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  • Can't remove first node in linked list

    - by carlmonday
    I'm trying to make a linked list class in python (pointless I know, but it's a learning exercise), and the method I have written to remove a node doesn't work if I try to remove the first element of the linked list. If the node to be removed is anywhere else in the linked list the method works fine. Can someone give me some insight as to where I've gone wrong? Here's my code thus far: class Node: def __init__(self, data=None, next=None): self.data = data self.next = next def __repr__(self): return repr(self.data) def printNodes(self): while self: print self.data self = self.next def removeNode(self, datum): """removes node from linked list""" if self.data == datum: return self.next while self.next: if self.next.data == datum: self.next = self.next.next return self self = self.next

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  • CS, SE, HCI, Information Science, Please recommendation for further education of the former performing art manager seeking career in IT industries? [on hold]

    - by Baek Seungjoo
    IT specialists there J Thank you very much for your collective efforts here, and I got huge help reading your professional comments and advices on each questions I have searched so far! This time, I would like to ask for your practical advices or recommendation on what I am struggling on at this moment. I am currently seeking higher education for my career transition from performing art manager and director to “IT software and/or service development and management specialist”. However, as this field is quite new to me, and there are lots of different work positions, I have no idea which grad major I better pursue in order to get qualification. Of course I know this question could sounds wired as it is kind of personal choice. But my lack of understanding on how IT software companies work in general, your practical and experience-based advice will be great help to me, who spent more than two months of self-research on net. OK. Before my question, here is my plan and history, which are quite different from those currently in IT industry I think… 1) Target Firstly, get career transition into IT service or products companies and get experiences. Eventually, pursue IT entrepreneurship in combination with my arts and cultural production and business expertise. 2) Background Career: performing arts director and manager in theatre-based scale opera and musical Art education in youth BA in literature and Chinese studies (Art & Humanities) MA in Cultural & Creative Industries (Art & Humanities) – dissertation with focus on digital prosumption and the lived experience of the prosumer. (a qualitative research on the agents in the digital world) 2) Personally Huge interest in IT hardware and software, and their trend. Skills to build up, repair, tune PCs -of course this is no more than personal hobby, but shows my interests in this field. 4) Problem Encounter a question “So, what do you think you can contribute practically in this position”. This question turn me down everytime I go through job interviews, and I decided more education in the relevant area. Here are my questions. 1) In terms of work positions in IT software companies, I wonder if I can put the comparison of what “Artists” is to “Arts Manager or Director” is what “Developer” is to “Product Manager”. (Of course, this stereotypical division of Artist-Art Manager is out of sense because the domain overlaps to some extent, and is blurring at least in my field, and they are in different contexts, but just speaking easily.) Normally, artist comes with special arts educations, and they live in their own world of artistic inspiration and creation, and they feel alive in practice and on stages. Meanwhile, from the point of staging and managing productions, the role of art manager is critical as well. Our role cares how the production appeals to the audience in effective way, how to make profit and future sustainable management through that, how to set up future strategy in consideration of the external conditions such as political and social circumstances, audience trend and level, other production trends from on-going and historical perspectives, how and what the production make voice to the society from political, economic, humanitarian stances. So, we need keen eyes on economic, political, and societal environment, have to understand human-being and their desires, must know how to make presentation and attract investors, must have sense in managing and fighting over the limited financial resource, how to extend networking and so on. It is common that the two agents create productions in collaboration (normally not in that ideal way but in conflict and fight though J ). So, we need to know each other’s expertise to some extent, for better production. What are the work positions in IT software industries equivalent to the role of “art manager” in performing arts? From my view, considering developers come with special education in the world of computer science, software engineering, or others (self-education sometimes), and they express themselves with the arts of coding, computer languages on the black screen, and make sort of their artistic production online to the audience, I guess there might be someone who collaborate with developers in creating, managing, and launching IT services or products. 2) Which education among CS, SE, HCI, Information Science, is needed for those seeking such work position? Especially for person like me. (At this moment, Information Science has the highest possibility to get in, since I lack Calculus and Math in undergrad educaiton. But please let me know irrespective of this concern, I think there are ways to back it up if CS or SE education needed in my case) 3) Which field between Information Science and HCI can be more practical background regarding job hungting? And which of them have more demands in job market? AS I checked, HCI is more close to CS than IS in its focus of study area. Thank you very much for your patience reading such a long inquiry, and I appreciate to your efforts in advance. Have a nice day in this beautiful summer.

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  • Self-healing Cloud vs Failover Boxes

    - by IMB
    Now that self-healing cloud servers are becoming more and more popular, I am currently torn between the decision if I should setup a HAproxy failover for my VPS or if should save myself the trouble and just put my sites on a self-healing cloud server. Does it still make sense to setup your own failover system (HAproxy + 2 or more servers for example) when self healing cloud seems like a practical solution? They seem to do the same job or am I missing something?

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  • CS Education, where was it? Where is it now? Where is it going?

    - by CheesePls
    I'm planning on doing research into Computer Science education for my senior project and I could think of no better group of people to consult than the SO community. So, what do you think about the state of CS education in the United States (and the rest of the world, though I had planned on focusing on the US)? What do you feel are necessary topics? What topics are superfluous? Objects first vs. Objects early vs. Objects later? ALSO, if anyone has or knows of any blogs, studies, etc., those would be very helpful as well.

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  • Self referencing userdata and garbage collection

    - by drtwox
    Because my userdata objects reference themselves, I need to delete and nil a variable for the garbage collector to work. Lua code: obj = object:new() -- -- Some time later obj:delete() -- Removes the self reference obj = nil -- Ready for collection C Code: typedef struct { int self; // Reference to the object // Other members and function references removed } Object; // Called from Lua to create a new object static int object_new( lua_State *L ) { Object *obj = lua_newuserdata( L, sizeof( Object ) ); // Create the 'self' reference, userdata is on the stack top obj->self = luaL_ref( L, LUA_REGISTRYINDEX ); // Put the userdata back on the stack before returning lua_rawgeti( L, LUA_REGISTRYINDEX, obj->self ); // The object pointer is also stored outside of Lua for processing in C return 1; } // Called by Lua to delete an object static int object_delete( lua_State *L ) { Object *obj = lua_touserdata( L, 1 ); // Remove the objects self reference luaL_unref( L, LUA_REGISTRYINDEX, obj->self ); return 0; } Is there some way I can set the object to nil in Lua, and have the delete() method called automatically? Alternatively, can the delete method nil all variables that reference the object? Can the self reference be made 'weak'?

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  • Changing pointer of self

    - by rob5408
    I have an object that I alloc/init like normal just to get a instance. Later in my application I want to load state from disk for that object. I figure I could unarchive my class (which conforms to NSCoding) and just swap where my instance points to. To this end I use this code... NSString* pathForDataFile = [self pathForDataFile]; if([[NSFileManager defaultManager] fileExistsAtPath:pathForDataFile] == YES) { NSLog(@"Save file exists"); NSData *data = [[NSMutableData alloc] initWithContentsOfFile:pathForDataFile]; NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; [data release]; Person *tempPerson = [unarchiver decodeObjectForKey:@"Person"]; [unarchiver finishDecoding]; [unarchiver release]; if (tempPerson) { [self release]; self = [tempPerson retain]; } } Now when I sprinkled some NSLogs throughout my application I noticed self.person: <Person: 0x3d01a10> (After I create the object with alloc/init) self: <Person: 0x3d01a10> (At the start of this method) tempPerson: <Person: 0x3b1b880> (When I create the tempPerson) self: <Person: 0x3b1b880> (after i point self to the location of the tempPerson) self.person: <Person: 0x3d01a10> (After the method back in the main program) What am I missing?

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  • PyML 0.7.2 - How to prevent accuracy from dropping after storing/loading a classifier?

    - by Michael Aaron Safyan
    This is a followup from "Save PyML.classifiers.multi.OneAgainstRest(SVM()) object?". The solution to that question was close, but not quite right, (the SparseDataSet is broken, so attempting to save/load with that dataset container type will fail, no matter what. Also, PyML is inconsistent in terms of whether labels should be numbers or strings... it turns out that the oneAgainstRest function is actually not good enough, because the labels need to be strings and simultaneously convertible to floats, because there are places where it is assumed to be a string and elsewhere converted to float) and so after a great deal of hacking and such I was finally able to figure out a way to save and load my multi-class classifier without it blowing up with an error.... however, although it is no longer giving me an error message, it is still not quite right as the accuracy of the classifier drops significantly when it is saved and then reloaded (so I'm still missing a piece of the puzzle). I am currently using the following custom mutli-class classifier for training, saving, and loading: class SVM(object): def __init__(self,features_or_filename,labels=None,kernel=None): if isinstance(features_or_filename,str): filename=features_or_filename; if labels!=None: raise ValueError,"Labels must be None if loading from a file."; with open(os.path.join(filename,"uniquelabels.list"),"rb") as uniquelabelsfile: self.uniquelabels=sorted(list(set(pickle.load(uniquelabelsfile)))); self.labeltoindex={}; for idx,label in enumerate(self.uniquelabels): self.labeltoindex[label]=idx; self.classifiers=[]; for classidx, classname in enumerate(self.uniquelabels): self.classifiers.append(PyML.classifiers.svm.loadSVM(os.path.join(filename,str(classname)+".pyml.svm"),datasetClass = PyML.VectorDataSet)); else: features=features_or_filename; if labels==None: raise ValueError,"Labels must not be None when training."; self.uniquelabels=sorted(list(set(labels))); self.labeltoindex={}; for idx,label in enumerate(self.uniquelabels): self.labeltoindex[label]=idx; points = [[float(xij) for xij in xi] for xi in features]; self.classifiers=[PyML.SVM(kernel) for label in self.uniquelabels]; for i in xrange(len(self.uniquelabels)): currentlabel=self.uniquelabels[i]; currentlabels=['+1' if k==currentlabel else '-1' for k in labels]; currentdataset=PyML.VectorDataSet(points,L=currentlabels,positiveClass='+1'); self.classifiers[i].train(currentdataset,saveSpace=False); def accuracy(self,pts,labels): logger=logging.getLogger("ml"); correct=0; total=0; classindexes=[self.labeltoindex[label] for label in labels]; h=self.hypotheses(pts); for idx in xrange(len(pts)): if h[idx]==classindexes[idx]: logger.info("RIGHT: Actual \"%s\" == Predicted \"%s\"" %(self.uniquelabels[ classindexes[idx] ], self.uniquelabels[ h[idx] ])); correct+=1; else: logger.info("WRONG: Actual \"%s\" != Predicted \"%s\"" %(self.uniquelabels[ classindexes[idx] ], self.uniquelabels[ h[idx] ])) total+=1; return float(correct)/float(total); def prediction(self,pt): h=self.hypothesis(pt); if h!=None: return self.uniquelabels[h]; return h; def predictions(self,pts): h=self.hypotheses(self,pts); return [self.uniquelabels[x] if x!=None else None for x in h]; def hypothesis(self,pt): bestvalue=None; bestclass=None; dataset=PyML.VectorDataSet([pt]); for classidx, classifier in enumerate(self.classifiers): val=classifier.decisionFunc(dataset,0); if (bestvalue==None) or (val>bestvalue): bestvalue=val; bestclass=classidx; return bestclass; def hypotheses(self,pts): bestvalues=[None for pt in pts]; bestclasses=[None for pt in pts]; dataset=PyML.VectorDataSet(pts); for classidx, classifier in enumerate(self.classifiers): for ptidx in xrange(len(pts)): val=classifier.decisionFunc(dataset,ptidx); if (bestvalues[ptidx]==None) or (val>bestvalues[ptidx]): bestvalues[ptidx]=val; bestclasses[ptidx]=classidx; return bestclasses; def save(self,filename): if not os.path.exists(filename): os.makedirs(filename); with open(os.path.join(filename,"uniquelabels.list"),"wb") as uniquelabelsfile: pickle.dump(self.uniquelabels,uniquelabelsfile,pickle.HIGHEST_PROTOCOL); for classidx, classname in enumerate(self.uniquelabels): self.classifiers[classidx].save(os.path.join(filename,str(classname)+".pyml.svm")); I am using the latest version of PyML (0.7.2, although PyML.__version__ is 0.7.0). When I construct the classifier with a training dataset, the reported accuracy is ~0.87. When I then save it and reload it, the accuracy is less than 0.001. So, there is something here that I am clearly not persisting correctly, although what that may be is completely non-obvious to me. Would you happen to know what that is?

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  • PyML 0.7.2 - How to prevent accuracy from dropping after stroing/loading a classifier?

    - by Michael Aaron Safyan
    This is a followup from "Save PyML.classifiers.multi.OneAgainstRest(SVM()) object?". The solution to that question was close, but not quite right, (the SparseDataSet is broken, so attempting to save/load with that dataset container type will fail, no matter what. Also, PyML is inconsistent in terms of whether labels should be numbers or strings... it turns out that the oneAgainstRest function is actually not good enough, because the labels need to be strings and simultaneously convertible to floats, because there are places where it is assumed to be a string and elsewhere converted to float) and so after a great deal of hacking and such I was finally able to figure out a way to save and load my multi-class classifier without it blowing up with an error.... however, although it is no longer giving me an error message, it is still not quite right as the accuracy of the classifier drops significantly when it is saved and then reloaded (so I'm still missing a piece of the puzzle). I am currently using the following custom mutli-class classifier for training, saving, and loading: class SVM(object): def __init__(self,features_or_filename,labels=None,kernel=None): if isinstance(features_or_filename,str): filename=features_or_filename; if labels!=None: raise ValueError,"Labels must be None if loading from a file."; with open(os.path.join(filename,"uniquelabels.list"),"rb") as uniquelabelsfile: self.uniquelabels=sorted(list(set(pickle.load(uniquelabelsfile)))); self.labeltoindex={}; for idx,label in enumerate(self.uniquelabels): self.labeltoindex[label]=idx; self.classifiers=[]; for classidx, classname in enumerate(self.uniquelabels): self.classifiers.append(PyML.classifiers.svm.loadSVM(os.path.join(filename,str(classname)+".pyml.svm"),datasetClass = PyML.VectorDataSet)); else: features=features_or_filename; if labels==None: raise ValueError,"Labels must not be None when training."; self.uniquelabels=sorted(list(set(labels))); self.labeltoindex={}; for idx,label in enumerate(self.uniquelabels): self.labeltoindex[label]=idx; points = [[float(xij) for xij in xi] for xi in features]; self.classifiers=[PyML.SVM(kernel) for label in self.uniquelabels]; for i in xrange(len(self.uniquelabels)): currentlabel=self.uniquelabels[i]; currentlabels=['+1' if k==currentlabel else '-1' for k in labels]; currentdataset=PyML.VectorDataSet(points,L=currentlabels,positiveClass='+1'); self.classifiers[i].train(currentdataset,saveSpace=False); def accuracy(self,pts,labels): logger=logging.getLogger("ml"); correct=0; total=0; classindexes=[self.labeltoindex[label] for label in labels]; h=self.hypotheses(pts); for idx in xrange(len(pts)): if h[idx]==classindexes[idx]: logger.info("RIGHT: Actual \"%s\" == Predicted \"%s\"" %(self.uniquelabels[ classindexes[idx] ], self.uniquelabels[ h[idx] ])); correct+=1; else: logger.info("WRONG: Actual \"%s\" != Predicted \"%s\"" %(self.uniquelabels[ classindexes[idx] ], self.uniquelabels[ h[idx] ])) total+=1; return float(correct)/float(total); def prediction(self,pt): h=self.hypothesis(pt); if h!=None: return self.uniquelabels[h]; return h; def predictions(self,pts): h=self.hypotheses(self,pts); return [self.uniquelabels[x] if x!=None else None for x in h]; def hypothesis(self,pt): bestvalue=None; bestclass=None; dataset=PyML.VectorDataSet([pt]); for classidx, classifier in enumerate(self.classifiers): val=classifier.decisionFunc(dataset,0); if (bestvalue==None) or (val>bestvalue): bestvalue=val; bestclass=classidx; return bestclass; def hypotheses(self,pts): bestvalues=[None for pt in pts]; bestclasses=[None for pt in pts]; dataset=PyML.VectorDataSet(pts); for classidx, classifier in enumerate(self.classifiers): for ptidx in xrange(len(pts)): val=classifier.decisionFunc(dataset,ptidx); if (bestvalues[ptidx]==None) or (val>bestvalues[ptidx]): bestvalues[ptidx]=val; bestclasses[ptidx]=classidx; return bestclasses; def save(self,filename): if not os.path.exists(filename): os.makedirs(filename); with open(os.path.join(filename,"uniquelabels.list"),"wb") as uniquelabelsfile: pickle.dump(self.uniquelabels,uniquelabelsfile,pickle.HIGHEST_PROTOCOL); for classidx, classname in enumerate(self.uniquelabels): self.classifiers[classidx].save(os.path.join(filename,str(classname)+".pyml.svm")); I am using the latest version of PyML (0.7.2, although PyML.__version__ is 0.7.0). When I construct the classifier with a training dataset, the reported accuracy is ~0.87. When I then save it and reload it, the accuracy is less than 0.001. So, there is something here that I am clearly not persisting correctly, although what that may be is completely non-obvious to me. Would you happen to know what that is?

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  • How do I add a trailing slash for Django MPTT-based categorization app?

    - by Patrick Beeson
    I'm using Django-MPTT to develop a categorization app for my Django project. But I can't seem to get the regex pattern for adding a trailing slash that doesn't also break on child categories. Here's an example URL: http://mydjangoapp.com/categories/parentcat/childcat/ I'd like to be able to use http://mydjangoapp.com/categories/parentcat and have it redirect to the trailing slash version. The same should apply to http://mydjangoapp.com/categories/parentcat/childcat (it should redirect to http://mydjangoapp.com/categories/parentcat/childcat/). Here's my urls.py: from django.conf.urls.defaults import patterns, include, url from django.views.decorators.cache import cache_page from storefront.categories.models import Category from storefront.categories.views import SimpleCategoryView urlpatterns = patterns('', url(r'^(?P<full_slug>[-\w/]+)', cache_page(SimpleCategoryView.as_view(), 60 * 15), name='category_view'), ) And here is my view: from django.core.exceptions import ImproperlyConfigured from django.core.urlresolvers import reverse from django.views.generic import TemplateView, DetailView from django.views.generic.detail import SingleObjectTemplateResponseMixin, SingleObjectMixin from django.utils.translation import ugettext as _ from django.contrib.syndication.views import Feed from storefront.categories.models import Category class SimpleCategoryView(TemplateView): def get_category(self): return Category.objects.get(full_slug=self.kwargs['full_slug']) def get_context_data(self, **kwargs): context = super(SimpleCategoryView, self).get_context_data(**kwargs) context["category"] = self.get_category() return context def get_template_names(self): if self.get_category().template_name: return [self.get_category().template_name] else: return ['categories/category_detail.html'] And finally, my model: from django.db import models from mptt.models import MPTTModel from mptt.fields import TreeForeignKey class CategoryManager(models.Manager): def get(self, **kwargs): defaults = {} defaults.update(kwargs) if 'full_slug' in defaults: if defaults['full_slug'] and defaults['full_slug'][-1] != "/": defaults['full_slug'] += "/" return super(CategoryManager, self).get(**defaults) class Category(MPTTModel): title = models.CharField(max_length=255) description = models.TextField(blank=True, help_text='Please use <a href="http://daringfireball.net/projects/markdown/syntax">Markdown syntax</a> for all text-formatting and links. No HTML is allowed.') slug = models.SlugField(help_text='Prepopulates from title field.') full_slug = models.CharField(max_length=255, blank=True) template_name = models.CharField(max_length=70, blank=True, help_text="Example: 'categories/category_parent.html'. If this isn't provided, the system will use 'categories/category_detail.html'. Use 'categories/category_parent.html' for all parent categories and 'categories/category_child.html' for all child categories.") parent = TreeForeignKey('self', null=True, blank=True, related_name='children') objects = CategoryManager() class Meta: verbose_name = 'category' verbose_name_plural = 'categories' def save(self, *args, **kwargs): orig_full_slug = self.full_slug if self.parent: self.full_slug = "%s%s/" % (self.parent.full_slug, self.slug) else: self.full_slug = "%s/" % self.slug obj = super(Category, self).save(*args, **kwargs) if orig_full_slug != self.full_slug: for child in self.get_children(): child.save() return obj def available_product_set(self): """ Returns available, prioritized products for a category """ from storefront.apparel.models import Product return self.product_set.filter(is_available=True).order_by('-priority') def __unicode__(self): return "%s (%s)" % (self.title, self.full_slug) def get_absolute_url(self): return '/categories/%s' % (self.full_slug)

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  • Google App Engine python - Self is not defined

    - by sdasdas
    I have a request that maps to this class ChatMsg It takes in 3 get variables, username, roomname, and msg. But it fails on this last line here. class ChatMsg(webapp.RequestHandler): # this is line 239 def get(self): username = urllib.unquote(self.request.get('username')) roomname = urllib.unquote(self.request.get('roomname')) # this is line 242 When it tries to assign roomname, it tells me: <type 'exceptions.NameError'>: name 'self' is not defined Traceback (most recent call last): File "/base/data/home/apps/chatboxes/1.341998073649951735/chatroom.py", line 239, in <module> class ChatMsg(webapp.RequestHandler): File "/base/data/home/apps/chatboxes/1.341998073649951735/chatroom.py", line 242, in ChatMsg roomname = urllib.unquote(self.request.get('roomname')) what the hell is going on to make self not defined

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  • if (self = [super init]) vs. if ((self = [super init]))

    - by JOM
    Was just doing a code review and started to wonder: I thought if (self = [super init]) checks whether assigning return value of [super init] to variable self was successful or not (value of operation). Thus (self = nil) would actually be TRUE. I thought if ((self = [super init])) checks what is the value of self after assignment (value of variable). Thus ((self = nil)) would be FALSE. Which one is the correct way to use when initializing your own classes? Apple documentation uses the former one (for example here), which style I'm actually using now.

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  • Is it possible to force the WCF test client to accept a self-signed certificate?

    - by Lawrence Johnston
    I have a WCF web service running in IIS 7 using a self-signed certificate (it's a proof of concept to make sure this is the route I want to go). It's required to use SSL. Is it possible to use the WCF Test Client to debug this service without needing a non-self-signed certificate? When I try I get this error: Error: Cannot obtain Metadata from https:///Service1.svc If this is a Windows (R) Communication Foundation service to which you have access, please check that you have enabled metadata publishing at the specified address. For help enabling metadata publishing, please refer to the MSDN documentation at http://go.microsoft.com/fwlink/?LinkId=65455.WS-Metadata Exchange Error URI: https:///Service1.svc Metadata contains a reference that cannot be resolved: 'https:///Service1.svc'. Could not establish trust relationship for the SSL/TLS secure channel with authority ''. The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel. The remote certificate is invalid according to the validation procedure.HTTP GET Error URI: https:///Service1.svc There was an error downloading 'https:///Service1.svc'. The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel. The remote certificate is invalid according to the validation procedure.

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  • Is it Possible to Use Constraints on Hierarchical Data in a Self-Referential Table?

    - by pbarney
    Suppose you have the following table, intended to represent hierarchical data: +--------+-------------+ | Field | Type | +--------+-------------+ | id | int(10) | | parent | int(10) | | name | varchar(45) | +--------+-------------+ The table is self-referential in that the parent_id refers to id. So you might have the following data: +----+--------+---------------+ | id | parent | name | +----+--------+---------------+ | 1 | 0 | fruit | | 2 | 0 | vegetable | | 3 | 1 | apple | | 4 | 1 | orange | | 5 | 3 | red delicious | | 6 | 3 | granny smith | | 7 | 3 | gala | +----+--------+---------------+ Using MySQL, I am trying to impose a (self-referential) foreign key constraint upon the data to cascade on update and prevent deletion of a record if it has any "children." So I used the following: CREATE TABLE `test`.`fruit` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `parent` INT(10) UNSIGNED, `name` VARCHAR(45) NOT NULL, PRIMARY KEY (`id`), CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE ON DELETE RESTRICT ) ENGINE = InnoDB; From what I understand, this should fit my requirements. (And parent must default to null to allow insertions, correct?) The problem is, if I change the id of a record, it will not cascade: Cannot delete or update a parent row: a foreign key constraint fails (`test`.`fruit`, CONSTRAINT `fk_parent` FOREIGN KEY (`parent`) REFERENCES `fruit` (`id`) ON UPDATE CASCADE) What am I missing? Feel free to correct me if my terminology is screwed up... I'm new to constraints.

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  • Play mp3 using Python, PyQt, and Phonon

    - by KeyboardInterrupt
    I been trying all day to figure out the Qt's Phonon library with Python. My long term goal is to see if I could get it to play a mms:// stream, but since I can't find an implementation of this done anywhere, I will figure that part out myself. (figured I'd put it out there if anyone knew more about this specifically, if not no big deal.) Anyway, I figured I'd work backwards from a working example I found online. This launches a file browser and will play the mp3 file specified. I wanted to strip out the file browser stuff and get it down to the essentials of executing the script and having it play an Mp3 file with a hardcoded path. I'm assuming my problem is a misunderstanding of setCurrentSource() and specifying the data types. (see: http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/phonon-mediasource.html#fileName) I'm keeping my question kind of broad because ANY help with understanding Phonon would be greatly appreciated. import sys from PyQt4.QtGui import QApplication, QMainWindow, QDirModel, QColumnView from PyQt4.QtGui import QFrame from PyQt4.QtCore import SIGNAL from PyQt4.phonon import Phonon class MainWindow(QMainWindow): m_model = QDirModel() def __init__(self): QMainWindow.__init__(self) self.m_fileView = QColumnView(self) self.m_media = None self.setCentralWidget(self.m_fileView) self.m_fileView.setModel(self.m_model) self.m_fileView.setFrameStyle(QFrame.NoFrame) self.connect(self.m_fileView, SIGNAL("updatePreviewWidget(const QModelIndex &)"), self.play) def play(self, index): self.delayedInit() self.m_media.setCurrentSource( Phonon.MediaSource(self.m_model.filePath(index))) self.m_media.play() def delayedInit(self): if not self.m_media: self.m_media = Phonon.MediaObject(self) audioOutput = Phonon.AudioOutput(Phonon.MusicCategory, self) Phonon.createPath(self.m_media, audioOutput) def main(): app = QApplication(sys.argv) QApplication.setApplicationName("Phonon Tutorial 2 (Python)") mw = MainWindow() mw.show() sys.exit(app.exec_()) if __name__ == '__main__': main()

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  • Python Tkinter comparing PhotoImage objects

    - by Kyle Schmidt
    In a simple LightsOut game, when I click on a light I need to toggle the image on a button. I'm doing this with Tkinter, so I thought I'd just check and see what image is currently on the button (either 'on.gif' or 'off.gif') and set it to the other one, like this: def click(self,x,y): if self.buttons[x][y].image == self.on: self.buttons[x][y].config(image=self.off) self.buttons[x][y].image == self.off else: self.buttons[x][y].config(image=self.on) self.buttons[x][y].image == self.on This ends up always being True - I can turn a lgiht off, but never turn it back on. Did some research, realized that I should probably be using cmp: def click(self,x,y): if cmp(self.buttons[x][y].image,self.on) == 0: self.buttons[x][y].config(image=self.off) self.buttons[x][y].image == self.off else: self.buttons[x][y].config(image=self.on) self.buttons[x][y].image == self.on But that gave me the exact same result. Both self.on and self.off are PhotoImage objects. Aside from keeping a separate set of lists which tracks what type of light is in each position and redrawing them every click, is there a way to directly compare two PhotoImage objects like this?

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  • PyGTK: Trouble with size of ScrolledWindow

    - by canavanin
    Hi everyone! I am using PyGTK and the gtk.Assistant. On one page I have placed a treeview (one column, just strings) in a gtk.ScrolledWindow (I wanted the vertical scrollbar, since the list contains about 35 items). Everything is working fine; the only thing that bugs me is that I have not been able to figure out from the documentation how to set the size of the scrolled window. Currently only three items are displayed at a time; I would like to set this number to 10 or so. Below is the code. As you can see I have tried using a gtk.Adjustment to influence the scrolled window's size, but as - once more - I have been incompetent at retrieving the required info from the documentation, I don't actually know what values should be put into there. self.page7 = gtk.VBox() # The gtk.Adjustment: page_size = gtk.Adjustment(lower=10, page_size=100) # just used some arbitrary numbers here >_< scrolled_win = gtk.ScrolledWindow(page_size) scrolled_win.set_policy(gtk.POLICY_AUTOMATIC, gtk.POLICY_AUTOMATIC) # only display scroll bars when required self.character_traits_treeview = gtk.TreeView() self.character_traits_treestore = gtk.TreeStore(str) self.character_traits_treeview.set_model(self.character_traits_treestore) tc = gtk.TreeViewColumn("Character traits") self.character_traits_treeview.append_column(tc) cr = gtk.CellRendererText() tc.pack_start(cr, True) tc.add_attribute(cr, "text", 0) self.character_trait_selection = self.character_traits_treeview.get_selection() self.character_trait_selection.connect('changed', self.check_number_of_character_trait_selections) self.character_trait_selection.set_mode(gtk.SELECTION_MULTIPLE) self.make_character_traits_treestore() # adding the treeview to the scrolled window: scrolled_win.add(self.character_traits_treeview) self.page7.pack_start(scrolled_win, False, False, 0) self.assistant.append_page(self.page7) self.assistant.set_page_title(self.page7, "Step 7: Select 2-3 character traits") self.assistant.set_page_type(self.page7, gtk.ASSISTANT_PAGE_CONTENT) self.assistant.set_page_complete(self.page7, False) def check_number_of_character_trait_selections(self, blah): # ... def make_character_traits_treestore(self): # ... I know I should RTFM, but as I can't make head or tail of it, and as further searching, too, has been to no avail, I'm just hoping that someone on here can give me a hint. Thanks a lot in advance! PS: Here are the links to: the gtk.ScrolledWindow documentation the gtk.Adjustment documentation

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  • Would having an undergraduate certificate in Computer Science help me get employed as a computer programmer? [on hold]

    - by JDneverSleeps
    I am wondering how would employers perceive the Universtiy Certificate in Computing and Information Systems offered by Athabasca University (a distance education institution... The university is legit and accredited by the Government of Alberta, Canada). I already have a BSc in Statistics from University of Alberta (a classic brick and mortar public university in Alberta, Canada)...so I can state in my resume that I have a "university degree"..... Luckily, I was able to secure a very good employment in my field after the graduation from the U of A. The main reason why I am interested in taking the certificate program through Athabasca is because knowing how to program can increase the chance for promotion in my current job. I also believe that if something turns out bad in my current job and if I ever need to look for a new place to work, having the certificate in computer science will help me get employed as a computer programmer (i.e. my choice for the new job wouldn't be restricted to the field of Statistics). Athabasca University is claiming that the certificate program is meant to be equivalent to the undergraduate minor in computing science. I carefully looked at the certificate's curriculum and as far as I am concerned, the certificate program does have the same level of rigour as the undergraduate minor in Computer Science programs offered by other Canadian universities. I am also confident that the certificate program will get me to pick up enough skills/background to start a career as a computer programmer. The reasons why I am not 100% sure on getting the certificate is worth the tuition are: Athabasca University is a distance education institution (accredited by government but still) The credential that I will receive is "university certificate", not a "undergraduate degree" Do you think it's a good idea for me to pursue the certificate, given the two facts above? again, I already have my Bachelor's degree - although it is not in CS Thanks,

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  • How can I change 'self.view' within a button method created outside of 'loadView'

    - by Scott
    Hey guys. So I am creating buttons dynamically within loadView. Each of these buttons is given an action using the @Selector method, such as : [button addTarget:self action:@selector(showCCView) forControlEvents:UIControlEventTouchUpInside]; Now that showCCView method is defined outside of loadView, where this above statement is located. The point of the method is to change the view currently on the screen (so set self.view = ccView). It gives me an error every time I try and access self.view outside of loadView, and even sometimes when I try and access it at random places within loadView, it just has been acting really weird. I tried to change it around so I wouldn't have to deal with this either. I had made a function + (void) showView: (UIView*) oldView: (UIView*) newView; but this didn't work out either because the @Selector was being real prissy about using it with a function that needed two parameters. Any help please? Here is my code: // // SiteOneController.m // InstantNavigator // // Created by dni on 2/22/10. // Copyright 2010 __MyCompanyName__. All rights reserved. // #import "SiteOneController.h" @implementation SiteOneController + (UIView*) ccContent { UIView *ccContent = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; ccContent.backgroundColor = [UIColor whiteColor]; [ccContent addSubview:[SiteOneController myNavBar1:@"Constitution Center Content"]]; return ccContent; } // Button Dimensions int a = 62; int b = 80; int c = 200; int d = 30; // NPSIN Green Color + (UIColor*)myColor1 { return [UIColor colorWithRed:0.0f/255.0f green:76.0f/255.0f blue:29.0f/255.0f alpha:1.0f]; } // Creates Nav Bar with default Green at top of screen with given String as title + (UINavigationBar*)myNavBar1: (NSString*)input { UIView *test = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; UINavigationBar *navBar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0.0, 0.0, test.bounds.size.width, 45)]; navBar.tintColor = [SiteOneController myColor1]; UINavigationItem *navItem; navItem = [UINavigationItem alloc]; navItem.title = input; [navBar pushNavigationItem:navItem animated:false]; return navBar; } //-------------------------------------------------------------------------------------------// //-------------------------------------------------------------------------------------------// //-------------------------------------------------------------------------------------------// // Implement loadView to create a view hierarchy programmatically, without using a nib. - (void)loadView { //hard coded array of content for each site // CC NSMutableArray *allccContent = [[NSMutableArray alloc] init]; NSString *cc1 = @"House Model"; NSString *cc2 = @"James Dexter History"; [allccContent addObject: cc1]; [cc1 release]; [allccContent addObject: cc2]; [cc2 release]; // FC NSMutableArray *allfcContent = [[NSMutableArray alloc] init]; NSString *fc1 = @"Ghost House"; NSString *fc2 = @"Franklins Letters"; NSString *fc3 = @"Franklins Business"; [allfcContent addObject: fc1]; [fc1 release]; [allfcContent addObject: fc2]; [fc2 release]; [allfcContent addObject: fc3]; [fc3 release]; // PC NSMutableArray *allphContent = [[NSMutableArray alloc] init]; NSString *ph1 = @"Changing Occupancy"; NSString *ph2 = @"Sketches"; NSString *ph3 = @"Servant House"; NSString *ph4 = @"Monument"; NSString *ph5 = @"Virtual Model"; [allphContent addObject: ph1]; [ph1 release]; [allphContent addObject: ph2]; [ph2 release]; [allphContent addObject: ph3]; [ph3 release]; [allphContent addObject: ph4]; [ph4 release]; [allphContent addObject: ph5]; [ph5 release]; // Each content page's view //UIView *ccContent = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; UIView *fcContent = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; UIView *phContent = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; //ccContent.backgroundColor = [UIColor whiteColor]; fcContent.backgroundColor = [UIColor whiteColor]; phContent.backgroundColor = [UIColor whiteColor]; //[ccContent addSubview:[SiteOneController myNavBar1:@"Constitution Center Content"]]; [fcContent addSubview:[SiteOneController myNavBar1:@"Franklin Court Content"]]; [phContent addSubview:[SiteOneController myNavBar1:@"Presidents House Content"]]; //allocate the view self.view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; //set the view's background color self.view.backgroundColor = [UIColor whiteColor]; [self.view addSubview:[SiteOneController myNavBar1:@"Sites"]]; NSMutableArray *sites = [[NSMutableArray alloc] init]; NSString *one = @"Constution Center"; NSString *two = @"Franklin Court"; NSString *three = @"Presidents House"; [sites addObject: one]; [one release]; [sites addObject: two]; [two release]; [sites addObject: three]; [three release]; NSString *ccName = @"Constitution Center"; NSString *fcName = @"Franklin Court"; NSString *element; int j = 0; for (element in sites) { UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom]; //setframe (where on screen) //separation is 15px past the width (45-30) button.frame = CGRectMake(a, b + (j*45), c, d); [button setTitle:element forState:UIControlStateNormal]; button.backgroundColor = [SiteOneController myColor1]; /*- (void) fooFirstInput:(NSString*) first secondInput:(NSString*) second { NSLog(@"Logs %@ then %@", first, second); } - (void) performMethodsViaSelectors { [self performSelector:@selector(fooNoInputs)]; [self performSelector:@selector(fooOneInput:) withObject:@"first"]; [self performSelector;@selector(fooFirstInput:secondInput:) withObject:@"first" withObject:@"second"];*/ //UIView *old = self.view; if (element == ccName) { [button addTarget:self action:@selector(showCCView) forControlEvents:UIControlEventTouchUpInside]; } else if (element == fcName) { } else { } [self.view addSubview: button]; j++; } } // This method show the content views for each of the sites. /*+ (void) showCCView { self.view = [SiteOneController ccContent]; }*/

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  • How I understood monads, part 1/2: sleepless and self-loathing in Seattle

    For some time now, I had been noticing some interest for monads, mostly in the form of unintelligible (to me) blog posts and comments saying oh, yeah, thats a monad about random stuff as if it were absolutely obvious and if I didnt know what they were talking about, I was probably an uneducated idiot, ignorant about the simplest and most fundamental concepts of functional programming. Fair enough, I am pretty much exactly that. Being the kind of guy who can spend eight years in college just to...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • How I understood monads, part 1/2: sleepless and self-loathing in Seattle

    - by Bertrand Le Roy
    For some time now, I had been noticing some interest for monads, mostly in the form of unintelligible (to me) blog posts and comments saying “oh, yeah, that’s a monad” about random stuff as if it were absolutely obvious and if I didn’t know what they were talking about, I was probably an uneducated idiot, ignorant about the simplest and most fundamental concepts of functional programming. Fair enough, I am pretty much exactly that. Being the kind of guy who can spend eight years in college just to understand a few interesting concepts about the universe, I had to check it out and try to understand monads so that I too can say “oh, yeah, that’s a monad”. Man, was I hit hard in the face with the limitations of my own abstract thinking abilities. All the articles I could find about the subject seemed to be vaguely understandable at first but very quickly overloaded the very few concept slots I have available in my brain. They also seemed to be consistently using arcane notation that I was entirely unfamiliar with. It finally all clicked together one Friday afternoon during the team’s beer symposium when Louis was patient enough to break it down for me in a language I could understand (C#). I don’t know if being intoxicated helped. Feel free to read this with or without a drink in hand. So here it is in a nutshell: a monad allows you to manipulate stuff in interesting ways. Oh, OK, you might say. Yeah. Exactly. Let’s start with a trivial case: public static class Trivial { public static TResult Execute<T, TResult>( this T argument, Func<T, TResult> operation) { return operation(argument); } } This is not a monad. I removed most concepts here to start with something very simple. There is only one concept here: the idea of executing an operation on an object. This is of course trivial and it would actually be simpler to just apply that operation directly on the object. But please bear with me, this is our first baby step. Here’s how you use that thing: "some string" .Execute(s => s + " processed by trivial proto-monad.") .Execute(s => s + " And it's chainable!"); What we’re doing here is analogous to having an assembly chain in a factory: you can feed it raw material (the string here) and a number of machines that each implement a step in the manufacturing process and you can start building stuff. The Trivial class here represents the empty assembly chain, the conveyor belt if you will, but it doesn’t care what kind of raw material gets in, what gets out or what each machine is doing. It is pure process. A real monad will need a couple of additional concepts. Let’s say the conveyor belt needs the material to be processed to be contained in standardized boxes, just so that it can safely and efficiently be transported from machine to machine or so that tracking information can be attached to it. Each machine knows how to treat raw material or partly processed material, but it doesn’t know how to treat the boxes so the conveyor belt will have to extract the material from the box before feeding it into each machine, and it will have to box it back afterwards. This conveyor belt with boxes is essentially what a monad is. It has one method to box stuff, one to extract stuff from its box and one to feed stuff into a machine. So let’s reformulate the previous example but this time with the boxes, which will do nothing for the moment except containing stuff. public class Identity<T> { public Identity(T value) { Value = value; } public T Value { get; private set;} public static Identity<T> Unit(T value) { return new Identity<T>(value); } public static Identity<U> Bind<U>( Identity<T> argument, Func<T, Identity<U>> operation) { return operation(argument.Value); } } Now this is a true to the definition Monad, including the weird naming of the methods. It is the simplest monad, called the identity monad and of course it does nothing useful. Here’s how you use it: Identity<string>.Bind( Identity<string>.Unit("some string"), s => Identity<string>.Unit( s + " was processed by identity monad.")).Value That of course is seriously ugly. Note that the operation is responsible for re-boxing its result. That is a part of strict monads that I don’t quite get and I’ll take the liberty to lift that strange constraint in the next examples. To make this more readable and easier to use, let’s build a few extension methods: public static class IdentityExtensions { public static Identity<T> ToIdentity<T>(this T value) { return new Identity<T>(value); } public static Identity<U> Bind<T, U>( this Identity<T> argument, Func<T, U> operation) { return operation(argument.Value).ToIdentity(); } } With those, we can rewrite our code as follows: "some string".ToIdentity() .Bind(s => s + " was processed by monad extensions.") .Bind(s => s + " And it's chainable...") .Value; This is considerably simpler but still retains the qualities of a monad. But it is still pointless. Let’s look at a more useful example, the state monad, which is basically a monad where the boxes have a label. It’s useful to perform operations on arbitrary objects that have been enriched with an attached state object. public class Stateful<TValue, TState> { public Stateful(TValue value, TState state) { Value = value; State = state; } public TValue Value { get; private set; } public TState State { get; set; } } public static class StateExtensions { public static Stateful<TValue, TState> ToStateful<TValue, TState>( this TValue value, TState state) { return new Stateful<TValue, TState>(value, state); } public static Stateful<TResult, TState> Execute<TValue, TState, TResult>( this Stateful<TValue, TState> argument, Func<TValue, TResult> operation) { return operation(argument.Value) .ToStateful(argument.State); } } You can get a stateful version of any object by calling the ToStateful extension method, passing the state object in. You can then execute ordinary operations on the values while retaining the state: var statefulInt = 3.ToStateful("This is the state"); var processedStatefulInt = statefulInt .Execute(i => ++i) .Execute(i => i * 10) .Execute(i => i + 2); Console.WriteLine("Value: {0}; state: {1}", processedStatefulInt.Value, processedStatefulInt.State); This monad differs from the identity by enriching the boxes. There is another way to give value to the monad, which is to enrich the processing. An example of that is the writer monad, which can be typically used to log the operations that are being performed by the monad. Of course, the richest monads enrich both the boxes and the processing. That’s all for today. I hope with this you won’t have to go through the same process that I did to understand monads and that you haven’t gone into concept overload like I did. Next time, we’ll examine some examples that you already know but we will shine the monadic light, hopefully illuminating them in a whole new way. Realizing that this pattern is actually in many places but mostly unnoticed is what will enable the truly casual “oh, yes, that’s a monad” comments. Here’s the code for this article: http://weblogs.asp.net/blogs/bleroy/Samples/Monads.zip The Wikipedia article on monads: http://en.wikipedia.org/wiki/Monads_in_functional_programming This article was invaluable for me in understanding how to express the canonical monads in C# (interesting Linq stuff in there): http://blogs.msdn.com/b/wesdyer/archive/2008/01/11/the-marvels-of-monads.aspx

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  • More Animation - Self Dismissing Dialogs

    - by Duncan Mills
    In my earlier articles on animation, I discussed various slide, grow and  flip transitions for items and containers.  In this article I want to discuss a fade animation and specifically the use of fades and auto-dismissal for informational dialogs.  If you use a Mac, you may be familiar with Growl as a notification system, and the nice way that messages that are informational just fade out after a few seconds. So in this blog entry I wanted to discuss how we could make an ADF popup behave in the same way. This can be an effective way of communicating information to the user without "getting in the way" with modal alerts. This of course, has been done before, but everything I've seen previously requires something like JQuery to be in the mix when we don't really need it to be.  The solution I've put together is nice and generic and will work with either <af:panelWindow> or <af:dialog> as a the child of the popup. In terms of usage it's pretty simple to use we  just need to ensure that the popup itself has clientComponent is set to true and includes the animation JavaScript (animateFadingPopup) on a popupOpened event: <af:popup id="pop1" clientComponent="true">   <af:panelWindow title="A Fading Message...">    ...  </af:panelWindow>   <af:clientListener method="animateFadingPopup" type="popupOpened"/> </af:popup>   The popup can be invoked in the normal way using showPopupBehavior or JavaScript, no special code is required there. As a further twist you can include an additional clientAttribute called preFadeDelay to define a delay before the fade itself starts (the default is 5 seconds) . To set the delay to just 2 seconds for example: <af:popup ...>   ...   <af:clientAttribute name="preFadeDelay" value="2"/>   <af:clientListener method="animateFadingPopup" type="popupOpened"/>  </af:popup> The Animation Styles  As before, we have a couple of CSS Styles which define the animation, I've put these into the skin in my case, and, as in the other articles, I've only defined the transitions for WebKit browsers (Chrome, Safari) at the moment. In this case, the fade is timed at 5 seconds in duration. .popupFadeReset {   opacity: 1; } .popupFadeAnimate {   opacity: 0;   -webkit-transition: opacity 5s ease-in-out; } As you can see here, we are achieving the fade by simply setting the CSS opacity property. The JavaScript The final part of the puzzle is, of course, the JavaScript, there are four functions, these are generic (apart from the Style names which, if you've changed above, you'll need to reflect here): The initial function invoked from the popupOpened event,  animateFadingPopup which starts a timer and provides the initial delay before we start to fade the popup. The function that applies the fade animation to the popup - initiatePopupFade. The callback function - closeFadedPopup used to reset the style class and correctly hide the popup so that it can be invoked again and again.   A utility function - findFadeContainer, which is responsible for locating the correct child component of the popup to actually apply the style to. Function - animateFadingPopup This function, as stated is the one hooked up to the popupOpened event via a clientListener. Because of when the code is called it does not actually matter how you launch the popup, or if the popup is re-used from multiple places. All usages will get the fade behavior. /**  * Client listener which will kick off the animation to fade the dialog and register  * a callback to correctly reset the popup once the animation is complete  * @param event  */ function animateFadingPopup(event) { var fadePopup = event.getSource();   var fadeCandidate = false;   //Ensure that the popup is initially Opaque   //This handles the situation where the user has dismissed   //the popup whilst it was in the process of fading   var fadeContainer = findFadeContainer(fadePopup);   if (fadeContainer != null) {     fadeCandidate = true;     fadeContainer.setStyleClass("popupFadeReset");   }   //Only continue if we can actually fade this popup   if (fadeCandidate) {   //See if a delay has been specified     var waitTimeSeconds = event.getSource().getProperty('preFadeDelay');     //Default to 5 seconds if not supplied     if (waitTimeSeconds == undefined) {     waitTimeSeconds = 5;     }     // Now call the fade after the specified time     var fadeFunction = function () {     initiatePopupFade(fadePopup);     };     var fadeDelayTimer = setTimeout(fadeFunction, (waitTimeSeconds * 1000));   } } The things to note about this function is the initial check that we have to do to ensure that the container is currently visible and reset it's style to ensure that it is.  This is to handle the situation where the popup has begun the fade, and yet the user has still explicitly dismissed the popup before it's complete and in doing so has prevented the callback function (described later) from executing. In this particular situation the initial display of the dialog will be (apparently) missing it's normal animation but at least it becomes visible to the user (and most users will probably not notice this difference in any case). You'll notice that the style that we apply to reset the  opacity - popupFadeReset, is not applied to the popup component itself but rather the dialog or panelWindow within it. More about that in the description of the next function findFadeContainer(). Finally, assuming that we have a suitable candidate for fading, a JavaScript  timer is started using the specified preFadeDelay wait time (or 5 seconds if that was not supplied). When this timer expires then the main animation styleclass will be applied using the initiatePopupFade() function Function - findFadeContainer As a component, the <af:popup> does not support styleClass attribute, so we can't apply the animation style directly.  Instead we have to look for the container within the popup which defines the window object that can have a style attached.  This is achieved by the following code: /**  * The thing we actually fade will be the only child  * of the popup assuming that this is a dialog or window  * @param popup  * @return the component, or null if this is not valid for fading  */ function findFadeContainer(popup) { var children = popup.getDescendantComponents();   var fadeContainer = children[0];   if (fadeContainer != undefined) {   var compType = fadeContainer.getComponentType();     if (compType == "oracle.adf.RichPanelWindow" || compType == "oracle.adf.RichDialog") {     return fadeContainer;     }   }   return null; }  So what we do here is to grab the first child component of the popup and check its type. Here I decided to limit the fade behaviour to only <af:dialog> and <af:panelWindow>. This was deliberate.  If  we apply the fade to say an <af:noteWindow> you would see the text inside the balloon fade, but the balloon itself would hang around until the fade animation was over and then hide.  It would of course be possible to make the code smarter to walk up the DOM tree to find the correct <div> to apply the style to in order to hide the whole balloon, however, that means that this JavaScript would then need to have knowledge of the generated DOM structure, something which may change from release to release, and certainly something to avoid. So, all in all, I think that this is an OK restriction and frankly it's windows and dialogs that I wanted to fade anyway, not balloons and menus. You could of course extend this technique and handle the other types should you really want to. One thing to note here is the selection of the first (children[0]) child of the popup. It does not matter if there are non-visible children such as clientListener before the <af:dialog> or <af:panelWindow> within the popup, they are not included in this array, so picking the first element in this way seems to be fine, no matter what the underlying ordering is within the JSF source.  If you wanted a super-robust version of the code you might want to iterate through the children array of the popup to check for the right type, again it's up to you.  Function -  initiatePopupFade  On to the actual fading. This is actually very simple and at it's heart, just the application of the popupFadeAnimate style to the correct component and then registering a callback to execute once the fade is done. /**  * Function which will kick off the animation to fade the dialog and register  * a callback to correctly reset the popup once the animation is complete  * @param popup the popup we are animating  */ function initiatePopupFade(popup) { //Only continue if the popup has not already been dismissed    if (popup.isPopupVisible()) {   //The skin styles that define the animation      var fadeoutAnimationStyle = "popupFadeAnimate";     var fadeAnimationResetStyle = "popupFadeReset";     var fadeContainer = findFadeContainer(popup);     if (fadeContainer != null) {     var fadeContainerReal = AdfAgent.AGENT.getElementById(fadeContainer.getClientId());       //Define the callback this will correctly reset the popup once it's disappeared       var fadeCallbackFunction = function (event) {       closeFadedPopup(popup, fadeContainer, fadeAnimationResetStyle);         event.target.removeEventListener("webkitTransitionEnd", fadeCallbackFunction);       };       //Initiate the fade       fadeContainer.setStyleClass(fadeoutAnimationStyle);       //Register the callback to execute once fade is done       fadeContainerReal.addEventListener("webkitTransitionEnd", fadeCallbackFunction, false);     }   } } I've added some extra checks here though. First of all we only start the whole process if the popup is still visible. It may be that the user has closed the popup before the delay timer has finished so there is no need to start animating in that case. Again we use the findFadeContainer() function to locate the correct component to apply the style to, and additionally we grab the DOM id that represents that container.  This physical ID is required for the registration of the callback function. The closeFadedPopup() call is then registered on the callback so as to correctly close the now transparent (but still there) popup. Function -  closeFadedPopup The final function just cleans things up: /**  * Callback function to correctly cancel and reset the style in the popup  * @param popup id of the popup so we can close it properly  * @param contatiner the window / dialog within the popup to actually style  * @param resetStyle the syle that sets the opacity back to solid  */ function closeFadedPopup(popup, container, resetStyle) { container.setStyleClass(resetStyle);   popup.cancel(); }  First of all we reset the style to make the popup contents opaque again and then we cancel the popup.  This will ensure that any of your user code that is waiting for a popup cancelled event will actually get the event, additionally if you have done this as a modal window / dialog it will ensure that the glasspane is dismissed and you can interact with the UI again.  What's Next? There are several ways in which this technique could be used, I've been working on a popup here, but you could apply the same approach to in-line messages. As this code (in the popup case) is generic it will make s pretty nice declarative component and maybe, if I get time, I'll look at constructing a formal Growl component using a combination of this technique, and active data push. Also, I'm sure the above code can be improved a little too.  Specifically things like registering a popup cancelled listener to handle the style reset so that we don't loose the subtle animation that takes place when the popup is opened in that situation where the user has closed the in-fade dialog.

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  • Bullet physics in python and pygame

    - by Pomg
    I am programming a 2D sidescroller in python and pygame and am having trouble making a bullet go farther than just farther than the player. The bullet travels straight to the ground after i fire it. How, in python code using pygame do I make the bullet go farther. If you need code, here is the method that handles the bullet firing: self.xv += math.sin(math.radians(self.angle)) * self.attrs['speed'] self.yv += math.cos(math.radians(self.angle)) * self.attrs['speed'] self.rect.left += self.xv self.rect.top += self.yv

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