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• Multiple port asynchronous I/O over serialport in C#

  - by firoso

  I'm trying to write a test application for serial I/O (RS-232) with multiple units in C# and I'm running into an issue with my lack of threading experience so I'm soliciting feedback for a best known method. I've got a pool of COM ports COM1-16 each of which can read/write at any time and I need to be able to manage them simultaneously. Is this a situation for a thread pool? What is some guidance on structuring this applet? Edit: Upon review I was wondering is I really even need to do asynchronous threads here, I could just maintain states for each COM-port and do flow logic (i.e., statemachine) for each COM-port individually.

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• Databind Parent/Child relation with Mysql

  - by e2k

  What is the best way to databind parent/child relations? Lets say I have two simple objects: Parent with the following properties, ParentId, Name and Childs and Child with the following properties, ChildId, Name and Parent. I want to write a repository using MySql for this but is failing when I bind both Childs and Parent properties, I have only been able to bind either the Childs property of parent or the Parent property och Child or else I would get a infinite loop. Thinking of it the preferable solution would be to only bind this properties when requested. If I use Linq to sql i would be able to write Parent.Childs[0].Parent.Name but how should I accomplish this with my own repository and with MySql, could anyone point me in the right direction? Looking at the Linq 2 sql generated classes they use EntitySet<Child and EntityRef<Parent could this be used with Mysql? I had a thought of using my IChildRepository in the Parent object and let the Public IEnumerable Childs databind the childs but it seems not right? Best regards E2k

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• How to fake Azure Table Storage in .NET for Unit Testing?

  - by Erick T

  I am working on a system that uses Azure Table Storage. In other systems (e.g., SQL, File based, etc), I can write a fake that allows me to test my data persistence logic. However, I can't see an easy way to create a fake for the Azure Table Service. I could create a new IIS project that behaves the same way, but that isn't a good way to write a unit test, it is more of an integration test. Any thoughts on how to unit test data access code that uses the Azure Table Storage client? Thanks, Erick

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• Accents in file name using Java on Solaris

  - by Stef

  I have a problem where I can't write files with accents in the file name on Solaris. Given following code public static void main(String[] args) { System.out.println("Charset = "+ Charset.defaultCharset().toString()); System.out.println("testéörtkuoë"); FileWriter fw = null; try { fw = new FileWriter("testéörtkuoë"); fw.write("testéörtkuoëéörtkuoë"); fw.close(); I get following output Charset = ISO-8859-1 test??rtkuo? and I get a file called "test??rtkuo?" Based on info I found on StackOverflow, I tried to call the Java app by adding "-Dfile.encoding=UTF-8" at startup. This returns following output Charset = UTF-8 testéörtkuoë But the filename is still "test??rtkuo?" Any help is much appreciated. Stef

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• c# copy constructor generator

  - by Shawn Mclean

  I want to copy values from one object to another object. Something similiar to pass by value but with assignment. Eg. PushPin newValPushPin = oldPushPin; //I want to break the reference here. I was told to write a copy constructor for this. But this class has alot of properties, it will probably take an hour to write a copy constructor by hand. Is there a better way to assign an object to another object by value? If not, is there a copy constructor generator?

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• What are possible reasons for java.io.IOException: "The filename, directory name, or volume label sy

  - by Turismo

  I am trying to copy a file using the following code: File targetFile = new File(targetPath + File.separator + filename); ... targetFile.createNewFile(); fileInputStream = new FileInputStream(fileToCopy); fileOutputStream = new FileOutputStream(targetFile); byte[] buffer = new byte[64*1024]; int i = 0; while((i = fileInputStream.read(buffer)) != -1) { fileOutputStream.write(buffer, 0, i); } For some users the targetFile.createNewFile results in this exception: java.io.IOException: The filename, directory name, or volume label syntax is incorrect at java.io.WinNTFileSystem.createFileExclusively(Native Method) at java.io.File.createNewFile(File.java:850) Filename and directory name seem to be correct. The directory targetPath is even checked for existence before the copy code is executed and the filename looks like this: AB_timestamp.xml The user has write permissions to the targetPath and can copy the file without problems using the OS. As I don't have access to a machine this happens on yet and can't reproduce the problem on my own machine I turn to you for hints on the reason for this exception.

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• Beginner SQL question: arithmetic with multiple COUNT(*) results

  - by polygenelubricants

  Continuing with the spirit of using the Stack Exchange Data Explorer to learn SQL, (see: Can we become our own “Northwind” for teaching SQL / databases?), I've decided to try to write a query to answer a simple question (on meta): What % of stackoverflow users have over 10,000 rep?. Here's what I've done: Query#1 SELECT COUNT(*) FROM Users WHERE Users.Reputation >= 10000 Result: 556 Query#2 SELECT COUNT(*) FROM USERS Result: 227691 Now, how do I put them together into one query? What is this query idiom called? What do I need to write so I can get, say, a one-row three-column result like this: 556 227691 0,00244190592

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• questions about multi threading for sockets/tcp-connections.

  - by Fantastic Fourier

  I have a server that connects to multiple clients using TCP/IP connections, using C in Unix. Since it won't have more than 20 connections at a time, I figured I would use a thread per connection/socket. But the problem is writing to the sockets as I'll be sending user prompted msgs to clients. Once each socket is handled by a thread, how do I interact with the created thread to write to the sockets? Should each thread just read from the sockets and I'll write to sockets in the main program? Not sure if that's a good way to go about it.

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• Testing install procedure of a program requiring administrative privileges

  - by Lucas Meijer

  I'm trying to write automated test, to ensure that the installer for my program works okay. The program can be installed for all users (requires admin privs), or for current user (does not require admin privs). The program can also autoupdate itself, which in some cases requires admin privileges, and in some cases doesn't. I'm looking for a way where I can have an automated test click "Yes, Allow" on the UAC dialogs, so I can write tests for all different scenarios, on many different operating systems, so that I can be confident when I make changes to the installer that I didn't break anything. Obviously, the installer process itself cannot do this. However, I control the complete machine, and could easily start some sort of daemon process with administrative rights, that the testprogram could make a socket connection to, to request it to "please click ok on the UAC now".

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• Reducing Code Repetition: Calling functions with slightly different signatures

  - by Brian

  Suppose I have two functions which look like this: public static void myFunction1(int a, int b, int c, string d) { //dostuff someoneelsesfunction(c,d); //dostuff2 } public static void myFunction2(int a, int b, int c, Stream d) { //dostuff someoneelsesfunction(c,d); //dostuff2 } What would be a good way to avoid repeated dostuff? Ideas I've thought of, but don't like: I could make d an object and cast at runtype based on type, but this strikes me as not being ideal; it removes a type check which was previously happening at compile time. I could also write a private helper class that takes an object and write both signatures as public functions. I could replace dostuff and dostuff2 with delegates or function calls or something.

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• Complex relationship between tables in NHibernate

  - by Ilya Kogan

  Hi all, I'm writing a Fluent NHibernate mapping for a legacy Oracle database. The challenge is that the tables have composite primary keys. If I were at total freedom, I would redesign the relationships and auto-generate primary keys, but other applications must write to the same database and read from it, so I cannot do it. These are the two tables I'll focus on: Example data Trips table: 1, 10:00, 11:00 ... 1, 12:00, 15:00 ... 1, 16:00, 19:00 ... 2, 12:00, 13:00 ... 3, 9:00, 18:00 ... Faults table: 1, 13:00 ... 1, 23:00 ... 2, 12:30 ... In this case, vehicle 1 made three trips and has two faults. The first fault happened during the second trip, and the second fault happened while the vehicle was resting. Vehicle 2 had one trip, during which a fault happened. Constraints Trips of the same vehicle never overlap. So the tables have an optional one-to-many relationship, because every fault either happens during a trip or it doesn't. If I wanted to join them in SQL, I would write: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime and then I'd get a dataset where every fault appears exactly once (one-to-many as I said). Note that there is no Vehicles table, and I don't need one. But I did create a view that contains all VehicleIds from both tables, so I can use it as a junction table. What am I actually looking for? The tables are huge because they cover years of data, and every time I only need to fetch a range of a few hours. So I need a mapping and a criteria that will run something like the following SQL underneath: select ... from Faults left outer join Trips on Faults.VehicleId = Trips.VehicleId and Faults.FaultTime between Trips.TripStartTime and Trips.TripEndTime where Faults.FaultTime between :p0 and :p1 Do you have any ideas how to achieve it? Note 1: Currently the application shouldn't write to the database, so persistence is not a must, although if the mapping supports persistence, it may help at some point in the future. Note 2: I know it's a tough one, so if you give me a great answer, you will be properly rewarded :) Thank you for reading this long question, and now I only hope for the best :)

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• App Engine webapp.RequestHandler child instances has no self.request during __init__

  - by grucha

  i use modified webapp.RequestHandler for handling requests in my app: class MyRequestHandler(webapp.RequestHandler): """ Request handler with some facilities like user. self.out is the dictionary to pass to templates """ def __init__(self, *args, **kwargs): super(MyRequestHandler, self).__init__(*args, **kwargs) self.out = { 'user': users.get_current_user(), 'logout_url': users.create_logout_url(self.request.uri) } def render(self, template_name): """ Shortcut to render templates """ self.response.out.write(template.render(template_name, self.out)) class DeviceList(MyRequestHandler): def get(self): self.out['devices'] = GPSDevice.all().fetch(1000) self.render('templates/device_list.html') but I get an exception: line 28, in __init__ self.out['logout_url'] = users.create_logout_url(self.request.uri) AttributeError: 'DeviceList' object has no attribute 'request' When the code causing exception is moved out of __init__ everything's fine: class MyRequestHandler(webapp.RequestHandler): """ Request handler with some facilities like user. self.out is the dictionary to pass to templates and initially it contains user object for example """ def __init__(self, *args, **kwargs): super(MyRequestHandler, self).__init__(*args, **kwargs) self.out = { 'user': users.get_current_user(), } def render(self, template_name): """ Shortcut to render templates """ self.out['logout_url'] = users.create_logout_url(self.request.uri) self.response.out.write(template.render(template_name, self.out)) Whi is that? Why there's no self.request after parent's (i.e. webapp.RequestHandler's) __init__ was executed?

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• graphviz segmentation fault

  - by LucaB

  Hi I'm building a graph with many nodes, around 3000. I wrote a simple python program to do the trick with graphviz, but it gives me segmentation fault and I don't know why, if the graph is too big or if i'm missing something. The code is: #!/usr/bin/env python # Import graphviz import sys sys.path.append('..') sys.path.append('/usr/lib/graphviz') import gv # Import pygraph from pygraph.classes.graph import graph from pygraph.classes.digraph import digraph from pygraph.algorithms.searching import breadth_first_search from pygraph.readwrite.dot import write # Graph creation gr = graph() file = open('nodes.dat', 'r') line = file.readline() while line: gr.add_nodes([line[0:-1]]) line = file.readline() file.close() print 'nodes finished, beginning edges' edges = open('edges_ok.dat', 'r') edge = edges.readline() while edge: gr.add_edge((edge.split()[0], edge.split()[1])) edge = edges.readline() edges.close() print 'edges finished' print 'Drawing' # Draw as PNG dot = write(gr) gvv = gv.readstring(dot) gv.layout(gvv,'dot') gv.render(gvv,'svg','graph.svg') and it crashes at the gv.layout() call. The files are somthing like: nodes: node1 node2 node3 edges_ok: node1 node2 node2 node3

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• Windows cmd.exe output in PowerShell

  - by noledgeispower

  I have a script for remotely executing commands on other machines, however... when using windows cmd.exe commands It does not write to the file on the remote server. Here is the code. $server = 'serverName' $Username = 'userName' $Password = 'passWord' $cmd = "cmd /c ipconfig" ######################## ######################## $ph = "C:\mPcO.txt" $rph = "\\$server\C$\mPcO.txt" $cmde = "$cmd > $ph" $pass = ConvertTo-SecureString -AsPlainText $Password -Force $mycred = new-object -typename System.Management.Automation.PSCredential -argumentlist "$Username",$pass Invoke-WmiMethod win32_process -name create -ComputerName $server -ArgumentList $cmde Credential $mycred cmd /c net use \\$server\C$ $password /USER:$username Get-Content $rph Remove-Item $rph cmd /c net use \\$server\C$ /delete As you can see we simply write $cmde = "$cmd > $ph" if I use a PowerShell command I use $cmde = "$cmd | Out-File $ph" and it works fine. Any advice Appreciated

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• the rmagick manual is quite vague. can you help me by changing a pictures filetype and size?

  - by Joern Akkermann

  Hi, it's about RMagick with Ruby On Rails. I do the following: image = params[:image] # params[:image] is the image from the file-form. name = image.original_filename.scan(/[^\/\\]+/).last name = dir + t.day.to_s + t.month.to_s + t.year.to_s + t.hour.to_s + t.min.to_s + t.sec.to_s + name f = File.new(name, "wb") f.write image f.close image = Magick::Image.read(name) image = image.resize_to_fit(200, 250) f = File.new(name, "wb") f.write image.to_blob f.close Do I really need to first save and then change it? And how about changing not only the size, changing also the Filetype? I want a JPG with 60% quality. Please help me. Yours, Joern.

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• Pattern Matching in Scheme

  - by kunjaan

  How do I accept the following input? (list of 0 or more charcters and ends with 3) or (list of 1 or more characters 4 and 0 or more characters after 4) something like (match ( list 3)) -> #t (match ( list 1 2 3)) -> #t (match (list 1 2 3 4)) -> #t (match (list 1 2 3 4 5)) -> #t (match (list 4)) -> #f EDIT: THIS IS NOT MY HOMEWORK. I trying to write something like ELIZA from PAIP but I know only how to write a pattern that begins with a word.

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• Python nested function scopes

  - by Thomas O

  I have code like this: def write_postcodes(self): """Write postcodes database. Write data to file pointer. Data is ordered. Initially index pages are written, grouping postcodes by the first three characters, allowing for faster searching.""" status("POSTCODE", "Preparing to sort...", 0, 1) # This function returns the key of x whilst updating the displayed # status of the sort. ctr = 0 def keyfunc(x): ctr += 1 status("POSTCODE", "Sorting postcodes", ctr, len(self.postcodes)) return x sort_res = self.postcodes[:] sort_res.sort(key=keyfunc) But ctr responds with a NameError: Traceback (most recent call last): File "PostcodeWriter.py", line 53, in <module> w.write_postcodes() File "PostcodeWriter.py", line 47, in write_postcodes sort_res.sort(key=keyfunc) File "PostcodeWriter.py", line 43, in keyfunc ctr += 1 UnboundLocalError: local variable 'ctr' referenced before assignment How can I fix this? I thought nester scopes would have allowed me to do this. I've tried with 'global', but it still doesn't work.

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• C# setup project output automatically start with administrative rights

  - by Alex

  Hi, i've created an setup project for a .net-application which works fine. The problem is, that the application begins to write log-files after startup and this requires administrative rights on windows vista and windows 7. I know there are some folders which i could use to write into without administrative rights. When i start the application as administrator, everything works fine. I asked myself, if it's possible to change the setup project in visual studio in a way that the installed application automatically owns administrative rights on the target system? Thanks for every help in advance! Alex

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• C# Loop on all possible guids

  - by thekaido

  How can I write a loop in C# to iterate over every possible guid?

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• echo newline suppression

  - by Happy Mittal

  Why $echo '-n' doesn't write -n on terminal although -n is written within quotes ?

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• Stream a file to the HTTP response in Pylons

  - by Evgeny

  I have a Pylons controller action that needs to return a file to the client. (The file is outside the web root, so I can't just link directly to it.) The simplest way is, of course, this: with open(filepath, 'rb') as f: response.write(f.read()) That works, but it's obviously inefficient for large files. What's the best way to do this? I haven't been able to find any convenient methods in Pylons to stream the contents of the file. Do I really have to write the code to read a chunk at a time myself from scratch?

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• Displaying Error Page based on the error exception?

  - by Ramesh

  I am using the exception catching procedure which is the module to track the errors and it write the error description in a log file in the server.I want to display the error details in a common Error page which is having a multi-line textbox from the common function in the module.Is it possible to do that.If possible,How can I do that.... Try ;;;;;;;;;;;;;;;;; ;;;;;;;;;;;;;;;;; Catch ex as exception CreateLogFile(Ex) End Try The above description is the error catching portion from the code In the module I have written the CreateLogFile function which write the log file. I want to display the Error Page after writing the log file which should contain the error details.... Please Help...?.

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• Vbscript / webcam. using flash API - Save streaming file as image

  - by remi

  Hi. Based on a php app we've tried to developp our own webapp in vbscript. All is working well. The camera starts, etc.. The problem we're left with is the following: the flash API is streaming the content of the video to a webpage, this page saves the photo as a jpg. The PHP code we're trying to emulate is as follow $str = file_get_contents("php://input"); file_put_contents("/tmp/upload.jpg", pack("H*", $str)); After intensive googling the best we can come up with is Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Dim sImagePath As String = Server.MapPath("/registration/") & "test.jpg" Dim data As Byte() = Request.BinaryRead(Request.TotalBytes) Dim Ret As Array Dim imgbmp As New System.Drawing.Bitmap("test.jpg") Dim ms As MemoryStream = New MemoryStream(data) imgbmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg) Ret = ms.ToArray() Dim fs As New FileStream(sImagePath, FileMode.Create, FileAccess.Write) fs.Write(Ret, 0, Ret.Length) fs.Flush() fs.Close() End Sub which is not working, does anybody have any suggestion?

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• Writing temporary data from R

  - by Shane

  I want to write some temporary data to disk in an R package, and I want to be sure that it can run on every OS without assuming the user has admin rights. Is there an existing R function that can provide a path to a temporary directory on all major OS's? Or a way to reference a user's home directory? Otherwise, I was thinking of trying this: Sys.getenv("temp") I presume that I can't expect people to have write access to their R locations, otherwise I could reference a path within the package directory: .find.package("package.name").

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• How do you add a row to a databound datagridview using the datagridview in the gui?

  - by IsaacB

  Hi guys, I've bound a datagridview to a collection of objects. It's giving me a null reference exception when I try to add a new row to a collection (empty or otherwise) using the gui. More specifically, when there is a write event it does this. How can I override the behavior of the write event and manually add all of the columns contents to the object collection? I could disable the add new row feature and make an add button, but the built in datagridview row add looks so much more slick.

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