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• Logging with log4j on tomcat jruby-rack for a Rails 3 application

  - by John

  I just spent the better part of 3 hours trying to get my Rails application logging with Log4j. I've finally got it working, but I'm not sure if what I did is correct. I tried various methods to no avail until my various last attempt. So I'm really looking for some validation here, perhaps some pointers and tips as well -- anything would be appreciated to be honest. I've summarized all my feeble methods into three attempts below. I'm hoping for some enlightenment on where I went wrong with each attempt -- even if it means I get ripped up. Thanks for the help in advance! System Specs Rails 3.0 Windows Server 2008 Log4j 1.2 Tomact 6.0.29 Java 6 Attempt 1 - Configured Tomcat to Use Log4J I basically followed the guide on the Apache Tomcat website here. The steps are: Create a log4j.properties file in $CATALINA_HOME/lib Download and copy the log4j-x.y.z.jar into $CATALINA_HOME/lib Replace $CATALINA_HOME/bin/tomcat-juli.jar with the tomcat-juli.jar from the Apache Tomcat Extras folder Copy tomcat-juli-adapters.jar from the Apache Tomcat Extras folder into $CATALINA_HOME/lib Delete $CATALINA_BASE/conf/logging.properties Start Tomcat (as a service) Expected Results According to the Guide I should have seen a tomcat.log file in my $CATALINA_BASE/logs folder. Actual Results No tomcat.log Saw three of the standard logs instead jakarta_service_20101231.log stderr_20101231.log stdout_20101231.log Question Shouldn't I have at least seen a tomcat.log file? Attempt 2 - Use default Tomcat logging (commons-logging) Reverted all the changes from the previous setup Modified $CATALINA_BASE/conf/logging.properties by doing the following: Adding a setting for my application in the handlers line: 5rails3.org.apache.juli.FileHandler Adding Handler specific properties 5rails3.org.apache.juli.FileHandler.level = FINE 5rails3.org.apache.juli.FileHandler.directory = ${catalina.base}/logs 5rails3.org.apache.juli.FileHandler.prefix = rails3. Adding Facility specific properties org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/rails3].level = INFO org.apache.catalina.core.ContainerBase.[Catalina].[localhost].[/rails3].handlers = 4host-manager.org.apache.juli.FileHandler Modified my web.xml by adding the following context parameter as per the Logging section of the jruby-rack readme (I also modified my warbler.rb accordingly, but I did opted to change the web.xml directly to test things faster). <context-param> <param-name>jruby.rack.logging</param-name> <param-value>commons_logging</param-value> </context-param> Restarted Tomcat Results A log file was created (rails3.log), however there was no log information in the file. Attempt 2A - Use Log4j with existing set up I decided to go Log4j another whirl with this new web.xml setting. Copied the log4j.jar into my WEB-INF/lib folder Created a log4j.properties file and put it into WEB-INF/classes log4j.rootLogger=INFO, R log4j.logger.javax.servlet=DEBUG log4j.appender.R=org.apache.log4j.RollingFileAppender log4j.appender.R.File=${catalina.base}/logs/rails3.log log4j.appender.R.MaxFileSize=5036KB log4j.appender.R.MaxBackupIndex=4 log4j.appender.R.layout=org.apache.log4j.PatternLayout log4j.appender.R.layout.ConversionPattern=%d{dd MMM yyyy HH:mm:ss} [%t] %-5p %c %x - %m%n Restarted Tomcat Results Same as Attempt 2 NOTE: I used log4j.logger.javax.servlet=DEBUG because I read in the jruby-rack README that all logging output is automatically redirected to the javax.servlet.ServletContext#log method. So I though this would capture it. I was obviously wrong. Question Why didn't this work? Isn't Log4J using the commons_logging API? Attempt 3 - Tried out slf4j (WORKED) A bit uncertain as to why Attempt 2A didn't work, I thought to myself, maybe I can't use commons_logging for the jruby.rack.logging parameter because it's probably not using commons_logging API... (but I was still not sure). I saw slf4j as an option. I have never heard of it and by stroke of luck, I decided to look up what it is. After reading briefly about what it does, I thought it was good of a shot as any and decided to try it out following the instructions here. Continuing from the setup of Attempt 2A: Copied slf4j-api-1.6.1.jar and slf4j-simple-1.6.1.jar into my WEB-INF/lib folder I also copied slf4j-log4j12-1.6.1.jar into my WEB-INF/lib folder Restarted Tomcat And VIOLA! I now have logging information going into my rails3.log file. So the big question is: WTF? Even though logging seems to be working now, I'm really not sure if I did this right. So like I said earlier, I'm really looking for some validation more or less. I'd also appreciate any pointers/tips/advice if you have any. Thanks!

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• MySQL Select problems

  - by John Nuñez

  Table #1: qa_returns_items Table #2: qa_returns_residues I have a long time trying to get this Result: item_code - item_quantity 2 - 1 3 - 2 IF qa_returns_items.item_code = qa_returns_residues.item_code AND status_code = 11 THEN item_quantity = qa_returns_items.item_quantity - qa_returns_residues.item_quantity ELSEIF qa_returns_items.item_code = qa_returns_residues.item_code AND status_code = 12 THEN item_quantity = qa_returns_items.item_quantity + qa_returns_residues.item_quantity ELSE show diferendes END IF I tried this Query: select SubQueryAlias.item_code, total_ecuation, SubQueryAlias.item_unitprice, SubQueryAlias.item_unitprice * total_ecuation as item_subtotal, item_discount, (SubQueryAlias.item_unitprice * total_ecuation) - item_discount as item_total from ( select ri.item_code , case status_code when 11 then ri.item_quantity - rr.item_quantity when 12 then ri.item_quantity + rr.item_quantity end as total_ecuation , rr.item_unitprice , rr.item_quantity , rr.item_discount * rr.item_quantity as item_discount from qa_returns_residues rr left join qa_returns_items ri on ri.item_code = rr.item_code WHERE ri.returnlog_code = 1 ) as SubQueryAlias where total_ecuation > 0 GROUP BY (item_code); The query returns this result: item_code - item_quantity 1 - 2 2 - 2

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• Why does autoboxing in Java allow me to have 3 possible values for a boolean?

  - by John

  Reference: http://java.sun.com/j2se/1.5.0/docs/guide/language/autoboxing.html If your program tries to autounbox null, it will throw a NullPointerException. javac will give you a compile-time error if you try to assign null to a boolean. makes sense. assigning null to a Boolean is a-ok though. also makes sense, i guess. but let's think about the fact that you'll get a NPE when trying to autounbox null. what this means is that you can't safely perform boolean operations on Booleans without null-checking or exception handling. same goes for doing math operations on an Integer. for a long time, i was a fan of autoboxing in java1.5+ because I thought it got java closer to be truly object-oriented. but, after running into this problem last night, i gotta say that i think this sucks. the compiler giving me an error when I'm trying to do stuff with an uninitialized primitive is a good thing. I think I may be misunderstanding the point of autoboxing, but at the same time I will never accept that a boolean should be able to have 3 values. can anyone explain this? what am i not getting?

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• Play sound in mobile browser?

  - by John

  I want to make myself a web based stop watch for training that I can use on my Blackberry mobile browser. The stopwatch should count 3 minutes, then ring a bell, wait 1 minute, then ring another bell and then repeat. My problem is I can't seem to get sound to work on my blackberry browser. I tried using <embed src="bell.wav"> which works fine in the browser of a normal computer, but it doesn't make a sound on my blackberry. Should I build this stopwatch with Javascript and HTML or should I build it with flash?

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• R: How to remove outliers from a smoother in ggplot2?

  - by John

  I have the following data set that I am trying to plot with ggplot2, it is a time series of three experiments A1, B1 and C1 and each experiment had three replicates. I am trying to add a stat which detects and removes outliers before returning a smoother (mean and variance?). I have written my own outlier function (not shown) but I expect there is already a function to do this, I just have not found it. I've looked at stat_sum_df("median_hilow", geom = "smooth") from some examples in the ggplot2 book, but I didn't understand the help doc from Hmisc to see if it removes outliers or not. Is there a function to remove outliers like this in ggplot, or where would I amend my code below to add my own function? library (ggplot2) data = data.frame (day = c(1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7,1,3,5,7), od = c( 0.1,1.0,0.5,0.7 ,0.13,0.33,0.54,0.76 ,0.1,0.35,0.54,0.73 ,1.3,1.5,1.75,1.7 ,1.3,1.3,1.0,1.6 ,1.7,1.6,1.75,1.7 ,2.1,2.3,2.5,2.7 ,2.5,2.6,2.6,2.8 ,2.3,2.5,2.8,3.8), series_id = c( "A1", "A1", "A1","A1", "A1", "A1", "A1","A1", "A1", "A1", "A1","A1", "B1", "B1","B1", "B1", "B1", "B1","B1", "B1", "B1", "B1","B1", "B1", "C1","C1", "C1", "C1", "C1","C1", "C1", "C1", "C1","C1", "C1", "C1"), replicate = c( "A1.1","A1.1","A1.1","A1.1", "A1.2","A1.2","A1.2","A1.2", "A1.3","A1.3","A1.3","A1.3", "B1.1","B1.1","B1.1","B1.1", "B1.2","B1.2","B1.2","B1.2", "B1.3","B1.3","B1.3","B1.3", "C1.1","C1.1","C1.1","C1.1", "C1.2","C1.2","C1.2","C1.2", "C1.3","C1.3","C1.3","C1.3")) > data day od series_id replicate 1 1 0.10 A1 A1.1 2 3 1.00 A1 A1.1 3 5 0.50 A1 A1.1 4 7 0.70 A1 A1.1 5 1 0.13 A1 A1.2 6 3 0.33 A1 A1.2 7 5 0.54 A1 A1.2 8 7 0.76 A1 A1.2 9 1 0.10 A1 A1.3 10 3 0.35 A1 A1.3 11 5 0.54 A1 A1.3 12 7 0.73 A1 A1.3 13 1 1.30 B1 B1.1 This is what I have so far and is working nicely, but outliers are not removed: r <- ggplot(data = data, aes(x = day, y = od)) r + geom_point(aes(group = replicate, color = series_id)) + # add points geom_line(aes(group = replicate, color = series_id)) + # add lines geom_smooth(aes(group = series_id)) # add smoother, average of each replicate

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• R: ggplot2, can I set the plot title to wrap around and shrink the text to fit the plot?

  - by John

  library(ggplot2) my_title = "This is a really long title of a plot that I want to nicely wrap \n and fit onto the plot without having to manually add the backslash n, but at the moment it does not" r <- ggplot(data = cars, aes(x = speed, y = dist)) r + geom_smooth() + #(left) opts(title = my_title) can I set the plot title to wrap around and shrink the text to fit the plot?

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• ASP.Net Cross Page Posting

  - by John

  Currently I have two pages: The first page contains an input form, and the 2nd page generates an excel document. The input form's button posts to this 2nd page. What I'd like to do is add a second button which also posts to the 2nd page; however, I'll need requests created from this new button to act differently, which brings me to my question: Is there a way I can tell, from the 2nd page, which button was pressed to submit the request? The main reason I'm asking is I'd like to re-use the 2nd page's logic in parsing the information from the first page if possible; I'd rather not have to copy it to a new page and have the new button post to that. Thanks!

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• For Loops in MIPS assembly

  - by John Moffitt

  I'm having problems getting my processor to simulate correctly and I think I've narrowed it down to the program I'm giving it. 1. li $R1, 0 2. li $R2, 0x100 3. li $R6, 1 4. li $R8, 0 5. li $R9, 20 6. lw $R3, 0($R1) 7. lw $R4, 4($R1) 8. add $R5, $R3, $R4 9. srlv $R5, $R5, $R6 10. sw $R5, 0($R2) 11. addi $R1, $R1, 4 12. addi $R2, $R2, 4 13. addi $R8, $R8, 1 14. slt $R7, $R8, $R9 15. bnq $R7, $zero, -9 It should iterate through the bottom portion 20 times and then exit. I'm particularly unsure about the branch instruction but I can't find anything wrong with it so : /

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• Why can't I access elements inside an XML file with XPath in XML::LibXML?

  - by John

  I have an XML file, part of which looks like this: <wave waveID="1"> <well wellID="1" wellName="A1"> <oneDataSet> <rawData>0.1123975676</rawData> </oneDataSet> </well> ... more wellID's and rawData continues here... I am trying to parse the file with Perl's libXML and output the wellName and the rawData using the following: use XML::LibXML; my $parser = XML::LibXML->new(); my $doc = $parser->parse_file('/Users/johncumbers/Temp/1_12-18-09-111823.orig.xml'); my $xc = XML::LibXML::XPathContext->new( $doc->documentElement() ); $xc->registerNs('ns', 'http://moleculardevices.com/microplateML'); my @n = $xc->findnodes('//ns:wave[@waveID="1"]'); #xc is xpathContent # should find a tree from the node representing everything beneath the waveID 1 foreach $nod (@n) { my @c = $nod->findnodes('//rawData'); #element inside the tree. print @c; } It is not printing out anything right now and I think I have a problem with my Xpath statements. Please can you help me fix it, or can you show me how to trouble shoot the xpath statements? Thanks.

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• Using Unix Process Controll Methods in Ruby

  - by John F. Miller

  Ryan Tomayko touched off quite a fire storm with this post about using Unix process control commands. We should be doing more of this. A lot more of this. I'm talking about fork(2), execve(2), pipe(2), socketpair(2), select(2), kill(2), sigaction(2), and so on and so forth. These are our friends. They want so badly just to help us. I have a bit of code (a delayed_job clone for DataMapper that I think would fit right in with this, but I'm not clear on how to take advantage of the listed commands. Any Ideas on how to improve this code? def start say "*** Starting job worker #{@name}" t = Thread.new do loop do delay = Update.work_off(self) break if $exit sleep delay break if $exit end clear_locks end trap('TERM') { terminate_with t } trap('INT') { terminate_with t } trap('USR1') do say "Wakeup Signal Caught" t.run end end

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• Sending mail from Python using SMTP

  - by Eli Bendersky

  I'm using the following method to send mail from Python using SMTP. Is it the right method to use or are there gotchas I'm missing ? from smtplib import SMTP import datetime debuglevel = 0 smtp = SMTP() smtp.set_debuglevel(debuglevel) smtp.connect('YOUR.MAIL.SERVER', 26) smtp.login('USERNAME@DOMAIN', 'PASSWORD') from_addr = "John Doe <[email protected]>" to_addr = "[email protected]" subj = "hello" date = datetime.datetime.now().strftime( "%d/%m/%Y %H:%M" ) message_text = "Hello\nThis is a mail from your server\n\nBye\n" msg = "From: %s\nTo: %s\nSubject: %s\nDate: %s\n\n%s" % ( from_addr, to_addr, subj, date, message_text ) smtp.sendmail(from_addr, to_addr, msg) smtp.quit()

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• Nservicebus serization issue of derived types

  - by Tiju John

  Hi Guys, for the context setting, I am exchanging messages between my nServiceBus client and nSerivceBus server. its is the namespace xyz.Messages and and a class, Message : IMessage I have more messages that are in the other dlls, like xyz.Messages.Domain1, xyz.Messages.Domain2, xyz.Messages.Domain3. and messages that derive form that base message, Message. I have the endpoints defined as like : at client <UnicastBusConfig> <MessageEndpointMappings> <add Messages="xyz.Messages" Endpoint="xyzServerQueue" /> <add Messages="xyz.Messages.Domain1" Endpoint="xyzServerQueue" /> <add Messages="xyz.Messages.Domain2" Endpoint="xyzServerQueue" /> </MessageEndpointMappings> </UnicastBusConfig> at Server <UnicastBusConfig> <MessageEndpointMappings> <add Messages="xyz.Messages" Endpoint="xyzClientQueue" /> <add Messages="xyz.Messages.Domain1" Endpoint="xyzClientQueue" /> <add Messages="xyz.Messages.Domain2" Endpoint="xyzClientQueue" /> </MessageEndpointMappings> </UnicastBusConfig> and the bus initialized as IBus serviceBus = Configure.With() .SpringBuilder() .XmlSerializer() .MsmqTransport() .UnicastBus() .LoadMessageHandlers() .CreateBus() .Start(); now when i try sending instance of Message type or any type derived types of Message, it successfully sends the message over and at the server, i get the proper type. eg. Message message= new Message(); Bus.Send(message); // works fine, transfers Message type message = new MessageDerived1(); Bus.Send(message); // works fine, transfers MessageDerived1 type message = new MessageDerived2(); Bus.Send(message); // works fine, transfers MessageDerived2 type My problem arises when any type, say MessageDerived1, contains a member variable of type Message, and when i assign it to a derived type, the type is not properly transferred over the wire. It transfers only as Message type, not the derived type. public class MessageDerived2 : Message { public Message message; } MessageDerived2 messageDerived2= new MessageDerived2(); messageDerived2.message = new MessageDerived1(); message = messageDerived2; Bus.Send(message); // incorrect behaviour, transfers MessageDerived2 correctly, but looses type of MessageDerived2.Message (it deserializes as Message type, instead of MessageDerived1) any help is strongly appreciated. Thanks TJ

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• Why function Ellipse(...) are needed twice here to draw an ellipse?

  - by John Son

  MFC: I read this code which is to draw an ellipse (not solid interior), but I cannot understand why function "pDC-Ellipse(...)" is needed twice here? CDC *pDC=GetDC(); CPen pen; CBrush brush; getpen(pen,pDC,col,bol); if(do_what>=DRAW_LINE&&do_what<=DRAW_RRECT){ p->p[0]=start; p->p[1]=end; if(sol==1){ getbrush(brush,pDC,col); } if(do_what==DRAW_LINE){ pDC->MoveTo(start); pDC->LineTo(end); } else if(do_what==DRAW_ELLIPSE||do_what==DRAW_CIRCLE){ pDC->SetROP2(R2_NOT); assist=start; if(do_what==DRAW_CIRCLE){ assist.y=end.y-end.x+start.x; } pDC->Ellipse(start.x,assist.y,end.x,end.y); pDC->SetROP2(R2_COPYPEN); if(sol==0){ pDC->SelectStockObject(NULL_BRUSH); } if(do_what==DRAW_CIRCLE){ assist.y=point.y-point.x+start.x; } pDC->Ellipse(start.x,assist.y,point.x,point.y); end=point; } } If I remove the first one, the ellipse will be black solid inside. If I remove the second one, the ellipse will never be drawn but disappears when left mouse button is up. the dialog: when moving mouse: mouse moving when mouse button pops: mouse button pops Besides, what color of CBrush is if I use "CBrush brush; pDC-Ellipse(start.x,assist.y,end.x,end.y);"

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• Correct way to replace CHeaderCtrl with custom version in a CListCtrl

  - by John

  CListCtrl has a CHeaderCtrl 'built-in' and we want to override it with something customized, i.e a class which derives from CHeaderCtrl. What's the best/correct way to do this, assuming we have a dialog CMyDlg which contains a CListCtrl m_List, and a custom header CCustomHeader.

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• How to call a Web Service from the Controller?

  - by John

  I have an asp.net MVC2 application that needs to call a web service from the controller. How do I do this? It is a RESTful service that returns Json data. I cant seem to find a good example. Thanks

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• Will asking users to upgrade their browser cause issues?

  - by John Isaacks

  Ok I am considering putting up something asking ie6 users to upgrade their browser. However, I am concerned that users will upgrade it, not like it. Then blame me. Is this a real concern? am I going to get people calling me asking me how to use their new browser or how to get their old one back? Whats your thought on this topic? Thanks!!

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• How can I write 'n <<= 1' (Python) in PHP?

  - by john misoskian

  I have the Python expression n <<= 1 How do you express this in PHP?

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• How to update a custom dependency property when the datasource list changes

  - by John

  Hi We have a user control with a custom dependency property (DP). The DP is bound to an ObservableCollection. When a new item is added to the collection programatically, the databinding does not update the target DP. Why? We think it's because, unfortunately, in our case the target is not a ListBox or ListView, but a Canvas. The DP, when changed or initialized, is supposed to draw a Shape (!) onto the Canvas, and the shape's position and size is bound to the collection item's two properties: WIDTH, LEFT. Ideally we don't want to clear the Canvas and redraw all items just becasue one has been added (or deleted). But how? So: How can the custom DP take care of drawing the shape for the new collection item? What callback do we need, at what point in time does this have to happen, and what specific MetaDataOptions might there? Also, are there any good resources out there concerning all these dependency property options. They are quite confusing. MSDN does not really help with what we're trying to do. Thanks!

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• A Big-Oh proof (factorial)

  - by John

  Prove that 2^n = O(n!) I was trying to use L'Hospital's rule [f'(x)/g'(x)] as n-infinity but I don't know what the derivative of n! is. Ideas?

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• How to use DLL reference with an ActiveX <object> via JavaScript

  - by John Factorial

  My question: how can I set an ActiveX object's property via JavaScript to an enum value found in a non-ActiveX DLL? Problem description: I am instantiating an ActiveX object with the following object tag: <object classid="clsid:F338193D-2491-4D7B-80CE-03487041A278" id="VideoCapture1" width="500" height="500"></object> (This is the guid for the 3rd party ActiveX I'm using, "VisioForge_Video_Capture_4.VFVideoCapture4X") I have example C# code for using this ActiveX, which I am porting to JavaScript. Code like this works just fine: VideoCapture1.Debug_Mode = true; var devcount = VideoCapture1.Video_CaptureDevices_GetCount(); var devs = []; for (var i =0; i < devcount; ++i) { devs[devs.length] = VideoCapture1.Video_CaptureDevices_GetItem(i); } ... etc ... However, VideoCapture1 has some settings which refer to a DLL enum, like so (C# code): VideoCapture1.Mode = VisioForge_Video_Capture_4.TxVFMode.Mode_Video_Preview; I can see in Visual Web Developer that TxVFMode.Mode_Video_Preview is value 1 in the enum. However, the following JS does not appear to set the Mode properly: VideoCapture1.Mode = 1; Does anyone know how I can set VideoCapture1.Mode to the enum value found in the TxVFMode? PS: In Visual Web Developer, when I "Go to definition" on TxVFMode, I get the Guid for the enum. I thought I could create an with this Guid or instantiate a VisioForge_Video_Capture_4.TxVFMode in JS, but neither gives me a usable object.

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• Trying to setup android sdk on PC with windows XP

  - by John Donovan

  When I start setup I get this message: XML verification failed for http://dl-ssl.google.com/android/repository/repository.xml. Error: cvc-elt.1: Cannot find the declaration of element 'sdk:sdk-repository'. Failed to fetch URL reason: Unknown Even when I force the download to use http nothing happens. I get no downloads etc for the SDK. Any help would be greatly appreciated.

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• Aggregate Functions on subsets of data based on current row values with SQL

  - by aasukisuki

  Hopefully that title makes sense... Let's say I have an employee table: ID | Name | Title | Salary ---------------------------- 1 | Bob | Manager | 15285 2 | Joe | Worker | 10250 3 | Al | Worker | 11050 4 | Paul | Manager | 16025 5 | John | Worker | 10450 What I'd like to do is write a query that will give me the above table, along with an averaged salary column, based on the employee title: ID | Name | Title | Salary | Pos Avg -------------------------------------- 1 | Bob | Manager | 15285 | 15655 2 | Joe | Worker | 10250 | 10583 3 | Al | Worker | 11050 | 10583 4 | Paul | Manager | 16025 | 15655 5 | John | Worker | 10450 | 10583 I've tried doing this with a sub-query along the lines of: Select *, (select Avg(e2.salary) from employee e2 where e2.title = e.title) from employee e But I've come to realize that the sub-query is executed first, and has no knowledge of the table alias'd e I'm sure I'm missing something REALLY obvious here, can anyone point me in the right diretion?

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• C, Objective-C preprocessor output

  - by John Smith

  Is there a way to get pre-processed C/Objective-C code? I have some files I acquired and would like to see the code produced by some #defines.

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• Compiled Haskell libraries with FFI imports are invalid when imported into GHCI

  - by John Millikin

  I am using GHC 6.12.1, in Ubuntu 10.04 When I try to use the FFI syntax for static storage, only modules running in interpreted mode (ie GHCI) work properly. Compiled modules have invalid pointers, and do not work. I'd like to know whether anybody can reproduce the problem, whether this an error in my code or GHC, and (if the latter) whether it's a known issue. I'm using sys_siglist because it's present in a standard library on my system, but I don't believe the actual storage used matters (I discovered this while writing a binding to libidn). If it helps, sys_siglist is defined in <signal.h> as: extern __const char *__const sys_siglist[_NSIG]; I thought this type might be the problem, so I also tried wrapping it in a plain C procedure: #include<stdio.h> const char **test_ffi_import() { printf("C think sys_siglist = %X\n", sys_siglist); return sys_siglist; } However, importing that doesn't change the result, and the printf() call prints the same pointer value as show siglist_a. My suspicion is that it's something to do with static and dynamic library loading. Update: somebody in #haskell suggested this might be 64-bit specific; if anybody tries to reproduce it, can you mention your architecture and whether it worked in a comment? Code as follows: -- A.hs {-# LANGUAGE ForeignFunctionInterface #-} module A where import Foreign import Foreign.C foreign import ccall "&sys_siglist" siglist_a :: Ptr CString -- -- B.hs {-# LANGUAGE ForeignFunctionInterface #-} module B where import Foreign import Foreign.C foreign import ccall "&sys_siglist" siglist_b :: Ptr CString -- -- Main.hs {-# LANGUAGE ForeignFunctionInterface #-} module Main where import Foreign import Foreign.C import A import B foreign import ccall "&sys_siglist" siglist_main :: Ptr CString main = do putStrLn $ "siglist_a = " ++ show siglist_a putStrLn $ "siglist_b = " ++ show siglist_b putStrLn $ "siglist_main = " ++ show siglist_main peekSiglist "a " siglist_a peekSiglist "b " siglist_b peekSiglist "main" siglist_main peekSiglist name siglist = do ptr <- peekElemOff siglist 2 str <- maybePeek peekCString ptr putStrLn $ "siglist_" ++ name ++ "[2] = " ++ show str I would expect something like this output, where all pointer values identical and valid: $ runhaskell Main.hs siglist_a = 0x00007f53a948fe00 siglist_b = 0x00007f53a948fe00 siglist_main = 0x00007f53a948fe00 siglist_a [2] = Just "Interrupt" siglist_b [2] = Just "Interrupt" siglist_main[2] = Just "Interrupt" However, if I compile A.hs (with ghc -c A.hs), then the output changes to: $ runhaskell Main.hs siglist_a = 0x0000000040378918 siglist_b = 0x00007fe7c029ce00 siglist_main = 0x00007fe7c029ce00 siglist_a [2] = Nothing siglist_b [2] = Just "Interrupt" siglist_main[2] = Just "Interrupt"

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• Seeking References To MSVC 9.0's C++ Standards Compliance

  - by John Dibling

  I "know" (hopefully) that MSVC 9.0 Implements C++ 2003 (ISO/IEC 14882:2003). I am looking for a reference to this fact, and I am also looking for any research that has been done in to how compliant MSVC 9.0 is with that version of the Standard. I have searched for and not been able to find a specific reference from MicroSoft that actually says something to the effect that MSVC implements C++ 2003. Some of the out-of-date documentation says things like "this release achieves roughly 98% compliance" (when referring to MSVC .NET 2003's conformance to C++ 1997). But I want a link to a document from MS that says "MSVC 9.0 implements blah," and another link to an independent group that has tested the conformance of MSVC 9.0. Do you know of any such links?

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