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• Posting forms to a 404 + HttpHandler in IIS7: why has all POST data gone missing?

  - by Rahul

  OK, this might sound a bit confusing and complicated, so bear with me. We've written a framework that allows us to define friendly URLs. If you surf to any arbitrary URL, IIS tries to display a 404 error (or, in some cases, 403;14 or 405). However, IIS is set up so that anything directed to those specific errors is sent to an .aspx file. This allows us to implement an HttpHandler to handle the request and do stuff, which involves finding the an associated template and then executing whatever's associated with it. Now, this all works in IIS 5 and 6 and, to an extent, on IIS7 - but for one catch, which happens when you post a form. See, when you post a form to a non-existent URL, IIS says "ah, but that url doesn't exist" and throws a 405 "method not allowed" error. Since we're telling IIS to redirect those errors to our .aspx page and therefore handling it with our HttpHandler, this normally isn't a problem. But as of IIS7, all POST information has gone missing after being redirected to the 405. And so you can no longer do the most trivial of things involving forms. To solve this we've tried using a HttpModule, which preserves POST data but appears to not have an initialized Session at the right time (when it's needed). We also tried using a HttpModule for all requests, not just the missing requests that hit 404/403;14/405, but that means stuff like images, css, js etc are being handled by .NET code, which is terribly inefficient. Which brings me to the actual question: has anyone ever encountered this, and does anyone have any advice or know what to do to get things working again? So far someone has suggested using Microsoft's own URL Rewriting module. Would this help solve our problem? Thanks.

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• Passing Derived Class Instances as void* to Generic Callbacks in C++

  - by Matthew Iselin

  This is a bit of an involved problem, so I'll do the best I can to explain what's going on. If I miss something, please tell me so I can clarify. We have a callback system where on one side a module or application provides a "Service" and clients can perform actions with this Service (A very rudimentary IPC, basically). For future reference let's say we have some definitions like so: typedef int (*callback)(void*); // This is NOT in our code, but makes explaining easier. installCallback(string serviceName, callback cb); // Really handled by a proper management system sendMessage(string serviceName, void* arg); // arg = value to pass to callback This works fine for basic types such as structs or builtins. We have an MI structure a bit like this: Device <- Disk <- MyDiskProvider class Disk : public virtual Device class MyDiskProvider : public Disk The provider may be anything from a hardware driver to a bit of glue that handles disk images. The point is that classes inherit Disk. We have a "service" which is to be notified of all new Disks in the system, and this is where things unravel: void diskHandler(void *p) { Disk *pDisk = reinterpret_cast<Disk*>(p); // Uh oh! // Remainder is not important } SomeDiskProvider::initialise() { // Probe hardware, whatever... // Tell the disk system we're here! sendMessage("disk-handler", reinterpret_cast<void*>(this)); // Uh oh! } The problem is, SomeDiskProvider inherits Disk, but the callback handler can't receive that type (as the callback function pointer must be generic). Could RTTI and templates help here? Any suggestions would be greatly appreciated.

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• On-Demand thumbnail creation with django and nginx

  - by sharjeel

  I want to generate thumbnails of images on the fly. My site is built with django and deployed using nginx which serves all the static content and communicates with django/apache using reverse proxy. Right now, for every image in my site, I generate all required sizes of thumbnails on-hand and deliver them when required. The problem is that whenever I change the size of a thumbnail, I have to regenerate all of them (and they are tons). However now I'd like to generate the thumbnail the first time it is accessed and later on nginx would deliver the same file over n over. If I delete that thumbnail file because of lesser accesses, it should get generated automatically the next time. Thumbnails in my case also have watermarks which require some computation logic of my application so a webserver thumbnail module might not work very well. The size of the thumbnail can be embedded in the URL. So http://www.example.com/thumbnail/abc_320x240.jpg gets the 320x240 size of the thumbnail. The approach I'm looking right now is to let nginx lookup the file and if it doesn't exist, forward the query to my django application which would create the thumbnail and send either the response or a redirect string. However I'm not sure about the concurrency issues and any other issues which might pop up later. What is the appropriate way to achieve this?

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• Python subprocess: 64 bit windows server PIPE doesn't exist :(

  - by Spaceman1861

  I have a GUI that launches selected python scripts and runs it in cmd next to the gui window. I am able to get my launcher to work on my (windows xp 32 bit) laptop but when I upload it to the server(64bit windows iss7) I am running into some issues. The script runs, to my knowledge but spits back no information into the cmd window. My script is a bit of a Frankenstein that I have hacked and slashed together to get it to work I am fairly certain that this is a very bad example of the subprocess module. Just wondering if i could get a hand :). My question is how do i have to alter my code to work on a 64bit windows server. :) from Tkinter import * import pickle,subprocess,errno,time,sys,os PIPE = subprocess.PIPE if subprocess.mswindows: from win32file import ReadFile, WriteFile from win32pipe import PeekNamedPipe import msvcrt else: import select import fcntl def recv_some(p, t=.1, e=1, tr=5, stderr=0): if tr < 1: tr = 1 x = time.time()+t y = [] r = '' pr = p.recv if stderr: pr = p.recv_err while time.time() < x or r: r = pr() if r is None: if e: raise Exception(message) else: break elif r: y.append(r) else: time.sleep(max((x-time.time())/tr, 0)) return ''.join(y) def send_all(p, data): while len(data): sent = p.send(data) if sent is None: raise Exception(message) data = buffer(data, sent) The code above isn't mine def Run(): print filebox.get(0) location = filebox.get(0) location = location.__str__().replace(listbox.get(ANCHOR).__str__(),"") theTime = time.asctime(time.localtime(time.time())) lastbox.delete(0, END) lastbox.insert(END,theTime) for line in CookieCont: if listbox.get(ANCHOR) in line and len(line) > 4: line[4] = theTime else: "Fill In the rip Details to record the time" if __name__ == '__main__': if sys.platform == 'win32' or sys.platform == 'win64': shell, commands, tail = ('cmd', ('cd "'+location+'"',listbox.get(ANCHOR).__str__()), '\r\n') else: return "Please use contact admin" a = Popen(shell, stdin=PIPE, stdout=PIPE) print recv_some(a) for cmd in commands: send_all(a, cmd + tail) print recv_some(a) send_all(a, 'exit' + tail) print recv_some(a, e=0) The Code above is mine :)

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• heterogeneous comparisons in python3

  - by Matt Anderson

  I'm 99+% still using python 2.x, but I'm trying to think ahead to the day when I switch. So, I know that using comparison operators (less/greater than, or equal to) on heterogeneous types that don't have a natural ordering is no longer supported in python3.x -- instead of some consistent (but arbitrary) result we raise TypeError instead. I see the logic in that, and even mostly think its a good thing. Consistency and refusing to guess is a virtue. But what if you essentially want the python2.x behavior? What's the best way to go about getting it? For fun (more or less) I was recently implementing a Skip List, a data structure that keeps its elements sorted. I wanted to use heterogeneous types as keys in the data structure, and I've got to compare keys to one another as I walk the data structure. The python2.x way of comparing makes this really convenient -- you get an understandable ordering amongst elements that have a natural ordering, and some ordering amongst those that don't. Consistently using a sort/comparison key like (type(obj).__name__, obj) has the disadvantage of not interleaving the objects that do have a natural ordering; you get all your floats clustered together before your ints, and your str-derived class separates from your strs. I came up with the following: import operator def hetero_sort_key(obj): cls = type(obj) return (cls.__name__+'_'+cls.__module__, obj) def make_hetero_comparitor(fn): def comparator(a, b): try: return fn(a, b) except TypeError: return fn(hetero_sort_key(a), hetero_sort_key(b)) return comparator hetero_lt = make_hetero_comparitor(operator.lt) hetero_gt = make_hetero_comparitor(operator.gt) hetero_le = make_hetero_comparitor(operator.le) hetero_ge = make_hetero_comparitor(operator.gt) Is there a better way? I suspect one could construct a corner case that this would screw up -- a situation where you can compare type A to B and type A to C, but where B and C raise TypeError when compared, and you can end up with something illogical like a > b, a < c, and yet b > c (because of how their class names sorted). I don't know how likely it is that you'd run into this in practice.

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• Project Management and Scheduling Techniques

  - by Alec Smart

  Hello, I know this is probably the nth project management question. But am trying to move my team onto a more robust project management technique. Am wondering what is the best technique to use? I know that probably no technique is best, but which are the most popular techniques? Poker planning? Evidence Based Scheduling? COCOMO? Agile? Scrum? XP? Which one to use? Also, suppose I use EBS, wouldn't it be too time consuming to break down every single activity into fine grained tasks? E.g. "Design" is a goal, what kind of fine-grained tasks will I have under it? Is this is a waste of time i.e. dividing work into so many micro parts. Usually when I give my programmers a task, I follow up every week, and they complete quite a lot of the task assigned to them (the tasks are very broad e.g. X module). Is EBS worth it? Are there any white-papers on it so that I can implement it on my own? (instead of using Fogbugz) Most of my projects are web-based projects. Thank you for your time.

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• general learning methodology

  - by momo

  just wanted to hear on the different general learning paths people embark on when learning a new language/framework. the one i currently use, which is how i learned bash and am currently learning python, is: instant hacking tutorial (very short tutorial introducing the basic syntax, variable declaration, loops, data types, etc. and how they are generally used) in depth tutorial with good programming style and slightly topic-specific (e.g. Mark Pilgrim's Dive into Python), important topics for me personally are regex methods, file IO, and ways the different data types are utilized best (i wrote a very primitive bayesian spam filter using python's dictionaries to keep track of word occurrences) spaced-repition of syntax or short recipes (i use anki, with questions like 'create dictionary with filename and filesize metadata, human-readable' or simpler ones like 'match 0 - 3 occurences of the letter M in a string', or 'return/create an iterator from two sequences') the use of spaced-repitition has been invaluable, and i credit it with the ease that i can recall/create python algorithms. however, i've recently started looking into django, and i've found that spaced-repitition, at least in my case, doesn't work very well for learning a framework, it works best with short code recipes (either that or i should start looking into more basic django framework tutorials). the problem i'm encountering is that since framework programming is not only algorithms, but actually learning the API, which can be quite complex since you have to learn all the methods, modules, the places where they are stored, and the sequence of which things have to be done. for ex. in django to start a project that deals with polls (from the django tutorial), one has to create the project, edit the settings.py file, create the polls app, edit the models.py file (which requires knowing the classes that are present in the module models), edit the urls.py file, etc. i found that my spaced-repition method didn't work very well for this type of learning, so i wanted to ask you guys what method(s) you use for learning the different frameworks/APIs.

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• Python: How can I use Twisted as the transport for SUDS?

  - by jathanism

  I have a project that is based on Twisted used to communicate with network devices and I am adding support for a new vendor (Citrix NetScaler) whose API is SOAP. Unfortunately the support for SOAP in Twisted still relies on SOAPpy, which is badly out of date. In fact as of this question (I just checked), twisted.web.soap itself hasn't even been updated in 21 months! I would like to ask if anyone has any experience they would be willing to share with utilizing Twisted's superb asynchronous transport functionality with SUDS. It seems like plugging in a custom Twisted transport would be a natural fit in SUDS' Client.options.transport, I'm just having a hard time wrapping my head around it. I did come up with a way to call the SOAP method with SUDS asynchronously by utilizing twisted.internet.threads.deferToThread(), but this feels like a hack to me. Here is an example of what I've done, to give you an idea: # netscaler is a module I wrote using suds to interface with NetScaler SOAP # Source: http://bitbucket.org/jathanism/netscaler-api/src import netscaler import os import sys from twisted.internet import reactor, defer, threads # netscaler.API is the class that sets up the suds.client.Client object host = 'netscaler.local' username = password = 'nsroot' wsdl_url = 'file://' + os.path.join(os.getcwd(), 'NSUserAdmin.wsdl') api = netscaler.API(host, username=username, password=password, wsdl_url=wsdl_url) results = [] errors = [] def handleResult(result): print '\tgot result: %s' % (result,) results.append(result) def handleError(err): sys.stderr.write('\tgot failure: %s' % (err,)) errors.append(err) # this converts the api.login() call to a Twisted thread. # api.login() should return True and is is equivalent to: # api.service.login(username=self.username, password=self.password) deferred = threads.deferToThread(api.login) deferred.addCallbacks(handleResult, handleError) reactor.run() This works as expected and defers return of the api.login() call until it is complete, instead of blocking. But as I said, it doesn't feel right. Thanks in advance for any help, guidance, feedback, criticism, insults, or total solutions.

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• how to implement a really efficient bitvector sorting in python

  - by xiao

  Hello guys! Actually this is an interesting topic from programming pearls, sorting 10 digits telephone numbers in a limited memory with an efficient algorithm. You can find the whole story here What I am interested in is just how fast the implementation could be in python. I have done a naive implementation with the module bitvector. The code is as following: from BitVector import BitVector import timeit import random import time import sys def sort(input_li): return sorted(input_li) def vec_sort(input_li): bv = BitVector( size = len(input_li) ) for i in input_li: bv[i] = 1 res_li = [] for i in range(len(bv)): if bv[i]: res_li.append(i) return res_li if __name__ == "__main__": test_data = range(int(sys.argv[1])) print 'test_data size is:', sys.argv[1] random.shuffle(test_data) start = time.time() sort(test_data) elapsed = (time.time() - start) print "sort function takes " + str(elapsed) start = time.time() vec_sort(test_data) elapsed = (time.time() - start) print "sort function takes " + str(elapsed) start = time.time() vec_sort(test_data) elapsed = (time.time() - start) print "vec_sort function takes " + str(elapsed) I have tested from array size 100 to 10,000,000 in my macbook(2GHz Intel Core 2 Duo 2GB SDRAM), the result is as following: test_data size is: 1000 sort function takes 0.000274896621704 vec_sort function takes 0.00383687019348 test_data size is: 10000 sort function takes 0.00380706787109 vec_sort function takes 0.0371489524841 test_data size is: 100000 sort function takes 0.0520560741425 vec_sort function takes 0.374383926392 test_data size is: 1000000 sort function takes 0.867373943329 vec_sort function takes 3.80475401878 test_data size is: 10000000 sort function takes 12.9204008579 vec_sort function takes 38.8053860664 What disappoints me is that even when the test_data size is 100,000,000, the sort function is still faster than vec_sort. Is there any way to accelerate the vec_sort function?

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• Help for Platform plus Plugin development by J2ee

  - by echo

  Hi, everybody. I want to develop a monitor platform which can monitor many different subjects such as database, OS, middle ware etc. The system includes two parts: 1. Report center(Show some useful chart and report) 2. Collector(Collect information from monitored subject) For the time being, I just want to monitor some parameters of oracle and Linux. And I will add more monitor subject like MS SqlServer, IBM Db2 ect. later. I need a good architecture so I can easily add new monitor module and not to disturb original framework too much. I want to develop it by the method of “Platform + plugin”. A plugin should have its own UI, setting part and something else. I plan to use struts2 + spring + hibernate to develop report center. I am not very sure how to do design this architecture for I have any “Platform + plugin” experience. I ever googled some information such as OSGI and Portlet. I am not sure which one should be my best choice. Can anyone give me some instruction about it. Your help will be appreciated.

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• Catching / blocking SIGINT during system call

  - by danben

  I've written a web crawler that I'd like to be able to stop via the keyboard. I don't want the program to die when I interrupt it; it needs to flush its data to disk first. I also don't want to catch KeyboardInterruptedException, because the persistent data could be in an inconsistent state. My current solution is to define a signal handler that catches SIGINT and sets a flag; each iteration of the main loop checks this flag before processing the next url. However, I've found that if the system happens to be executing socket.recv() when I send the interrupt, I get this: ^C Interrupted; stopping... // indicates my interrupt handler ran Traceback (most recent call last): File "crawler_test.py", line 154, in <module> main() ... File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/socket.py", line 397, in readline data = recv(1) socket.error: [Errno 4] Interrupted system call and the process exits completely. Why does this happen? Is there a way I can prevent the interrupt from affecting the system call?

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• Requested operation requires an OLE DB Session object... - Connecting Excel to SQL server via ADO

  - by Frank V

  I'm attempting to take Excel 2003 and connect it to SQL Server 2000 to run a few dynamicly generated SQL Queries which ultimately filling certain cells. I'm attempting to do this via VBA via ADO (I've tried 2.8 to 2.0) but I'm getting an error while setting the ActiveConnection variable which is inside the ADODB.Connection object. I need to resolve this pretty quick... Requested operation requires an OLE DB Session object, which is not supported by the current provider. I'm honestly not sure what this error means and right now I don't care. How can get this connection to succeed so that I can run my queries? Here is my VB code: Dim SQL As String, RetValue As String SQL = " select top 1 DateTimeValue from SrcTable where x='value' " 'Not the real SQL RetValue = "" Dim RS As ADODB.Recordset Dim Con As New ADODB.Connection Dim Cmd As New ADODB.Command Con.ConnectionString = "Provider=sqloledb;DRIVER=SQL Server;Data Source=Server\Instance;Initial Catalog=MyDB_DC;User Id=<UserName>;Password=<Password>;" Con.CommandTimeout = (60 * 30) Set Cmd.ActiveConnection = Con ''Error occurs here. ' I'm not sure if the rest is right. I've just coded it. Can't get past the line above. Cmd.CommandText = SQL Cmd.CommandType = adCmdText Con.Open Set RS = Cmd.Execute() If Not RS.EOF Then RetValue = RS(0).Value Debug.Print "RetValue is: " & RetValue End If Con.Close I imagine something is wrong with the connection string but I've tried over a dozen variations. Now I'm just shooting in the dark.... Note/Update: To make matters more confusing, if I Google for the error quote above, I get a lot of hits back but nothing seems relevant or I'm not sure what information is relevant.... I've got the VBA code in "Sheet1" under "Microsoft Excel Objects." I've done this before but usually put things in a module. Could this make a difference?

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• Perl's Devel::LeakTrace::Fast Pointing to blank files and evals

  - by kt

  I am using Devel::LeakTrace::Fast to debug a memory leak in a perl script designed as a daemon which runs an infinite loop with sleeps until interrupted. I am having some trouble both reading the output and finding documentation to help me understand the output. The perldoc doesn't contain much information on the output. Most of it makes sense, such as pointing to globals in DBI. Intermingled with the output, however, are several leaked SV(<LOCATION>) from (eval #) line # Where the numbers are numbers and <LOCATION> is a location in memory. The script itself is not using eval at any point - I have not investigated each used module to see if evals are present. Mostly what I want to know is how to find these evals (if possible). I also find the following entries repeated over and over again leaked SV(<LOCATION>) from line # Where line # is always the same #. Not very helpful in tracking down what file that line is in.

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• Dynamically adding controls from an Event after Page_Init

  - by GenericTypeTea

  Might seem like a daft title as you shouldn't add dynamic controls after Page_Init if you want to maintain ViewState, but I couldn't think of a better way of explaining the problem. I have a class similar to the following: public class WebCustomForm : WebControl, IScriptControl { internal CustomRender Content { get { object content = this.Page.Session[this.SESSION_CONTENT_TRACKER]; return content as CustomRender; } private set { this.Page.Session[this.SESSION_CONTENT_TRACKER] = value; } } } CustomRender is an abstract class that implements ITemplate that I use to self-contain a CustomForms module I'm in the middle of writing. On the Page_Init of the page that holds the WebCustomForm, I Initialise the control by passing the relevant Ids to it. Then on the overridden OnInit method of the WebCustomForm I call the Instantiate the CustomRender control that's currently active: if (this.Content != null) { this.Content.InstantiateIn(this); } The problem is that my CustomRender controls need the ability to change the CustomRender control of the WebCustomForm. But when the events that fire on the CustomRender fire, the Page_Init event has obviously already gone off. So, my question is, how can I change the content of the WebCustomForm from a dynamically added control within it? The way I see it, I have two options: I separate the CustomRender controls out into their own stand alone control and basically have an aspx page per control and handle the events myself on the page (although I was hoping to just make a control I drop on the page and forget about) I don't use events and just keep requesting the current page, but with different Request Parameters Or I go back to the drawing board with any better suggetions anyone can give me.

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• Risking the exception anti-pattern.. with some modifications

  - by Sridhar Iyer

  Lets say that I have a library which runs 24x7 on certain machines. Even if the code is rock solid, a hardware fault can sooner or later trigger an exception. I would like to have some sort of failsafe in position for events like this. One approach would be to write wrapper functions that encapsulate each api a: returnCode=DEFAULT; try { returnCode=libraryAPI1(); } catch(...) { returnCode=BAD; } return returnCode; The caller of the library then restarts the whole thread, reinitializes the module if the returnCode is bad. Things CAN go horribly wrong. E.g. if the try block(or libraryAPI1()) had: func1(); char *x=malloc(1000); func2(); if func2() throws an exception, x will never be freed. On a similar vein, file corruption is a possible outcome. Could you please tell me what other things can possibly go wrong in this scenario?

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• PySide Qt script doesn't launch from Spyder but works from shell

  - by Maxim Zaslavsky

  I have a weird bug in my project that uses PySide for its Qt GUI, and in response I'm trying to test with simpler code that sets up the environment. Here is the code I am testing with: http://stackoverflow.com/a/6906552/130164 When I launch that from my shell (python test.py), it works perfectly. However, when I run that script in Spyder, I get the following error: Traceback (most recent call last): File "/home/test/Desktop/test/test.py", line 31, in <module> app = QtGui.QApplication(sys.argv) RuntimeError: A QApplication instance already exists. If it helps, I also get the following warning: /usr/lib/pymodules/python2.6/matplotlib/__init__.py:835: UserWarning: This call to matplotlib.use() has no effect because the the backend has already been chosen; matplotlib.use() must be called *before* pylab, matplotlib.pyplot, or matplotlib.backends is imported for the first time. Why does that code work when launched from my shell but not from Spyder? Update: Mata answered that the problem happens because Spyder uses Qt, which makes sense. For now, I've set up execution in Spyder using the "Execute in an external system terminal" option, which doesn't cause errors but doesn't allow debugging, either. Does Spyder have any built-in workarounds to this?

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• Problems running XNA game on 64-bit Windows 7

  - by Tesserex

  I'm having problems getting my game engine to run on my brother's machine, which is running 64-bit Windows 7. I'm developing on 32-bit XP SP2. My app uses XNA, FMOD.NET, and another dll I wrote entirely in C#. Everything is targeted to x86, not AnyCPU. I've read that this is required for XNA to work because there is no 64-bit xna framework. I recompiled FMOD.NET as x86 as well and made sure to be using the 32-bit version of the native dll. So I don't see any problems there. However when he tries to run my app, it gives an error which is mysterious, but not unheard of. A FileNotFoundException with an empty file name, and the top of the stack trace is in my main form constructor. The message is The specified module could not be found. (Exception from HRESULT: 0x8007007E) I found some threads online about this error, all with very vague, mixed, and fuzzy responses that don't really help me. Most remind people to target x86. Some say check that they have all the dlls necessary. I gave my brother Microsoft.Xna.Framework.dll, but does he need to install the entire XNA redistributable package? When I take everything I sent him and stick it in a random directory, it still runs fine for me. I developed the game in VS2008, not in game studio, using XNA 3.0 and a Windows Forms control that uses XNA drawing which I found in an msdn tutorial. I would also like to avoid requiring a full installer if possible. Any insight? Please?

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• Very slow guards in my monadic random implementation (haskell)

  - by danpriduha

  Hi! I was tried to write one random number generator implementation, based on number class. I also add there Monad and MonadPlus instance. What mean "MonadPlus" and why I add this instance? Because of I want to use guards like here: -- test.hs -- import RandomMonad import Control.Monad import System.Random x = Rand (randomR (1 ::Integer, 3)) ::Rand StdGen Integer y = do a <-x guard (a /=2) guard (a /=1) return a here comes RandomMonad.hs file contents: -- RandomMonad.hs -- module RandomMonad where import Control.Monad import System.Random import Data.List data RandomGen g => Rand g a = Rand (g ->(a,g)) | RandZero instance (Show g, RandomGen g) => Monad (Rand g) where return x = Rand (\g ->(x,g)) (RandZero)>>= _ = RandZero (Rand argTransformer)>>=(parametricRandom) = Rand funTransformer where funTransformer g | isZero x = funTransformer g1 | otherwise = (getRandom x g1,getGen x g1) where x = parametricRandom val (val,g1) = argTransformer g isZero RandZero = True isZero _ = False instance (Show g, RandomGen g) => MonadPlus (Rand g) where mzero = RandZero RandZero `mplus` x = x x `mplus` RandZero = x x `mplus` y = x getRandom :: RandomGen g => Rand g a ->g ->a getRandom (Rand f) g = (fst (f g)) getGen :: RandomGen g => Rand g a ->g -> g getGen (Rand f) g = snd (f g) when I run ghci interpreter, and give following command getRandom y (mkStdGen 2000000000) I can see memory overflow on my computer (1G). It's not expected, and if I delete one guard, it works very fast. Why in this case it works too slow? What I do wrong?

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• Why does this extension method throw a NullReferenceException in VB.NET?

  - by Dan

  From previous experience I had been under the impression that it's perfectly legal (though perhaps not advisable) to call extension methods on a null instance. So in C#, this code compiles and runs: // code in static class static bool IsNull(this object obj) { return obj == null; } // code elsewhere object x = null; bool exists = !x.IsNull(); However, I was just putting together a little suite of example code for the other members of my development team (we just upgraded to .NET 3.5 and I've been assigned the task of getting the team up to speed on some of the new features available to us), and I wrote what I thought was the VB.NET equivalent of the above code, only to discover that it actually throws a NullReferenceException. The code I wrote was this: ' code in module ' <Extension()> _ Function IsNull(ByVal obj As Object) As Boolean Return obj Is Nothing End Function ' code elsewhere ' Dim exampleObject As Object = Nothing Dim exists As Boolean = Not exampleObject.IsNull() The debugger stops right there, as if I'd called an instance method. Am I doing something wrong (e.g., is there some subtle difference in the way I defined the extension method between C# and VB.NET)? Is it actually not legal to call an extension method on a null instance in VB.NET, though it's legal in C#? (I would have thought this was a .NET thing as opposed to a language-specific thing, but perhaps I was wrong.) Can anybody explain this one to me?

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• Updating Data through Objects

  - by Chacha102

  So, lets say I have a record: $record = new Record(); and lets say I assign some data to that record: $record->setName("SomeBobJoePerson"); How do I get that into the database. Do I..... A) Have the module do it. class Record{ public function __construct(DatabaseConnection $database) { $this->database = $database; } public function setName($name) { $this->database->query("query stuff here"); $this->name = $name; } } B) Run through the modules at the end of the script class Record{ private $changed = false; public function __construct(array $data=array()) { $this->data = $data; } public function setName($name) { $this->data['name'] = $name; $this->changed = true; } public function isChanged() { return $this->changed; } public function toArray() { return $this->array; } } class Updater { public function update(array $records) { foreach($records as $record) { if($record->isChanged()) { $this->updateRecord($record->toArray()); } } } public function updateRecord(){ // updates stuff } }

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• .net layered design: return error code to forms indicating which controls have an error

  - by David Casillas

  Let's say I have a simple application. It tries to add a new entry to a database grabing the info from the user. The information is a tipical MasterDetail objetc like an invoice. The Invoice object used to collect the data has some simple atributes (Id, Date, etc...) and a List of InvoiceDetail, consisting of some simple atributes (invoiceId, productId, quantity, etc...) A form in the UI Layer collects the data from the user, creates an instance of Invoice and sends it to the Bussiness Layer. The Bussines layer sends the data to a Validation Module. If any error in the input is detected it has to return some kind of error code. The Bussiness Layer has to send the error code back to the Form to let the user correct the worng information. I want the application to display some kind of warning (a different background color for example) in every form control with an error. ¿What's a good aproach to I manage the errors to be able to inform the form which controls are wrong? ¿Can I create an error object?¿Use delegates?. I'm using VB.net but don't think this is relevant to the solution of the problem. P.D: Please suggest me some tags to this post.

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• Can't get RDFlib to work on windows

  - by john

  I have installed RDFlib 3.0 and everything that is needed, but when I run the following code I get an error. The code below is from: http://code.google.com/p/rdflib/wiki/IntroSparql. I have tried for hours to fix this but with no success. Can please someone help? import rdflib rdflib.plugin.register('sparql', rdflib.query.Processor, 'rdfextras.sparql.processor', 'Processor') rdflib.plugin.register('sparql', rdflib.query.Result, 'rdfextras.sparql.query', 'SPARQLQueryResult') from rdflib import ConjunctiveGraph g = ConjunctiveGraph() g.parse("http://bigasterisk.com/foaf.rdf") g.parse("http://www.w3.org/People/Berners-Lee/card.rdf") from rdflib import Namespace FOAF = Namespace("http://xmlns.com/foaf/0.1/") g.parse("http://danbri.livejournal.com/data/foaf") [g.add((s, FOAF['name'], n)) for s,_,n in g.triples((None, FOAF['member_name'], None))] for row in g.query( """SELECT ?aname ?bname WHERE { ?a foaf:knows ?b . ?a foaf:name ?aname . ?b foaf:name ?bname . }""", initNs=dict(foaf=Namespace("http://xmlns.com/foaf/0.1/"))): print "%s knows %s" % row The error I get is: Traceback (most recent call last): File "...", line 18 in <module> initNs=dict(foaf=Namespace("http://xmlns.com/foaf/0.1/"))): TypeError: query() got an unexpected keyword argument 'initNS'

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• Delphi Client-Server Application using Firebird 2.5 embedded connection error

  - by Japster

  0 down vote favorite 1 share [fb] share [tw] I have got a lengthy question to ask. First of all Im still very new when it comes to Delphi programming and my experience has beem mostly developing small single user database applications using ADO and an Access database. I need to take the transition now to a client server application and this is where the problem starts. I decided to use Firebird 2.5 embeded as my database, as it is open source, and it is can be used with the interbase components in Delphi and that multiple clients can access the database simultanously. So I followed the interbase tutorial in Delphi. I managed to connect the client to the server and see the data in the example (While both are running on my pc), but when i tried to move the client to another pc, keeping the server on mine and running it to see if I can connect to the server it gave me the following error. Exception EIdSocketError in module clientDemo.exe at 0029DCAC. Socket Error # 10061 Connection refused. I understand that this might be because the host is defined as localhost in the client. But here is my first question. In the TSQLConncetion you can set die hostname under Driver-Hostname. The thing I want to know is how do you do this at run time, as I cannot get the property when I try and make an edit box to allow the user to enter the value and then set it via code like for example: SQLConncetion1.Driver.Hostname := edtHost.text; This cannot be done this way and the only way I see you can set the hostname is with the object inspector, but that is not available at runtime and I need to set the hostname on the client when the program is running the first time, so how do you set the hostname/IP address at runtime? Im using Delphi XE2 There is still a lot of questions to come especially when it comes to deployment, but I will take this piece by piece and I appreciate the advice.

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• How to create custom pages (Drupal 6.x)

  - by jc70

  In the template.php file I inserted the code below: I found a tutorial online that gives the code, but I'm confused on how to get it to work. I copied the code below and inserted it into the template.php from the theme HTML5_base. I duplicated the page.tpl.php file and created custom pages -- page-gallery.tpl.php and page-articles.tpl.php. I inserted some text to the files just see that I've navigated to the pages w/ the changes. It looks like Drupal is not recognizing gallery.tpl.php and page-articles.tpl.php. In the template.php there are the following functions: html5_base_preprocess_page() html5_base_preprocess_node() html5_base_preprocess_block() In the tutorial it uses these functions: phptemplate_preprocess_page() phptemplate_preprocess_block() phptemplate_preprocess_node() function phptemplate_preprocess_page(&$vars) { //code block from the Drupal handbook //the path module is required and must be activated if(module_exists('path')) { //gets the "clean" URL of the current page $alias = drupal_get_path_alias($_GET['q']); $suggestions = array(); $template_filename = 'page'; foreach(explode('/', $alias) as $path_part) { $template_filename = $template_filename.'-'.$path_part; $suggestions[] = $template_filename; } $vars['template_files'] = $suggestions; } } function phptemplate_preprocess_node(&$vars) { //default template suggestions for all nodes $vars['template_files'] = array(); $vars['template_files'][] = 'node'; //individual node being displayed if($vars['page']) { $vars['template_files'][] = 'node-page'; $vars['template_files'][] = 'node-'.$vars['node']->type.'-page'; $vars['template_files'][] = 'node-'.$vars['node']->nid.'-page'; } //multiple nodes being displayed on one page in either teaser //or full view else { //template suggestions for nodes in general $vars['template_files'][] = 'node-'.$vars['node']->type; $vars['template_files'][] = 'node-'.$vars['node']->nid; //template suggestions for nodes in teaser view //more granular control if($vars['teaser']) { $vars['template_files'][] = 'node-'.$vars['node']->type.'-teaser'; $vars['template_files'][] = 'node-'.$vars['node']->nid.'-teaser'; } } } function phptemplate_preprocess_block(&$vars) { //the "cleaned-up" block title to be used for suggestion file name $subject = str_replace(" ", "-", strtolower($vars['block']->subject)); $vars['template_files'] = array('block', 'block-'.$vars['block']->delta, 'block-'.$subject); }

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• Getting basepath from view in zend framework

  - by mobmad

  Case: you're developing a site with Zend Framework and need relative links to the folder the webapp is deployed in. I.e. mysite.com/folder online and localhost:8080 under development. The following works nice in controllers regardless of deployed location: $this->_helper->redirector->gotoSimple($action, $controller, $module, $params); And the following inside a viewscript, ie. index.phtml: <a href="<?php echo $this->url(array('controller'=>'index', 'action' => 'index'), null, true); ?>"> But how do I get the correct basepath when linking to images or stylesheets? (in a layout.phtml file, for example): <img src='<?php echo WHAT_TO_TYPE_HERE; ?>images/logo.png' /> and $this->headLink()->appendStylesheet( WHAT_TO_TYPE_HERE . 'css/default.css'); WHAT_TO_TYPE_HERE should be replaced with something that gives <img src="/folder/images/logo.png />` on mysite.com and `<img src="/images/logo.png /> on localhost

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