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  • Matching blank entries in django queryset for optional field with corresponding ones in a required

    - by gramware
    I have a django queryset in my views whose values I pack before passing to my template. There is a problem when the queryset returns none since associated values are not unpacked. the quersyet is called comments. Here is my views.py def forums(request ): post_list = list(forum.objects.filter(child='0')&forum.objects.filter(deleted='0').order_by('postDate')) user = UserProfile.objects.get(pk=request.session['_auth_user_id']) newpostform = PostForm(request.POST) deletepostform = PostDeleteForm(request.POST) DelPostFormSet = modelformset_factory(forum, exclude=('child','postSubject','postBody','postPoster','postDate','childParentId')) readform = ReadForumForm(request.POST) comments =list( forum.objects.filter(deleted='0').filter(child='1').order_by('childParentId').values('childParentId').annotate(y=Count('childParentId'))) if request.user.is_staff== True : staff = 1 else: staff = 0 staffis = 1 if newpostform.is_valid(): topic = request.POST['postSubject'] poster = request.POST['postPoster'] newpostform.save() return HttpResponseRedirect('/forums') else: newpostform = PostForm(initial = {'postPoster':user.id}) if request.GET: form = SearchForm(request.GET) if form.is_valid(): query = form.cleaned_data['query'] post_list = list((forum.objects.filter(child='0')&forum.objects.filter(deleted='0')&forum.objects.filter(Q(postSubject__icontains=query)|Q(postBody__icontains=query)|Q(postDate__icontains=query)))or(forum.objects.filter(deleted='0')&forum.objects.filter(Q(postSubject__icontains=query)|Q(postBody__icontains=query)|Q(postDate__icontains=query)).values('childParentId'))) if request.method == 'POST': delpostformset = DelPostFormSet(request.POST) if delpostformset.is_valid(): delpostformset.save() return HttpResponseRedirect('/forums') else: delpostformset = DelPostFormSet(queryset=forum.objects.filter(child='0', deleted='0')) """if readform.is_valid(): user=get_object_or_404(UserProfile.objects.all()) readform.save() else: readform = ReadForumForm()""" post= zip( post_list,comments, delpostformset.forms) paginator = Paginator(post, 10) # Show 10 contacts per page # Make sure page request is an int. If not, deliver first page. try: page = int(request.GET.get('page', '1')) except ValueError: page = 1 # If page request (9999) is out of range, deliver last page of results. try: post = paginator.page(page) except (EmptyPage, InvalidPage): post = paginator.page(paginator.num_pages) return render_to_response('forum.html', {'post':post, 'newpostform': newpostform,'delpost':delpostformset, 'username':user.username, 'comments':comments, 'user':user, },context_instance = RequestContext( request )) I realised that the issue was with the comments queryset comments =list( forum.objects.filter(deleted='0').filter(child='1').order_by('childParentId').values('childParentId').annotate(y=Count('childParentId'))) which will only returns values for posts that have comments. so i now need a way to return 0 comments when a value in post-list post_list = list(forum.objects.filter(child='0')&forum.objects.filter(deleted='0').order_by('postDate')) does not have any comments (optional field). Here is my models.py class forum(models.Model): postID = models.AutoField(primary_key=True) postSubject = models.CharField(max_length=100) postBody = models.TextField() postPoster = models.ForeignKey(UserProfile) postDate = models.DateTimeField(auto_now_add=True) child = models.BooleanField() childParentId = models.ForeignKey('self',blank=True, null=True) deleted = models.BooleanField() def __unicode__(self): return u' %d' % ( self.postID)

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  • Django : presenting a form very different from the model and with multiple field values in a Django-

    - by sebpiq
    Hi ! I'm currently doing a firewall management application for Django, here's the (simplified) model : class Port(models.Model): number = models.PositiveIntegerField(primary_key=True) application = models.CharField(max_length=16, blank=True) class Rule(models.Model): port = models.ForeignKey(Port) ip_source = models.IPAddressField() ip_mask = models.IntegerField(validators=[MaxValueValidator(32)]) machine = models.ForeignKey("vmm.machine") What I would like to do, however, is to display to the user a form for entering rules, but with a very different organization than the model : Port 80 O Not open O Everywhere O Specific addresses : --------- delete field --------- delete field + add address field Port 443 ... etc Where Not open means that there is no rule for the given port, Everywhere means that there is only ONE rule (0.0.0.0/0) for the given port, and with specific addresses, you can add as many addresses as you want (I did this with JQuery), which will make as many rules. Now I did a version completely "handmade", meaning that I create the forms entirely in my templates, set input names with a prefix, and parse all the POSTed stuff in my view (which is quite painful, and means that there's no point in using a web framework). I also have a class which aggregates the rules together to easily pre-fill the forms with the informations "not open, everywhere, ...". I'm passing a list of those to the template, therefore it acts as an interface between my model and my "handmade" form : class MachinePort(object): def __init__(self, machine, port): self.machine = machine self.port = port @property def fully_open(self): for rule in self.port.rule_set.filter(machine=self.machine): if ipaddr.IPv4Network("%s/%s" % (rule.ip_source, rule.ip_mask)) == ipaddr.IPv4Network("0.0.0.0/0"): return True else : return False @property def partly_open(self): return bool(self.port.rule_set.filter(machine=self.machine)) and not self.fully_open @property def not_open(self): return not self.partly_open and not self.fully_open But all this is rather ugly ! Do anyone of you know if there is a classy way to do this ? In particular with the form... I don't know how to have a form that can have an undefined number of fields, neither how to transform these fields into Rule objects (because all the rule fields would have to be gathered from the form), neither how to save multiple objects... Well I could try to hack into the Form class, but seems like too much work for such a special case. Is there any nice feature I'm missing ?

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  • Django: Grouping by Dates and Servers

    - by TheLizardKing
    So I am trying to emulate google app's status page: http://www.google.com/appsstatus#hl=en but for backups for our own servers. Instead of service names on the left it'll be server names but the dates and hopefully the pagination will be there too. My models look incredibly similar to this: from django.db import models STATUS_CHOICES = ( ('UN', 'Unknown'), ('NI', 'No Issue'), ('IS', 'Issue'), ('NR', 'Not Running'), ) class Server(models.Model): name = models.CharField(max_length=32) def __unicode__(self): return self.name class Backup(models.Model): server = models.ForeignKey(Server) created = models.DateField(auto_now_add=True) modified = models.DateTimeField(auto_now=True) status = models.CharField(max_length=2, choices=STATUS_CHOICES, default='UN') issue = models.TextField(blank=True) def __unicode__(self): return u'%s: %s' % (self.server, self.get_status_display()) My issue is that I am having a hell of a time displaying the information I need. Everyday a little after midnight a cron job will run and add a row for each server for that day, defaulting on status unknown (UN). My backups.html: {% extends "base.html" %} {% block content %} <table> <tr> <th>Name</th> {% for server in servers %} <th>{{ created }}</th> </tr> <tr> <td>{{ server.name }}</td> {% for backup in server.backup_set.all %} <td>{{ backup.get_status_display }}</td> {% endfor %} </tr> {% endfor %} </table> {% endblock content %} This actually works but I do not know how to get the dates to show. Obviously {{ created }} doesn't do anything but the servers don't have create dates. Backups do and because it's a cron job there should only be X number of rows with any particular date (depending on how many servers we are following for that day). Summary I want to create a table, X being server names, Y being dates starting at today while all the cells being the status of a backup. The above model and template should hopefully give you an idea what my thought process but I am willing to alter anything. Basically I am create a fancy excel spreadsheet.

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  • getting Cannot identify image file when trying to create thumbnail in django

    - by Mo J. Mughrabi
    Am trying to create a thumbnail in django, am trying to build a custom class specifically to be used for generating thumbnails. As following from StringIO import StringIO from PIL import Image class Thumbnail(object): source = '' size = (50, 50) output = '' def __init__(self): pass @staticmethod def load(src): self = Thumbnail() self.source = src return self def generate(self, size=(50, 50)): if not isinstance(size, tuple): raise Exception('Thumbnail class: The size parameter must be an instance of a tuple.') self.size = size # resize properties box = self.size factor = 1 fit = True image = Image.open(self.source) # Convert to RGB if necessary if image.mode not in ('L', 'RGB'): image = image.convert('RGB') while image.size[0]/factor > 2*box[0] and image.size[1]*2/factor > 2*box[1]: factor *=2 if factor > 1: image.thumbnail((image.size[0]/factor, image.size[1]/factor), Image.NEAREST) #calculate the cropping box and get the cropped part if fit: x1 = y1 = 0 x2, y2 = image.size wRatio = 1.0 * x2/box[0] hRatio = 1.0 * y2/box[1] if hRatio > wRatio: y1 = int(y2/2-box[1]*wRatio/2) y2 = int(y2/2+box[1]*wRatio/2) else: x1 = int(x2/2-box[0]*hRatio/2) x2 = int(x2/2+box[0]*hRatio/2) image = image.crop((x1,y1,x2,y2)) #Resize the image with best quality algorithm ANTI-ALIAS image.thumbnail(box, Image.ANTIALIAS) # save image to memory temp_handle = StringIO() image.save(temp_handle, 'png') temp_handle.seek(0) self.output = temp_handle return self def get_output(self): return self.output.read() the purpose of the class is so i can use it inside different locations to generate thumbnails on the fly. The class works perfectly, I've tested it directly under a view.. I've implemented the thumbnail class inside the save method of the forms to resize the original images on saving. in my design, I have two fields for thumbnails. I was able to generate one thumbnail, if I try to generate two it crashes and I've been stuck for hours not sure whats the problem. Here is my model class Image(models.Model): article = models.ForeignKey(Article) title = models.CharField(max_length=100, null=True, blank=True) src = models.ImageField(upload_to='publication/image/') r128 = models.ImageField(upload_to='publication/image/128/', blank=True, null=True) r200 = models.ImageField(upload_to='publication/image/200/', blank=True, null=True) uploaded_at = models.DateTimeField(auto_now=True) Here is my forms class ImageForm(models.ModelForm): """ """ class Meta: model = Image fields = ('src',) def save(self, commit=True): instance = super(ImageForm, self).save(commit=True) file = Thumbnail.load(instance.src) instance.r128 = SimpleUploadedFile( instance.src.name, file.generate((128, 128)).get_output(), content_type='image/png' ) instance.r200 = SimpleUploadedFile( instance.src.name, file.generate((200, 200)).get_output(), content_type='image/png' ) if commit: instance.save() return instance the strange part is, when i remove the line which contains instance.r200 in the form save. It works fine, and it does the thumbnail and stores it successfully. Once I add the second thumbnail it fails.. Any ideas what am doing wrong here? Thanks Update: I tried earlier doing the following but I still got the same error class ImageForm(models.ModelForm): """ """ class Meta: model = Image fields = ('src',) def save(self, commit=True): instance = super(ImageForm, self).save(commit=True) instance.r128 = SimpleUploadedFile( instance.src.name, Thumbnail.load(instance.src).generate((128, 128)).get_output(), content_type='image/png' ) instance.r200 = SimpleUploadedFile( instance.src.name, Thumbnail.load(instance.src).generate((200, 200)).get_output(), content_type='image/png' ) if commit: instance.save() return instance

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  • Apache cannot find mysql database modules

    - by user809857
    I've created a simple django project and setup a mysql database. My simple project just creates an entry on the database. The project works fine when I use the built in development server provided by django (runserver) and it works well. But when I deployed the project on Apache and mod_Wsgi (Ubuntu server), django could not find 'books', which is in this case my table in the database. The mysql database that I use in runserver and apache are just the same. I also did rebuild the database using sqlall,validate and syncdb of django but still i get the error. What could be wrong with what I'm doing? Thanks

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  • Apache cannot find mysql database modules

    - by user809857
    I've created a simple django project and setup a mysql database. My simple project just creates an entry on the database. The project works fine when I use the built in development server provided by django (runserver) and it works well. But when I deployed the project on Apache and mod_Wsgi (Ubuntu server), django could not find 'books', which is in this case my table in the database. The mysql database that I use in runserver and apache are just the same. I also did rebuild the database using sqlall,validate and syncdb of django but still i get the error. What could be wrong with what I'm doing? Thanks

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  • Avoiding null in a controller

    - by Kevin Burke
    I'm trying to work through how to write this code. def get(params): """ Fetch a user's details, or 404 """ user = User.fetch_by_id(params['id']) if not user: abort(404) # Render some template for the user... What's the best way to handle the case where the lookup fails? One principle says you should avoid returning null values from functions. These lead to mistakes and AttributeErrors etc. later on in the file. Another idea is to have fetch_by_id raise a ValueError or similar if no user exists with that id. However there's a general principle that you shouldn't use exceptions for control flow, either, which doesn't help much. What could be done better in this case?

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  • Layering Design Pattern in Java clean code style

    - by zeraDev
    As a Java developer, I am developing trying to use the clean code rules. But in my team we are facing a concrete problem: We have a business layer offering a service called "createObject", this service makes a lot of operation which can result to problem. E.g: parentObjectDontExist, objectAlreadyExist, dontHaveAuthorizationToCreate, operationFailed... and we want the UI using this service to display different information messages depending which error occurred. In old java dev, we should have create all signed exception type and throw it in createObject. As Clean code says, it is forbidden to use Exception for business logic AND signed exceptions are evil... Why not...But i don't know how to solved this problem and i don't want to use return code. How do you do? Thanks for youre experience return.

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  • how can I handle user defined exceptions and after handling them resume the flow of program. here is

    - by fari
    /** * An exception thrown when an illegal side pit was * specified (i.e. not in the range 1-6) for a move */ public class IllegalSidePitNumException extends RuntimeException { /** * Exception constructor. * @param sidePitNum the illegal side pit that was selected. */ public IllegalSidePitNumException(int sidePitNum) { super("No such side pit number: "+sidePitNum); } } how do i use this ina program and then resume for there. I do not want the program to end but want to handle the exception and continue.

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  • Suggestions on error handling of Win32 C++ code: AtlThrow vs. STL exceptions

    - by EmbeddedProg
    In writing Win32 C++ code, I'd appreciate some hints on how to handle errors of Win32 APIs. In particular, in case of a failure of a Win32 function call (e.g. MapViewOfFile), is it better to: use AtlThrowLastWin32 define a Win32Exception class derived from std::exception, with an added HRESULT data member to store the HRESULT corresponding to value returned by GetLastError? In this latter case, I could use the what() method to return a detailed error string (e.g. "MapViewOfFile call failed in MyClass::DoSomething() method."). What are the pros and cons of 1 vs. 2? Is there any other better option that I am missing? As a side note, if I'd like to localize the component I'm developing, how could I localize the exception what() string? I was thinking of building a table mapping the original English string returned by what() into a Unicode localized error string. Could anyone suggest a better approach? Thanks much for your insights and suggestions.

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  • MySQL efficiency as it relates to the database/table size

    - by mlissner
    I'm building a system using django, Sphinx and MySQL that's very quickly becoming quite large. The database currently has about 2000 rows, and I've written a program that's going to populate it with another 40,000 rows in a couple days. Since the database is live right now, and since I've never had a database with this much information in it, I'm worried about some things: Is adding all these rows going to seriously degrade the efficiency of my django app? Will I need to go back through it and optimize all my database calls so they're doing things more cleverly? Or will this make the database slow all around to the extent that I can't do anything about it at all? If you scoff at my 40k rows, then, my next question is, at what point SHOULD I be concerned? I will likely be adding another couple hundred thousand soon, so I worry, and I fret. How is sphinx going to feel about all this? Is it going to freak out when it realizes it has to index all this data? Or will it be fine? Is this normal for it? If it is, at what point should I be concerned that it's too much data for Sphinx? Thanks for any thoughts.

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  • Select those objects whose related objects IDs are *all* in given string

    - by Jannis
    Hi Django people, I want to build a frontend to a recipe database which enables the user to search for a list of recipes which are cookable with the ingredients the user supplies. I have the following models class Ingredient(models.Model): name = models.CharField(max_length=100, unique=True) slug = models.SlugField(max_length=100, unique=True) importancy = models.PositiveSmallIntegerField(default=4) […] class Amount(models.Model): recipe = models.ForeignKey('Recipe') ingredient = models.ForeignKey(Ingredient) […] class Rezept(models.Model): name = models.CharField(max_length=100) slug = models.SlugField() instructions = models.TextField() ingredients = models.ManyToManyField(Ingredient, through=Amount) […] and a rawquery which does exactly what I want: It gets all the recipes whose required ingredients are all contained in the list of strings that the user supplies. If he supplies more than necessary, it's fine too. query = "SELECT *, COUNT(amount.zutat_id) AS selected_count_ingredients, (SELECT COUNT(*) FROM amount WHERE amount.recipe_id = amount.id) AS count_ingredients FROM amount LEFT OUTER JOIN amount ON (recipe.id = recipe.recipe_id) WHERE amount.ingredient_id IN (%s) GROUP BY amount.id HAVING count_ingredient=selected_count_ingredient" % ",".join([str(ingredient.id) for ingredient in ingredients]) rezepte = Rezept.objects.raw(query) Now, what I'm looking for is a way that does not rely on .raw() as I would like to do it purely with Django's queryset methods. Additionally, it would be awesome if you guys knew a way of including the ingredient's importancy in the lookup so that a recipe is still shown as a result even though one of its ingredients (that has an importancy of 0) is not supplied by the user.

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  • Dynamically setting the queryset of a ModelMultipleChoiceField to a custom recordset

    - by Daniel Quinn
    I've seen all the howtos about how you can set a ModelMultipleChoiceField to use a custom queryset and I've tried them and they work. However, they all use the same paradigm: the queryset is just a filtered list of the same objects. In my case, I'm trying to get the admin to draw a multiselect form that instead of using usernames as the text portion of the , I'd like to use the name field from my account class. Here's a breakdown of what I've got: # models.py class Account(models.Model): name = models.CharField(max_length=128,help_text="A display name that people understand") user = models.ForeignKey(User, unique=True) # Tied to the User class in settings.py class Organisation(models.Model): administrators = models.ManyToManyField(User) # admin.py from django.forms import ModelMultipleChoiceField from django.contrib.auth.models import User class OrganisationAdminForm(forms.ModelForm): def __init__(self, *args, **kwargs): from ethico.accounts.models import Account self.base_fields["administrators"] = ModelMultipleChoiceField( queryset=User.objects.all(), required=False ) super(OrganisationAdminForm, self).__init__(*args, **kwargs) class Meta: model = Organisation This works, however, I want queryset above to draw a selectbox with the Account.name property and the User.id property. This didn't work: queryset=Account.objects.all().order_by("name").values_list("user","name") It failed with this error: 'tuple' object has no attribute 'pk' I figured that this would be easy, but it's turned into hours of dead-ends. Anyone care to shed some light?

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  • Blocking error in celery

    - by dmitry
    I have no idea what's this. Python 2.7 + django-1.5.1 + httpd + rabbitmq + django-celery==3.0.17 Tasks are not executed because of some error. Below is celery's log. Maybe someone has faced it before. [2013-06-24 17:10:03,792: CRITICAL/MainProcess] Can't decode message body: AttributeError("'JoinInfo' object has no attribute '__dict__'",) (type:u'application/x-python-serialize' encoding:u'binary' raw:'\'\\x80\\x02}q\\x01(U\\x07expiresq\\x02NU\\x03utcq\\x03\\x88U\\x04argsq\\x04cdjango.contrib.auth.models\\nUser\\nq\\x05)\\x81q\\x06}q\\x07(U\\x08usernameq\\x08X\\x19\\x00\\x00\\[email protected]\\nfirst_nameq\\tX\\x05\\x00\\x00\\x00BibbyU\\tlast_nameq\\nX\\x08\\x00\\x00\\x00OffshoreU\\r_client_cacheq\\x0bccopy_reg\\n_reconstructor\\nq\\x0ccbongoregistration.models\\nClient\\nq\\rc__builtin__\\nobject\\nq\\x0eN\\x87Rq\\x0f}q\\x10(h\\nX\\x08\\x00\\x00\\x00OffshoreU\\x1bpurchase_confirmation_emailq\\x11X\\x1f\\x00\\x00\\[email protected]\\x1dpurchase_confirmation_email_1q\\x12X!\\x00\\x00\\[email protected]\\x06_stateq\\x13cdjango.db.models.base\\nModelState\\nq\\x14)\\x81q\\x15}q\\x16(U\\x06addingq\\x17\\x89U\\x02dbq\\x18U\\x07defaultq\\x19ubU\\x0buser_ptr_idq\\x1aJ\\xb4\\xa2\\x03\\x00U\\x08is_staffq\\x1b\\x89U\\x08postcodeq\\x1cX\\x08\\x00\\x00\\x00AB11 5BSU\\x0cdegree_limitq\\x1dK\\x06U\\x07messageq\\x1eX\\xd1E\\x00\\x00<table id="container" style="margin: 0px; padding: 0px; width: 100%; background-color: #ffffff;" cellspacing="0" cellpadding="0"... (22911b)'') Traceback (most recent call last): File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/messaging.py", line 556, in _receive_callback decoded = None if on_m else message.decode() File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/transport/base.py", line 147, in decode self.content_encoding, accept=self.accept) File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/serialization.py", line 187, in decode return decode(data) File "/opt/www/MyProject-main/eggs/kombu-2.5.10-py2.7.egg/kombu/serialization.py", line 74, in pickle_loads return load(BytesIO(s)) AttributeError: 'JoinInfo' object has no attribute '__dict__'

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  • Firefox handles xxx.submit(), Safari doesn't ... what can be done?

    - by Prairiedogg
    I'm trying to make a pull down menu post a form when the user selects (releases the mouse) on one of the options from the menu. This code works fine in FF but Safari, for some reason, doesn't submit the form. I re-wrote the code using jquery to see if jquery's .submit() implementation handled the browser quirks better. Same result, works in FF doesn't work in safari. The following snippets are from the same page, which has some django template language mixed in. Here's the vanilla js attempt: function formSubmit(lang) { if (lang != '{{ LANGUAGE_CODE }}') { document.getElementById("setlang_form").submit(); } } Here's the jquery attempt: $(document).ready(function() { $('#lang_submit').hide() $('#setlang_form option').mouseup(function () { if ($(this).attr('value') != '{{ LANGUAGE_CODE }}') { $('#setlang_form').submit() } }); }); and here's the form: <form id="setlang_form" method="post" action="{% url django.views.i18n.set_language %}"> <fieldset> <select name="language"> {% for lang in interface_languages %} <option value="{{ lang.code }}" onmouseup="formSubmit('{{ lang.name }}')" {% ifequal lang.code LANGUAGE_CODE %}selected="selected"{% endifequal %}>{{ lang.name }}</option> {% endfor %} </select> </fieldset> </form> My question is, how can I get this working in Safari?

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  • Do you use an exception class in your Perl programs? Why or why not?

    - by daotoad
    I've got a bunch of questions about how people use exceptions in Perl. I've included some background notes on exceptions, skip this if you want, but please take a moment to read the questions and respond to them. Thanks. Background on Perl Exceptions Perl has a very basic built-in exception system that provides a spring-board for more sophisticated usage. For example die "I ate a bug.\n"; throws an exception with a string assigned to $@. You can also throw an object, instead of a string: die BadBug->new('I ate a bug.'); You can even install a signal handler to catch the SIGDIE psuedo-signal. Here's a handler that rethrows exceptions as objects if they aren't already. $SIG{__DIE__} = sub { my $e = shift; $e = ExceptionObject->new( $e ) unless blessed $e; die $e; } This pattern is used in a number of CPAN modules. but perlvar says: Due to an implementation glitch, the $SIG{DIE} hook is called even inside an eval(). Do not use this to rewrite a pending exception in $@ , or as a bizarre substitute for overriding CORE::GLOBAL::die() . This strange action at a distance may be fixed in a future release so that $SIG{DIE} is only called if your program is about to exit, as was the original intent. Any other use is deprecated. So now I wonder if objectifying exceptions in sigdie is evil. The Questions Do you use exception objects? If so, which one and why? If not, why not? If you don't use exception objects, what would entice you to use them? If you do use exception objects, what do you hate about them, and what could be better? Is objectifying exceptions in the DIE handler a bad idea? Where should I objectify my exceptions? In my eval{} wrapper? In a sigdie handler? Are there any papers, articles or other resources on exceptions in general and in Perl that you find useful or enlightening.

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  • Why use try … finally without a catch clause?

    - by Nick Rosencrantz
    The classical way to program is with try / catch but when is it appropriate to use try without catch? In Python the following appears legal and can make sense: try: #do work finally: #do something unconditional But we didn't catch anything. Similarly one could think in Java it would be try { //for example try to get a database connection } finally { //closeConnection(connection) } It looks good and suddenly I don't have to worry about exception types etc. But if this is good practice, when is it good practice? Or reasons why this is not good practice or not legal (I didn't compile the source I'm asking about and it could be a syntax error for Java but I checked that the Python surely compiles.) A related problem I've run into is that I continue writing the function / method and at the end I must return something and I'm in a place which should not be reached and it must be a return point so even if I handle the exceptions above I'm still returning null or an empty string at some point in the code which should not be reached, often the end of the method / function. I've always managed to restructure to code so that I don't have to return null since that absolutely appears to look like less than good practice.

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  • Good practice or service for monitoring unhandled application errors for a small organization

    - by palto
    I'm working with multiple software with varying ways of monitoring for errors. When I make software, I usually send email with the stack trace to admins(usually me). Some customer software is monitored by a team who check that a particular batch run was successfull. Other software might not have any monitoring at all(someone will call when things go wrong horribly). Sending emails is good, except when things start going wrong, my mail gets filled fast. Also I don't want to solve the same problem in code for every software. Is there some relatively cheap and low maintenance software or practice to handle this. I want it to be cheap/low maintenance because usually I work alone or in teams of 5 or smaller. For example it would be great if errors would be aggregated so I don't get 10 000 emails when something unexpected happens... For clarification: By unhandled errors I mean Exceptions that were unhandled by application code that were propagated to Tomcat or Jboss. I don't need help with how to catch those errors. I need help with what to do with them. Is there any cloud application that I could send my errors to? Or some simple server to install? Or some library that can handle errors using configuration files. I use Java if that is any help.

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  • Catch All (handled or unhandled) Exceptions

    - by andySF
    Hi, I want to catch all exceptions raised (handled or unhandled) to log them. for unhandled i use ThreadExceptionEventHandler and UnhandledExceptionEventHandler but i want to catch and exceptions that are in try catch block with or without (Exception e). It's possible to inherit the exceptions class to create a general event?

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  • Exceptions & Interrupts

    - by Betamoo
    When I was searching for a distinction between Exceptions and Interrupts, I found this question Interrupts and exceptions on SO... Some answers there were not suitable (at least for assembly level): "Exception are software-version of an interrupt" But there exist software interrupts!! "Interrupts are asynchronous but exceptions are synchronous" Is that right? "Interrupts occur regularly" "Interrupts are hardware implemented trap, exceptions are software implemented" Same as above! I need to find if some of these answers were right , also I would be grateful if anyone could provide a better answer... Thanks!

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  • What to do of exceptions when implementing java.lang.Iterator

    - by Vincent Robert
    The java.lang.Iterator interface has 3 methods: hasNext, next and remove. In order to implement a read-only iterator, you have to provide an implementation for 2 of those: hasNext and next. My problem is that these methods does not declare any exceptions. So if my code inside the iteration process declares exceptions, I must enclose my iteration code inside a try/catch block. My current policy has been to rethrow the exception enclosed in a RuntimeException. But this has issues because the checked exceptions are lost and the client code no longer can catch those exceptions explicitly. How can I work around this limitation in the Iterator class? Here is a sample code for clarity: class MyIterator implements Iterator { @Override public boolean hasNext() { try { return implementation.testForNext(); } catch ( SomethingBadException e ) { throw new RuntimeException(e); } } @Override public boolean next() { try { return implementation.getNext(); } catch ( SomethingBadException e ) { throw new RuntimeException(e); } } ... }

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  • getting detailed information about structured exceptions

    - by Martin
    My Visual C++ application is compiled with /EHA option, letting me catch structured exceptions (division by zero, access violation, etc). I then translate those exceptions to my own exception class using _set_se_translator(). My goal is to improve our logging of those types of exceptions. I can get the type of exception from the EXCEPTION_RECORD structure, and the exception address. I would like to be able to gather more information, like the source file/location where the exception is thrown, the call stack, etc. Is that possible? I do create an exception minidump on structured exceptions - is there a tool to automatically get the call stack from that?

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  • protecting COM interfaces from exceptions

    - by rmeador
    I have several dozen objects exposed through COM interfaces, each of which with many methods, totaling a few hundred methods. These interfaces expose business objects from my app to a scripting engine. I have been given the task of protecting every single one of these methods from exceptions being thrown (to catch them and return an error using COM's Error() function, which incidentally I can find no documentation on because it's impossible to google). To my understanding, this requires that I add a try/catch around the guts of each one of these methods. The catch blocks are going to be similar or identical for each and every one of these hundreds of methods, which strongly smells of a problem (massively violates the DRY principle), but I can't think of any way to avoid changing every method. As far as I can tell, these methods are invoked directly by COM, with no intervening code that I can hook into to catch the exceptions. My current best idea is to make a macro for the catch block, but that has it's own sort of code-smell. Can anyone come up with a better approach? BTW, my app's exceptions do not derive from std::exception, so if there is some way of COM automatically handling standard exceptions, it won't help. And I sadly cannot change the existing exceptions to derive from std::exception.

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  • How to break on unhandled exceptions in Silverlight

    - by Bruno Martinez
    In console .Net applications, the debugger breaks at the point of the throw (before stack unwinding) for exceptions with no matching catch block. It seems that Silverlight runs all user code inside a try catch, so the debugger never breaks. Instead, Application.UnhandledException is raised, but after catching the exception and unwinding the stack. To break when unhandled exceptions are thrown and not catched, I have to enable first chance exception breaks, which also stops the program for handled exceptions. Is there a way to remove the Silverlight try block, so that exceptions get directly to the debugger?

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  • Which framework exceptions should every programmer know about ?

    - by Thibault Falise
    I've recently started a new project in C#, and, as I was coding some exception throw in a function, I figured out I didn't really know which exception I should use. Here are common exceptions that are often thrown in many programs : ArgumentException ArgumentNullException InvalidOperationException Are there any framework exceptions you often use in your programs ? Which exceptions should every .net programmer know about ? When do you use custom exception ?

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