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• Change JS alert to DOM error message div

  - by Jason

  I need to convert my error messaging to a positioned div (hidden initially) instead of the standard js alert. I realize I need to push the alert message to the DOM, but I'm new to javascript. Any help would be appreciated. Additionally, I need to do it without a confirm (so error message removes on field focus) if(el != null) { switch(el.name) { case "firstName": //First Name Field Validation, Return false if field is empty if( f.firstName.value == "" ) { alert( bnadd_msg_002 ); if ((typeof TeaLeaf != "undefined") && (typeof TeaLeaf.Client != "undefined") && (typeof TeaLeaf.Client.tlAddEvent != "undefined") ) { var nVO = { ErrorMessage : bnadd_msg_002} var subtype="CustomErrorMsg"; TeaLeaf.Event.tlAddCustomEvent(subtype, nVO); } return false; } break;

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• Mercurial hg clone error - "abort: error: Name or service not known"

  - by Bojan Milankovic

  I have installed the latest hg package available for Fedora Linux. However, hg clone reports an error. hg clone http://localmachine001:8000/ repository reports: "abort: error: Name or service not known" localmachine001 is a computer within the local network. I can ping it from my Linux box without any problems. I can also use the same http address and browse the existing code. However, hg clone does not work. If I execute the same command from my Macintosh machine, I can easily clone the repository. Some Internet resources recommend editing .hgrc file, and adding proxy to it: [http_proxy] host=proxy:8080 I have tried that without any success. Also, I assume that proxy is not needed in this case, since the hg server machine is in my local network. Can anyone recommend me what should I do, or how could I track the problem? Thank you in advance.

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• In Mercurial, when Peter "hg clone" me, and I commit and he pull and update, he gets my version, but

  - by Jian Lin

  That is, in Mercurial, if Peter cloned from me by hg clone c:\mycode into his e:\code let's say there is a file code.txt and it contains the text the code is 7 Now, when I change it to the code is 11 and hg commit, then he can get my code using hg pull and hg update. Now his version says the code is 11 But if I decide the change was wrong and hg rollback, then my repository should have the 7 version, while the working directory should have the 11 version. So when Peter does an hg pull and hg update, he should be sync'ed up to my current repository, which is the 7, but I found that it is not the case -- he still gets the 11 version. Why is that? Can he get the rolled back code (the 7)? Does Git behave the same way too?

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• Python "Every Other Element" Idiom

  - by Matt Luongo

  Hey guys, I feel like I spend a lot of time writing code in Python, but not enough time creating Pythonic code. Recently I ran into a funny little problem that I thought might have an easy, idiomatic solution. Paraphrasing the original, I needed to collect every sequential pair in a list. For example, given the list [1,2,3,4,5,6], I wanted to compute [(1,2),(3,4),(5,6)]. I came up with a quick solution at the time that looked like translated Java. Revisiting the question, the best I could do was l = [1,2,3,4,5,6] [(l[2*x],l[2*x+1]) for x in range(len(l)/2)] which has the side effect of tossing out the last number in the case that the length isn't even. Is there a more idiomatic approach that I'm missing, or is this the best I'm going to get?

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• Python's subprocess.Popen object hangs gathering child output when child process does not exit

  - by Daniel Miles

  When a process exits abnormally or not at all, I still want to be able to gather what output it may have generated up until that point. The obvious solution to this example code is to kill the child process with an os.kill, but in my real code, the child is hung waiting for NFS and does not respond to a SIGKILL. #!/usr/bin/python import subprocess import os import time import signal import sys child_script = """ #!/bin/bash i=0 while [ 1 ]; do echo "output line $i" i=$(expr $i \+ 1) sleep 1 done """ childFile = open("/tmp/childProc.sh", 'w') childFile.write(child_script) childFile.close() cmd = ["bash", "/tmp/childProc.sh"] finish = time.time() + 3 p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE) while p.poll() is None: time.sleep(0.05) if finish < time.time(): print "timed out and killed child, collecting what output exists so far" out, err = p.communicate() print "got it" sys.exit(0) In this case, the print statement about timing out appears and the python script never exits or progresses. Does anybody know how I can do this differently and still get output from my child processe

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• MSBuild Override Project Reference to resolve to Precompiled Assembly

  - by Ryu

  Situation I have about 400 csproj files using project references. About 3 of those a separate team wants to fork and incorporate into a standalone app. I branched the 3 projects of interest, and because the separate team uses a diff SVN repo I used svn externals to pull in these projects into the folder of the standalone app. Obviously since this team uses a different folder structure the project references no longer resolve. Attempted Solution I figured setting the msbuild properties ReferencePath and AdditionalLibPaths to point to a directory with all the precompiled dependencies would allow the project references a fallback point and resolve correctly. However that doesn't appear to be the case. Question Does anybody know a way to have a failed projectreference look up resolve to the precompiled dll? Perhaps point me to an automated tool to convert projectreferences to dll references? Or is there a better way to solve this problem? Thanks

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• Explain BFS and DFS in terms of backtracking

  - by HH

  Wikipedia about DFS Depth-first search (DFS) is an algorithm for traversing or searching a tree, tree structure, or graph. One starts at the root (selecting some node as the root in the graph case) and explores as far as possible along each branch before backtracking. So is BFS? "an algorithm that choose a starting node, checks all nodes -- backtracks --, chooses the shortest path, chose neighbour nodes -- backtracks --, chose the shortest path -- finally finds the optimal path because of traversing each path due to continuos backtracking. Regex, find's pruning -- backtracking? The term backtracking confuseses due to its variety of use. UNIX find's pruning an SO-user explained with backtracking. Regex Buddy uses the term "catastrophic backtracking" if you do not limit the scope of your Regexes. It seems to be too wide umbrella-term. So: how do you define "Backtracking" GRAPH-theoretically? what is "backtracking" in BFS and DFS?

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• How to replace all instances of a particular value in a mysql database with another?

  - by Joseph

  I'm looking for a MySQL equivalent of what str_replace is for PHP. I want to replace all instances of one word with another, I want to run a query that will replace all "apples" with "oranges". The reason why: UPDATE fruits SET name='oranges' WHERE name='apples'; isn't going to work for my situation, is because I often times have multiple words in a table row separated by commas like: "apples, pears, pineapples". In this case I want just apples to be replaced by oranges and pear and pineapples to stay in tact. Is there any way to do this?

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• A control that contains multiple duplicate properties causing deadlock issues on IIS

  - by heads5150

  I am trying to work out if the above case is true for our site. I've been told by my hosting provider that this fix (http://support.microsoft.com/kb/974165) has to applied to our server due to performance issues. It basically describes an issues where UI code like: <asp:gridview id="GridView1" runat="server" ... PageSize="100" PagerSettings-Mode="Numeric" PagerStyle-BorderStyle="None" PagerStyle-BorderColor="Navy" PagerStyle-HorizontalAlign="Right" PagerSettings-PageButtonCount="2" PagerSettings-Position="Bottom"> <PagerStyle HorizontalAlign="Left" BorderColor="Navy" BorderStyle="None"></PagerStyle> ... <PagerSettings PageButtonCount="2"></PagerSettings> ... </asp:gridview> causing the following warning on the server "ISAPI 'C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll' reported itself as unhealthy for the following reason: 'Deadlock detected'." Does anybody know of a way that I can detect this issue in the build process or the debugger? Any help would be much appreciate.

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• Main pricing and support for individual client pricing (Database Architecture ideas help - Rails)

  - by slythic

  Hi all, I have a personal project I'm planning and I came to a small hurdle. I want to have an item with price that will be the default for all clients/users. However, in my business I have some clients that are grandfathered in to some special pricing. In the case of these grandfathered in cases, I'll manually plug their special price in my admin section. Then all they will see is their special pricing while the regular users/clients see the default price. What is the best and simplest way to design the back-end for this? FYI - I'll be using rails as my framework. Many thanks! -Tony

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• Using sed for introducing newline after each > in a +1 gigabyte large one-line text file

  - by wasatz

  I have a giant text file (about 1,5 gigabyte) with xml data in it. All text in the file is on a single line, and attempting to open it in any text editor (even the ones mentioned in this thread: http://stackoverflow.com/questions/159521/text-editor-to-open-big-giant-huge-large-text-files ) either fails horribly or is totally unusable due to the text editor hanging when attempting to scroll. I was hoping to introduce newlines into the file by using the following sed command sed 's/>/>\n/g' data.xml > data_with_newlines.xml Sadly, this caused sed to give me a segmentation fault. From what I understand, sed reads the file line-by-line which would in this case mean that it attempts to read the entire 1,5 gig file in one line which would most certainly explain the segfault. However, the problem remains. How do I introduce newlines after each in the xml file? Do I have to resort to writing a small program to do this for me by reading the file character-by-character?

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• Difference between implementing an interface and applying an attribute in C#

  - by RemotecUk

  This might be a stupid question but Ill ask anyway, I was reading "OOP Demystified: A Self-Teaching Guide by Jim Keogh and Mario Giannini" chapter 11 which covers interfaces. The examples in this book are C++. I noticed that C++ uses ISerializable to make a class serializable which you would implement where as in C# you just attribute the class with the [Serializable] attribute. What is the key difference here? Is it that with an interface you must provide the implementation where as if you attribute something the compiler will work out the implementation for you? I guess that with the [Serializable] attribute the .Net framework uses reflection to make the serialized object from the actual object. That said is it possible in that case to have an [Disposable] attribute or using my theory above the framework wont know how to actually dispose of an object hence you have to do it yourself? Would be grateful for a clarification. Thanks.

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• Inside the Concurrent Collections: ConcurrentDictionary

  - by Simon Cooper

  Using locks to implement a thread-safe collection is rather like using a sledgehammer - unsubtle, easy to understand, and tends to make any other tool redundant. Unlike the previous two collections I looked at, ConcurrentStack and ConcurrentQueue, ConcurrentDictionary uses locks quite heavily. However, it is careful to wield locks only where necessary to ensure that concurrency is maximised. This will, by necessity, be a higher-level look than my other posts in this series, as there is quite a lot of code and logic in ConcurrentDictionary. Therefore, I do recommend that you have ConcurrentDictionary open in a decompiler to have a look at all the details that I skip over. The problem with locks There's several things to bear in mind when using locks, as encapsulated by the lock keyword in C# and the System.Threading.Monitor class in .NET (if you're unsure as to what lock does in C#, I briefly covered it in my first post in the series): Locks block threads The most obvious problem is that threads waiting on a lock can't do any work at all. No preparatory work, no 'optimistic' work like in ConcurrentQueue and ConcurrentStack, nothing. It sits there, waiting to be unblocked. This is bad if you're trying to maximise concurrency. Locks are slow Whereas most of the methods on the Interlocked class can be compiled down to a single CPU instruction, ensuring atomicity at the hardware level, taking out a lock requires some heavy lifting by the CLR and the operating system. There's quite a bit of work required to take out a lock, block other threads, and wake them up again. If locks are used heavily, this impacts performance. Deadlocks When using locks there's always the possibility of a deadlock - two threads, each holding a lock, each trying to aquire the other's lock. Fortunately, this can be avoided with careful programming and structured lock-taking, as we'll see. So, it's important to minimise where locks are used to maximise the concurrency and performance of the collection. Implementation As you might expect, ConcurrentDictionary is similar in basic implementation to the non-concurrent Dictionary, which I studied in a previous post. I'll be using some concepts introduced there, so I recommend you have a quick read of it. So, if you were implementing a thread-safe dictionary, what would you do? The naive implementation is to simply have a single lock around all methods accessing the dictionary. This would work, but doesn't allow much concurrency. Fortunately, the bucketing used by Dictionary allows a simple but effective improvement to this - one lock per bucket. This allows different threads modifying different buckets to do so in parallel. Any thread making changes to the contents of a bucket takes the lock for that bucket, ensuring those changes are thread-safe. The method that maps each bucket to a lock is the GetBucketAndLockNo method: private void GetBucketAndLockNo( int hashcode, out int bucketNo, out int lockNo, int bucketCount) { // the bucket number is the hashcode (without the initial sign bit) // modulo the number of buckets bucketNo = (hashcode & 0x7fffffff) % bucketCount; // and the lock number is the bucket number modulo the number of locks lockNo = bucketNo % m_locks.Length; } However, this does require some changes to how the buckets are implemented. The 'implicit' linked list within a single backing array used by the non-concurrent Dictionary adds a dependency between separate buckets, as every bucket uses the same backing array. Instead, ConcurrentDictionary uses a strict linked list on each bucket: This ensures that each bucket is entirely separate from all other buckets; adding or removing an item from a bucket is independent to any changes to other buckets. Modifying the dictionary All the operations on the dictionary follow the same basic pattern: void AlterBucket(TKey key, ...) { int bucketNo, lockNo; 1: GetBucketAndLockNo( key.GetHashCode(), out bucketNo, out lockNo, m_buckets.Length); 2: lock (m_locks[lockNo]) { 3: Node headNode = m_buckets[bucketNo]; 4: Mutate the node linked list as appropriate } } For example, when adding another entry to the dictionary, you would iterate through the linked list to check whether the key exists already, and add the new entry as the head node. When removing items, you would find the entry to remove (if it exists), and remove the node from the linked list. Adding, updating, and removing items all follow this pattern. Performance issues There is a problem we have to address at this point. If the number of buckets in the dictionary is fixed in the constructor, then the performance will degrade from O(1) to O(n) when a large number of items are added to the dictionary. As more and more items get added to the linked lists in each bucket, the lookup operations will spend most of their time traversing a linear linked list. To fix this, the buckets array has to be resized once the number of items in each bucket has gone over a certain limit. (In ConcurrentDictionary this limit is when the size of the largest bucket is greater than the number of buckets for each lock. This check is done at the end of the TryAddInternal method.) Resizing the bucket array and re-hashing everything affects every bucket in the collection. Therefore, this operation needs to take out every lock in the collection. Taking out mutiple locks at once inevitably summons the spectre of the deadlock; two threads each hold a lock, and each trying to acquire the other lock. How can we eliminate this? Simple - ensure that threads never try to 'swap' locks in this fashion. When taking out multiple locks, always take them out in the same order, and always take out all the locks you need before starting to release them. In ConcurrentDictionary, this is controlled by the AcquireLocks, AcquireAllLocks and ReleaseLocks methods. Locks are always taken out and released in the order they are in the m_locks array, and locks are all released right at the end of the method in a finally block. At this point, it's worth pointing out that the locks array is never re-assigned, even when the buckets array is increased in size. The number of locks is fixed in the constructor by the concurrencyLevel parameter. This simplifies programming the locks; you don't have to check if the locks array has changed or been re-assigned before taking out a lock object. And you can be sure that when a thread takes out a lock, another thread isn't going to re-assign the lock array. This would create a new series of lock objects, thus allowing another thread to ignore the existing locks (and any threads controlling them), breaking thread-safety. Consequences of growing the array Just because we're using locks doesn't mean that race conditions aren't a problem. We can see this by looking at the GrowTable method. The operation of this method can be boiled down to: private void GrowTable(Node[] buckets) { try { 1: Acquire first lock in the locks array // this causes any other thread trying to take out // all the locks to block because the first lock in the array // is always the one taken out first // check if another thread has already resized the buckets array // while we were waiting to acquire the first lock 2: if (buckets != m_buckets) return; 3: Calculate the new size of the backing array 4: Node[] array = new array[size]; 5: Acquire all the remaining locks 6: Re-hash the contents of the existing buckets into array 7: m_buckets = array; } finally { 8: Release all locks } } As you can see, there's already a check for a race condition at step 2, for the case when the GrowTable method is called twice in quick succession on two separate threads. One will successfully resize the buckets array (blocking the second in the meantime), when the second thread is unblocked it'll see that the array has already been resized & exit without doing anything. There is another case we need to consider; looking back at the AlterBucket method above, consider the following situation: Thread 1 calls AlterBucket; step 1 is executed to get the bucket and lock numbers. Thread 2 calls GrowTable and executes steps 1-5; thread 1 is blocked when it tries to take out the lock in step 2. Thread 2 re-hashes everything, re-assigns the buckets array, and releases all the locks (steps 6-8). Thread 1 is unblocked and continues executing, but the calculated bucket and lock numbers are no longer valid. Between calculating the correct bucket and lock number and taking out the lock, another thread has changed where everything is. Not exactly thread-safe. Well, a similar problem was solved in ConcurrentStack and ConcurrentQueue by storing a local copy of the state, doing the necessary calculations, then checking if that state is still valid. We can use a similar idea here: void AlterBucket(TKey key, ...) { while (true) { Node[] buckets = m_buckets; int bucketNo, lockNo; GetBucketAndLockNo( key.GetHashCode(), out bucketNo, out lockNo, buckets.Length); lock (m_locks[lockNo]) { // if the state has changed, go back to the start if (buckets != m_buckets) continue; Node headNode = m_buckets[bucketNo]; Mutate the node linked list as appropriate } break; } } TryGetValue and GetEnumerator And so, finally, we get onto TryGetValue and GetEnumerator. I've left these to the end because, well, they don't actually use any locks. How can this be? Whenever you change a bucket, you need to take out the corresponding lock, yes? Indeed you do. However, it is important to note that TryGetValue and GetEnumerator don't actually change anything. Just as immutable objects are, by definition, thread-safe, read-only operations don't need to take out a lock because they don't change anything. All lockless methods can happily iterate through the buckets and linked lists without worrying about locking anything. However, this does put restrictions on how the other methods operate. Because there could be another thread in the middle of reading the dictionary at any time (even if a lock is taken out), the dictionary has to be in a valid state at all times. Every change to state has to be made visible to other threads in a single atomic operation (all relevant variables are marked volatile to help with this). This restriction ensures that whatever the reading threads are doing, they never read the dictionary in an invalid state (eg items that should be in the collection temporarily removed from the linked list, or reading a node that has had it's key & value removed before the node itself has been removed from the linked list). Fortunately, all the operations needed to change the dictionary can be done in that way. Bucket resizes are made visible when the new array is assigned back to the m_buckets variable. Any additions or modifications to a node are done by creating a new node, then splicing it into the existing list using a single variable assignment. Node removals are simply done by re-assigning the node's m_next pointer. Because the dictionary can be changed by another thread during execution of the lockless methods, the GetEnumerator method is liable to return dirty reads - changes made to the dictionary after GetEnumerator was called, but before the enumeration got to that point in the dictionary. It's worth listing at this point which methods are lockless, and which take out all the locks in the dictionary to ensure they get a consistent view of the dictionary: Lockless: TryGetValue GetEnumerator The indexer getter ContainsKey Takes out every lock (lockfull?): Count IsEmpty Keys Values CopyTo ToArray Concurrent principles That covers the overall implementation of ConcurrentDictionary. I haven't even begun to scratch the surface of this sophisticated collection. That I leave to you. However, we've looked at enough to be able to extract some useful principles for concurrent programming: Partitioning When using locks, the work is partitioned into independant chunks, each with its own lock. Each partition can then be modified concurrently to other partitions. Ordered lock-taking When a method does need to control the entire collection, locks are taken and released in a fixed order to prevent deadlocks. Lockless reads Read operations that don't care about dirty reads don't take out any lock; the rest of the collection is implemented so that any reading thread always has a consistent view of the collection. That leads us to the final collection in this little series - ConcurrentBag. Lacking a non-concurrent analogy, it is quite different to any other collection in the class libraries. Prepare your thinking hats!

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• how to add "Existing solution folder recursively" to my VS2005 solution

  - by user36753

  I tried drag and drop from the explorer, but no luck with following error: "Folders cannot be dropped or pasted as solution items. Choose an individual document instead." I know we can create each folders/subfolders manually and add each file, but any quick way to do this on visual studio 2005? Updated: Thank you for the reply, but I do not want the folders to be added under any project, It should appear as a separate node inside my solution, like any other project. In this case the show all files does not work, since the solution itself does not have any folder, it is only if we select any project it works. I know we can create each folders/subfolders manually and add each file, but any quick way, because there are few hundreds of files.

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• Running Perl on Windows 7 error

  - by Eyla

  Greeting, I'm trying to run smaple perl script on windows 7 and I configured IIS 7 to allow activeperl to run but I'm getting this error: HTTP Error 502.2 - Bad Gateway The specified CGI application misbehaved by not returning a complete set of HTTP headers. The headers it did return are "Hello World. ". Module CgiModule Notification ExecuteRequestHandler Handler Perl Script (PL) Error Code 0x00000000 Requested URL http://localhost:80/hello.pl Physical Path C:\inetpub\wwwroot\hello.pl Logon Method Anonymous Logon User Anonymous and here is my perl script : #!/usr/bin/perl print "Hello World.\n"; please any advice to handle this case!!!

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• Exposing .NET enums to COM clients{VBScript}

  - by Codex

  Am trying create of PoC for exposing/invoking various .NET objects from COM clients. The .NET library contains some classes and Enums. Am able to successfully access the classes in VBScript but not able to access the Enums. I know that Enums are value types and hence 'CreateObject' wont work in this case. But am able to access the same Enum in VBA code. Questions: How can I access the enums in VBScript? Why does the behaviour differ in the two COM clients? If VBA object browser can see the enum, why cant VBScript allow me to create one? .NET [ComVisible(true)] [GuidAttribute("ebc25cf6-9120-4283-b972-0e5520d0000E")] public enum Currency { GBP = CurrencyConvertorBL.CurrencyConvertorRef.Currency.GBP, USD = CurrencyConvertorBL.CurrencyConvertorRef.Currency.USD, INR = CurrencyConvertorBL.CurrencyConvertorRef.Currency.INR, AUD = CurrencyConvertorBL.CurrencyConvertorRef.Currency.AUD } VBA Private Function ConvertCurrency(fromCurrency As Currency, toCurrency As Currency) As Double VBScript ??? Set currencyConvertorCCY = CreateObject("CurrencyConvertorBL.Currency") Thanks in advance.

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• Linq - How to query specific columns and return a lists

  - by Billy Logan

  Hello Everyone, I am trying to write a linq query that will only return certain columns from my entity object into a list object. Below is my code which produces an error(can't implicitly convert a generic list of anonymous types to a generic list of type TBLPROMOTION): List<TBLPROMOTION> promotionInfo = null; promotionInfo = (from p in matches orderby p.PROMOTION_NM descending select new { p.EFFECTIVE_DT, p.EXPIRE_DT, p.IS_ACTIVE, p.PROMOTION_DESC, p.PROMOTION_ID, p.PROMOTION_NM }).ToList(); What would be the best way to accomplish this. I do not want to do a "select p" in this case and return all the columns associated with the query. thanks in advance, Billy

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• One check constraint or multiple check constraints?

  - by RenderIn

  Any suggestions on whether fewer check constraints are better, or more? How should they be grouped if at all? Suppose I have 3 columns which are VARCHAR2(1 BYTE), each of which is a 'T'/'F' flag. I want to add a check constraint to each column specifying that only characters IN ('T', 'F') are allowed. Should I have 3 separate check constraints, one for each column: COL_1 IN ('T', 'F') COL_2 IN ('T', 'F') COL_3 IN ('T', 'F') Or a single check constraint: COL_1 IN ('T', 'F') AND COL_2 IN ('T', 'F') AND COL_3 IN ('T', 'F') My thoughts are it is best to keep these three separate, as the columns are logically unrelated to each other. The only case I would have a check constraint that examines more than one column is if there was some relationship between the value in one and the value in another, e.g.: (PARENT_CNT > 0 AND PRIMARY_PARENT IS NOT NULL) OR (PARENT_CNT = 0 AND PRIMARY_PARENT IS NULL)

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• Having problems with a mask in C#

  - by Nard Dog

  I guess this would be a DevExpress mask, but here is what I have: var dlEdit = new DevExpress.XtraEditors.Repository.RepositoryItemTextEdit(); dlEdit.Mask.MaskType = MaskType.RegEx; dlEdit.Mask.EditMask = "\\d{1,10}"; I'm trying to get a number that can be up to 10 digits in length that WILL accept leading 0's, as it is now it will show the leading 0's (ex. 0032421243) until the field is clicked off in which case it removes them. I tried a numeric masktype but same thing only it wouldn't let me enter the 0's to start with at all. I thought this would be my answer but this custom type isn't. Can someone point me in the right direction for what I need? Maybe a different type of mask or something?

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• What useful GDB scripts have you used/written?

  - by nik

  People use gdb on and off for debugging, of course there are lots of other debugging tools across the varied OSes, with and without GUI and, maybe other fancy IDE features. I would like to know what useful gdb scripts you have written and liked. While, I do not mean a dump of commands in a something.gdb file that you source to pull out a bunch of data, if that made your day, go ahead and talk about it. Lets think conditional processing, control loops and functions written for more elegant and refined programming to debug and, maybe even for whitebox testing Things get interesting when you start debugging remote systems (say, over a serial/ethernet interface) And, what if the target is a multi-processor (and, multithreaded) system Let me put a simple case as an example... Say, A script that traversed serially over entries to locate a bad entry in a large hash-table that is implemented on an embedded platform. That helped me debug a broken hash-table once.

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• How does TransactionScope guarantee data integrity across multiple databases?

  - by Bas Smit

  Hey guys, Can someone tell me the principle of how TransactionScope guarantees data integrity across multiple databases? I imagine it first sends the commands to the databases and then waits for the databases to respond before sending them a message to apply the command sent earlier. However when execution is stopped abruptly when sending those apply messages we could still end up with a database that has applied the command and one that has not. Can anyone shed some light on this? Edit: I guess what Im asking is can I rely on TransactionScope to guarantee data integrity when writing to multiple databases in case of a power outage or a sudden shutdown. Thanks, Bas Example: using(var scope=new TransactionScope()) { using (var context = new FirstEntities()) { context.AddToSomethingSet(new Something()); context.SaveChanges(); } using (var context = new SecondEntities()) { context.AddToSomethingElseSet(new SomethingElse()); context.SaveChanges(); } scope.Complete(); }

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• Explanation of Pingdom Results

  - by Computer Guru

  Hi, I'm trying to optimize my page load times, and I'm using Pingdom to test the site response times. However, I'm not exactly sure what the various components of the "time bar" mean. Example link: http://tools.pingdom.com/fpt/?url=http://neosmart.net/forums//&id=2230361 According to them, the portion of the bar that is yellow is the time between "start" and "connect" and the portion of the bar that is green is the time between "connect" and "first byte" with the blue section being the actual transfer time (time between "first byte" and "last byte"). If I'm trying to the first two (which take very long in my case), what's the recommended course of action? Thanks.

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• Convert from Procedural to Object Oriented Code

  - by Anthony

  I have been reading Working Effectively with Legacy Code and Clean Code with the goal of learning strategies on how to begin cleaning up the existing code-base of a large ASP.NET webforms application. This system has been around since 2005 and since then has undergone a number of enhancements. Originally the code was structured as follows (and is still largely structured this way): ASP.NET (aspx/ascx) Code-behind (c#) Business Logic Layer (c#) Data Access Layer (c#) Database (Oracle) The main issue is that the code is procedural masquerading as object-oriented. It virtually violates all of the guidelines described in both books. This is an example of a typical class in the Business Logic Layer: public class AddressBO { public TransferObject GetAddress(string addressID) { if (StringUtils.IsNull(addressID)) { throw new ValidationException("Address ID must be entered"); } AddressDAO addressDAO = new AddressDAO(); return addressDAO.GetAddress(addressID); } public TransferObject Insert(TransferObject addressDetails) { if (StringUtils.IsNull(addressDetails.GetString("EVENT_ID")) || StringUtils.IsNull(addressDetails.GetString("LOCALITY")) || StringUtils.IsNull(addressDetails.GetString("ADDRESS_TARGET")) || StringUtils.IsNull(addressDetails.GetString("ADDRESS_TYPE_CODE")) || StringUtils.IsNull(addressDetails.GetString("CREATED_BY"))) { throw new ValidationException( "You must enter an Event ID, Locality, Address Target, Address Type Code and Created By."); } string addressID = Sequence.GetNextValue("ADDRESS_ID_SEQ"); addressDetails.SetValue("ADDRESS_ID", addressID); string syncID = Sequence.GetNextValue("SYNC_ID_SEQ"); addressDetails.SetValue("SYNC_ADDRESS_ID", syncID); TransferObject syncDetails = new TransferObject(); Transaction transaction = new Transaction(); try { AddressDAO addressDAO = new AddressDAO(); addressDAO.Insert(addressDetails, transaction); // insert the record for the target TransferObject addressTargetDetails = new TransferObject(); switch (addressDetails.GetString("ADDRESS_TARGET")) { case "PARTY_ADDRESSES": { addressTargetDetails.SetValue("ADDRESS_ID", addressID); addressTargetDetails.SetValue("ADDRESS_TYPE_CODE", addressDetails.GetString("ADDRESS_TYPE_CODE")); addressTargetDetails.SetValue("PARTY_ID", addressDetails.GetString("PARTY_ID")); addressTargetDetails.SetValue("EVENT_ID", addressDetails.GetString("EVENT_ID")); addressTargetDetails.SetValue("CREATED_BY", addressDetails.GetString("CREATED_BY")); addressDAO.InsertPartyAddress(addressTargetDetails, transaction); break; } case "PARTY_CONTACT_ADDRESSES": { addressTargetDetails.SetValue("ADDRESS_ID", addressID); addressTargetDetails.SetValue("ADDRESS_TYPE_CODE", addressDetails.GetString("ADDRESS_TYPE_CODE")); addressTargetDetails.SetValue("PUBLIC_RELEASE_FLAG", addressDetails.GetString("PUBLIC_RELEASE_FLAG")); addressTargetDetails.SetValue("CONTACT_ID", addressDetails.GetString("CONTACT_ID")); addressTargetDetails.SetValue("EVENT_ID", addressDetails.GetString("EVENT_ID")); addressTargetDetails.SetValue("CREATED_BY", addressDetails.GetString("CREATED_BY")); addressDAO.InsertContactAddress(addressTargetDetails, transaction); break; } << many more cases here >> default: { break; } } // synchronise SynchronisationBO synchronisationBO = new SynchronisationBO(); syncDetails = synchronisationBO.Synchronise("I", transaction, "ADDRESSES", addressDetails.GetString("ADDRESS_TARGET"), addressDetails, addressTargetDetails); // commit transaction.Commit(); } catch (Exception) { transaction.Rollback(); throw; } return new TransferObject("ADDRESS_ID", addressID, "SYNC_DETAILS", syncDetails); } << many more methods are here >> } It has a lot of duplication, the class has a number of responsibilities, etc, etc - it is just generally 'un-clean' code. All of the code throughout the system is dependent on concrete implementations. This is an example of a typical class in the Data Access Layer: public class AddressDAO : GenericDAO { public static readonly string BASE_SQL_ADDRESSES = "SELECT " + " a.address_id, " + " a.event_id, " + " a.flat_unit_type_code, " + " fut.description as flat_unit_description, " + " a.flat_unit_num, " + " a.floor_level_code, " + " fl.description as floor_level_description, " + " a.floor_level_num, " + " a.building_name, " + " a.lot_number, " + " a.street_number, " + " a.street_name, " + " a.street_type_code, " + " st.description as street_type_description, " + " a.street_suffix_code, " + " ss.description as street_suffix_description, " + " a.postal_delivery_type_code, " + " pdt.description as postal_delivery_description, " + " a.postal_delivery_num, " + " a.locality, " + " a.state_code, " + " s.description as state_description, " + " a.postcode, " + " a.country, " + " a.lock_num, " + " a.created_by, " + " TO_CHAR(a.created_datetime, '" + SQL_DATETIME_FORMAT + "') as created_datetime, " + " a.last_updated_by, " + " TO_CHAR(a.last_updated_datetime, '" + SQL_DATETIME_FORMAT + "') as last_updated_datetime, " + " a.sync_address_id, " + " a.lat," + " a.lon, " + " a.validation_confidence, " + " a.validation_quality, " + " a.validation_status " + "FROM ADDRESSES a, FLAT_UNIT_TYPES fut, FLOOR_LEVELS fl, STREET_TYPES st, " + " STREET_SUFFIXES ss, POSTAL_DELIVERY_TYPES pdt, STATES s " + "WHERE a.flat_unit_type_code = fut.flat_unit_type_code(+) " + "AND a.floor_level_code = fl.floor_level_code(+) " + "AND a.street_type_code = st.street_type_code(+) " + "AND a.street_suffix_code = ss.street_suffix_code(+) " + "AND a.postal_delivery_type_code = pdt.postal_delivery_type_code(+) " + "AND a.state_code = s.state_code(+) "; public TransferObject GetAddress(string addressID) { //Build the SELECT Statement StringBuilder selectStatement = new StringBuilder(BASE_SQL_ADDRESSES); //Add WHERE condition selectStatement.Append(" AND a.address_id = :addressID"); ArrayList parameters = new ArrayList{DBUtils.CreateOracleParameter("addressID", OracleDbType.Decimal, addressID)}; // Execute the SELECT statement Query query = new Query(); DataSet results = query.Execute(selectStatement.ToString(), parameters); // Check if 0 or more than one rows returned if (results.Tables[0].Rows.Count == 0) { throw new NoDataFoundException(); } if (results.Tables[0].Rows.Count > 1) { throw new TooManyRowsException(); } // Return a TransferObject containing the values return new TransferObject(results); } public void Insert(TransferObject insertValues, Transaction transaction) { // Store Values string addressID = insertValues.GetString("ADDRESS_ID"); string syncAddressID = insertValues.GetString("SYNC_ADDRESS_ID"); string eventID = insertValues.GetString("EVENT_ID"); string createdBy = insertValues.GetString("CREATED_BY"); // postal delivery string postalDeliveryTypeCode = insertValues.GetString("POSTAL_DELIVERY_TYPE_CODE"); string postalDeliveryNum = insertValues.GetString("POSTAL_DELIVERY_NUM"); // unit/building string flatUnitTypeCode = insertValues.GetString("FLAT_UNIT_TYPE_CODE"); string flatUnitNum = insertValues.GetString("FLAT_UNIT_NUM"); string floorLevelCode = insertValues.GetString("FLOOR_LEVEL_CODE"); string floorLevelNum = insertValues.GetString("FLOOR_LEVEL_NUM"); string buildingName = insertValues.GetString("BUILDING_NAME"); // street string lotNumber = insertValues.GetString("LOT_NUMBER"); string streetNumber = insertValues.GetString("STREET_NUMBER"); string streetName = insertValues.GetString("STREET_NAME"); string streetTypeCode = insertValues.GetString("STREET_TYPE_CODE"); string streetSuffixCode = insertValues.GetString("STREET_SUFFIX_CODE"); // locality/state/postcode/country string locality = insertValues.GetString("LOCALITY"); string stateCode = insertValues.GetString("STATE_CODE"); string postcode = insertValues.GetString("POSTCODE"); string country = insertValues.GetString("COUNTRY"); // esms address string esmsAddress = insertValues.GetString("ESMS_ADDRESS"); //address/GPS string lat = insertValues.GetString("LAT"); string lon = insertValues.GetString("LON"); string zoom = insertValues.GetString("ZOOM"); //string validateDate = insertValues.GetString("VALIDATED_DATE"); string validatedBy = insertValues.GetString("VALIDATED_BY"); string confidence = insertValues.GetString("VALIDATION_CONFIDENCE"); string status = insertValues.GetString("VALIDATION_STATUS"); string quality = insertValues.GetString("VALIDATION_QUALITY"); // the insert statement StringBuilder insertStatement = new StringBuilder("INSERT INTO ADDRESSES ("); StringBuilder valuesStatement = new StringBuilder("VALUES ("); ArrayList parameters = new ArrayList(); // build the insert statement insertStatement.Append("ADDRESS_ID, EVENT_ID, CREATED_BY, CREATED_DATETIME, LOCK_NUM "); valuesStatement.Append(":addressID, :eventID, :createdBy, SYSDATE, 1 "); parameters.Add(DBUtils.CreateOracleParameter("addressID", OracleDbType.Decimal, addressID)); parameters.Add(DBUtils.CreateOracleParameter("eventID", OracleDbType.Decimal, eventID)); parameters.Add(DBUtils.CreateOracleParameter("createdBy", OracleDbType.Varchar2, createdBy)); // build the insert statement if (!StringUtils.IsNull(syncAddressID)) { insertStatement.Append(", SYNC_ADDRESS_ID"); valuesStatement.Append(", :syncAddressID"); parameters.Add(DBUtils.CreateOracleParameter("syncAddressID", OracleDbType.Decimal, syncAddressID)); } if (!StringUtils.IsNull(postalDeliveryTypeCode)) { insertStatement.Append(", POSTAL_DELIVERY_TYPE_CODE"); valuesStatement.Append(", :postalDeliveryTypeCode "); parameters.Add(DBUtils.CreateOracleParameter("postalDeliveryTypeCode", OracleDbType.Varchar2, postalDeliveryTypeCode)); } if (!StringUtils.IsNull(postalDeliveryNum)) { insertStatement.Append(", POSTAL_DELIVERY_NUM"); valuesStatement.Append(", :postalDeliveryNum "); parameters.Add(DBUtils.CreateOracleParameter("postalDeliveryNum", OracleDbType.Varchar2, postalDeliveryNum)); } if (!StringUtils.IsNull(flatUnitTypeCode)) { insertStatement.Append(", FLAT_UNIT_TYPE_CODE"); valuesStatement.Append(", :flatUnitTypeCode "); parameters.Add(DBUtils.CreateOracleParameter("flatUnitTypeCode", OracleDbType.Varchar2, flatUnitTypeCode)); } if (!StringUtils.IsNull(lat)) { insertStatement.Append(", LAT"); valuesStatement.Append(", :lat "); parameters.Add(DBUtils.CreateOracleParameter("lat", OracleDbType.Decimal, lat)); } if (!StringUtils.IsNull(lon)) { insertStatement.Append(", LON"); valuesStatement.Append(", :lon "); parameters.Add(DBUtils.CreateOracleParameter("lon", OracleDbType.Decimal, lon)); } if (!StringUtils.IsNull(zoom)) { insertStatement.Append(", ZOOM"); valuesStatement.Append(", :zoom "); parameters.Add(DBUtils.CreateOracleParameter("zoom", OracleDbType.Decimal, zoom)); } if (!StringUtils.IsNull(flatUnitNum)) { insertStatement.Append(", FLAT_UNIT_NUM"); valuesStatement.Append(", :flatUnitNum "); parameters.Add(DBUtils.CreateOracleParameter("flatUnitNum", OracleDbType.Varchar2, flatUnitNum)); } if (!StringUtils.IsNull(floorLevelCode)) { insertStatement.Append(", FLOOR_LEVEL_CODE"); valuesStatement.Append(", :floorLevelCode "); parameters.Add(DBUtils.CreateOracleParameter("floorLevelCode", OracleDbType.Varchar2, floorLevelCode)); } if (!StringUtils.IsNull(floorLevelNum)) { insertStatement.Append(", FLOOR_LEVEL_NUM"); valuesStatement.Append(", :floorLevelNum "); parameters.Add(DBUtils.CreateOracleParameter("floorLevelNum", OracleDbType.Varchar2, floorLevelNum)); } if (!StringUtils.IsNull(buildingName)) { insertStatement.Append(", BUILDING_NAME"); valuesStatement.Append(", :buildingName "); parameters.Add(DBUtils.CreateOracleParameter("buildingName", OracleDbType.Varchar2, buildingName)); } if (!StringUtils.IsNull(lotNumber)) { insertStatement.Append(", LOT_NUMBER"); valuesStatement.Append(", :lotNumber "); parameters.Add(DBUtils.CreateOracleParameter("lotNumber", OracleDbType.Varchar2, lotNumber)); } if (!StringUtils.IsNull(streetNumber)) { insertStatement.Append(", STREET_NUMBER"); valuesStatement.Append(", :streetNumber "); parameters.Add(DBUtils.CreateOracleParameter("streetNumber", OracleDbType.Varchar2, streetNumber)); } if (!StringUtils.IsNull(streetName)) { insertStatement.Append(", STREET_NAME"); valuesStatement.Append(", :streetName "); parameters.Add(DBUtils.CreateOracleParameter("streetName", OracleDbType.Varchar2, streetName)); } if (!StringUtils.IsNull(streetTypeCode)) { insertStatement.Append(", STREET_TYPE_CODE"); valuesStatement.Append(", :streetTypeCode "); parameters.Add(DBUtils.CreateOracleParameter("streetTypeCode", OracleDbType.Varchar2, streetTypeCode)); } if (!StringUtils.IsNull(streetSuffixCode)) { insertStatement.Append(", STREET_SUFFIX_CODE"); valuesStatement.Append(", :streetSuffixCode "); parameters.Add(DBUtils.CreateOracleParameter("streetSuffixCode", OracleDbType.Varchar2, streetSuffixCode)); } if (!StringUtils.IsNull(locality)) { insertStatement.Append(", LOCALITY"); valuesStatement.Append(", :locality"); parameters.Add(DBUtils.CreateOracleParameter("locality", OracleDbType.Varchar2, locality)); } if (!StringUtils.IsNull(stateCode)) { insertStatement.Append(", STATE_CODE"); valuesStatement.Append(", :stateCode"); parameters.Add(DBUtils.CreateOracleParameter("stateCode", OracleDbType.Varchar2, stateCode)); } if (!StringUtils.IsNull(postcode)) { insertStatement.Append(", POSTCODE"); valuesStatement.Append(", :postcode "); parameters.Add(DBUtils.CreateOracleParameter("postcode", OracleDbType.Varchar2, postcode)); } if (!StringUtils.IsNull(country)) { insertStatement.Append(", COUNTRY"); valuesStatement.Append(", :country "); parameters.Add(DBUtils.CreateOracleParameter("country", OracleDbType.Varchar2, country)); } if (!StringUtils.IsNull(esmsAddress)) { insertStatement.Append(", ESMS_ADDRESS"); valuesStatement.Append(", :esmsAddress "); parameters.Add(DBUtils.CreateOracleParameter("esmsAddress", OracleDbType.Varchar2, esmsAddress)); } if (!StringUtils.IsNull(validatedBy)) { insertStatement.Append(", VALIDATED_DATE"); valuesStatement.Append(", SYSDATE "); insertStatement.Append(", VALIDATED_BY"); valuesStatement.Append(", :validatedBy "); parameters.Add(DBUtils.CreateOracleParameter("validatedBy", OracleDbType.Varchar2, validatedBy)); } if (!StringUtils.IsNull(confidence)) { insertStatement.Append(", VALIDATION_CONFIDENCE"); valuesStatement.Append(", :confidence "); parameters.Add(DBUtils.CreateOracleParameter("confidence", OracleDbType.Decimal, confidence)); } if (!StringUtils.IsNull(status)) { insertStatement.Append(", VALIDATION_STATUS"); valuesStatement.Append(", :status "); parameters.Add(DBUtils.CreateOracleParameter("status", OracleDbType.Varchar2, status)); } if (!StringUtils.IsNull(quality)) { insertStatement.Append(", VALIDATION_QUALITY"); valuesStatement.Append(", :quality "); parameters.Add(DBUtils.CreateOracleParameter("quality", OracleDbType.Decimal, quality)); } // finish off the statement insertStatement.Append(") "); valuesStatement.Append(")"); // build the insert statement string sql = insertStatement + valuesStatement.ToString(); // Execute the INSERT Statement Dml dmlDAO = new Dml(); int rowsAffected = dmlDAO.Execute(sql, transaction, parameters); if (rowsAffected == 0) { throw new NoRowsAffectedException(); } } << many more methods go here >> } This system was developed by me and a small team back in 2005 after a 1 week .NET course. Before than my experience was in client-server applications. Over the past 5 years I've come to recognise the benefits of automated unit testing, automated integration testing and automated acceptance testing (using Selenium or equivalent) but the current code-base seems impossible to introduce these concepts. We are now starting to work on a major enhancement project with tight time-frames. The team consists of 5 .NET developers - 2 developers with a few years of .NET experience and 3 others with little or no .NET experience. None of the team (including myself) has experience in using .NET unit testing or mocking frameworks. What strategy would you use to make this code cleaner, more object-oriented, testable and maintainable?

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• Unique SMS sender id?

  - by Pascal

  Hello, I want to build an app that send SMS to people. However, I want my users to know that the SMS comes from the app and nothing else so they can't fake it. Is there a way to guarantee that the sender ID is unique to my app? It seems that sending a SMS by phone is with a unique SENDER ID for each phone number. But, from what I read, I don't think it is the case when sending a SMS through a web gateway. Is this correct? I am not an expert in mobile phone security. Of course, I am willing to pay the price for a unique sender id, if such thing is possible. Regards, Pascal

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• Linux, static lib referring to other static lib within an executable

  - by andras

  Hello, I am creating an application, which consists of two static libs and an executable. Let's call the two static libs: libusefulclass.a libcore.a And the application: myapp libcore instantiates and uses the class defined in libusefulclass (let's call it UsefulClass) Now, if I link the application in the following way: g++ -m64 -Wl,-rpath,/usr/local/Trolltech/Qt-4.5.4/lib -o myapp src1.o src2.o srcN.o -lusefulclass -lcore The linker complains about the methods in libusefulclass not being found: undefined reference to `UsefulClass::foo()' etc. I found a workaround for this: If UsefulClass is also instantiated within the source files of the executable itself, the application is linked without any problems. My question is: is there a more clean way to make libcore refer to methods defined in libusefulclass, or static libs just cannot be linked against eachother? TIA P.S.: In case that matters: the application is being developed in C++ using Qt, but I feel this is not a Qt problem, but a library problem in general.

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