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  • Does anyone else think instance variables are problematic in database-backed applications?

    - by Ben Aston
    It occurs to me that state control in languages like C# is not well supported. By this, I mean, it is left upto the programmer to manage the state of in-memory objects. A common use-case is that instance variables in the domain-model are copies of information residing in persistent storage (i.e. the database). Clearly this violates the single point of authority principle, and "synchronisation" has to be managed by the developer. I envisage a system where instead of instance variables, we have simple public access/mutator methods marked with attributes that link them to the database, and where reads and writes are mediated by a framework that decides whether to hit the database. Does such a system exist? Am I completely missing the point, or is there some truth to this idea?

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  • Can you dynamically combine multiple conditional functions into one in Python?

    - by erich
    I'm curious if it's possible to take several conditional functions and create one function that checks them all (e.g. the way a generator takes a procedure for iterating through a series and creates an iterator). The basic usage case would be when you have a large number of conditional parameters (e.g. "max_a", "min_a", "max_b", "min_b", etc.), many of which could be blank. They would all be passed to this "function creating" function, which would then return one function that checked them all. Below is an example of a naive way of doing what I'm asking: def combining_function(max_a, min_a, max_b, min_b, ...): f_array = [] if max_a is not None: f_array.append( lambda x: x.a < max_a ) if min_a is not None: f_array.append( lambda x: x.a > min_a ) ... return lambda x: all( [ f(x) for f in f_array ] ) What I'm wondering is what is the most efficient to achieve what's being done above? It seems like executing a function call for every function in f_array would create a decent amount of overhead, but perhaps I'm engaging in premature/unnecessary optimization. Regardless, I'd be interested to see if anyone else has come across usage cases like this and how they proceeded. Also, if this isn't possible in Python, is it possible in other (perhaps more functional) languages?

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  • streaming to correct network interface

    - by robin hood
    I have IP cam that supports RTSP streaming. It's connected to router with 2 network cards with IP1 and IP2 addresses. I make 2 connections to IP cam by IP1 and IP2 addresses from the same IP and I need to receive corresponding streams thru correct network card, but both streams (RTP over UDP) go thru IP1. How this can be resolved? I don't know if RTSP server binds UDP sockets to corresponding IP and I don't know what IP stack is in IP cam (weak end system or strong end system). I haven't found anything interesting in router configuration. As I understand, routing table cannot help me cos I'm connected from the same IP, is it right? Also Sorry for incomplete info but it's all I have at the moment. Thanks for your time.

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  • Using excel, how can I count the number of cells in a column containing the text "true" or "false"?

    - by Jay Elston
    I have a spreadsheet that has a column of cells where each cell contains a single work. I would like to count the occurrences of some words. I can use the COUNTIF function for most words, but if the word is "true" or "false", I get 0. A B 1 apples 2 2 true 0 3 false 0 4 oranges 1 5 apples In the above spreadsheet table, I have these formulas in cells B1, B2, B3 and B4: =COUNTIF(A1:A5,"apples") =COUNTIF(A1:A5,"true") =COUNTIF(A1:A5,"false") =COUNTIF(A1:A5,"oranges) As you can see, I can count apples, but not true or false. I have also tried this: =COUNTIF(A1:A5,TRUE) But that does not work either. Note -- I am using Excel 2007.

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  • Kernel module for /proc

    - by sb2367
    How to write a kernel module that creates a directory in /proc named mymod and a file in it name is mymodfile. This file should accept a number ranged from 1 to 3 when written into it and return the following messages when read based on the number already written into it: • 1: Current system time (in microseconds precision) • 2: System uptime • 3: Number of processes currently in the system “The Output” root@Paradise# echo 1 > /proc/mymod/mymodfile root@Paradise# cat /proc/mymod/mymodfile 08:30:24 342us root@Paradise# echo 2 > /proc/mymod/mymodfile root@Paradise# cat /proc/mymod/mymodfile up 1 day, 8 min root@Paradise# echo 3 > /proc/mymod/mymodfile root@Paradise# cat /proc/mymod/mymodfile process count: 48 please give me some hint how to write a kernel modules and how to compile and install it .

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  • Regarding PID Shell Script

    - by arav
    I am calling another shell script testarg.sh within my main script. the logfiles of testarg.sh are stored in $CUSTLOGS in the below format testarg.DDMONYY.PID.log example: testarg.09Jun10.21165.log In the main script after the testarg process gets completed i need to grep the log file for the text "ERROR" and "COMPLETED SUCCESSFULLY". How do i get the PID of the process and combine with DDMONYY for grepping. Also i need to check whether file exists before grepping $CUSTBIN/testarg.sh $CUSTBIN/testarg.sh rc=$? if [ $rc -ne 0 ]; then return $CODE_WARN fi

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  • Avoiding dependency carrying

    - by dotnetdev
    When coding, I often come across the following pattern: -A method calls another method (Fine), but the method being called/callee takes parameters, so in the wrapping method, I pass in parameters. Problem is, this dependency carrying can go on and on. How could I avoid this (any sample code appreciated)? Thanks

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  • What experience is the most valued in a programmer?

    - by Christo
    I've been coding application level software for a while now. I've had some experience with internet (server/client based) applications, but that has been fairly scant. The field doesn't scare although I know that experience can be almost be measured in gold. I see myself as a highly qualified and experienced programmer, but I also see my short comings in these fields. Does this count against me (and others like me?) and would this cut anyone from obtaining the shortlist or are there other factors which bear more weight?

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  • What language is .NET Framework written in?

    - by chester89
    The question I always wanted to ask and was afraid to, actually - what language is .NET Framework written in? I mean library itself. It seems to me that it was C and C++ mostly. (I hope Jon Skeet is reading this one, it`ll be very interesting to hear what he thinks about it)

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  • Java Or C++ Or What???

    - by Kronass
    Hi, My friends and I are starting a new project and we are shifting from windows to linux (for some reasons) and all of us are .Net background. for the new platform I decided to go with Java since many parts are similar with .Net but my friend is insisting on C++ saying it is much faster very mature and working with it will not effect on the productivity and development speed. The project that we will work on it will have threading, extensive string and datetime manipulation, some socket programing and of-course work with RDBMS (MySql Or Postgre not decided yet). I have some fears with java since oracle acquired sun and these people will do anything to make money out of it. some have advised in python and ruby and I like python but don't know should I make it the default language in this project. the project is not web application and we will make services and executables. what do you think, if you have other opinion you very welcome. Hint: Mono is not an option

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  • Hold a network connection although IP address change

    - by rursw1
    Hi, Is it possible to hold an open TCP connection with a client, while the IP address of the client is externally changed? For example, the connection is establishes against address X, but somewhen while the connection is open, the client-side user asks for IP renew and gets another IP address. Can the connection remains alive in this case? Thanks in advance.

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  • PHP: prepared statement, IF statement help needed

    - by JGreig
    I have the following code: $sql = "SELECT name, address, city FROM tableA, tableB WHERE tableA.id = tableB.id"; if (isset($price) ) { $sql = $sql . ' AND price = :price '; } if (isset($sqft) ) { $sql = $sql . ' AND sqft >= :sqft '; } if (isset($bedrooms) ) { $sql = $sql . ' AND bedrooms >= :bedrooms '; } $stmt = $dbh->prepare($sql); if (isset($price) ) { $stmt->bindParam(':price', $price); } if (isset($sqft) ) { $stmt->bindParam(':price', $price); } if (isset($bedrooms) ) { $stmt->bindParam(':bedrooms', $bedrooms); } $stmt->execute(); $result_set = $stmt->fetchAll(PDO::FETCH_ASSOC); What I notice is the redundant multiple IF statements I have. Question: is there any way to clean up my code so that I don't have these multiple IF statements for prepared statements?

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  • How can I manually uninstall .NET Framework Beta 2?

    - by DannyAsher
    Uninstalled VS2010 Beta 2. Uninstalled .NET Framework 4 Extended Beta 2. On attempting to uninstall .NET Framework 4 Client Profile Beta 2. I get Blocking Issues: You must uninstall the .NET Framework 4 Extended Beta 2 before you uninstall the .NET Framework 4 Client Profile Beta 2. On attempting to reinstall Framework 4 Beta 2 I get: Details: Same or higher version of .NET Framework 4 Beta 2 has already been installed on this computer. Please help! Can I simply remove registry entries and the C:\WINDOWS\Microsoft.NET\Framework\v4.0.21006 directory?

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  • Can I access elements/methods named "button1" "button2" "button3" etc. using "buttoni" inside a for-

    - by cksubs
    I have a bunch of buttons named: button1 button2 button3 etc. Is there a way to basically do this? pseudocode for(int i = 1, i < 15, i++) { button{i}.selected = YES; } This also goes for method calls, etc. I've often thought such a way of calling methods would be very convenient, but I don't think I've ever seen it done when using compiled languages. But I have done it using PHP. Is there any way to do this in Objective-C? (That's where my problem is now, but I'd also be interested in if you can do this in other languages.) Alternately, is there a reason why this is NOT a good way to go about accessing all the UI elements? Thanks!

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  • Is this multi line if statement too complex?

    - by AndHeCodedIt
    I am validating input on a form and attempting to prompt the user of improper input(s) based on the combination of controls used. For example, I have 2 combo boxes and 3 text boxes. The 2 combo boxes must always have a value other than the first (default) value, but one of three, or two of three, or all text boxes can be filled to make the form valid. In one such scenario I have a 6 line if statement to try to make the test easily readable: if ((!String.Equals(ComboBoxA.SelectedValue.ToString(), DEFAULT_COMBO_A_CHOICE.ToString()) && !String.IsNullOrEmpty(TextBoxA.Text) && !String.Equals(ComboBoxB.SelectedValue.ToString(), DEFAULT_COMBO_B_CHOICE.ToString())) || (!String.IsNullOrEmpty(TextBoxB.Text) || !String.IsNullOrEmpty(TextBoxC.Text))) { //Do Some Validation } I have 2 questions: Should this type of if statement be avoided at all cost? Would it be better to enclose this test in another method? (This would be a good choice as this validation will happen in more than one scenario) Thanks for your input(s)!

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  • Problem when trying to define Show for my Point3D type in Haskell

    - by devoured elysium
    I am trying to define Show for my Point3D type: type Point3D = (Integer, Integer, Integer) instance Show Point3D where show (x,y,z) = "<" ++ (show x) ++ "," ++ (show y) ++ "," ++ (show z) ++ ">" yet I must be missing something in the sintax, as I am always getting an error: Illegal instance declaration for `Show Point3D' (All instance types must be of the form (T t1 ... tn) where T is not a synonym. Use -XTypeSynonymInstances if you want to disable this.) In the instance declaration for `Show Point3D' What am I doing wrong?

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  • Best ways to write a method that updates two objects in a multithreaded java environment?

    - by DanielHonig
    Suppose we have a class called AccountService that manages the state of accounts. AccountService is defined as interface AccountService{ public void debit(account); public void credit(account); public void transfer(Account account, Account account1); } Given this definition, what is the best way to implement transfer() so that you can guarantee that transfer is an atomic operation. I'm interested in answers that reference Java 1.4 code as well as answers that might use resources from java.util.concurrent in Java 5

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  • When will a TCP network packet be fragmented at the application layer?

    - by zooropa
    When will a TCP packet be fragmented at the application layer? When a TCP packet is sent from an application, will the recipient at the application layer ever receive the packet in two or more packets? If so, what conditions cause the packet to be divided. It seems like a packet won't be fragmented until it reaches the Ethernet (at the network layer) limit of 1500 bytes. But, that fragmentation will be transparent to the recipient at the application layer since the network layer will reassemble the fragments before sending the packet up to the next layer, right?

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