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  • PyParsing: Not all tokens passed to setParseAction()

    - by Rosarch
    I'm parsing sentences like "CS 2110 or INFO 3300". I would like to output a format like: [[("CS" 2110)], [("INFO", 3300)]] To do this, I thought I could use setParseAction(). However, the print statements in statementParse() suggest that only the last tokens are actually passed: >>> statement.parseString("CS 2110 or INFO 3300") Match [{Suppress:("or") Re:('[A-Z]{2,}') Re:('[0-9]{4}')}] at loc 7(1,8) string CS 2110 or INFO 3300 loc: 7 tokens: ['INFO', 3300] Matched [{Suppress:("or") Re:('[A-Z]{2,}') Re:('[0-9]{4}')}] -> ['INFO', 3300] (['CS', 2110, 'INFO', 3300], {'Course': [(2110, 1), (3300, 3)], 'DeptCode': [('CS', 0), ('INFO', 2)]}) I expected all the tokens to be passed, but it's only ['INFO', 3300]. Am I doing something wrong? Or is there another way that I can produce the desired output? Here is the pyparsing code: from pyparsing import * def statementParse(str, location, tokens): print "string %s" % str print "loc: %s " % location print "tokens: %s" % tokens DEPT_CODE = Regex(r'[A-Z]{2,}').setResultsName("DeptCode") COURSE_NUMBER = Regex(r'[0-9]{4}').setResultsName("CourseNumber") OR_CONJ = Suppress("or") COURSE_NUMBER.setParseAction(lambda s, l, toks : int(toks[0])) course = DEPT_CODE + COURSE_NUMBER.setResultsName("Course") statement = course + Optional(OR_CONJ + course).setParseAction(statementParse).setDebug()

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  • named_scope + average is causing the table to be specified more then once in the sql query run on po

    - by hadees
    I have a named scopes like so... named_scope :gender, lambda { |gender| { :joins => {:survey_session => :profile }, :conditions => { :survey_sessions => { :profiles => { :gender => gender } } } } } and when I call it everything works fine. I also have this average method I call... Answer.average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") which also works fine if I call it like that. However if I were to call it like so... Answer.gender('m').average(:rating, :include => {:survey_session => :profile}, :group => "profiles.career") I get... ActiveRecord::StatementInvalid: PGError: ERROR: table name "profiles" specified more than once : SELECT avg("answers".rating) AS avg_rating, profiles.career AS profiles_career FROM "answers" LEFT OUTER JOIN "survey_sessions" survey_sessions_answers ON "survey_sessions_answers".id = "answers".survey_session_id LEFT OUTER JOIN "profiles" ON "profiles".id = "survey_sessions_answers".profile_id INNER JOIN "survey_sessions" ON "survey_sessions".id = "answers".survey_session_id INNER JOIN "profiles" ON "profiles".id = "survey_sessions".profile_id WHERE ("profiles"."gender" = E'm') GROUP BY profiles.career Which is a little hard to read but says I'm including the table profiles twice. If I were to just remove the include from average it works but it isn't really practical because average is actually being called inside a method which gets passed the scoped. So there is some times gender or average might get called with out each other and if either was missing the profile include it wouldn't work. So either I need to know how to fix this apparent bug in Rails or figure out a way to know what scopes were applied to a ActiveRecord::NamedScope::Scope object so that I could check to see if they have been applied and if not add the include for average.

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  • Slow performance with MVC2 DisplayFor

    - by PretzelSteelersFan
    I'm iterating through a collection on my view model. The collection contains HealthLifeDentalRates which implement IBeginsEnds. I have a Display Template BeginsEnds that displays the date range. This results in very slow performance. If I simply the date range (see commented code), it's fine. I think how I'm defining the lambda is the problem but not sure how to change it. <% foreach (var item in Model.Data.OrderBy(x=x.HealthLifeDentalRateCode)) { % <tr> <td> <%= Html.Encode(item.FiscalPeriodString()) %> </td> <td> <%= Html.Encode(item.HealthLifeDentalRateCode) %> </td> <td> <%= Html.Encode(item.Rate) %> </td> <td> <%= Html.Encode(item.IsDental.YesNo()) %> </td> <td> <%= Html.DisplayFor(i = item, "BeginsEnds") % - <%= Html.Encode(item.Ends.ToDateString()) % -- <%= Html.Encode(String.Format("{0:g}", item.Loaded)) % - <%= Html.Encode(item.LoadedBy) % <% } %>

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  • Join two list comparing their elements properties

    - by 100r
    public class Person() { int ID; string Name; DateTime ChangeDate } var list1 = new List<Person> { new Person { ID= 1, Name = "Peter", ChangeDate= "2011-10-21" }, new Person { ID= 2, Name = "John", ChangeDate= "2011-10-22" }, new Person { ID= 3, Name = "Mike", ChangeDate= "2011-10-23" }, new Person { ID= 4, Name = "Dave", ChangeDate= "2011-10-24" } }; var list2 = new List<Person> { new Person { ID= 1, Name = "Pete", ChangeDate= "2011-10-21" }, new Person { ID= 2, Name = "Johny", ChangeDate= "2011-10-20" }, new Person { ID= 3, Name = "Mikey", ChangeDate= "2011-10-24" }, new Person { ID= 5, Name = "Larry", ChangeDate= "2011-10-27" } }; As output I would like to have list1 + list2 = Person { ID= 1, Name = "Peter", ChangeDate= "2011-10-21" }, Person { ID= 2, Name = "John", ChangeDate= "2011-10-22" }, Person { ID= 3, Name = "Mikey", ChangeDate= "2011-10-24" }, Person { ID= 4, Name = "Dave", ChangeDate= "2011-10-24" } Person { ID= 5, Name = "Larry", ChangeDate= "2011-10-27" } And the Algorithm is like this. Join two list. If elements of lists have same ID, compare them by ChangeDate and take the ond with bigger date. If ChangeDate are equeal take any of them but not both. Maybe its easier to concat both lists and than to filter them with lambda. I tried, but always came out with some ugly code :/ Anyone have any idea?

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  • Django filters - Using an AllValuesFilter (with a LinkWidget) on a ManyToManyField

    - by magnetix
    This is my first Stack Overflow question, so please let me know if I do anything wrong. I wish to create an AllValues filter on a ManyToMany field using the wonderful django-filters application. Basically, I want to create a filter that looks like it does in the Admin, so I also want to use the LinkWidget too. Unfortunately, I get an error (Invalid field name: 'operator') if I try this the standard way: # Models class Organisation(models.Model): name = models.CharField() ... class Sign(models.Model): name = models.CharField() operator = models.ManyToManyField('Organisation', blank=True) ... # Filter class SignFilter(LinkOrderFilterSet): operator = django_filters.AllValuesFilter(widget=django_filters.widgets.LinkWidget) class Meta: model = Sign fields = ['operator'] I got around this by creating my own filter with the many to many relationship hard coded: # Models class Organisation(models.Model): name = models.CharField() ... class Sign(models.Model): name = models.CharField() operator = models.ManyToManyField('Organisation', blank=True) ... # Filter class MyFilter(django_filters.ChoiceFilter): @property def field(self): cd = {} for row in self.model.objects.all(): orgs = row.operator.select_related().values() for org in orgs: cd[org['id']] = org['name'] choices = zip(cd.keys(), cd.values()) list.sort(choices, key=lambda x:(x[1], x[0])) self.extra['choices'] = choices return super(AllValuesFilter, self).field class SignFilter(LinkOrderFilterSet): operator = MyFilter(widget=django_filters.widgets.LinkWidget) I am new to Python and Django. Can someone think of a more generic/elegant way of doing this?

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  • Initialize Static Array of Structs in C

    - by russell_h
    I implementing a card game in C. There are lots of types of cards and each has a bunch of information, including some actions that will need to be individually scripted associated with it. Given a struct like this (and I'm not certain I have the syntax right for the function pointer) struct CARD { int value; int cost; // This is a pointer to a function that carries out actions unique // to this card int (*do_actions) (struct GAME_STATE *state, int choice1, int choice2); }; I would like to initialize a static array of these, one for each card. I'm guessing this would look something like this int do_card0(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } int do_card1(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } extern static struct cardDefinitions[] = { {0, 1, do_card0}, {1, 3, do_card1} }; Will this work, and am I going about this the right way at all? I'm trying to avoid huge numbers of switch statements. Do I need to define the 'do_cardN' functions ahead of time, or is there some way to define them inline in the initialization of the struct (something like a lambda function in python)? I'll need read-only access to cardDefinitions from a different file - is 'extern static' correct for that? I know this is a lot of questions rolled into one but I'm really a bit vague about how to go about this. Thanks.

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  • Multiple generic parameters on a html helper extension method

    - by WestDiscGolf
    What I'm trying to do is create an extension method for the HtmlHelper to create a specific output and associated details like TextBoxFor<. What I want to do is specify the property from the model class as per TextBoxFor<, then an associated controller action and other parameters. So far the signature of the method looks like: public static MvcHtmlString Create<TModel, TProperty, TController>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, Expression<Action<TController>> action, object htmlAttributes) where TController : Controller where TModel : class The issue occurs when I go to call it. In my view if I call it as per the TextBoxFor without specifying the Model type I am able to specify the lambda expression to set the property which it's for, but when I go to specify the action I am unable to. However, when I specify the controller type Html.Create<HomeController>( ... ) I am unable to specify the model property that the control is to be created for. I want to be able to call it like <%= Html.Create(x => x.Title, controller => controller.action, null) %> I've been hitting my head for a few hours now on this issue over the past day, can anyone point me in the right direction?

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  • Django: Determining if a user has voted or not

    - by TheLizardKing
    I have a long list of links that I spit out using the below code, total votes, submitted by, the usual stuff but I am not 100% on how to determine if the currently logged in user has voted on a link or not. I know how to do this from within my view but do I need to alter my below view code or can I make use of the way templates work to determine it? I have read http://stackoverflow.com/questions/1528583/django-vote-up-down-method but I don't quite understand what's going on ( and don't need any ofjavascriptery). Models (snippet): class Link(models.Model): category = models.ForeignKey(Category, blank=False, default=1) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add=True) modified = models.DateTimeField(auto_now=True) url = models.URLField(max_length=1024, unique=True, verify_exists=True) name = models.CharField(max_length=512) def __unicode__(self): return u'%s (%s)' % (self.name, self.url) class Vote(models.Model): link = models.ForeignKey(Link) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add=True) def __unicode__(self): return u'%s vote for %s' % (self.user, self.link) Views (snippet): def hot(request): links = Link.objects.select_related().annotate(votes=Count('vote')).order_by('-created') for link in links: delta_in_hours = (int(datetime.now().strftime("%s")) - int(link.created.strftime("%s"))) / 3600 link.popularity = ((link.votes - 1) / (delta_in_hours + 2)**1.5) if request.user.is_authenticated(): try: link.voted = Vote.objects.get(link=link, user=request.user) except Vote.DoesNotExist: link.voted = None links = sorted(links, key=lambda x: x.popularity, reverse=True) links = paginate(request, links, 15) return direct_to_template( request, template = 'links/link_list.html', extra_context = { 'links': links, }) The above view actually accomplishes what I need but in what I believe to be a horribly inefficient way. This causes the dreaded n+1 queries, as it stands that's 33 queries for a page containing just 29 links while originally I got away with just 4 queries. I would really prefer to do this using Django's ORM or at least .extra(). Any advice?

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  • Comparing all properties of an object using expression trees

    - by stringargs
    Hi, I'm trying to write a simple generator that uses an expression tree to dynamically generate a method that compares all properties of an instance of a type to the properties of another instance of that type. This works fine for most properties, like int an string, but fails for DateTime? (and presumably other nullable value types). The method: static Delegate GenerateComparer(Type type) { var left = Expression.Parameter(type, "left"); var right = Expression.Parameter(type, "right"); Expression result = null; foreach (var p in type.GetProperties()) { var leftProperty = Expression.Property(left, p.Name); var rightProperty = Expression.Property(right, p.Name); var equals = p.PropertyType.GetMethod("Equals", new[] { p.PropertyType }); var callEqualsOnLeft = Expression.Call(leftProperty, equals, rightProperty); result = result != null ? (Expression)Expression.And(result, callEqualsOnLeft) : (Expression)callEqualsOnLeft; } var method = Expression.Lambda(result, left, right).Compile(); return method; } On a DateTime? property it fails with: Expression of type 'System.Nullable`1[System.DateTime]' cannot be used for parameter of type 'System.Object' of method 'Boolean Equals(System.Object)' OK, so it finds an overload of Equals that expects object. So why can't I pass a DateTime? into that, as it's convertible to object? If I look at Nullable<T>, it indeed has an override of Equals(object o). PS: I realize that this isn't a proper generator yet as it can't deal with null values, but I'll get to that :)

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  • Non standard interaction among two tables to avoid very large merge

    - by riko
    Suppose I have two tables A and B. Table A has a multi-level index (a, b) and one column (ts). b determines univocally ts. A = pd.DataFrame( [('a', 'x', 4), ('a', 'y', 6), ('a', 'z', 5), ('b', 'x', 4), ('b', 'z', 5), ('c', 'y', 6)], columns=['a', 'b', 'ts']).set_index(['a', 'b']) AA = A.reset_index() Table B is another one-column (ts) table with non-unique index (a). The ts's are sorted "inside" each group, i.e., B.ix[x] is sorted for each x. Moreover, there is always a value in B.ix[x] that is greater than or equal to the values in A. B = pd.DataFrame( dict(a=list('aaaaabbcccccc'), ts=[1, 2, 4, 5, 7, 7, 8, 1, 2, 4, 5, 8, 9])).set_index('a') The semantics in this is that B contains observations of occurrences of an event of type indicated by the index. I would like to find from B the timestamp of the first occurrence of each event type after the timestamp specified in A for each value of b. In other words, I would like to get a table with the same shape of A, that instead of ts contains the "minimum value occurring after ts" as specified by table B. So, my goal would be: C: ('a', 'x') 4 ('a', 'y') 7 ('a', 'z') 5 ('b', 'x') 7 ('b', 'z') 7 ('c', 'y') 8 I have some working code, but is terribly slow. C = AA.apply(lambda row: ( row[0], row[1], B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))), axis=1).set_index(['a', 'b']) Profiling shows the culprit is obviously B.ix[row[0]].irow(np.searchsorted(B.ts[row[0]], row[2]))). However, standard solutions using merge/join would take too much RAM in the long run. Consider that now I have 1000 a's, assume constant the average number of b's per a (probably 100-200), and consider that the number of observations per a is probably in the order of 300. In production I will have 1000 more a's. 1,000,000 x 200 x 300 = 60,000,000,000 rows may be a bit too much to keep in RAM, especially considering that the data I need is perfectly described by a C like the one I discussed above. How would I improve the performance?

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  • What features are heavily used in C# 2.0, but is not available in VBNET 2.0, and how to workaround?

    - by Will Marcouiller
    I don't want a war between VBNET and C# developpers, neither is my goal to open a C# VS VBNET confrontation. I would like you all to list a feature that is heavily used in C#, but is not available in VBNET 2.0, and how would you work around to achieve a similar behaviour or purpose? For example: C# Accepts void (return) lambda expressions. Here's an example with FNH mapping: Component(x => x.Address, m => { m.Map(x => x.Number); m.Map(x => x.Street); m.Map(x => x.PostCode); }); This is impossible to do before VBNET 4.0 (supposed to be doable in VBNET 4.0) VBNET Must write a helping method (Sub), and provide the AddressOf this method in order to workaround. Private Sub Helper(ByVal m As MType) m.Map(Function(x) x.Number) m.Map(Function(x) x.Street) m.Map(Function(x) x.PostCode) End Sub ... Component(Function(x) x.Address, AddressOf Helper) Now I know, it is not VBNET 2.0, but this is an example. VBNET 3.0 and 3.5 can used too. Please just mention what version of VBNET this refers to.

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  • MySQL to PostreSQL and Named Scope

    - by Lowgain
    I've got a named scope for one of my models that works fine. The code is: named_scope :inbox_threads, lambda { |user| { :include => [:deletion_flags, :recipiences], :conditions => ["recipiences.user_id = ? AND deletion_flags.user_id IS NULL", user.id], :group => "msg_threads.id" }} This works fine on my local copy of the app with a MySQL database, but when I push my app to Heroku (which only uses PostgreSQL), I get the following error: ActiveRecord::StatementInvalid (PGError: ERROR: column "msg_threads.subject" must appear in the GROUP BY clause or be used in an aggregate function: SELECT "msg_threads"."id" AS t0_r0, "msg_threads"."subject" AS t0_r1, "msg_threads"."originator_id" AS t0_r2, "msg_thr eads"."created_at" AS t0_r3, "msg_threads"."updated_at" AS t0_r4, "msg_threads"."url_key" AS t0_r5, "deletion_flags"."id" AS t1_r0, "deletion_flags"."user_id" AS t1_r1, "deletion_flags"."msg_thread_id" AS t1_r2, "deletion_flags"."confirmed" AS t1_r3, "deletion_flags"."created_at" AS t1_r4, "deletion_flags"."updated_at" AS t1_r5, "recipiences"."id" AS t2_r0, "recipiences"."user_id" AS t2_r1, "recipiences"."msg_thread_id" AS t2_r2, "recipiences"."created_at" AS t2_r3, "recipien ces"."updated_at" AS t2_r4 FROM "msg_threads" LEFT OUTER JOIN "deletion_flags" ON deletion_flags.msg_thread_id = msg_threads.id LEFT OUTER JOIN "recipiences" ON recipiences.msg_thread_id = msg_threads.id WHERE (recipiences.user_id = 1 AND deletion_flags.user_id IS NULL) GROUP BY msg_threads.id) I'm not as familiar with the working of Postgres, so what would I need to add here to get this working? Thanks!

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  • How can I assign a name to a task in TPL

    - by mehrandvd
    I'm going to use lots of tasks running on my application. Each bunch of tasks is running for some reason. I would like to name these tasks so when I watch the Parallel Tasks window, I could recognize them easily. With another point of view, consider I'm using tasks at the framework level to populate a list. A developer that use my framework is also using tasks for her job. If she looks at the Parallel Tasks Window she will find some tasks having no idea about. I want to name tasks so she can distinguish the framework tasks from her tasks. It would be very convenient if there was such API: var task = new Task(action, "Growth calculation task") or maybe: var task = Task.Factory.StartNew(action, "Populating the datagrid") or even while working with Parallel.ForEach Parallel.ForEach(list, action, "Salary Calculation Task" Is it possible to name a task? Is it possible to give ???Parallel.ForEach a naming structure (maybe using a lambda) so it creates tasks with that naming? Is there such API somewhere that I'm missing? I've also tried to use an inherited task to override it's ToString(). But unfortunately the Parallel Tasks window doesn't use ToString()! class NamedTask : Task { private string TaskName { get; set; } public NamedTask(Action action, string taskName):base(action) { TaskName = taskName; } public override string ToString() { return TaskName; } }

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  • re.sub emptying list

    - by jmau5
    def process_dialect_translation_rules(): # Read in lines from the text file specified in sys.argv[1], stripping away # excess whitespace and discarding comments (lines that start with '##'). f_lines = [line.strip() for line in open(sys.argv[1], 'r').readlines()] f_lines = filter(lambda line: not re.match(r'##', line), f_lines) # Remove any occurances of the pattern '\s*<=>\s*'. This leaves us with a # list of lists. Each 2nd level list has two elements: the value to be # translated from and the value to be translated to. Use the sub function # from the re module to get rid of those pesky asterisks. f_lines = [re.split(r'\s*<=>\s*', line) for line in f_lines] f_lines = [re.sub(r'"', '', elem) for elem in line for line in f_lines] This function should take the lines from a file and perform some operations on the lines, such as removing any lines that begin with ##. Another operation that I wish to perform is to remove the quotation marks around the words in the line. However, when the final line of this script runs, f_lines becomes an empty lines. What happened? Requested lines of original file: ## English-Geek Reversible Translation File #1 ## (Moderate Geek) ## Created by Todd WAreham, October 2009 "TV show" <=> "STAR TREK" "food" <=> "pizza" "drink" <=> "Red Bull" "computer" <=> "TRS 80" "girlfriend" <=> "significant other"

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  • LINQ extention SelectMany in 3.5 vs 4.0?

    - by Moberg
    Hi When I saw Darins suggestion here .. IEnumerable<Process> processes = new[] { "process1", "process2" } .SelectMany(Process.GetProcessesByName); ( http://stackoverflow.com/questions/3059667/process-getprocessesbyname/3059733#3059733 ) .. I was a bit intrigued and I tried it in VS2008 with .NET 3.5 - and it did not compiling unless I changed it to .. IEnumerable<Process> res = new string[] { "notepad", "firefox", "outlook" } .SelectMany(s => Process.GetProcessesByName(s)); Having read some Darins answers before I suspected that it was me that were the problem, and when I later got my hands on a VS2010 with.NET 4.0 - as expected - the original suggestion worked beautifully. My question is : What have happend from 3.5 to 4.0 that makes this (new syntax) possible? Is it the extentionmethods that have been extended(hmm) or new rules for lambda syntax or? I've tried to search but my google-fu was not strong enough. Please forgive if the question is a bit naive and note that I've taged it as beginner :)

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  • Databinding expression for retrieving value of related collection using LINQ

    - by joshb
    I have a GridView that is bound to a LINQDataSource control that is returning a collection of customers. Within my DataGrid I need to display the home phone number of a customer, if they have one. The phone numbers of a customer are stored in a separate table with a foreign key pointing to the customer table. The following binding expression gets me the first phone number for a customer: <asp:TemplateField HeaderText="LastName" SortExpression="LastName"> <ItemTemplate> <asp:Label ID="PhoneLabel" runat="server" Text='<%# Eval("Phones[0].PhoneNumber") %>'></asp:Label> </ItemTemplate> </asp:TemplateField> I need to figure out how to get the home phone number specifically (filter based on phone type) and handle the scenario where the customer does not have a home phone in the database. Right now it's throwing an out of range exception if the customer does not have any phone numbers. I've tried using the Where operator with a lambda expression to filter the phone type but it doesn't work: <%# Eval("Phones.Where(p => p.PhoneTypeId == 2).PhoneNumber") %> Solutions or links to any good articles on the subject would be much appreciated.

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  • Comparison of Java and .NET technologies/frameworks

    - by Paul Sasik
    I work in a shop that is a mix of mostly Java and .NET technologists. When discussing new solutions and architectures we often encounter impedance in trying to compare the various technologies, frameworks, APIs etc. in use between the two camps. It seems that each camp knows little about the other and we end up comparing apples to oranges and forgetting about the bushels. While researching the topic I found this: Java -- .Net rough equivalents It's a nice list but it's not quite exhaustive and is missing the key .NET 3.0 technologies and a few other tidbits. To complete that list: what are the near/rough equivalents (or a combination of technologies) in Java to the following in .NET? WCF WPF Silverlight = JavaFx WF = jBMP (Java Business Process Management) Generics Lambda expressions = lambdaJ project or Closures Linq (not Linq-to-SQL) ...have i missed anything else? Note that I omitted technologies that are already covered in the linked article. I would also like to hear feedback on whether the linked article is accurate. Thanks. (Will CW if requested.)

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  • access properties of current model in has_many declaration

    - by seth.vargo
    Hello, I didn't exactly know how to pose this question other than through example... I have a class we will call Foo. Foo :has_many Bar. Foo has a boolean attribute called randomize that determines the order of the the Bars in the :has_many relationship: class CreateFoo < ActiveRecord::Migration def self.up create_table :foos do |t| t.string :name t.boolean :randomize, :default => false end end end   class CreateBar < ActiveRecord::Migration def self.up create_table :bars do |t| t.string :name t.references :foo end end end   class Bar < ActiveRecord::Base belongs_to :foo end   class Foo < ActiveRecord::Base # this is the line that doesn't work has_many :bars, :order => self.randomize ? 'RAND()' : 'id' end How do I access properties of self in the has_many declaration? Things I've tried and failed: creating a method of Foo that returns the correct string creating a lambda function crying Is this possible? UPDATE The problem seems to be that the class in :has_many ISN'T of type Foo: undefined method `randomize' for #<Class:0x1076fbf78> is one of the errors I get. Note that its a general Class, not a Foo object... Why??

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  • C#. Saving information about events and event handlers and removing handlers using this information

    - by Philipp
    I have an object which is creating several event handlers using lambda expressions, and I need to remove all handlers created in that object in one time. I'm trying to create some unified static object which will 'know' which handler relates to which object and event if event handler was created through this static object. I tried something like code below, but I don't understand how to save events and event handlers objects, to be able remove handlers in one time. class Program { static void Main(string[] args) { var EventSender = new EventSender(); var EventReceiver = new EventReceiver(EventSender); EventSender.Invoke(" some var "); LinkSaver.RemoveEvent(EventReceiver); // ?? Console.ReadKey(); } } public class ObjLink{ public object Event; public object Action; } public static class LinkSaver { public static void SetEvent<T>(object obj, Action<T> Event, T Action) { Event(Action); var objLink = new ObjLink{Event = Event, Action = Action}; if (!Links.ContainsKey(obj)) Links.Add(obj, new List<ObjLink>{objLink}); else Links[obj].Add(objLink); } static Dictionary<object,List<ObjLink>> Links = new Dictionary<object, List<ObjLink>>(); public static void RemoveEvent(object obj){ foreach(var objLink in Links[obj]){ // objLink.Event -= objLink.Action; ??? } } } public class EventReceiver { public EventReceiver(EventSender obj) { LinkSaver.SetEvent<EventSender.TestDelegate>(this, obj.SetEvent, str => Console.WriteLine(str + " test event!")); } } public class EventSender { public void Invoke(string var) { if (eventTest != null) eventTest(var); } public void SetEvent(TestDelegate Action) { eventTest += Action; } public delegate void TestDelegate(string var); private event TestDelegate eventTest; // by the way public void RemoveFromEvent() { foreach (var handler in eventTest.GetInvocationList()) eventTest -= (TestDelegate)handler; } }

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  • Templates, Function Pointers and C++0x

    - by user328543
    One of my personal experiments to understand some of the C++0x features: I'm trying to pass a function pointer to a template function to execute. Eventually the execution is supposed to happen in a different thread. But with all the different types of functions, I can't get the templates to work. #include `<functional`> int foo(void) {return 2;} class bar { public: int operator() (void) {return 4;}; int something(int a) {return a;}; }; template <class C> int func(C&& c) { //typedef typename std::result_of< C() >::type result_type; typedef typename std::conditional< std::is_pointer< C >::value, std::result_of< C() >::type, std::conditional< std::is_object< C >::value, std::result_of< typename C::operator() >::type, void> >::type result_type; result_type result = c(); return result; } int main(int argc, char* argv[]) { // call with a function pointer func(foo); // call with a member function bar b; func(b); // call with a bind expression func(std::bind(&bar::something, b, 42)); // call with a lambda expression func( [](void)->int {return 12;} ); return 0; } The result_of template alone doesn't seem to be able to find the operator() in class bar and the clunky conditional I created doesn't compile. Any ideas? Will I have additional problems with const functions?

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  • LINQ to SQL: NOTing a prebuilt expression

    - by ck
    I'm building a library of functions for one of my core L2S classes, all of which return a bool to allow checking for certain situations. Example: Expression<Func<Account, bool>> IsSomethingX = a => a.AccountSupplementary != null && a.AccountSupplementary.SomethingXFlag != null && a.AccountSupplementary.SomethingXFlag.Value; Now to query where this is not true, I CAN'T do this: var myAccounts= context.Accounts .Where(!IsSomethingX); // does not compile However, using the syntax from the PredicateBuilder class, I've come up with this: public static IQueryable<T> WhereNot<T>(this IQueryable<T> items, Expression<Func<T, bool>> expr1) { var invokedExpr = Expression.Invoke(expr1, expr1.Parameters.Cast<Expression>()); return items.Where(Expression.Lambda<Func<T, bool>> (Expression.Not(invokedExpr), expr1.Parameters)); } var myAccounts= context.Accounts .WhereNot(IsSomethingX); // does compile which actually produces the correct SQL. Does this look like a good solution, and is there anything I need to be aware of that might cause me problems in future?

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  • Reordering fields in Django model

    - by Alex Lebedev
    I want to add few fields to every model in my django application. This time it's created_at, updated_at and notes. Duplicating code for every of 20+ models seems dumb. So, I decided to use abstract base class which would add these fields. The problem is that fields inherited from abstract base class come first in the field list in admin. Declaring field order for every ModelAdmin class is not an option, it's even more duplicate code than with manual field declaration. In my final solution, I modified model constructor to reorder fields in _meta before creating new instance: class MyModel(models.Model): # Service fields notes = my_fields.NotesField() created_at = models.DateTimeField(auto_now_add=True) updated_at = models.DateTimeField(auto_now=True) class Meta: abstract = True last_fields = ("notes", "created_at", "updated_at") def __init__(self, *args, **kwargs): new_order = [f.name for f in self._meta.fields] for field in self.last_fields: new_order.remove(field) new_order.append(field) self._meta._field_name_cache.sort(key=lambda x: new_order.index(x.name)) super(TwangooModel, self).__init__(*args, **kwargs) class ModelA(MyModel): field1 = models.CharField() field2 = models.CharField() #etc ... It works as intended, but I'm wondering, is there a better way to acheive my goal?

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  • STI and accepts_nested_attributes_for in rails

    - by ryanshackintosh
    I have models as follows: class Entity < ActiveRecord::Base has_many :addresses accepts_nested_attributes_for :addresses, :reject_if => lambda { |a| a[:label].blank?} , :allow_destroy => true end class Client < Entity before_save :set_type private def set_type self.type = "Client" end end class Address < ActiveRecord::Base belongs_to :entity end I have recently implemented accepts_nested_attributes_for on the /clients/new form, as follows: <% form_for(@client, :html => {:class => 'form'}) do |f| -%> <%= f.label :name %> <%= f.text_field :name -%> <%= f.label :phone %> <%= f.text_field :phone %> <% f.fields_for :addresses do |a| %> <%= a.label :street %> <%= a.text_field :street%> <%= a.label :city %> <%= a.text_field :city %> <% end %> <% end %> And my controller as follows: class ClientsController < ApplicationController before_filter :load_client , :except => [:index, :new, :create, :render_clients] def new @client = Client.new @client.addresses.build end def create @client = Client.new(params[:client]) if @client.save flash[:notice] = 'Client has been successfully added' redirect_to @client else render :action => 'new' end end The issue is that when the record is saved it gives an error stating: "Entity can't be blank" I assume it is something to do with the fact that a 'Client' and not an 'Entity' is being added. Can anyone point me in the right direction?

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  • Syntax errors on Heroku, but not on local server (postgresql related?)

    - by Phil_Ken_Sebben
    I'm trying to deploy my first app on Heroku (rails 3). It works fine on my local server, but when I pushed it to Heroku and ran it, it crashes, giving a number of syntax errors. These are related to a collection of scopes I use like the one below: scope :scored, lambda { |score = nil| score.nil? ? {} : where('products.votes_count >= ?', score) } it produces errors of this form: "syntax error, unexpected '=', expecting '|' " "syntax error, unexpected '}', expecting kEND" Why is this syntax making Heroku choke and how can I correct it? Thanks! EDIT: I was using sqlite on my local machine and Heroku does not support that. Trying to make sure the db is properly configured for PG. I believe I have done that by specifying in the gemfile that sqlite only be used in development. Yet I still get these syntax errors, that interrupt even the db:migrate. EDIT: So now it seems more likely that my scope syntax doesn't work in postgreSQL. Does anyone know how to convert this properly?

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  • Making Extension method Generic

    - by Ian
    In this post there's a very interesting way of updating UI threads using a static extension method. public static void InvokeIfRequired(this Control c, Action<Control> action) { if(c.InvokeRequired) { c.Invoke(() => action(c)); } else { action(c); } } What I want to do, is to make a generic version, so I'm not constrained by a control. This would allow me to do the following for example (because I'm no longer constrained to just being a Control) this.progressBar1.InvokeIfRequired(pb => pb.Value = e.Progress); I've tried the following: public static void InvokeIfRequired<T>(this T c, Action<T> action) where T : Control { if (c.InvokeRequired) { c.Invoke(() => action(c)); } else { action(c); } } But I get the following error that I'm not sure how to fix. Anyone any suggestions? Error 5 Cannot convert lambda expression to type 'System.Delegate' because it is not a delegate type

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