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  • scala currying by nested functions or by multiple parameter lists

    - by Morgan Creighton
    In Scala, I can define a function with two parameter lists. def myAdd(x :Int)(y :Int) = x + y This makes it easy to define a partially applied function. val plusFive = myAdd(5) _ But, I can accomplish something similar by defining and returning a nested function. def myOtherAdd(x :Int) = { def f(y :Int) = x + y f _ } Cosmetically, I've moved the underscore, but this still feels like currying. val otherPlusFive = myOtherAdd(5) What criteria should I use to prefer one approach over the other?

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  • Why is there a limit of max 20 parameters to a clojure function

    - by GuyC
    Hi, there seems to be a limit to the number of parameters a clojure function can take. When defining a function with more than 20 parameters I receive the following: Obviously this can be avoided, but I was hitting this limit porting the execution model of an existing DSL to clojure, and I have constructs in my DSL like the following, which by macro expansion can be mapped to functions quite easily except for this limit: (defAlias nn1 ((element ?e1) (element ?e2)) number "@doc features of the elements are calculated for entry into the first neural network, the result is the score computed by the latter" (nn1-recall (nn1-feature00 ?e1 ?e2) (nn1-feature01 ?e1 ?e2) ... (nn1-feature89 ?e1 ?e2))) which is a DSL statement to call a neural network with 90 input nodes. Can work around it of course, but was wondering where the limit comes from. Thanks.

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  • templates of functions

    - by anotr67
    I'm told to create template of function , that will take 4 arguments : pointer reference pointer to array pointer to function How to perform this task ? I was trying : template<typename TYPE> TYPE biggest(TYPE *L, TYPE $M, TYPE *K[], TYPE *O()) { } but it is wrong.

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  • seperating interface and implemention with normal functions

    - by ace
    this seems like it should be pretty simple, im probably leaving something simple out. this is the code im trying to run. it is 3 files, 2*cpp and 1*header. -------------lab6.h ifndef LAB6_H_INCLUDED define LAB6_H_INCLUDED int const arraySize = 10; int array1[arraySize]; int array2[arraySize]; void generateArray(int[], int ); void displayArray(int[], int[], int ); void reverseOrder(int [],int [], int); endif // LAB6_H_INCLUDED -----------------lab6.cpp include using std::cout; using std::endl; include using std::rand; using std::srand; include using std::time; include using std::setw; include "lab6.h" void generateArray(int array1[], int arraySize) { srand(time(0)); for (int i=0; i<10; i++) { array1[i]=(rand()%10); } } void displayArray(int array1[], int array2[], int arraySize) { cout<<endl<<"Array 1"<<endl; for (int i=0; i<arraySize; i++) { cout<<array1[i]<<", "; } cout<<endl<<"Array 2"<<endl; for (int i=0; i<arraySize; i++) { cout<<array2[i]<<", "; } } void reverseOrder(int array1[],int array2[], int arraySize) { for (int i=0, j=arraySize-1; i<arraySize;j--, i++) { array2[j] = array1[i]; } } ------------and finally main.cpp include "lab6.h" int main() { generateArray(array1, arraySize); reverseOrder(array1, array2, arraySize); displayArray(array1, array2, arraySize); return 0; }

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  • Override number of parameters of pure virtual functions

    - by Jir
    I have implemented the following interface: template <typename T> class Variable { public: Variable (T v) : m_value (v) {} virtual void Callback () = 0; private: T m_value; }; A proper derived class would be defined like this: class Derived : public Variable<int> { public: Derived (int v) : Variable<int> (v) {} void Callback () {} }; However, I would like to derive classes where Callback accepts different parameters (eg: void Callback (int a, int b)). Is there a way to do it?

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  • T-SQL String Functions: difference between using Left/Right and Substring and strange behaviour

    - by TheObserver
    I am using SQL Server 2008 & 2005 (Express). I'm trying to extract part of an alpha numeric string from a varchar field. RIGHT(str_field,3) yields null values but substring(str_field, len(str_field)-2, len(str_field)) gives the right value. left(str_field,7) gives the expected values. What gives? I would have thought that RIGHT(str_field,3) and substring(str_field, len(str_field)-2, len(str_field)) are equivalent expressions.

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  • Oracle analytic functions for "the atatrbute from the row with the max date"

    - by tpdi
    I'm refactoring a colleague's code, and I have several cases where he's using a cursor to get "the latest row that matches some predicate": His technique is to write the join as a cursor, order it by the date field descending, open the cursor, get the first row, and close the cursor. This requires calling a cursor for each row of the result set that drives this, which is costly for many rows. I'd prefer to be able to join, but what something cheaper than a correlated subquery: select a.id_shared_by_several_rows, a.foo from audit_trail a where a.entry_date = (select max(a.entry_date) from audit_trail b where b.id_shared_by_several_rows = a.id_shared_by_several_rows ); I'm guessing that since this is a common need, there's an Oracle analytic function that does this?

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  • Calling PHP functions within HEREDOC strings

    - by Doug Kavendek
    In PHP, the HEREDOC string declarations are really useful for outputting a block of html. You can have it parse in variables just by prefixing them with $, but for more complicated syntax (like $var[2][3]), you have to put your expression inside {} braces. In PHP 5, it is possible to actually make function calls within {} braces inside a HEREDOC string, but you have to go through a bit of work. The function name itself has to be stored in a variable, and you have to call it like it is a dynamically-named function. For example: $fn = 'testfunction'; function testfunction() { return 'ok'; } $string = <<< heredoc plain text and now a function: {$fn()} heredoc; As you can see, this is a bit more messy than just: $string = <<< heredoc plain text and now a function: {testfunction()} heredoc; There are other ways besides the first code example, such as breaking out of the HEREDOC to call the function, or reversing the issue and doing something like: ?> <!-- directly outputting html and only breaking into php for the function --> plain text and now a function: <?PHP print testfunction(); ?> The latter has the disadvantage that the output is directly put into the output stream (unless I'm using output buffering), which might not be what I want. So, the essence of my question is: is there a more elegant way to approach this? Edit based on responses: It certainly does seem like some kind of template engine would make my life much easier, but it would require me basically invert my usual PHP style. Not that that's a bad thing, but it explains my inertia.. I'm up for figuring out ways to make life easier though, so I'm looking into templates now.

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  • When to use "property" builtin: auxiliary functions and generators

    - by Seth Johnson
    I recently discovered Python's property built-in, which disguises class method getters and setters as a class's property. I'm now being tempted to use it in ways that I'm pretty sure are inappropriate. Using the property keyword is clearly the right thing to do if class A has a property _x whose allowable values you want to restrict; i.e., it would replace the getX() and setX() construction one might write in C++. But where else is it appropriate to make a function a property? For example, if you have class Vertex(object): def __init__(self): self.x = 0.0 self.y = 1.0 class Polygon(object): def __init__(self, list_of_vertices): self.vertices = list_of_vertices def get_vertex_positions(self): return zip( *( (v.x,v.y) for v in self.vertices ) ) is it appropriate to add vertex_positions = property( get_vertex_positions ) ? Is it ever ok to make a generator look like a property? Imagine if a change in our code meant that we no longer stored Polygon.vertices the same way. Would it then be ok to add this to Polygon? @property def vertices(self): for v in self._new_v_thing: yield v.calculate_equivalent_vertex()

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  • How to get global variable in JQuery functions

    - by Tahir Akram
    I want to access my global javascript variable in JQuery methods. But I am unable to get it when I go to attach a click even to a div. As following. How can I do that? I mean do I need to rely on hidden fields for some state management? var divCount = 3; $(function() { //divCount is accessible here $("#sortable").sortable({ revert: true }); $("#new").click(function(){ if (divCount<7){ //divCount is not accessible here. why? and how? var thisCount = ++divCount; $("#draggable_"+thisCount).addClass("draggable"); } }); });

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  • Overriding deep functions in javascript

    - by PintSizedCat
    I'm quite new to javascript but have undertaken a task to get better aquainted with it. However, I am running into some problems with jQuery. The following javascript is the code that is in a third party jQuery plugin and I would love to be able to override the funFunction() function here to do my own implementation. Is this possible, if so, how can I do it? I've been doing a fair amount of searching and have tried a number of methods for overriding the function using things like: jQuery.blah.funFunction = funtion() { alert("like this"); }; Main code: (function($) { $.extend( { blah: new function() { this.construct = = function(settings) { //Construct... stuff }; function funFunction() { //Function I want to override } } }); })(jQuery); For those further interested I am trying to override tablesorter so that the only way a user can sort a column is in ascending order only. Edit: There is a wordpress installation that uses WP-Table-Reloaded which in turn uses this plugin. I don't want to change the core code for this plugin because if there was ever an update I would then have to make sure that my predecessor knew exactly what I had done. I've been programming for a long time and feel like I should easily be able to pick up javascript whilst also looking at jQuery. I know exactly what I need to do for this, just not how I can override this function.

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  • SQL with Regular Expressions vs Indexes with Logical Merging Functions

    - by geeko
    Hello Lads, I am trying to develop a complex textual search engine. I have thousands of textual pages from many books. I need to search pages that contain specified complex logical criterias. These criterias can contain virtually any compination of the following: A: Full words. B: Word roots (semilar to stems; i.e. all words with certain key letters). C: Word templates (in some languages are filled in certain templates to form various part of speech such as adjactives, past/present verbs...). D: Logical connectives: AND/OR/XOR/NOT/IF/IFF and parentheses to state priorities. Now, would it be faster to have the pages' full text in database (not indexed) and search though them all using SQL and Regular Expressions ? Or would it be better to construct indexes of word/root/template-page-location tuples. Hence, we can boost searching for individual words/roots/templates. However, it gets tricky as we interdouce logical connectives into our query. I thought of doing the following steps in such cases: 1: Seperately search for each individual words/roots/templates in the specified query. 2: On priority bases, we merge two result lists (from step 1) at a time depedning on the logical connective For example, if we are searching for "he AND (is OR was)": 1: We shall search for "he", "is" and "was" seperately and get result lists for each word. 2: Merge the result lists of "is" and "was" using the merging function OR-MERGE 3: Merge the merged result list from the OR-MERGE function with the one of "he" using the merging function AND-MERGE The result of step 3 is then returned as the result of the specified query. What do you think gurues ? Which is faster ? Any better ideas ? Thank you all in advance.

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  • Scoping inside Javascript anonymous functions

    - by DCD
    I am trying to make a function return data from an ajax call that I can then use. The issue is the function itself is called by many objects, e.g.: function ajax_submit (obj) { var id = $(obj).attr('id'); var message = escape ($("#"+id+" .s_post").val ()); var submit_string = "action=post_message&message="+message; $.ajax({ type: "POST", url: document.location, data: submit_string, success: function(html, obj) { alert (html); } }); return false; } Which means that inside the anonymous 'success' function I have no way of knowing what the calling obj (or id) actually are. The only way I can think of doing it is to attach id to document but that just seems a bit too crude. Is there another way of doing this?

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  • cannot edit any php files using specific functions

    - by user458474
    I cannot update any txt files using php. When I write a simple code like the following: <?php // create file pointer $fp = fopen("C:/Users/jj/bob.txt", 'w') or die('Could not open file, or fike does not exist and failed to create.'); $mytext = '<b>hi. This is my test</b>'; // write text to file fwrite($fp, $mytext) or die('Could not write to file.'); $content = file("C:/Users/jj/bob.txt"); // close file fclose($fp); ?> Both files do exist in the folder. I just cannot see any updates on bob.txt. Is this a permission error in windows? It works fine on my laptop at home. I also cannot change the php files on my website, using filezilla.

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  • How do you document anonymous functions ?

    - by clutch
    I'm specifically referring to JavaScript anonymous function but this could be relevant to other languages. I like to use JSDoc notations in my scripts because I know other people will be hacking at it sooner or later. When i have pretty complex anonymous function how do people document it so that it gets picked up by Eclipse and other IDE's that understand JSDoc or JavaDoc notations? /** * Blah Blah blah * * @param Object Blah blah blah * @return Blah Blah Blah * @type Object */ function foo(this) { ...... this.bar = function () { ... complex code .....}; ...... return obj; } Thanks

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  • PHP anonymous functions scope question

    - by Dan
    Hi, I'm trying to sort an array of objects by a common property, however I cannot get my $property parameter to register in the inner function (I can use it in the outer one OK). The way I read the documentation, it sounded like the parameter would be available, have I misunderstood something? Here is what I have: public static function sortObjectsByProperty($objects, $property) { function compare_object($a, $b) { $a = $a->$property; $b = $b->$property; if ($a->$property == $b->$property) { return 0; } return ($a->$property > $b->$property) ? +1 : -1; } usort($objects, 'compare_object'); return $objects; } Any advice appreciated. Thanks.

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  • GCC, functions, and pointer arguments, warning behaviour

    - by James Morris
    I've recently updated to a testing distribution, which is now using GCC 4.4.3. Now I've set everything up, I've returned to coding and have built my project and I get one of these horrible messages: *** glibc detected *** ./boxyseq: free(): invalid pointer: 0x0000000001d873e8 *** I absolutely know what is wrong here, but was rather confused as to when I saw my C code where I call a function which frees a dynamically allocated data structure - I had passed it an incompatible pointer type - a pointer to a completely different data structure. warning: passing argument 1 of 'data_A_free' from incompatible pointer type note: expected 'struct data_A *' but argument is of type 'struct data_B *' I'm confused because I'm sure this would have been an error before and compilation would never have completed. Is this not just going to make life more difficult for C programmers? Can I change it back to an error without making a whole bunch of other warnings errors too? Or am I loosing the plot and it's always been a warning?

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  • Using hash functions with Bloom filters

    - by dangerstat
    Hi, A bloom filter uses a hash function (or many) to generate a value between 0 and m given an input string X. My question is how to you use a hash function to generate a value in this way, for example an MD5 hash is typically represented by a 32 length hex string, how would I use an MD5 hashing algorithm to generate a value between 0 and m where I can specify m? I'm using Java at the moment so an example of to do this with the MessageDigest functionality it offers would be great, though just a generic description of how to do about it would be fine too. Thanks

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  • Help needed with Javascript Variable Scope / OOP and Call Back Functions

    - by gargantaun
    I think this issue goes beyond typical variable scope and closure stuff, or maybe I'm an idiot. Here goes anyway... I'm creating a bunch of objects on the fly in a jQuery plugin. The object look something like this function WedgePath(canvas){ this.targetCanvas = canvas; this.label; this.logLabel = function(){ console.log(this.label) } } the jQuery plugin looks something like this (function($) { $.fn.myPlugin = function() { return $(this).each(function() { // Create Wedge Objects for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; globalFunction(i, newWedge]); } }); } })(jQuery); So... the plugin creates a bunch of wedgeObjects, then calls 'globalFunction' for each one, passing in the latest WedgePath instance. Global function looks like this. function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; targetWedge.logLabel(); } What happens next is that the console logs each wedges label correctly. However, I need a bit more complexity inside globalFunction. So it actually looks like this... function globalFunction(indicator_id, pWedge){ var targetWedge = pWedge; someSql = "SELECT * FROM myTable WHERE id = ?"; dbInterface.executeSql(someSql, [indicator_id], function(transaction, result){ targetWedge.logLabel(); }) } There's a lot going on here so i'll explain. I'm using client side database storage (WebSQL i call it). 'dbInterface' an instance of a simple javascript object I created which handles the basics of interacting with a client side database [shown at the end of this question]. the executeSql method takes up to 4 arguments The SQL String an optional arguments array an optional onSuccess handler an optional onError handler (not used in this example) What I need to happen is: When the WebSQL query has completed, it takes some of that data and manipulates some attribute of a particular wedge. But, when I call 'logLabel' on an instance of WedgePath inside the onSuccess handler, I get the label of the very last instance of WedgePath that was created way back in the plugin code. Now I suspect that the problem lies in the var newWedge = new WedgePath(canvas); line. So I tried pushing each newWedge into an array, which I thought would prevent that line from replacing or overwriting the WedgePath instance at every iteration... wedgeArray = []; // Inside the plugin... for(var i = 1; i <= 30; i++){ var newWedge = new WedgePath(canvas); newWedge.label = "my_wedge_"+i; wedgeArray.push(newWedge); } for(var i = 0; i < wedgeArray.length; i++){ wedgeArray[i].logLabel() } But again, I get the last instance of WedgePath to be created. This is driving me nuts. I apologise for the length of the question but I wanted to be as clear as possible. END ============================================================== Also, here's the code for dbInterface object should it be relevant. function DatabaseInterface(db){ var DB = db; this.sql = function(sql, arr, pSuccessHandler, pErrorHandler){ successHandler = (pSuccessHandler) ? pSuccessHandler : this.defaultSuccessHandler; errorHandler = (pErrorHandler) ? pErrorHandler : this.defaultErrorHandler; DB.transaction(function(tx){ if(!arr || arr.length == 0){ tx.executeSql(sql, [], successHandler, errorHandler); }else{ tx.executeSql(sql,arr, successHandler, errorHandler) } }); } // ---------------------------------------------------------------- // A Default Error Handler // ---------------------------------------------------------------- this.defaultErrorHandler = function(transaction, error){ // error.message is a human-readable string. // error.code is a numeric error code console.log('WebSQL Error: '+error.message+' (Code '+error.code+')'); // Handle errors here var we_think_this_error_is_fatal = true; if (we_think_this_error_is_fatal) return true; return false; } // ---------------------------------------------------------------- // A Default Success Handler // This doesn't do anything except log a success message // ---------------------------------------------------------------- this.defaultSuccessHandler = function(transaction, results) { console.log("WebSQL Success. Default success handler. No action taken."); } }

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  • useful customize/enhanced php functions that make thing easy and better

    - by I Like PHP
    Hello All, i like to work in php bcoz it's just amazing language. please share basic, useful, enhanced and customize function that make things better and easy in php and must be used in our all PHP project, i m sharing some of them please share your customize function that may be useful for everyone alternative/ enhanced print_r() and var_dump() function watch( $what ) { echo '<pre>'; if ( is_array( $what ) ) { print_r ( $what ); } else { var_dump ( $what ); } echo '</pre>'; } usage: 1. watch($_POST); // to see all post variable 2. watch($array); // to see any variable may b array, string or a variable enhanced mysql_escape_string() for multidimensional array to prevent sql injection function recursive_escape(&$value) { if (is_array($value)) array_map('recursive_escape', $value); else $value = mysql_escape_string($value); } usage array_map('recursive_escape', $_POST); ---------------------For encoding Get variables-------------------------------------- function nkode($k) { if ( is_array( $k ) ) return array_map("base64_encode",$k); else return base64_encode($k); } ---------------------for decoding varaibles from GET--------------------------------- function dkode($k) { if ( is_array( $k ) ) return array_map("base64_decode",$k); else return base64_decode($k); } Usage <a href="somelink.php?pid=<?php echo nkode($someid)?>"> and on next page(somelink.php) $findID=dkode($_GET[pid]); date convert to mm/dd/yyyy to yyyy-mm-dd( if we use date datatype in mysql) and also change into mm/dd/yyyy to disply on page function dateconvert($date,$func) { if ($func == 1){ //insert conversion list($month, $day, $year) = split('[/.-]', $date); $date = "$year-$month-$day"; return $date; } if ($func == 2){ //output conversion list($year, $month, $day) = split('[-.]', $date); $date = "$month/$day/$year"; return $date; } } usage $firstDate=dateconvert($_POST['firstdate'],1); // for insertion in database $showDate=dateconvert($fetch->date_field,2) // to display on browser to clean(sql injection proof) data before doing some action with that variable function cleandata($data) { $success=0; $data=trim($data); $data=strtolower($data); $data=strip_tags($data); return $data; } usage cleandata($_POST[username]); cleandata($_GET[pid]); please share any basic function that must be used , Thanks

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  • Design problem with callback functions in android

    - by Franz Xaver
    Hi folks! I'm currently developing an app in android that is accessing wifi values, that is, the application needs to scan for all access point and their specific signal strengths. I know that I have to extend the class BroadcastReceiver overwriting the method BroadcastReceiver.onReceive(Context context, Intent intent) which is called when the values are ready. Perhaps there exist solutions provided by the android system itself but I'm relatively new to android so I could need some help. The problem I encountered is that I got one class (an activity, thus controlled by the user) that needs this scan results for two different things (first to save the values in a database or second, to use them for further calculations but not both at one moment!) So how to design the callback system in order to "transport" the scan results from onReceive(Context context, Intent intent) to the operation intended by the user? My first solution was to define enums for each use case (save or use for calculations) which wlan-interested classes have to submit when querying for the values. But that would force the BroadcastReceiverextending class to save the current enum and use it as a parameter in the callback function of the querying class (this querying class needs to know what it asked for when getting backcalled) But that seems to me kind of dirty ;) So anyone a good idea for this?

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