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  • Referencing not-yet-defined variables - Java

    - by user2537337
    Because I'm tired of solving math problems, I decided to try something more engaging with my very rusty (and even without the rust, very basic) Java skills. I landed on a super-simple people simulator, and thus far have been having a grand time working through the various steps of getting it to function. Currently, it generates an array of people-class objects and runs a for loop to cycle through a set of actions that alter the relationships between them, which I have stored in a 2d integer array. When it ends, I go look at how much they all hate each other. Fun stuff. Trouble has arisen, however, because I would like the program to clearly print what action is happening when it happens. I thought the best way to do this would be to add a string, description, to my "action" class (which stores variables for the actor, reactor, and the amount the relationship changes). This works to a degree, in that I can print a generic message ("A fight has occurred!") with no problem. However, ideally I would like it to be a little more specific ("Person A has thrown a rock at Person B's head!"). This latter goal is proving more difficult: attempting to construct an action with a description string that references actor and reactor gets me a big old error, "Cannot reference field before it is defined." Which makes perfect sense. I believe I'm not quite in programmer mode, because the only other way I can think to do this is an unwieldy switch statement that negates the need for each action to have its own nicely-packaged description. And there must be a neater way. I am not looking for examples of code, only a push in the direction of the right concept to handle this.

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  • Bitwise operators and converting an int to 2 bytes and back again.

    - by aKiwi
    first time user, Hi guys! So hopefully someone can help.. My background is php so entering the word of lowend stuff like, char is bytes, which are bits.. which is binary values.. etc is taking some time to get the hang of ;) What im trying to do here is sent some values from an Ardunio board to openFrameWorks (both are c++). What this script currently does (and works well for one sensor i might add) when asked for the data to be sent is.. int value_01 = analogRead(0); // which outputs between 0-1024 unsigned char val1; unsigned char val2; //some Complicated bitshift operation val1 = value_01 &0xFF; val2 = (value_01 >> 8) &0xFF; //send both bytes Serial.print(val1, BYTE); Serial.print(val2, BYTE); Apparently this is the most reliable way of getting the data across.. So now that it is send via serial port, the bytes are added to a char string and converted back by.. int num = ( (unsigned char)bytesReadString[1] << 8 | (unsigned char)bytesReadString[0] ); So to recap, im trying to get 4 sensors worth of data (which im assuming will be 8 of those serialprints?) and to have int num_01 - num_04... at the end of it all. Im assuming this (as with most things) might be quite easy for someone with experience in these concepts.. Any help would be greatly appreciated. Thanks

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  • How do I create a Status Icon / System Tray Icon with custom text and transparent background using P

    - by Raugturi
    Here is the code that I have so far to define the icon: icon_bg = gtk.gdk.pixbuf_new_from_file('gmail.png') w, h = icon_bg.get_width(), icon_bg.get_height() cmap = gtk.gdk.Colormap(gtk.gdk.visual_get_system(), False) drawable = gtk.gdk.Pixmap(None, w, h, 24) drawable.set_colormap = cmap gc = drawable.new_gc() drawable.draw_pixbuf(gc, icon_bg, 0, 0, 0, 0, w, h) drawn_icon = gtk.gdk.Pixbuf(gtk.gdk.COLORSPACE_RGB, False, 8, w, h) drawn_icon.get_from_drawable(drawable, cmap, 0, 0, 0, 0, w, h) icon = gtk.status_icon_new_from_pixbuf(drawn_icon) This works to get the png into the icon, but falls short in two areas. First, transparency is not working. If I use a 22x22 png with transparent background and the image centered, I end up with sections of other active icons showing up inside of mine, like this: http://i237.photobucket.com/albums/ff311/Raugturi/22x22_image_with_transparency.png The icon it choose to steal from is somewhat random. Sometimes it's part of the dropbox icon, others the NetworkManager Applet. If I instead use this code: icon_bg = gtk.gdk.pixbuf_new_from_file('gmail.png') w, h = icon_bg.get_width(), icon_bg.get_height() cmap = gtk.gdk.Colormap(gtk.gdk.visual_get_system(), False) drawable = gtk.gdk.Pixmap(None, w, h, 24) drawable.set_colormap = cmap gc = drawable.new_gc() drawable.draw_pixbuf(gc, icon_bg, 0, 0, 0, 0, w, h) drawn_icon = gtk.gdk.Pixbuf(gtk.gdk.COLORSPACE_RGB, False, 8, 22, 22) drawn_icon.get_from_drawable(drawable, cmap, 0, 0, 3, 6, w, h) icon = gtk.status_icon_new_from_pixbuf(drawn_icon) And an image that is only 16x11 with the transparent edges removed, what I end up with is this: Same URL but file is 16x11_image_positioned_in_middle.png So how do I end up with a transparent block like the 1st one that doesn't pull in stuff from other icons? As for the second problem, I need the ability to write on the image before converting it to the icon. I tried using draw_glyphs and it told me I should be using Pango layout/context instead. Unfortunately all the Pango tutorials I could find deal with actual windows, not the status icon. Is there a good tutorial out there for Pango that would apply to this issue (and also maybe have at least some explanation of how to tell it what font to use as all of them that I found seem to lack this and it won't write anything without it). Note: Sorry for the lack of actual images and only one working link, apparently this is a spam prevention feature due to my lack of reputation.

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  • Getting started with open source

    - by lola
    Hi all, I'm an undergraduate who has decided that he wants to join the open source community and contribute. However, I have come to think that, once you have chosen an open source project, a lot of time is spent in learning the nitty gritties of that project in addition to stuff like subversion,etc which a typical undergraduate isn't exposed to. So, you have to stick with that project for a long time, say a year or two, before moving on to other projects. In this case, choosing the right(for you) initial project is very important since if you choose one,and say, the development in your field of interest(in that project) is a low priority and not exciting enough, you'll lose interest and stop contributing to open source all together. So what I wanted to know was, since there are thousands of open source projects, is all this being documented somewhere with tags,etc so that a beginner can choose his projects. The GSoc 2010 ideas list is a great starting point, but it only covers a handful. Hence, I thought why not ask this at stackoverflow: if you have any pointers as to where to start, when choosing a FOSS project or any other tips related to starting with FOSS. P.S. I'm interested in projects involving mobile ad hoc networks(those using TinyOS, preferably), so pointers related to these will be great. I'm looking through Freifunk and OLPC as of now, needed more ideas.

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  • Maven POM: how to insist property is not overridden

    - by Joe Thomas
    I have a parent POM that uses a gmaven script to do some stuff: <plugin> <groupId>org.codehaus.gmaven</groupId> <artifactId>gmaven-plugin</artifactId> <version>1.4</version> <configuration combine.children="override"> <providerSelection>2.0</providerSelection> <scriptPath>${basedir}/build/groovy</scriptPath> </configuration> <executions> <execution> <id>groovy-properties-script</id> <phase>validate</phase> <goals> <goal>execute</goal> </goals> <configuration> <source>computeProperties.groovy</source> </configuration> </execution> <!-- ... --> All of the children are supposed to run this script as well, but they try to resolve the scriptpath based on their OWN basedir. Usually this is exactly what you want with properties, but here it doesn't work, and I can't figure out any way around it.

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  • UnicodeEncodeError: 'ascii' codec can't encode character [...]

    - by user1461135
    I have read the HOWTO on Unicode from the official docs and a full, very detailed article as well. Still I don't get it why it throws me this error. Here is what I attempt: I open an XML file that contains chars out of ASCII range (but inside allowed XML range). I do that with cfg = codecs.open(filename, encoding='utf-8, mode='r') which runs fine. Looking at the string with repr() also shows me a unicode string. Now I go ahead and read that with parseString(cfg.read().encode('utf-8'). Of course, my XML file starts with this: <?xml version="1.0" encoding="utf-8"?>. Although I suppose it is not relevant, I also defined utf-8 for my python script, but since I am not writing unicode characters directly in it, this should not apply here. Same for the following line: from __future__ import unicode_literals which also is right at the beginning. Next thing I pass the generated Object to my own class where I read tags into variables like this: xmldata.getElementsByTagName(tagName)[0].firstChild.data and assign it to a variable in my class. Now what perfectly works are those commands (obj is an instance of the class): for element in obj: print element And this command does work as well: print obj.__repr__() I defined __iter__() to just yield every variable while __repr__() uses the typical printf stuff: "%s" % self.varname Both commands print perfectly and can output the unicode character. What does not work is this: print obj And now I am stuck because this throws the dreaded UnicodeEncodeError: 'ascii' codec can't encode character u'\xfc' in position 47: So what am I missing? What am I doing wrong? I am looking for a general solution, I always want to handle strings as unicode, just to avoid any possible errors and write a compatible program. Edit: I also defined this: def __str__(self): return self.__repr__() def __unicode__(self): return self.__repr__() From documentation I got that this

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  • Anchor as a Submit button

    - by griegs
    I have an MVC 2 application that has the following on it; <% using( Html.BeginForm("Results","Quote", FormMethod.Post, new { name="Results" })){ %> <% Html.RenderPartial("Needs", Model.needs); %> <div class="But green" style=""> <a href="." onclick="javascript:document.Results.submit();">Go</a> </div> <input type="submit" /> <%} %> Pressing the Submit button or the anchor both post back to the right ActionResult. However, when in the controller I return View(stuff..) only the Submit button will come back to the page. When the call finishes from pressing the anchor, I go to an error page informing me that the resource cannot be found. I suspect it has something to do with href="." but am unsure what to set it to.

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  • Help me clean up this crazy lambda with the out keyword

    - by Sarah Vessels
    My code looks ugly, and I know there's got to be a better way of doing what I'm doing: private delegate string doStuff( PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt ); private bool tryEncryptPassword( doStuff encryptPassword, out string errorMessage ) { ...get some variables... string encryptedPassword = encryptPassword(encrypter, publicKey, privateKey, out salt); ... } This stuff so far doesn't bother me. It's how I'm calling tryEncryptPassword that looks so ugly, and has duplication because I call it from two methods: public bool method1(out string errorMessage) { string rawPassword = "foo"; return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 1 rawPassword, publicKey, privateKey, out salt ), out errorMessage ); } public bool method2(SecureString unencryptedPassword, out string errorMessage) { return tryEncryptPassword( (PasswordEncrypter encrypter, RSAPublicKey publicKey, string privateKey, out string salt) => encrypter.EncryptPasswordAndDoStuff( // Overload 2 unencryptedPassword, publicKey, privateKey, out salt ), out errorMessage ); } Two parts to the ugliness: I have to explicitly list all the parameter types in the lambda expression because of the single out parameter. The two overloads of EncryptPasswordAndDoStuff take all the same parameters except for the first parameter, which can either be a string or a SecureString. So method1 and method2 are pretty much identical, they just call different overloads of EncryptPasswordAndDoStuff. Any suggestions? Edit: if I apply Jeff's suggestions, I do the following call in method1: return tryEncryptPassword( (encrypter, publicKey, privateKey) => { var result = new EncryptionResult(); string salt; result.EncryptedValue = encrypter.EncryptPasswordAndDoStuff( rawPassword, publicKey, privateKey, out salt ); result.Salt = salt; return result; }, out errorMessage ); Much the same call is made in method2, just with a different first value to EncryptPasswordAndDoStuff. This is an improvement, but it still seems like a lot of duplicated code.

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  • How do I display java.lang.* object allocations in Eclipse profiler?

    - by Martin Wickman
    I am profiling an application using the Eclipse profiler. I am particularly interested in number of allocated object instances of classes from java.lang (for instance java.lang.String or java.util.HashMap). I also want to know stuff like number of calls to String.equals() etc. I use the "Object Allocations" tab and I shows all classes in my application and a count. It also shows all int[], byte[], long[] etc, but there is no mention of any standard java classes. For instance, this silly code: public static void main(String[] args) { Object obj[] = new Object[1000]; for (int i = 0; i < 1000; i++) { obj[i] = new StringBuffer("foo" + i); } System.out.println (obj[30]); } Shows up in the Object Allocations tab as 7 byte[]s, 4 char[]s and 2 int[]s. It doesn't matter if I use 1000 or 1 iterations. It seems the profiler simply ignores everything that is in any of the java.* packages. The same applies to Execution Statistics as well. Any idea how to display instances of java.* in the Eclipse Profiler?

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  • Weird output of Throwable getMessage()

    - by Ravi Gupta
    Hi I have below pseudo code with throws an exception like this throw new MyException("Bad thing happened","com.stuff.errorCode"); where MyException extends Exception class. So the problem is when I try to get the message from MyException class by calling myEx.getMessage() it returns ???en_US.Bad thing happened??? instead of my original message i.e. Bad thing happened I have checked that MyException class doesn't overrides Throwable class's getMessage() behavior. Below is the how the call passes from MyException.getMessage() to Throwable.getMessage() public MyException(String msg, String sErrorCode){ super(msg); this.sErrorCode = sErrorCode; this.iSeverity = 0; } which then calls public Exception(String message) { super(message); } and finally public Throwable(String message) { fillInStackTrace(); detailMessage = message; } when I do a getMessage on myexception it calls Throwable's getMessage as below public String getMessage() { return detailMessage; } So ideally it should return the original message as I set when throwing the exception. What's the ???en_US thing ?

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  • A question about entities, roles and interfaces in Entity Framework 4.

    - by mvole
    Hi, I am an experienced .NET developer but new to EF - so please bear with me. I will use an example of a college application to illustrate my problem. I have these user roles: Lecturer, Student, Administrator. In my code I envisage working with these entities as distinct classes so e.g. a Lecturer teaches a collection of Students. And work with 'is Student' 'TypeOf' etc. Each of these entities share lots of common properties/methods e.g. they can all log onto the system and do stuff related to their role. In EF designer I can create a base entity Person (or User...) and have Lecturer, Student and Administrator all inherit from that. The difficulty I have is that a Lecturer can be an Administrator - and in fact on occasion a Student can be a Lecturer. If I were to add other entities such as Employee and Warden then this gets even more of an issue. I could presumably work with Interfaces so a person could implement ILecturer and IStudent, however I do not see how this fits within EF. I would like to work within the EF designer if possible and I'm working model-first (coding in C#). So any help and advice/samples would be very welcome and much appreciated. Thanks

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  • Emptying the datastore in GAE

    - by colwilson
    I know what you're thinking, 'O not that again!', but here we are since Google have not yet provided a simpler method. I have been using a queue based solution which worked fine: import datetime from models import * DELETABLE_MODELS = [Alpha, Beta, AlphaBeta] def initiate_purge(): for e in config.DELETABLE_MODELS: deferred.defer(delete_entities, e, 'purging', _queue = 'purging') class NotEmptyException(Exception): pass def delete_entities(e, queue): try: q = e.all(keys_only=True) db.delete(q.fetch(200)) ct = q.count(1) if ct > 0: raise NotEmptyException('there are still entities to be deleted') else: logging.info('processing %s completed' % queue) except Exception, err: deferred.defer(delete_entities, e, then, queue, _queue = queue) logging.info('processing %s deferred: %s' % (queue, err)) All this does is queue a request to delete some data (once for each class) and then if the queued process either fails or knows there is still some stuff to delete, it re-queues itself. This beats the heck out of hitting the refresh on a browser for 10 minutes. However, I'm having trouble deleting AlphaBeta entities, there are always a few left at the end. I think because it contains Reference Properties: class AlphaBeta(db.Model): alpha = db.ReferenceProperty(Alpha, required=True, collection_name='betas') beta = db.ReferenceProperty(Beta, required=True, collection_name='alphas') I have tried deleting the indexes relating to these entity types, but that did not make any difference. Any advice would be appreciated please.

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  • Ruby On Rails with HTML5 offline apps - Firefox does not cache the application.manifest but Safari does

    - by hoitomt
    I'm working off of this Railscast tutorial: episode 247 I’m up to this point in the tutorial: added the rack-offline gem, added the application.manifest route, and added a reference to the manifest in the html tag. Right before it starts talking about problems with caching. Safari works as intended – When the server is running the page is served. From the server logs I can see that Safari is making a single request to the server every time for the items page. When I turn off the server the page displays as well, even after shutting down the browser and restarting. It appears to be pulling from the application.manifest (cache manifest). Firefox does not work as intended – When accessing the page for the first time, Firefox lets me know that the web page wants to store something locally, I allow. After clicking on allow, Firefox makes 5 requests to the server for the page (from the server log). The hash is different in every request. Is it is possible that the changing hash is triggering Firefox to keep trying to get the new manifest until it reaches some maximum (5 attempts)? Then, after the server is stopped, Firefox will not show the page at all. It looks like it isn’t caching the application.manifest. Firefox also gives you a way to see what sites are storing stuff locally by going to Tools/Options/Advanced/Network (Firefox/Preferences/Advanced/Network on Apple). I see localhost there but the size is 0 bytes. So for some reason, Firefox is not downloading my application.manifest along with the files

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  • Is there any benefit to my rather quirky character sizing convention?

    - by Paul Alan Taylor
    I love things that are a power of 2. I celebrated my 32nd birthday knowing it was the last time in 32 years I'd be able to claim that my age was a power of 2. I'm obsessed. It's like being some Z-list Batman villain, except without the colourful adventures and a face full of batarangs. I ensure that all my enum values are powers of 2, if only for future bitwise operations, and I'm reasonably assured that there is some purpose (even if latent) for doing it. Where I'm less sure, is in how I define the lengths of database fields. Again, I can't help it. Everything ends up being a power of 2. CREATE TABLE Person ( PersonID int IDENTITY PRIMARY KEY ,Firstname varchar(64) ,Surname varchar(128) ) Can any SQL super-boffins who know about the internals of how stuff is stored and retrieved tell me whether there is any benefit to my inexplicable obsession? Is it more efficient to size character fields this way? Can anyone pop in with an "actually, what you're doing works because ....."? I suspect I'm just getting crazier in my older age, but it'd be nice to know that there is some method to my madness.

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  • java: "downcasting" to new object / opposite of slicing

    - by rhavin
    Sorry, i really dont know how to make a headline for that question; maybe there is a name for what im trying to do that i dont know, but i can explain it with some code: Guess you have a class that unfortunately neither has a copy-constructor nor a public static copy method. class A { private int i; // <- private, cant access String x; // <- even worse: cant access unless in same pkg! /* … other stuff, ctor, etc. … */ public A clone() { A a = new A(); a.i = i; a.x = x; return x; } } Guess further, there is some function that returns an object of that class: public static A someFn(x,y,z); Now the problem: I want to derive from that class to add some functionality. Unfortunately, i neither have a sizeof in java nor a cc or static copy method. So when i do a class B extends A { protected w; public B clone() { /* as usual */ } } then i can clone my B and get a new one, but how can i convert the returned A from someFn() into a B. Is there anyway to do the opposite of slicing in java? if i clone it, it's still an A, and i cant copy it field by field. This is all simple in c++, but how to do this in Java?

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  • Semantically correct XHTML markup

    - by Dori
    Hello all. Just trying to get the hang of using the semantically correct XHTML markup. Just writing the code for a small navigation item. Where each button has effectivly a title and a descrption. I thought a definition list would therefore be great so i wrote the following <dl> <dt>Import images</dt> <dd>Read in new image names to database</dd> <dt>Exhibition Management</dt> <dd>Create / Delete an exhibition </dd> <dt>Image Management</dt> <dd>Edit name, medium and exhibition data </dd> </dl> But...I want the above to be 3 buttons, each button containing the dt and dd text. How can i do this with the correct code? Normally i would make each button a div and use that for the visual button behaviour (onHover and current page selection stuff). Any advice please Thanks

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  • Practice of checking 'trueness' or 'equality' in conditional statements - does it really make sense?

    - by Senthil
    I remember many years back, when I was in school, one of my computer science teachers taught us that it was better to check for 'trueness' or 'equality' of a condition and not the negative stuff like 'inequality'. Let me elaborate - If a piece of conditional code can be written by checking whether an expression is true or false, we should check the 'trueness'. Example: Finding out whether a number is odd - it can be done in two ways: if ( num % 2 != 0 ) { // Number is odd } or if ( num % 2 == 1 ) { // Number is odd } When I was beginning to code, I knew that num % 2 == 0 implies the number is even, so I just put a ! there to check if it is odd. But he was like 'Don't check NOT conditions. Have the practice of checking the 'trueness' or 'equality' of conditions whenever possible.' And he recommended that I use the second piece of code. I am not for or against either but I just wanted to know - what difference does it make? Please don't reply 'Technically the output will be the same' - we ALL know that. Is it a general programming practice or is it his own programming practice that he is preaching to others?

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  • Refactoring or Rewriting Monolithic PHP Spaghetti Codebase

    - by nategood
    I've inherited a really poorly designed PHP spaghetti code project. It's been gaining a good bit of traffic recently and is starting to have performance issues on top of the poor monolithic code base. Its maxing out performance on a chunky 16GB dedicated machine when it really shouldn't be. I'm planning on doing some performance tweaks right off the bat to help the performance issue, but this still won't really help the horrible code base. The team is small but expecting to grow very soon. I've read Joel's article on the troubles of doing a complete rewrite and see the concerns. But how bad does the code base have to be before you consider a rewrite? There is PHP handling logic interjected into what one would usually consider a "view". Even worse, in some places SQL statements are in these same files! The only real separation of presentation and logic are a few PHP scripts that serve as function libraries. These scripts do most of the ORM stuff... if you can even call it that. Trying to slowly refractor this seems like a nightmare. Open to your thoughts and opinions... however not interested in hearing, "Run away, Run away!".

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  • how does one _model_ data from relational databases in clojure ?

    - by sandeep
    I have asked this question on twitter as well the #clojure IRC channel, yet got no responses. There have been several articles about Clojure-for-Ruby-programmers, Clojure-for-lisp-programmers.. but what is the missing part is Clojure for ActiveRecord programmers . There have been articles about interacting with MongoDB, Redis, etc. - but these are key value stores at the end of the day. However, coming from a Rails background, we are used to thinking about databases in terms of inheritance - has_many, polymorphic, belongs_to, etc. The few articles about Clojure/Compojure + MySQL (ffclassic) - delve right into sql. Of course, it might be that an ORM induces impedence mismatch, but the fact remains that after thinking like ActiveRecord, it is very difficult to think any other way. I believe that relational DBs, lend themselves very well to the object-oriented paradigm because of them being , essentially, Sets. Stuff like activerecord is very well suited for modelling this data. For e.g. a blog - simply put class Post < ActiveRecord::Base has_many :comments end class Comment < ActiveRecord::Base belongs_to :post end How does one model this in Clojure - which is so strictly anti-OO ? Perhaps the question would have been better if it referred to all functional programming languages, but I am more interested from a Clojure standpoint (and Clojure examples)

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  • pure/const functions in C++

    - by Albert
    Hi, I'm thinking of using pure/const functions more heavily in my C++ code. (pure/const attribute in GCC) However, I am curious how strict I should be about it and what could possibly break. The most obvious case are debug outputs (in whatever form, could be on cout, in some file or in some custom debug class). I probably will have a lot of functions, which don't have any side effects despite this sort of debug output. No matter if the debug output is made or not, this will absolutely have no effect on the rest of my application. Or another case I'm thinking of is the use of my own SmartPointer class. In debug mode, my SmartPointer class has some global register where it does some extra checks. If I use such an object in a pure/const function, it does have some slight side effects (in the sense that some memory probably will be different) which should not have any real side effects though (in the sense that the behaviour is in any way different). Similar also for mutexes and other stuff. I can think of many complex cases where it has some side effects (in the sense of that some memory will be different, maybe even some threads are created, some filesystem manipulation is made, etc) but has no computational difference (all those side effects could very well be left out and I would even prefer that). How does it work out in practice? If I mark such functions as pure/const, could it break anything (considering that the code is all correct)?

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  • C# / IronPython Interop with shared C# Class Library

    - by Adam Haile
    I'm trying to use IronPython as an intermediary between a C# GUI and some C# libraries, so that it can be scripted post compile time. I have a Class library DLL that is used by both the GUI and the python and is something along the lines of this: namespace MyLib { public class MyClass { public string Name { get; set; } public MyClass(string name) { this.Name = name; } } } The IronPython code is as follows: import clr clr.AddReferenceToFile(r"MyLib.dll") from MyLib import MyClass ReturnObject = MyClass("Test") Then, in C# I would call it as follows: ScriptEngine engine = Python.CreateEngine(); ScriptScope scope = null; scope = engine.CreateScope(); ScriptSource source = engine.CreateScriptSourceFromFile("Script.py"); source.Execute(scope); MyClass mc = scope.GetVariable<MyClass>("ReturnObject ") When I call this last bit of code, source.Execute(scope) runs returns successfully, but when I try the GetVariable call, it throw the following exception Microsoft.Scripting.ArgumentTypeException: expected MyClass , got MyClass So, you can see that the class names are exactly the same, but for some reason it thinks they are different. The DLL is in a different directory than the .py file (I just didn't bother to write out all the path setup stuff), could it be that there is an issue with the interpreter for IronPython seeing these objects as difference because it's somehow seeing them as being in a different context or scope?

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  • C# Virtual method call in constructor - how to refactor?

    - by Cristi Diaconescu
    I have an abstract class for database-agnostic cursor actions. Derived from that, there are classes that implement the abstract methods for handling database-specific stuff. The problem is, the base class ctor needs to call an abstract method - when the ctor is called, it needs to initialize the database-specific cursor. I know why this shouldn't be done, I don't need that explanation! This is my first implementation, that obviously doesn't work - it's the textbook "wrong way" of doing it. The overridden method accesses a field from the derived class, which is not yet instantiated: public abstract class CursorReader { private readonly int m_rowCount; protected CursorReader() { m_rowCount = CreateCursor(sqlCmd); //virtual call ! } protected abstract int CreateCursor(string sqlCmd); } public class SqlCursorReader : CursorReader { private SqlConnection m_sqlConnection; public SqlCursorReader(string sqlCmd, SqlConnection sqlConnection) { m_sqlConnection = sqlConnection; //field initialized here } protected override int CreateCursor(string sqlCmd) { //uses not-yet-initialized member *m_sqlConnection* //so this throws a NullReferenceException var cursor = new CustomCursor(sqlCmd, m_sqlConnection); return cursor.Count(); } } I will follow up with an answer on my attempts to fix this...

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  • Scala newbie vproducer/consumer attempt running out of memory

    - by Nick
    I am trying to create a producer/consumer type Scala app. The LoopControl just sends a message to the MessageReceiver continually. The MessageReceiver then delegates work to the MessageCreatorActor (whose work is to check a map for an object, and if not found create one and start it up). Each MessageActor created by this MessageCreatorActor is associated with an Id. Eventually this is where I want to do business logic. But I run out of memory after 15 minutes. Its finding the cached actors,but quickly runs out of memory. Any help is appreciated. Or any one has any good code on producers consumers doing real stuff (not just adding numbers), please post. import scala.actors.Actor import java.util.HashMap import scala.actors.Actor._ case object LoopControl case object MessageReceiver case object MessageActor case object MessageActorCreator class MessageReceiver(msg: String) extends Actor { var messageActorMap = new HashMap[String, MessageActor] val messageCreatorActor = new MessageActorCreator(null, null) def act() { messageCreatorActor.start loop { react { case MessageActor(messageId) => if (msg.length() > 0) { var messageActor = messageActorMap.get(messageId); if(messageActor == null) { messageCreatorActor ! MessageActorCreator(messageId, messageActorMap) }else { messageActor ! MessageActor } } } } } } case class MessageActorCreator(msg:String, messageActorMap: HashMap[String, MessageActor]) extends Actor { def act() { loop { react { case MessageActorCreator(messageId, messageActorMap) => if(messageId != null ) { var messageActor = new MessageActor(messageId); messageActorMap.put(messageId, messageActor) println(messageActorMap) messageActor.start messageActor ! MessageActor } } } } } class LoopControl(messageReceiver:MessageReceiver) extends Actor { var count : Int = 0; def act() { while (true) { messageReceiver ! MessageActor ("00-122-0X95-FEC0" + count) //Thread.sleep(100) count = count +1; if(count > 5) { count = 0; } } } } case class MessageActor(msg: String) extends Actor { def act() { loop { react { case MessageActor => println() println("MessageActor: Got something-> " + msg) } } } } object messages extends Application { val messageReceiver = new MessageReceiver("bootstrap") val loopControl = new LoopControl(messageReceiver) messageReceiver.start loopControl.start }

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  • How to handle management trying to interfere with the project (including architecture decision)

    - by Zwei Steinen
    I feel this is not a very good question to post on SO, but I need some advice from experienced developers... (I'm a second year developer) I guess this is a problem to many, many projects, but in our case, it is getting intense. There were so much interference from people that don't know a bit about software development, that our development came to an almost complete stop. We had to literary escape to another location to get any useful job done. Now we were happily producing results, but then I get a request for a "meeting" and it's them again. I have a friendly relationship with them, but I feel very daunted at the thought of talking about non-sense all over again. Should I be firm and tell them to shut up and wait for our results? Or should I be diplomatic and create an illusion they are making a positive contribution or something?? My current urge is to be unfriendly and murmur some stuff so they will give up or something. What would you do if you were in this situation?

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  • How would I code a complex formula parser manually?

    - by StormianRootSolver
    Hm, this is language - agnostic, I would prefer doing it in C# or F#, but I'm more interested this time in the question "how would that work anyway". What I want to accomplish ist: a) I want to LEARN it - it's about my ego this time, it's for a fun project where I want to show myself that I'm a really good at this stuff b) I know a tiny little bit about EBNF (although I don't know yet, how operator precedence works in EBNF - Irony.NET does it right, I checked the examples, but this is a bit ominous to me) c) My parser should be able to take this: 5 * (3 + (2 - 9 * (5 / 7)) + 9) for example and give me the right results d) To be quite frankly, this seems to be the biggest problem in writing a compiler or even an interpreter for me. I would have no problem generating even 64 bit assembler code (I CAN write assembler manually), but the formula parser... e) Another thought: even simple computers (like my old Sharp 1246S with only about 2kB of RAM) can do that... it can't be THAT hard, right? And even very, very old programming languages have formula evaluation... BASIC is from 1964 and they already could calculate the kind of formula I presented as an example f) A few ideas, a few inspirations would be really enough - I just have no clue how to do operator precedence and the parentheses - I DO, however, know that it involves an AST and that many people use a stack So, what do you think?

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