID = @OriginalGroupID ) This causes a PrimaryKey violation since it will end up reusing the same Max(ID)+1 value multiple times as it seems. Is my only recourse to a bunch of INSERT statements in a T-SQL WHILE statement that has an incrementing Counter value? I also don't have the option of turning the ID into an auto-incrementing Identity column since that would breaking code I don't have source for.

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