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• NASM - Load code from USB Drive

  - by new123456

  Hola, Would any assembly gurus know the argument (register dl) that signifies the first USB drive? I'm working through a couple of NASM tutorials, and would like to get a physical boot (I can get a clean one with qemu). This is the section of code that loads the "kernel" data from disk: loadkernel: mov si, LMSG ;; 'Loading kernel',13,10,0 call prints ;; ex puts() mov dl, 0x00 ;; The disk to load from mov ah, 0x02 ;; Read operation mov al, 0x01 ;; Sectors to read mov ch, 0x00 ;; Track mov cl, 0x02 ;; Sector mov dh, 0x00 ;; Head mov bx, 0x2000 ;; Buffer end mov es, bx mov bx, 0x0000 ;; Buffer start int 0x13 jc loadkernel mov ax, 0x2000 mov ds, ax jmp 0x2000:0x00 If it makes any difference, I'm running a stock Dell Inspiron 15 BIOS. Apparently, the correct value for me is 0x80. The BIOS loads the hard drives and labels them starting at 0x80 according to this answer. My particular BIOS decides to load the USB drive up as the first, for some reason, so I can boot from there.

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• Using LINQ on observable with GroupBy and Sum aggregate

  - by Mark Oates

  I have the following block of code which works fine; var boughtItemsToday = (from DBControl.MoneySpent bought in BoughtItemDB.BoughtItems select bought); BoughtItems = new ObservableCollection<DBControl.MoneySpent>(boughtItemsToday); It returns data from my MoneySpent table which includes ItemCategory, ItemAmount, ItemDateTime. I want to change it to group by ItemCategory and ItemAmount so I can see where I am spending most of my money, so I created a GroupBy query, and ended up with this; var finalQuery = boughtItemsToday.AsQueryable().GroupBy(category => category.ItemCategory); BoughtItems = new ObservableCollection<DBControl.MoneySpent>(finalQuery); Which gives me 2 errors; Error 1 The best overloaded method match for 'System.Collections.ObjectModel.ObservableCollection.ObservableCollection(System.Collections.Generic.List)' has some invalid arguments Error 2 Argument 1: cannot convert from 'System.Linq.IQueryable' to 'System.Collections.Generic.List' And this is where I'm stuck! How can I use the GroupBy and Sum aggregate function to get a list of my categories and the associated spend in 1 LINQ query?! Any help/suggestions gratefully received. Mark

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• How do I reference my MainViewController from another class?

  - by todd412

  Hi, I am building an iPhone Utility app that uses UIImageView to display an animation. Within the MainViewController's viewDidLoad() method, I am creating an instance of a CustomClass, and then setting up the animations: - (void)viewDidLoad { [super viewDidLoad]; cc = [CustomClass new]; NSArray * imageArray = [[NSArray alloc] initWithObjects: [UIImage imageNamed:@"image-1-off.jpg"], [UIImage imageNamed:@"image-2-off.jpg"], [UIImage imageNamed:@"image-3-off.jpg"], [UIImage imageNamed:@"image-4-off.jpg"], nil]; offSequence = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 320, 480)]; offSequence.animationImages = imageArray; offSequence.animationDuration = .8; offSequence.contentMode = UIViewContentModeBottomLeft; [self.view addSubview:offSequence]; [offSequence startAnimating]; } That works fine. However, I would like to be able to move all the above code that sets up the UIImageView into my CustomClass. The problem is in the second to last line: [self.view addSubview:offSequence]; I basically need to replace 'self' with a reference to the MainControllerView, so I can call addSubview from within my CustomClass. I tried creating an instance var of CustomClass called mvc and a setter method that takes a reference to the MainViewController as an argument as such: - (void) setMainViewController: (MainViewController *) the_mvc { mvc = the_mvc; } And then I called it within MainViewController like so: [cc setMainController:MainViewController:self]; But this yields all sorts of errors which I can post here, but it strikes me that I may be overcomplicating this. Is there an easier way to reference the MainViewController that instanatiated my CustomClass?

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• Connecting an overloaded PyQT signal using new-style syntax

  - by Claudio

  I am designing a custom widget which is basically a QGroupBox holding a configurable number of QCheckBox buttons, where each one of them should control a particular bit in a bitmask represented by a QBitArray. In order to do that, I added the QCheckBox instances to a QButtonGroup, with each button given an integer ID: def populate(self, num_bits, parent = None): """ Adds check boxes to the GroupBox according to the bitmask size """ self.bitArray.resize(num_bits) layout = QHBoxLayout() for i in range(num_bits): cb = QCheckBox() cb.setText(QString.number(i)) self.buttonGroup.addButton(cb, i) layout.addWidget(cb) self.setLayout(layout) Then, each time a user would click on a checkbox contained in self.buttonGroup, I'd like self.bitArray to be notified so I can set/unset the corresponding bit in the array. For that I intended to connect QButtonGroup's buttonClicked(int) signal to QBitArray's toggleBit(int) method and, to be as pythonic as possible, I wanted to use new-style signals syntax, so I tried this: self.buttonGroup.buttonClicked.connect(self.bitArray.toggleBit) The problem is that buttonClicked is an overloaded signal, so there is also the buttonClicked(QAbstractButton*) signature. In fact, when the program is executing I get this error when I click a check box: The debugged program raised the exception unhandled TypeError "QBitArray.toggleBit(int): argument 1 has unexpected type 'QCheckBox'" which clearly shows the toggleBit method received the buttonClicked(QAbstractButton*) signal instead of the buttonClicked(int) one. So, the question is, how can we specify, using new-style syntax, that self.buttonGroup emits the buttonClicked(int) signal instead of the default overload - buttonClicked(QAbstractButton*)?

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• Disable validation in an object in Ruby on Rails

  - by J. Pablo Fernández

  I have an object which whether validation happens or not should depend on a boolean, or in another way, validation is optional. I haven't found a clean way to do it. What I'm currently doing is this (disclaimer: you cannot unsee, leave this page if you are too sensitive): def valid? if perform_validation super else super # Call valid? so that callbacks get called and things like encrypting passwords and generating salt in before_validation actually happen errors.clear # but then clear the errors true # and claim ourselves to be valid. This is super hacky! end end Any better ways? Before you point to the :if argument of many validations, this is for a user model which is using authlogic so it has a lot of validation rules. You can stop reading here if you belive me. If you don't, authlogic already sets some :ifs like: :if => :email_changed? which I have to turn into :if => Proc.new {|user| user.email_changed? and user.perform_validation} and in some other cases, since I'm also using authlogic-oid (OpenID) I just don't have control over the :if, authlogic-oid sets it in a way I cannot change it (in time) without further monkey patching. So I have to override seemingly unrelated functions, catch exceptions if a method doesn't exist, etc. The previous hacky solution if the best of my two attempts.

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• Printing a field with additional dots in haskell

  - by Frank Kluyt

  I'm writing a function called printField. This function takes an int and a string as arguments and then then prints a field like this "Derp..." with this: printField 7 "Derp". When the field consists of digits the output should be "...3456". The function I wrote looks like this: printField :: Int -> String -> String printField x y = if isDigit y then concat(replicate n ".") ++ y else y ++ concat(replicate n ".") where n = x - length y This obviously isn't working. The error I get from GHC is: Couldn't match type `[Char]' with `Char' Expected type: Char Actual type: String In the first argument of `isDigit', namely `y' In the expression: isDigit y In the expression: if isDigit y then concat (replicate n ".") ++ y else y ++ concat (replicate n ".") I can't get it to work :(. Can anyone help me out? Please keep in mind that I'm new to Haskell and functional programming in general.

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• Bytecode and Objects

  - by HH

  Hey everyone, I am working on a bytecode instrumentation project. Currently when handling objects, the verifier throws an error most of the time. So I would like to get things clear concerning rules with objects (I read the JVMS but couldn't find the answer I was looking for): I am instrumenting the NEW instruction: original bytecode NEW <MyClass> DUP INVOKESPECIAL <MyClass.<init>> after instrumentation NEW <MyClass> DUP INVOKESTATIC <Profiler.handleNEW> DUP INVOKESPECIAL <MyClass.<init>> Note that I added a call to Profiler.handleNEW() which takes as argument an object reference (the newly created object). The piece of code above throws a VerificationError. While if I don't add the INVOKESTATIC (leaving only the DUP), it doesn't. So what is the rule that I'm violating? I can duplicate an uninitialized reference but I can't pass it as parameter? I would appreciate any help. Thank you

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• can a webservice load jars during run time

  - by KItis

  I have created a simple web-service using Java. i want to load jars related to web-service during runtime. I have done this task for normal Java application. there what I did was JarFile jar = new JarFile(f.getPath()); final Manifest manifest = jar.getManifest(); final Attributes mattr = manifest.getMainAttributes(); // Read the manifset in jar files and get the Name attribute // whare it specified the class that need to load //for (Object a : mattr.keySet()) { for (Iterator iter = mattr.keySet().iterator(); iter.hasNext();) { Object obj = (Object)iter.next(); if ("ServiceName".equals(obj.toString())) className = mattr.getValue((Name) obj); //System.out.println(className); } /* * Create the jar class loader and use the first argument passed * in from the command line as the jar file to use. */ JarClassLoader jarLoader = new JarClassLoader(f.getPath()); /* Load the class from the jar file and resolve it. */ Class c = jarLoader.loadClass(className, true); My problem is can I put jars that need to be loaded during run time in to separate folder rather than putting in to WEBINF folder. do i have to put jars both in axis and web-application. thanks in advance for any contribution for this question.

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• Ruby TypeErrors involving `expected Data`

  - by Kenny Peng

  I've ran into situations where I have gotten these expected Data errors before, but they have always pointed to ActiveRecord not playing well with other libraries in the past. This piece of code: def load(kv_block, debug=false) # Converts a string block to a Hash using split kv_map = StringUtils.kv_array_to_hash(kv_block) # Loop through each key, value kv_map.each do |mem,val| # Format the member from camel case to underscore member = mem.camel_to_underscore() # If the object includes a method to set the key (i.e. the key # is a member of self), invoke the method, setting the value of # the member) if self.methods.include?(member.to_set_method_name()) then # Exception thrown here self.send(member.to_set_method_name(), val) # Else, check for the same case, this time for an instance variable elsif self.instance_variable_defined?(member.to_instance_var_name()) self.instance_variable_set(member.to_instance_var_name(), val) # Else, complain that the object doesn't understand the key with # respect to its class definition. else raise ArgumentError, "I don't know what to do with #{member}. #{self.class} does not have a member or function called #{member}" end end end produces the error wrong argument type #<Class:0x11a02088> (expected Data) (TypeError) in the each loop on the first if test. I've inspected a post-mortem debugging instance using rdebug, and running that line manually, it works without a hitch. Has anyone seen this error before and what's been your solution to it? I used to think it was ActiveRecord and other gems stomping on each other's definitions, but I removed any references to ActiveRecord and this still occurs.

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• getting CS1502 compiler error on dev environment but not production.

  - by nw

  When I try to run my ASP.NET app from my development environment I get the following error message: Compiler Error Message: CS1502: The best overloaded method match for 'mmars.Printing.printFunctions.SetPrintSummaryProperties(mmars.contextInfo, ref mmars.Printing.printObjSummary)' has some invalid arguments. When I publish and run on our production server I don't get this error. It seems to compile fine when I build from the build menu (in fact if I change the second argument of the bolded function call below, i get a compiler error in visual studio), but now i've suddenly started getting this error message at runtime. So another question I have in addition to getting rid of the error is why is the .NET development server even trying to do JIT compilation on my project if it is already compiled into a DLL? Printing.printObjSummary myPrintObj = new Printing.printObjSummary(); Printing.printFunctions.SetPrintSummaryProperties(ci, ref myPrintObj); printObjects.Add(myPrintObj); This seems to have just suddenly appeared from nowhere today and it's extremely frustrating. Also, though there are no warnings at compile-time, when I get redirected to the page with that first compilation error there are many warnings like the following: Warning: CS0436: The type 'mmars.MMARSSummaryDataItem' in 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3dad423c\40569048\App_Code.b0rgpkzr.4.cs' conflicts with the imported type 'mmars.MMARSSummaryDataItem' in 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3dad423c\40569048\assembly\dl3\7179c19a\345f948c_ece7ca01\mmars.DLL'. Using the type defined in 'c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3dad423c\40569048\App_Code.b0rgpkzr.4.cs'. What's the deal with that? Is the webserver complaining about name conflicts in the source file and dll resulting from the source file?

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• Overlapping template partial specialization when wanting an "override" case: how to avoid the error?

  - by user173342

  I'm dealing with a pretty simple template struct that has an enum value set by whether its 2 template parameters are the same type or not. template<typename T, typename U> struct is_same { enum { value = 0 }; }; template<typename T> struct is_same<T, T> { enum { value = 1 }; }; This is part of a library (Eigen), so I can't alter this design without breaking it. When value == 0, a static assert aborts compilation. So I have a special numerical templated class SpecialCase that can do ops with different specializations of itself. So I set up an override like this: template<typename T> struct SpecialCase { ... }; template<typename LT, typename RT> struct is_same<SpecialCase<LT>, SpecialCase<RT>> { enum { value = 1 }; }; However, this throws the error: more than one partial specialization matches the template argument list Now, I understand why. It's the case where LT == RT, which steps on the toes of is_same<T, T>. What I don't know is how to keep my SpecialCase override and get rid of the error. Is there a trick to get around this? edit: To clarify, I need all cases where LT != RT to also be considered the same (have value 1). Not just LT == RT.

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• MVC View Model Intellesense / Compile error

  - by Marty Trenouth

  I have one Library with my ORM and am working with a MVC Application. I have a problem where the pages won't compile because the Views can't see the Model's properties (which are inherited from lower level base classes). They system throws a compile error saying that 'object' does not contain a definition for 'ID' and no extension method 'ID' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?) implying that the View is not seeing the model. In the Controller I have full access to the Model and have check the Inherits from portion of the view to validate the correct type is being passed. Controller: return View(new TeraViral_Blog()); View: <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<com.models.TeraViral_Blog>" %> <asp:Content ID="Content1" ContentPlaceHolderID="TitleContent" runat="server"> Index2 </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server"> <h2>Index2</h2> <fieldset> <legend>Fields</legend> <p> ID: <%= Html.Encode(Model.ID) %> </p> </fieldset> </asp:Content>

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• Warning: cast increases required alignment

  - by dash-tom-bang

  I'm recently working on this platform for which a legacy codebase issues a large number of "cast increases required alignment to N" warnings, where N is the size of the target of the cast. struct Message { int32_t id; int32_t type; int8_t data[16]; }; int32_t GetMessageInt(const Message& m) { return *reinterpret_cast<int32_t*>(&data[0]); } Hopefully it's obvious that a "real" implementation would be a bit more complex, but the basic point is that I've got data coming from somewhere, I know that it's aligned (because I need the id and type to be aligned), and yet I get the message that the cast is increasing the alignment, in the example case, to 4. Now I know that I can suppress the warning with an argument to the compiler, and I know that I can cast the bit inside the parentheses to void* first, but I don't really want to go through every bit of code that needs this sort of manipulation (there's a lot because we load a lot of data off of disk, and that data comes in as char buffers so that we can easily pointer-advance), but can anyone give me any other thoughts on this problem? I mean, to me it seems like such an important and common option that you wouldn't want to warn, and if there is actually the possibility of doing it wrong then suppressing the warning isn't going to help. Finally, can't the compiler know as I do how the object in question is actually aligned in the structure, so it should be able to not worry about the alignment on that particular object unless it got bumped a byte or two?

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• Popen is no able to process a command that runs in shell

  - by IceMan85

  Hello everybody, I have already read the previous questions posted on the same argument but I really haven't figured it out yet. I am trying to run a command that works without issues from the command line : xyz@klm:~/python-remoteWorkspace/PyLogParser/src:18:43ush -o PPP -p PRD -n log 'pwd' 6:43PM PPP:prd:lgsprdppp:/ama/log/PRD/ppp but when I do the same in python I always get errors : stringa = Popen(["ush -o PPP -p PRD -n log 'pwd'"], stdout=PIPE, stdin=PIPE).communicate()[0] Here the error. Traceback (most recent call last): File "getStatData.py", line 134, in retrieveListOfFiles(infoToRetList) File "getStatData.py", line 120, in retrieveListOfFiles stringa = Popen(["ush -o PPP -p PRD -n log 'pwd'"], stdout=PIPE, stdin=PIPE).communicate()[0] File "/opt/python-2.6-64/lib/python2.6/subprocess.py", line 595, in init errread, errwrite) File "/opt/python-2.6-64/lib/python2.6/subprocess.py", line 1092, in _execute_child raise child_exception OSError: [Errno 2] No such file or directory I've tried also different solutions like stringa = Popen(["ush", "-o", "PPP", "-p" "PRD", "-n", "log", '"pwd"'], stdout=PIPE, stdin=PIPE).communicate()[0] but nothing seems to work. I have also tried to put the absolute path to ush but nothing... Can somebody please explain me what am I doing wrong ? Thanks in advance, AM.

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• How best to deal with warning c4305 when type could change?

  - by identitycrisisuk

  I'm using both Ogre and NxOgre, which both have a Real typedef that is either float or double depending on a compiler flag. This has resulted in most of our compiler warnings now being: warning C4305: 'argument' : truncation from 'double' to 'Ogre::Real' When initialising variables with 0.1 for example. Normally I would use 0.1f but then if you change the compiler flag to double precision then you would get the reverse warning. I guess it's probably best to pick one and stick with it but I'd like to write these in a way that would work for either configuration if possible. One fix would be to use #pragma warning (disable : 4305) in files where it occurs, I don't know if there are any other more complex problems that can be hidden by not having this warning. I understand I would push and pop these in header files too so that they don't end up spreading across code. Another is to create some macro based on the accuracy compiler flag like: #if OGRE_DOUBLE_PRECISION #define INIT_REAL(x) (x) #else #define INIT_REAL(x) static_cast<float>( x ) #endif which would require changing all the variable initialisation done so far but at least it would be future proof. Any preferences or something I haven't thought of?

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• how to elegantly duplicate a graph (neural network)

  - by macias

  I have a graph (network) which consists of layers, which contains nodes (neurons). I would like to write a procedure to duplicate entire graph in most elegant way possible -- i.e. with minimal or no overhead added to the structure of the node or layer. Or yet in other words -- the procedure could be complex, but the complexity should not "leak" to structures. They should be no complex just because they are copyable. I wrote the code in C#, so far it looks like this: neuron has additional field -- copy_of which is pointer the the neuron which base copied from, this is my additional overhead neuron has parameterless method Clone() neuron has method Reconnect() -- which exchanges connection from "source" neuron (parameter) to "target" neuron (parameter) layer has parameterless method Clone() -- it simply call Clone() for all neurons network has parameterless method Clone() -- it calls Clone() for every layer and then it iterates over all neurons and creates mappings neuron=copy_of and then calls Reconnect to exchange all the "wiring" I hope my approach is clear. The question is -- is there more elegant method, I particularly don't like keeping extra pointer in neuron class just in case of being copied! I would like to gather the data in one point (network's Clone) and then dispose it completely (Clone method cannot have an argument though).

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• Texture2D.Bounds.Intersect, but the Bounds never move? - XNA, .Net 4.0

  - by Gineer

  Hi all, I am still shiny new to XNA, so please forgive any stupid question and statements in this post (The added issue is that I am using Visual Studio 2010 with .Net 4.0 which also means very few examples exist out on the web - well, none that I could find easily): I have two 2D objects in a "game" that I am using to learn more about XNA. I need to figure out when these two objects intersect. I noticed that the Texture2D objects has a property named "Bounds" which in turn has a method named "Intersects" which takes a Rectangle (the other Texture2D.Bounds) as an argument. However when you run the code, the objects always intersect even if they are on separate sides of the screen. When I step into the code, I noticed that for the Texture2D Bounds I get 4 parameters back when you mouse over the Bounds and the X, and Y coordinates always read "X = 0, Y = 0" for both objects (hence they always intersect). The thing that confuses me is the fact that the Bounds property is on the Texture rather than on the Position (or Vector2) of the objects. I eventually created a little helper method that takes in the objects and there positions and then calculate whether they intersect, but I'm sure there must be a better way. any suggestions, pointers would be much appreciated. Gineer

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• Parse multiple named command line parameters

  - by scholzr

  I need to add the ability to a program to accept multiple named parameters when opening the program via the command line. i.e. program.exe /param1=value /param2=value and then be able to utilize these parameters as variables in the program. I have found a couple of ways to accomplish pieces of this, but can't seem to figure out how to put it all together. I have been able to pass one named parameter and recover it using the code below, and while I could duplicate it for every possible named parameter, I know that can't be the preffered way to do this. Dim inputArgument As String = "/input=" Dim inputName As String = "" For Each s As String In My.Application.CommandLineArgs If s.ToLower.StartsWith(inputArgument) Then inputName = s.Remove(0, inputArgument.Length) End If Next Alternatively, I can get multiple unnamed parameters from the command line using My.Application.CommandLineArgs But this requires that the parameters all be passed in the same order/format each time. I need to be able to pass a random subset of parameters each time. Ultimately, what I would like to be able to do, is separate each argument and value, and load it into a multidimentional array for later use. I know that I could find a way to do this by separating the string at the "=" and stripping the "/", but as I am somewhat new to this, I wanted to see if there was a "preffered" way for dealing with multiple named parameters?

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• Running an RMI registry on one computer and connecting to it from another

  - by Hippopotamus

  Hello. I am doing a student assignment, using java RMI. I've programmed a simple RMI-server application that provides method which return some strings to the client. When I start the server on localhost and connect to it by client on the same computer, everything goes well. However, I am not able to do this between two computers on home network. The computers both have no trouble of connecting by a simple C program with similar functionality, so I guess the problem is with JVM here. I am binding the class to rmiregistry with try{ ComputeImpl R = new ComputeImpl(); Naming.rebind("rmi://localhost/ComputeService",R); } catch(Exception e){ System.out.println("Trouble: " +e); } And I'm doing the lookup for RMI registry in the client application with providing the argument while launching the application: StringBuffer rmi_address = new StringBuffer(); rmi_address.append("rmi://").append(args[1]).append("/ComputeService"); Compute R = (Compute) Naming.lookup(rmi_address.toString()); Is the problem with my code or with JVM? Thanks in advance.

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• Python and the self parameter

  - by Svend

  I'm having some issues with the self parameter, and some seemingly inconsistent behavior in Python is annoying me, so I figure I better ask some people in the know. I have a class, Foo. This class will have a bunch of methods, m1, through mN. For some of these, I will use a standard definition, like in the case of m1 below. But for others, it's more convinient to just assign the method name directly, like I've done with m2 and m3. import os def myfun(x, y): return x + y class Foo(): def m1(self, y, z): return y + z + 42 m2 = os.access m3 = myfun f = Foo() print f.m1(1, 2) print f.m2("/", os.R_OK) print f.m3(3, 4) Now, I know that os.access does not take a self parameter (seemingly). And it still has no issues with this type of assignment. However, I cannot do the same for my own modules (imagine myfun defined off in mymodule.myfun). Running the above code yields the following output: 3 True Traceback (most recent call last): File "foo.py", line 16, in <module> print f.m3(3, 4) TypeError: myfun() takes exactly 2 arguments (3 given) The problem is that, due to the framework I work in, I cannot avoid having a class Foo at least. But I'd like to avoid having my mymodule stuff in a dummy class. In order to do this, I need to do something ala def m3(self,a1, a2): return mymodule.myfun(a1,a2) Which is hugely redundant when you have like 20 of them. So, the question is, either how do I do this in a totally different and obviously much smarter way, or how can I make my own modules behave like the built-in ones, so it does not complain about receiving 1 argument too many.

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• How to use R's ellipsis feature when writing your own function?

  - by Ryan Thompson

  The R language has a nifty feature for defining functions that can take a variable number of arguments. For example, the function data.frame takes any number of arguments, and each argument becomes the data for a column in the resulting data table. Example usage: > data.frame(letters=c("a", "b", "c"), numbers=c(1,2,3), notes=c("do", "re", "mi")) letters numbers notes 1 a 1 do 2 b 2 re 3 c 3 mi The function's signature includes an ellipsis, like this: function (..., row.names = NULL, check.rows = FALSE, check.names = TRUE, stringsAsFactors = default.stringsAsFactors()) { [FUNCTION DEFINITION HERE] } I would like to write a function that does something similar, taking multiple values and consolidating them into a single return value (as well as doing some other processing). In order to do this, I need to figure out how to "unpack" the ... from the function's arguments within the function. I don't know how to do this. The relevant line in the function definition of data.frame is object <- as.list(substitute(list(...)))[-1L], which I can't make any sense of. So how can I convert the ellipsis from the function's signature into, for example, a list? To be more specific, how can I write get_list_from_ellipsis in the code below? my_ellipsis_function(...) { input_list <- get.list.from.ellipsis(...) output_list <- lapply(X=input_list, FUN=do_something_interesting) return(output_list) } my_ellipsis_function(a=1:10,b=11:20,c=21:30)

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• Strategies for when to use properties and when to use internal variables on internal classes?

  - by Edward Tanguay

  In almost all of my classes, I have a mixture of properties and internal class variables. I have always chosen one or the other by the rule "property if you need it externally, class variable if not". But there are many other issues which make me rethink this often, e.g.: at some point I want to use an internal variable from outside the class, so I have to refactor it into a property which makes me wonder why I don't just make all my internal variables properties in case I have to access them externally anyway, since most classes are internal classes anyway it aren't exposed on an API so it doesn't really matter if the internal variables are accessible from outside the class or not but then since C# doesn't allow you to instantiate e.g. List<string> property in the definition, then these properties have to be initialized in every possible constructor, so these variables I would rather have internal variables just to keep things cleaner in that they are all initialized in one place C# code reads more cleanly if constructor/method parameters are camel case and you assign them to pascal case properties instead of the ambiguity of seeing "templateIdCode" and having to look around to see if it is a local variable, method parameter or internal class variable, e.g. it is easier when you see "TemplateIdCode = templateIdCode" that this is a parameter being assigned to a class property. This would be an argument for always using only properties on internal classes. e.g.: public class TextFile { private string templateIdCode; private string absoluteTemplatePathAndFileName; private string absoluteOutputDirectory; private List<string> listItems = new List<string>(); public string Content { get; set; } public List<string> ReportItems { get; set; } public TextFile(string templateIdCode) { this.templateIdCode = templateIdCode; ReportItems = new List<string>(); Initialize(); } ... When creating internal (non-API) classes, what are your strategies in deciding if you should create an internal class variable or a property?

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• Strange results from OdbcDataReader reading Sqlite DB

  - by stout

  This method returns some strange results, and was wondering if someone could explain why this is happening, and possibly a solution to get my desired results. Results: FileName = what I'd expect FileSize = what I'd expect Buffer = all bytes = 0 BytesRead = 0 BlobString = string of binary data FieldType = BLOB (what I'd expect) ColumnType = System.String Furthermore, if the file is greater than a few KB, the reader throws an exception stating the StringBuilder capacity argument must be greater than zero (presummably because the size is greater than Int32.MaxValue). I guess my question is how does one properly read large BLOBs from an OdbcDataReader? public static String SaveBinaryFile(String Key) { try { Connect(); OdbcCommand Command = new OdbcCommand("SELECT [_filename_],[_filesize_],[_content_] FROM [_sys_content] WHERE [_key_] = '" + Key + "';", Connection); OdbcDataReader Reader = Command.ExecuteReader(CommandBehavior.SequentialAccess); if (Reader.HasRows == false) return null; String FileName = Reader.GetString(0); int FileSize = int.Parse(Reader.GetString(1)); byte[] Buffer = new byte[FileSize]; long BytesRead = Reader.GetBytes(2, 0, Buffer, 0, FileSize); String BlobString = (String)Reader["_content_"]; String FieldType = Reader.GetDataTypeName(2); Type ColumnType = Reader.GetFieldType(2); return null; } catch (Exception ex) { Tools.ErrorHandler.Catch(ex); return null; } }

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• How to associate application with existing file types using WiX installer?

  - by Marek

  related to this: http://stackoverflow.com/questions/138550/how-to-register-file-types-extensions-with-a-wix-installer but not a duplicate. I need to handle existing file types (.jpg files). I do not want to be the default handler for .jpg, I would just like to extend the "Open with" menu with a link to my app. I see HKCR\.jpg\OpenWithList\ and HKCR\.jpg\OpenWithProgIds\ in the registry but I am not sure whether to write to these and how to do it correctly with WiX. Should I use something like this? <ProgId Id='??what here?' Description='Jpeg handled by my App'> <Extension Id='jpg' ContentType='image/jpeg'> <Verb Id='openwithmyapp' Sequence='10' Command='OpenWithMyApp' Target='[!FileId]' Argument='"%1"' /> </Extension> </ProgId> There are many ways how to fail here (like Photo Mechanics did, the HKCR for image file types is a real mess after I have installed this software) How to do this correctly with WiX?

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• PHP Exceptions in Classes

  - by mike condiff

  I'm writing a web application (PHP) for my friend and have decided to use my limited OOP training from Java. My question is what is the best way to note in my class/application that specific critical things failed without actually breaking my page. Currently my problem is I have an Object "SummerCamper" which takes a camper_id as it's argument to load all of the necessary data into the object from the database. Say someone specifies a camper_id in the querystring that does not exist, I pass it to my objects constructor and the load fails. Currently I don't see a way for me to just return false from the constructor. I have read I could possibly do this with Exceptions, throwing an exception if no records are found in the database or if some sort of validation fails on input of the camper_id from the application etc. However, I have not really found a great way to alert my program that the Object Load has failed. I tried returning false from within the CATCH but the Object still persists in my php page. I do understand I could put a variable $is_valid = false if the load fails and then check the Object using a get method but I think there may be better ways. What is the best way of achieving the essential termination of an object if a load fails? Should I load data into the object from outside the constructor? Is there some osrt of design pattern that I should look into? Any help would be appreciated.

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