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  • Clojure multimethod dispatching on functions and values

    - by Josh Glover
    I have a function that returns the indexes in seq s at which value v exists: (defn indexes-of [v s] (map first (filter #(= v (last %)) (zipmap (range) s)))) What I'd like to do is extend this to apply any arbitrary function for the existence test. My idea is to use a multimethod, but I'm not sure exactly how to detect a function. I want to do this: (defmulti indexes-of ???) (defmethod indexes-of ??? [v s] ;; v is a function (map first (filter v (zipmap (range) s)))) (defmethod indexes-of ??? [v s] ;; v is not a function (indexes-of #(= v %) s)) Is a multimethod the way to go here? If so, how can I accomplish what I'm trying to do?

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  • Does JSLint parse DOM functions?

    - by Paul
    I tried to use the parse() function of JSLint to parse three pieces of JavaScript code: function(b, c){var a = b + c; return a; } window.addEventListener('click', click_hanlder, true); document.documentElement.innerHTML; Here's the code, which is copied and pasted from the JSLint self-parse example: ` try { parse = make_parse(); var source = "something to parse";//replaced by the code above tree = parse(source); if (tree) { document.write(JSON.stringify(tree, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4)); } } catch (e) { document.write(JSON.stringify(e, ['name', 'message', 'from', 'to', 'key', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4)); } ` The output: returns a correct tree. returns a tree with only one node of "window". crashes the browser. I'm wondering whether JSLint doesn't support DOM function.

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  • How to access widgets created within functions in later function calls in Qt

    - by Inanepenguin
    So currently I have code, in C++, that creates a few QLabels, a QLineEdit, and a QCheckBox when a selection is made from a QComboBox. However, I would like to be able to access the widgets I have created in a later function to destroy them if a new selection is made from the combo box. I am able to access the objects created from using the Designer by doing ui-Object but i am not able to do that with objects created by using my own code. Can I do that some how, because I know how to work with that. In short, I would like to be able to dynamically create/destroy QWidgets based on selections made by the user. Is there a reference I should know of to do this, or any documentation? Or am I just completely going about this the wrong way? Here is the code I presently have for creating the objects: if (eventType == QString::fromStdString("Birthday")) { QLabel *label1 = new QLabel ("Celebrant: "); QLabel *label2 = new QLabel ("Surprise: "); QLineEdit *lineEdit = new QLineEdit; QCheckBox *box = new QCheckBox; ui->gridLayout->addWidget(label1,3,0,1,1, 0); ui->gridLayout->addWidget(label2,4,0,1,1,0); ui->gridLayout->addWidget(lineEdit,3,1,1,1,0); ui->gridLayout->addWidget(box,4,1,1,2,0); }

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  • Function pointers to member functions

    - by Jacob
    There are several duplicates of this but nobody explains why I can use a member variable to store the pointer (in FOO) but when I try it with a local variable (in the commented portion of BAR), it's illegal. Could anybody explain this? #include <iostream> using namespace std; class FOO { public: int (FOO::*fptr)(int a, int b); int add_stuff(int a, int b) { return a+b; } void call_adder(int a, int b) { fptr = &FOO::add_stuff; cout<<(this->*fptr)(a,b)<<endl; } }; class BAR { public: int add_stuff(int a, int b) { return a+b; } void call_adder(int a, int b) { //int (BAR::*fptr)(int a, int b); //fptr = &BAR::add_stuff; //cout<<(*fptr)(a,b)<<endl; } }; int main() { FOO test; test.call_adder(10,20); return 0; }

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  • CRC function without order dependency

    - by Pirks
    I need a CRC mechanism to calculate the CRC of a number of strings, such that, given two strings, A and B, the sum crc(A) + crc(B) == crc(A+B). P.S. XOR is too weak---the algorithm should be not trivial for reverse engineering.

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  • SQL: How to order values inside group by

    - by Denis Yaremov
    Consider the following MS SQL Server table: ID | X | Y ------+-------+------- 1 | 1 | 1 2 | 1 | 2 3 | 1 | 3 4 | 2 | 40 5 | 2 | 500 6 | 3 | 1 7 | 3 | 100 8 | 3 | 10 I need to select the ID of the row that has the maximum value of Y grouped by x, i.e: ID | X | Y ------+-------+------- 3 | 1 | 3 5 | 2 | 500 7 | 3 | 100 The query will be nested several times so an optimal performance solution is required... Thank you!

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  • jquery live() method on custom functions

    - by user271619
    I have a custom event handler, or I suppose some call it a custom jquery function. My problem is I'm trying to apply the live() method to it. But I'm not too successful. Here's a simple custom jquery function: $.fn.myFunction = function() { return $(this).addClass('changed'); } And here I use it: $('.changePlease').myFunction(); Ok, simple enough. But how do I apply the live() method to it?? I actually have no idea if that's even possible. But I do use live() for other things, like: $(".changePlease").live("click",function(){ alert("hello"); }); Any thoughts on this?

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  • Generate encoding String according to creation order.

    - by Tony
    I need to generate encoding String for each item I inserted into the database. for example: x00001 for the first item x00002 for the sencond item x00003 for the third item The way I chose to do this is counting the rows. Before I insert the third item, I count against the database, I know there're already 2 rows, so the next encoding is ended with 3. But there is a problem. If I delete the second item, the forth item will not be the x00004,but x00003. I can add additional columns to table, to store the next encoding, I don't know if there's other better solutions ?

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  • C#: reflection alternative for switch on enum in order to select namespace/class

    - by Am
    Hi, I have an interface named IHarvester. There are 3 implementations of that interface, each under their own namespace: Google Yahoo Bing A HarvesterManager uses the given harvester. It knows the interface and all 3 implementations. I want some way of letting the class user say in which harvester it wants to use. And in the code select that implementation, without a switch-case implementation. Can reflection save my day? Here is the code bits: // repeat for each harvester namespace Harvester.Google { public abstract class Fetcher : BaseHarvester, IInfoHarvester {...} } public enum HarvestingSource { Google, Yahoo, Bing, } class HarvesterManager { public HarvestingSource PreferedSource {get;set;} public HarvestSomthing() { switch (PreferedSource) .... // awful... } } Thanks.

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  • Evaluating and graphing functions in Matlab

    - by thiol3
    New to programming, I am trying to graph the following Gaussian function in Matlab (should graph in 3 dimensions) but am making some mistakes somewhere. What is wrong? sigma = 1 for i = 1:20 for j = 1:20 z(i,j) = (1/(2*pi*sigma^2))*exp(-(i^2+j^2)/(2*sigma^2)); end end surf(z)

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  • ideas: per-file authentication in order to download

    - by suIIIha
    i would love to use mod_xsendfile but i live in a shared environment which does not provide such a module. processing large files such as videos through a server-side script and sending it to the browser that way seems to be unacceptable in my case, so i am looking for a way to enable per-file authentication in such a way that is not going to consume resources much. nobody shall know what the actual path is to the file they are downloading. please suggest how to do that.

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  • MySQL INSERT and SELECT Order of precedence

    - by Carlos Dubus
    Hi, if an INSERT and a SELECT are done simultaneously on a mysql table which one will go first? Example: Suppose "users" table row count is 0. Then this two queries are run at the same time (assume it's at the same mili/micro second): INSERT into users (id) values (1) and SELECT COUNT(*) from users Will the last query return 0 or 1?

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  • jquery: call functions immediately after plugin

    - by Dave
    I'm sure that there's an easy answer to this, but I can't find it. I have a table 'myTable' which I stripe using the following $("#myTable tr:even").css({ "background-color": "#FEE996" }); $("#myTable tr:odd").css({ "background-color": "#FFEFAF" }); This works fine. I am also using a table filter plugin as follows $('#myTable').tableFilter(); This plugin places a blank field at the top of each column into which the filter criteria can be typed. When the table is filtered it removes unmatched rows, which in turn messes up the striping. I would like to be able to re-invoke the lines to re-stripe the table. Something like $('#myTable').tableFilter().find("tr:even").css({ "background-color": "#FEE996" }).find("tr:even").css({ "background-color": "#FFEFAF" }); Is this possible please?

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  • Lambda recursive PHP functions.

    - by Kendall Hopkins
    Is it possible to have a PHP function that is both recursive and anonymous (lambda). This is my attempt to get it to work, but it doesn't pass in the function name. $factorial = function( $n ) use ( $factorial ) { if( $n == 1 ) return 1; return $factorial( $n - 1 ) * $n; }; print $factorial( 5 ); I'm also aware that this is a bad way to implement factorial, it's just an example.

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  • JavaScript's Associative Array / Object can't be read in functions

    - by Matrym
    At the very beginning of the javascript file, I have: var lbp = {}; lbp.defaults = { minLength: 40 }; I can successfully alert it afterwards, with: alert(lbp.defaults.minLength); But as soon as I put it inside a function, when I alert, I get "Undefined". What gives, and how do I avoid this? Is it absolutely necessary to pass this variable into each function, for example, by doing: function(lbp) { alert(lbp.defaults.minLength); } I would have thought that defining it first, it would attain global scope and not be required to be passed in? Thanks in advance for enlightening me :)

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  • Excel Functions

    - by dwyane
    =MAX(SUM(A1:A5)) How do i incorporate the above formula into =IF( AND( $H$14<F22, F22<=($H$14+$H$15) ), $I$15, IF( AND( $H$14+$H$15<F22, F22<($H$14+$H$15+$H$16) ), $I$16, IF( AND( $H$14+$H$15+$H$16<F22, F22<=($H$14+$H$15+$H$16+$H$17) ), $I$17, $I$14 ) ) ) It keeps running a circular reference error. Help! The sum value shouldnt exceed 150. If exceed, then replace the cell with zero value.

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  • Elegant way to reverse order Formtastic nested objects?

    - by stephan.com
    I'm presenting a list of items to the user with a field for a new item, like this: - current_user.tasks.build - semantic_form_for current_user do |f| - f.semantic_fields_for :tasks do |t| - t.inputs do = t.input :_destroy, :as => :boolean, :label => '' - if t.object.new_record? = t.input :name, :label => false - else = t.object.name Which looks lovely and works like a charm. My only problem is I want the new record at the TOP of the list, not the bottom. Is there an elegant and easy way to do this, or am I going to have to do the new element separately, or loop through the list manually?

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  • Where to store frequently used functions in a OOP correct way

    - by Stefan Kuijers
    I'm working on a project which I want to build up OO. Now I came with a function that checks or a value is valid. private function valid(value:*, acceptedValues:Array):Boolean { for(var i:uint = 0; i < acceptedValues.length; i++) { if (value == acceptedValues[i]) { return true; } } return false; } As you can see, the function is very general and will be accessed across different classes. Now my question is; where do I store it in a OO correct way? Thanks in advance!

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  • Aggregate Functions in Index with IBMDB2

    - by Erkan
    Is there any way to pre aggregate results of aggregate functionts (f.i. count()) and store it in an index? The background is: i want to speed up count() queries. So that: Select count(users) from TE123 where region = 'A'; would be supported by an index like Region Count(Users) A 548 E 458 I know that MQTs would also help for this problem. However, in this case it is not possible to use MQT, as we use kind of an ORM and we don't want to define Entities on MQTs. I just slightly remember - one DBA told me - that there is such a function planned for DB2 V10.

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  • order array containing text and numbers

    - by ptrn
    I'm looking for the easiest way to sort an array that consists of numbers and text, and a combination of these. E.g. '123asd' '19asd' '12345asd' 'asd123' 'asd12' turns into '19asd' '123asd' '12345asd' 'asd12' 'asd123' This is going to be used in combination with the solution to another question I've asked here. The sorting function in itself works, what I need is a function that can say that that '19asd' is smaller than '123asd'. I'm writing this in JavaScript.

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