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• What is the fastest way to do division in C for 8bit MCUs?

  - by Jordan S

  I am working on the firmware for a device that uses an 8bit mcu (8051 architecture). I am using SDCC (Small Device C Compiler). I have a function that I use to set the speed of a stepper motor that my circuit is driving. The speed is set by loading a desired value into the reload register for a timer. I have a variable, MotorSpeed that is in the range of 0 to 1200 which represents pulses per second to the motor. My function to convert MotorSpeed to the correct 16bit reload value is shown below. I know that float point operations are pretty slow and I am wondering if there is a faster way of doing this... void SetSpeed() { float t = MotorSpeed; unsigned int j = 0; t = 1/t ; t = t / 0.000001; j = MaxInt - t; TMR3RL = j; // Set reload register for desired freq return; }

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• How to properly implement the Strategy pattern in a web MVC framework?

  - by jboxer

  In my Django app, I have a model (lets call it Foo) with a field called "type". I'd like to use Foo.type to indicate what type the specific instance of Foo is (possible choices are "Number", "Date", "Single Line of Text", "Multiple Lines of Text", and a few others). There are two things I'd like the "type" field to end up affecting; the way a value is converted from its normal type to text (for example, in "Date", it may be str(the_date.isoformat())), and the way a value is converted from text to the specified type (in "Date", it may be datetime.date.fromtimestamp(the_text)). To me, this seems like the Strategy pattern (I may be completely wrong, and feel free to correct me if I am). My question is, what's the proper way to code this in a web MVC framework? In a client-side app, I'd create a Type class with abstract methods "serialize()" and "unserialize()", override those methods in subclasses of Type (such as NumberType and DateType), and dynamically set the "type" field of a newly-instantiated Foo to the appropriate Type subclass at runtime. In a web framework, it's not quite as straightforward for me. Right now, the way that makes the most sense is to define Foo.type as a Small Integer field and define a limited set of choices (0 = "Number", 1 = "Date", 2 = "Single Line of Text", etc.) in the code. Then, when a Foo object is instantiated, use a Factory method to look at the value of the instance's "type" field and plug in the correct Type subclass (as described in the paragraph above). Foo would also have serialize() and unserialize() methods, which would delegate directly to the plugged-in Type subclass. How does this design sound? I've never run into this issue before, so I'd really like to know if other people have, and how they've solved it.

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• How to calculate commision based on referred memebrs?

  - by RAJKISHOR SAHU

  Hello everybody, I am developing a small software in C# WPF for a consultancy which does chain system business. I have coded tree structure to show who referred whom. Now it has commission depending on level. If 1 referred 2 & 3 then 1 will get level-1 commission. If 2 referred 4, 5 & 3 referred 6, 7 then 1 will receive level-2 commission. This chain will go on to certain total number. My problem is how I would implement this logic; I am able to calculate who has referred how many members via UDF written for adding TreeViewItem to TreeView. Or tell me how I can count items in treeview in certain level? Node adding UDF: public void AddNodes(int uid, TreeViewItem tSubNode) { string query = "select fullname, id from members where refCode=" + uid + ";"; MySqlCommand cmd = new MySqlCommand(query, db.conn); MySqlDataAdapter _DA = new MySqlDataAdapter(cmd); DataTable _DT = new DataTable(); tSubNode.IsExpanded = true; _DA.Fill(_DT); foreach (DataRow _dr in _DT.Rows) { TreeViewItem tNode = new TreeViewItem(); tNode.Header = _dr["fullname"].ToString()+" ("+_dr["id"].ToString()+")"; tSubNode.Items.Add(tNode); if (db.HasMembers(Convert.ToInt32(_dr["id"].ToString()))) { AddNodes(Convert.ToInt32(_dr["id"]), tNode); } } //This line tracks who has referred how many members Console.WriteLine("Tree node Count : "+tSubNode.Items.Count.ToString()+", UID "+uid); } Help me PLEASE!!!!

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• What is the performance impact of CSS's universal selector?

  - by Bungle

  I'm trying to find some simple client-side performance tweaks in a page that receives millions of monthly pageviews. One concern that I have is the use of the CSS universal selector (*). As an example, consider a very simple HTML document like the following: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title>Example</title> <style type="text/css"> * { margin: 0; padding: 0; } </head> <body> <h1>This is a heading</h1> <p>This is a paragraph of text.</p> </body> </html> The universal selector will apply the above declaration to the body, h1 and p elements, since those are the only ones in the document. In general, would I see better performance from a rule such as: body, h1, p { margin: 0; padding: 0; } Or would this have exactly the same net effect? Essentially, what I'm asking is if these rules are effectively equivalent in this case, or if the universal selector has to perform more unnecessary work that I may not be aware of. I realize that the performance impact in this example may be very small, but I'm hoping to learn something that may lead to more significant performance improvements in real-world situations. Thanks for any help!

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• Improving performance in this query

  - by Luiz Gustavo F. Gama

  I have 3 tables with user logins: sis_login = administrators tb_rb_estrutura = coordinators tb_usuario = clients I created a VIEW to unite all these users by separating them by levels, as follows: create view `login_names` as select `n1`.`cod_login` as `id`, '1' as `level`, `n1`.`nom_user` as `name` from `dados`.`sis_login` `n1` union all select `n2`.`id` as `id`, '2' as `level`, `n2`.`nom_funcionario` as `name` from `tb_rb_estrutura` `n2` union all select `n3`.`cod_usuario` as `id`, '3' as `level`, `n3`.`dsc_nome` as `name` from `tb_usuario` `n3`; So, can occur up to three ids repeated for different users, which is why I separated by levels. This VIEW is just to return me user name, according to his id and level. considering it has about 500,000 registered users, this view takes about 1 second to load. too much time, but is becomes very small when I need to return the latest posts on the forum of my website. The tables of the forums return the user id and level, then look for a name in this VIEW. I have registered 18 forums. When I run the query, it takes one second for each forum = 18 seconds. OMG. This page loads every time somebody enter my website. This is my query: select `x`.`forum_id`, `x`.`topic_id`, `l`.`nome` from ( select `t`.`forum_id`, `t`.`topic_id`, `t`.`data`, `t`.`user_id`, `t`.`user_level` from `tb_forum_topics` `t` union all select `a`.`forum_id`, `a`.`topic_id`, `a`.`data`, `a`.`user_id`, `a`.`user_level` from `tb_forum_answers` `a` ) `x` left outer join `login_names` `l` on `l`.`id` = `x`.`user_id` and `l`.`level` = `x`.`user_level` group by `x`.`forum_id` asc USING EXPLAIN: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 6 Using temporary; Using filesort 1 PRIMARY <derived4> ALL NULL NULL NULL NULL 530415 4 DERIVED n1 ALL NULL NULL NULL NULL 114 5 UNION n2 ALL NULL NULL NULL NULL 2 6 UNION n3 ALL NULL NULL NULL NULL 530299 NULL UNION RESULT ALL NULL NULL NULL NULL NULL 2 DERIVED t ALL NULL NULL NULL NULL 3 3 UNION r ALL NULL NULL NULL NULL 3 NULL UNION RESULT ALL NULL NULL NULL NULL NULL Somebody can help me or give a suggestion?

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• Mysql many to many problem (leaderborad/scoreboard)

  - by zoko2902

  Hi all! I'm working on a small project in regards of the upcoming World Cup. I'm building a roster/leaderboard/scoredboard based on groups with national teams. The idea is to have information on all upcoming matches within the group or in the knockout phase (scores, time of the match, match stats etc.). Currently I'm stuck with the DB in that I can't come up with a query that would return paired teams in a row. I have these 3 tables: CREATE TABLE IF NOT EXISTS `wc_team` ( `id` INT NOT NULL AUTO_INCREMENT , `name` VARCHAR(45) NULL , `description` VARCHAR(250) NULL , `flag` VARCHAR(45) NULL , `image` VARCHAR(45) NULL , `added` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP , PRIMARY KEY (`id`) , CREATE TABLE IF NOT EXISTS `wc_match` ( `id` INT NOT NULL AUTO_INCREMENT , `score` VARCHAR(6) NULL , `date` DATE NULL , `time` VARCHAR(45) NULL , `added` TIMESTAMP NULL DEFAULT CURRENT_TIMESTAMP , PRIMARY KEY (`id`) , CREATE TABLE IF NOT EXISTS `wc_team_has_match` ( `wc_team_id` INT NOT NULL , `wc_match_id` INT NOT NULL , PRIMARY KEY (`wc_team_id`, `wc_match_id`) , I've simplified the tables so we don't go in the wrong direction. Now I've tried al kinds of joins and groupings I could think of, but I never seem to get. Example guery: SELECT t.wc_team_id,t.wc_match_id,c.id.c.name,d.id,d.name FROM wc_team_has_match AS t LEFT JOIN wc_match AS s ON t.wc_match_id = s.id LEFT JOIN wc_team AS c ON t.wc_team_id = c.id LEFT JOIN wc_team AS d ON t.wc_team_id = d.id Which returns: wc_team_id wc_match_id id name id name 16 5 16 Brazil 16 Brazil 18 5 18 Argentina 18 Argentina But what I really want is: wc_team_id wc_match_id id name id name 16 5 16 Brazil 18 Argentina Keep in mind that a group has more matches I want to see all those matches not only one. Any pointer or suggestion would be extremly appreciated since I'm stuck like a duck on this one :).

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• Out of memory while iterating through rowset

  - by Phliplip

  Hi All, I have a "small" table of 60400 rows with zipcode data. I wan't to iterate through them all, update a column value, and then save it. The following is part of my Zipcodes model which extends My_Db_Table that a totalRows function that - you guessed it.. returns the total number of rows in the table (60400 rows) public function normalizeTable() { $this->getAdapter()->setProfiler(false); $totalRows = $this->totalRows(); $rowsPerQuery = 5; for($i = 0; $i < $totalRows; $i = $i + $rowsPerQuery) { $select = $this->select()->limit($i, $rowsPerQuery); $rowset = $this->fetchAll($select); foreach ($rowset as $row) { $row->{self::$normalCityColumn} = $row->normalize($row->{self::$cityColumn}); $row->save(); } unset($rowset); } } My rowClass contains a normalize function (basicly a metaphone wrapper doing some extra magic). At first i tried a plain old $this-fetchAll(), but got a out of memory (128MB) right away. Then i tried splitting the rowset into chunks, only difference is that some rows actually gets updated. Any ideas on how i can acomplish this, or should i fallback to ye'olde mysql_query()

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• On C++ global operator new: why it can be replaced

  - by Jimmy

  I wrote a small program in VS2005 to test whether C++ global operator new can be overloaded. It can. #include "stdafx.h" #include "iostream" #include "iomanip" #include "string" #include "new" using namespace std; class C { public: C() { cout<<"CTOR"<<endl; } }; void * operator new(size_t size) { cout<<"my overload of global plain old new"<<endl; // try to allocate size bytes void *p = malloc(size); return (p); } int main() { C* pc1 = new C; cin.get(); return 0; } In the above, my definition of operator new is called. If I remove that function from the code, then operator new in C:\Program Files (x86)\Microsoft Visual Studio 8\VC\crt\src\new.cpp gets called. All is good. However, in my opinion, my implementations of operator new does NOT overload the new in new.cpp, it CONFLICTS with it and violates the one-definition rule. Why doesn't the compiler complain about it? Or does the standard say since operator new is so special, one-definition rule does not apply here? Thanks.

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• How to get the size of a binary tree ?

  - by Andrei Ciobanu

  I have a very simple binary tree structure, something like: struct nmbintree_s { unsigned int size; int (*cmp)(const void *e1, const void *e2); void (*destructor)(void *data); nmbintree_node *root; }; struct nmbintree_node_s { void *data; struct nmbintree_node_s *right; struct nmbintree_node_s *left; }; Sometimes i need to extract a 'tree' from another and i need to get the size to the 'extracted tree' in order to update the size of the initial 'tree' . I was thinking on two approaches: 1) Using a recursive function, something like: unsigned int nmbintree_size(struct nmbintree_node* node) { if (node==NULL) { return(0); } return( nmbintree_size(node->left) + nmbintree_size(node->right) + 1 ); } 2) A preorder / inorder / postorder traversal done in an iterative way (using stack / queue) + counting the nodes. What approach do you think is more 'memory failure proof' / performant ? Any other suggestions / tips ? NOTE: I am probably going to use this implementation in the future for small projects of mine. So I don't want to unexpectedly fail :).

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• Dynamically how to make a larger link into a smaller one?

  - by lovesang prince

  Currently i am passing one dynamically generated parameter to the facebook to post on the wall. $dynamicparamer="[160,2,4,3,[[0,0,0,0,0,0,0,0,0,1,1,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,1,0,0,0,1,0,0,0,0,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[1,0,0,0,0,1,0,0,0,0,0,0,1,0],[0,0,1,0,0,0,0,0,0,0,1,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0,0,0,1,0,0],[0,0,0,0,0,0,0,0,0,0,0,1,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0,0,0,0,1,0],[0,0,1,0,0,0,0,0,0,0,1,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0,0,0,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[1,0,1,0,0,0,0,0,0,0,0,0,1,0],[0,0,0,0,0,0,0,0,0,0,1,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,1,0,0,0,0,0,0,0,0,0,1,0],[0,0,0,0,0,0,0,0,0,0,0,0,0,0],[0,0,0,0,0,0,0,0,0,0,0,0,1,0]]]";strong text My post is working fine with some small parameter say( $dynamicparamer="[160,2,4,3,[[0,0,0,0,0,0,0,0,0,1,1,0,1,0]) BUT for larger parameter(as shown above), Facebook is not alloiwng to post (Error: link too long)

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• How to provide an inline model field with a queryset choices without losing field value for inline r

  - by Judith Boonstra

  The code displayed below is providing the choices I need for the app field, and the choices I need for the attr field when using Admin. I am having a problem with the attr field on the inline form for already saved records. The attr selected for these saved does show in small print above the field, but not within the field itself. # MODELS: Class Vocab(models.Model): entity = models.Charfield, max_length = 40, unique = True) Class App(models.Model): name = models.ForeignKey(Vocab, related_name = 'vocab_appname', unique = True) app = SelfForeignKey('self, verbose_name = 'parent', blank = True, null = True) attr = models.ManyToManyField(Vocab, related_name = 'vocab_appattr', through ='AppAttr' def parqs(self): a method that provides a queryset consisting of available apps from vocab, excluding self and any apps within the current app's dependent line. def attrqs(self): a method that provides a queryset consisting of available attr from vocab excluding those already selected by current app, 2) those already selected by any apps within the current app's parent line, and 3) those selected by any apps within the current app's dependent line. Class AppAttr(models.Model): app = models.ForeignKey(App) attr = models.ForeignKey(Vocab) # FORMS: from models import AppAttr def appattr_form_callback(instance, field, *args, **kwargs) if field.name = 'attr': if instance: return field.formfield(queryset = instance.attrqs(), *kwargs) return field.formfield(*kwargs) # ADMIN: necessary imports class AppAttrInline(admin.TabularInline): model = AppAttr def get_formset(self, request, obj = None, **kwargs): kwargs['formfield_callback'] = curry(appattr_form_callback, obj) return super(AppAttrInline, self).get_formset(request, obj, **kwargs) class AppForm(forms.ModelForm): class Meta: model = App def __init__(self, *args, **kwargs): super(AppForm, self).__init__(*args, **kwargs) if self.instance.id is None: working = App.objects.all() else: thisrec = App.objects.get(id = self.instance.id) working = thisrec.parqs() self.fields['par'].queryset = working class AppAdmin(admin.ModelAdmin): form = AppForm inlines = [AppAttrInline,] fieldsets = .......... necessary register statements

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• PHP Curl - returned html all messed up

  - by yoda

  I'm trying to fetch some contents about articles in a website via Curl, which I'm doing as follows : $url = 'http://lisboacity.olx.pt/oportunidade-pastor-alemao-7-meses-com-lop-iid-432402267'; $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 10); curl_setopt($ch, CURLOPT_USERAGENT, 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322'); curl_setopt($ch, CURLOPT_FAILONERROR, true); curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true); curl_setopt($ch, CURLOPT_AUTOREFERER, true); curl_setopt($ch, CURLOPT_TIMEOUT, 10); $data = curl_exec($ch); curl_close($ch); echo $data; However, as you can see, the result is this : result For indexation purposes, I'm leaving a small paste of the output here : ‹ÜW_oÛ6N€~F{hD’å?±“ØÜÄm‚&qZ;-Ö¢0h‰–™R¢JR¶Óapcèð}*ö²§)%Vœ&YÚ·†eêî~¿;òx<6×ö{{ƒ_N»èp|„NÏžî!ËvÝו=×Ýìg‚ªSòÐ@àXREyŒ™ëvO,dM”Jv\w6›9³ŠÃEè^º±ªË8—Ä TµW›ú•~À#" #mj“)¶¬=++{p‘ùÙ¨e)2Wmù,$Q­Ã~Ïn4jÛ¶g!÷.¨#‡)‹p‰26«>Í–M·.ƒTŽ8ö©ºp8›;‰r-¤°ÕJÂÆ£¢Š‘v/áB¥1 p@ÖN±T\ #Ñ'Žê("’H ŽÐQïÔ…#ƒ:10•(à £¨Ï%¼D]øá??ñ¦›d‘Å8"-+ Ò4Ñ3_ç:åÓÏÁ†ð’\[‘8]ÿÑëÎà zÕ;AOûý½ƒÞÓþA÷ðxíÑê£Uã»ôvS_pB“M ’aÙq€AŠX"øNa¦bx’;hŸÊäoCÃ0þjB3C@ Rå"™0Ãz€cž&ü{æäjúô '&äö'¤åUªõZ½î5êÀd2Ñø=„µ,Ç<†bÛìž3èGöØj±Ð{9Ø; ýÞÉ«,Æ]©.‘îO!Åb~–Á2 !°'uåÊj_Êÿ„œ=†žç;Æ$"Ó-3–­ I've also tried to load the url contents with PHP's DomDocument class with the same result. What could be causing this? Thanks in advance!

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• Do ORMs normally allow circular relations? If so, how would they handle it?

  - by SeanJA

  I was hacking around trying to make a basic orm that has support for the one => one and one => many relationships. I think I succeeded somewhat, but I am curious about how to handle circular relationships. Say you had something like this: user::hasOne('car'); car::hasMany('wheels'); car::property('type'); wheel::hasOne('car'); You could then do this (theoretically): $u = new user(); echo $u->car->wheels[0]->car->wheels[1]->car->wheels[2]->car->wheels[3]->type; #=> "monster truck" Now, I am not sure why you would want to do this. It seems like it wastes a whole pile of memory and time just to get to something that could have been done in a much shorter way. In my small ORM, I now have 4 copies of the wheel class, and 4 copies of the car class in memory, which causes a problem if I update one of them and save it back to the database, the rest get out of date, and could overwrite the changes that were already made. How do other ORMs handle circular references? Do they even allow it? Do they go back up the tree and create a pointer to one of the parents? DO they let the coder shoot themselves in the foot if they are silly enough to go around in circles?

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• Hide Image Title in Slimbox

  - by Stephen

  My issue is a lot like this solved thread, except I'm using Slimbox 2: http://stackoverflow.com/questions/940994/hide-image-title-tool-tip-popup-on-mouse-rollover-or-hover When you hover over an image, the "Title" attribute pops up. I need HTML in my image title in Slimbox. So, of course, when you're hovering, the "Title" attribute shows all the HTML code. The code works perfectly when you're viewing the image in Slimbox so no problems there. I just need the Title attribute to be hidden/modified not to show this HTML code. I tried to change Q.title in slimbox.js to something else (like captionname). Then changed the HTML to call for: <a href="images/team/large.jpg" title="Joe Smith" captionname="URL" rel="lightbox-team"><img src="images/team/small.jpg" class ="headline" border="1" hspace="2" /></a> "Joe Smith" displays as the Title but when you view the image in Slimbox, captionname does not come up at all and neither does the Title. It's just blank where it should be. What do I need to modify in slimbox2.js to make this work?

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• maximum memory which malloc can allocate!

  - by Vikas

  I was trying to figure out how much memory I can malloc to maximum extent on my machine (1 Gb RAM 160 Gb HD Windows platform). I read that maximum memory malloc can allocate is limited to physical memory.(on heap) Also when a program exceeds consumption of memory to a certain level, the computer stops working because other applications do not get enough memory that they require. So to confirm,I wrote a small program in C, int main(){ int *p; while(1){ p=(int *)malloc(4); if(!p)break; } } Hoping that there would be a time when memory allocation will fail and loop will be breaked. But my computer hanged as It was an infinite loop. I waited for about an hour and finally I had to forcely shut down my computer. Some questions: Does malloc allocate memory from HD also? What was the reason for above behaviour? Why didn't loop breaked at any point of time.? Why wasn't there any allocation failure?

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• Class Generics break completely seperate method

  - by TheLQ

  I found a strange problem when I used class Generics Today: Setting some broke a completely separate method. Here's a small example class that illustrates the problem. This code works just fine public class Sandbox { public interface ListenerManagerTest { public Set<Listener> getListeners(); } public void setListenerManager(ListenerManagerTest listenerManager) { for (Listener curListener : listenerManager.getListeners()) return; } } Now as soon as I use class Generics, the getListeners() method returns Set<Object> instead of Set<Listener> public class Sandbox { public interface ListenerManagerTest<E extends Object> { public Set<Listener> getListeners(); } public void setListenerManager(ListenerManagerTest listenerManager) { for (Listener curListener : listenerManager.getListeners()) //Expected Listener, not Object return; } } What would cause this error? The ##java channel on Freenode said it was because of compile time candy and that I was using a raw type. But how would an raw class type break all generics in the class? And how would of worked before?

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• C# / Silverlight / WPF / Fast rendering lots of circles

  - by Walt W

  I want to render a lot of circles or small graphics within either silverlight or wpf (around 1000-10000) as fast and as frequently as possible. If I have to go to DX or OGL, that's fine, but I'm wondering about doing this within either of those two frameworks first (read: it's OK if an answer is WPF-only or Silverlight-only). Also, if there is a way to access DX through WPF and render on a surface that way, I would be interested in that as well. So, what's the fastest way to draw a load of circles? They can be as plain as necessary, but they do need to have a radius. Currently I'm using DrawingVisual and a DrawingContext.DrawEllipse() command for each circle, then rendering the visual to a RenderTargetBItmap, but it becomes very slow as the number of circles rises. By the way, these circles move every frame, so caching isn't really an option unless you're going to suggest caching the individual circles . . . But their sizes are dynamic, so I'm not sure that's a great approach.

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• Preprocessor "macro function" vs. function pointer - best practice?

  - by Dustin

  I recently started a small personal project (RGB value to BGR value conversion program) in C, and I realised that a function that converts from RGB to BGR can not only perform the conversion but also the inversion. Obviously that means I don't really need two functions rgb2bgr and bgr2rgb. However, does it matter whether I use a function pointer instead of a macro? For example: int rgb2bgr (const int rgb); /* * Should I do this because it allows the compiler to issue * appropriate error messages using the proper function name, * not to mention possible debugging benefits? */ int (*bgr2rgb) (const int bgr) = rgb2bgr; /* * Or should I do this since it is merely a convenience * and they're really the same function anyway? */ #define bgr2rgb(bgr) (rgb2bgr (bgr)) I'm not necessarily looking for a change in execution efficiency as it's more of a subjective question out of curiosity. I am well aware of the fact that type safety is neither lost nor gained using either method. Would the function pointer merely be a convenience or are there more practical benefits to be gained of which I am unaware?

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• Rails original release source code

  - by user547057

  Hi, I've been looking to read some ruby code(specifically Rails) but I don't want to start with the current version of Rails since it has a lot of stuff I don't need and even more stuff that I wouldn't probably understand. I want to read only the core of Rails and supposedly the early versions were small and kind of easy to wrap one's head around(even for a neophyte like me). I have tried searching for the original release of rails, but have not been able to find it. The github repo consists of thousands of commits and I don't want to wade through those. What I want is to know whether there is any place I can get a zip or tar file with the original rails source or even the other early versions. Pointers to links will be very much appreciated. Thanks. p.s I'm new to ruby programming but not programming in general(I know a little python and scheme) and I understand blocks, lambdas and OO stuff, so I think I can tackle the rails source code. If anyone knows of other ruby projects that make for good code reading, i'd love to know of those too.

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• multiple definition in header file

  - by Jérôme

  Here is a small code-example from which I'd like to ask a question : complex.h : #ifndef COMPLEX_H #define COMPLEX_H #include <iostream> class Complex { public: Complex(float Real, float Imaginary); float real() const { return m_Real; }; private: friend std::ostream& operator<<(std::ostream& o, const Complex& Cplx); float m_Real; float m_Imaginary; }; std::ostream& operator<<(std::ostream& o, const Complex& Cplx) { return o << Cplx.m_Real << " i" << Cplx.m_Imaginary; } #endif // COMPLEX_H complex.cpp : #include "complex.h" Complex::Complex(float Real, float Imaginary) { m_Real = Real; m_Imaginary = Imaginary; } main.cpp : #include "complex.h" #include <iostream> int main() { Complex Foo(3.4, 4.5); std::cout << Foo << "\n"; return 0; } When compiling this code, I get the following error : multiple definition of operator<<(std::ostream&, Complex const&) I've found that making this fonction inline solves the problem, but I don't understand why. Why does the compiler complain about multiple definition ? My header file is guarded (with #define COMPLEX_H). And, if complaining about the operator<< fonction, why not complain about the public real() fonction, which is defined in the header as well ? And is there another solution as using the inline keyword ?

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• IntelliJ Doesn't Notice Changes in Interface

  - by yar

  [I've decided to give IntelliJ another go (to replace Eclipse), since its Groovy support is supposed to be the best. But back to Java...] I have an Interface that defines a constant public static final int CHANNEL_IN = 1; and about 20 classes in my Module that implement that interface. I've decided that this constant was a bad idea so I did what I do in Eclipse: I deleted the entire line. This should cause the Project tree to light up like a Christmas tree and all classes that implement that interface and use that constant to break. Instead, this is not happening. If I don't actually double-click on the relevant classes -- which I find using grep -- the module even builds correctly (using Build - Make Module). If I double-click on a relevant class, the error is shown both in the Project Tree and in the Editor. I am not able to replicate this behavior in small tests, but in large modules it works (incorrectly) this way. Is there some relevant setting in IntelliJ for this?

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• Box2D in Flash runs quicker when drawing debug data than not

  - by bowdengm

  I've created a small game with Box2d for AS3 - I have sprites attached to the stage that take their position from the underlying Box2d world. These sprites are mostly PNGs. When the game runs with DrawDebugData() bening called every update, it runs nice and smoothly. However when I comment this out, it runs choppily. In both cases all my sprites are being rendered. So it seems that it's running faster when it's drawing the debug data additionaly (i.e. my sprites are on the screen in both cases!) What's going on? Does drawing the debug data flick some sort of 'render quick' switch? If so, what's the switch!? I can't see it in the Box2D code. function Update(e){ m_world.Step(m_timeStep, m_velocityIterations, m_positionIterations); // draw debug? m_world.DrawDebugData(); // with the above line in, I get 27fps, without it, I get 19fps. // that's the only change that's causing such a huge difference. doStuff(); } Interestingly, If i set the debug draw scale to something different to my world scale, it slows down to 19fps. So there's something happening when it draws the boxes under my sprites causing it to run quicker.. Cheers, Guy

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• Which is better Java programming practice: stacking enums and enum constructors, or subclassing?

  - by Arvanem

  Hi folks, Given a finite number of items which differ in kind, is it better to represent them with stacked enums and enum constructors, or to subclass them? Or is there a better approach altogether? To give you some context, in my small RPG program (which ironically is supposed to be simple), a character has different kinds of items in his or her inventory. Items differ based on their type and use and effect. For example, one item of inventory is a spell scroll called Gremlin that adjusts the Utility attribute. Another item might be a sword called Mort that is used in combat and inflicts damage. In my RPG code, I now have tried two ways of representing inventory items. One way was subclassing (for example, InventoryItem - Spell - AdjustingAttributes; InventoryItem - Weapon - Sword) and instantiating each subclass when needed, and assigning values such as names like Gremlin and Mort. The other way was by stacking enums and enum constructors. For example, I created enums for itemCategory and itemSpellTypes and itemWeaponTypes, and the InventoryItem enum was like this: public enum InventoryItem { GREMLIN(itemType.SPELL, itemSpellTypes.ATTRIBUTE, Attribute.UTILITY), MORT(itemType.WEAPON, itemWeaponTypes.SWORD, 30); InventoryItem(itemType typeOfItem, itemSpellTypes spellType, Attribute attAdjusted) { // snip, enum logic here } InventoryItem(itemType typeOfItem, itemWeaponTypes weaponType, int dmg) { // snip, enum logic here } // and so on, for all the permutations of items. } Is there a better Java programming practice than these two approaches? Or if these are the only ways, which of the two is better? Thanks in advance for your suggestions.

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• Convert a Dynamic[] construct to a numerical list

  - by Leo Alekseyev

  I have been trying to put together something that allows me to extract points from a ListPlot in order to use them in further computations. My current approach is to select points with a Locator[]. This works fine for displaying points, but I cannot figure out how to extract numerical values from a construct with head Dynamic[]. Below is a self-contained example. By dragging the gray locator, you should be able to select points (indicated by the pink locator and stored in q, a list of two elements). This is the second line below the plot. Now I would like to pass q[[2]] to a function, or perhaps simply display it. However, Mathematica treats q as a single entity with head Dynamic, and thus taking the second part is impossible (hence the error message). Can anyone shed light on how to convert q into a regular list? EuclideanDistanceMod[p1_List, p2_List, fac_: {1, 1}] /; Length[p1] == Length[p2] := Plus @@ (fac.MapThread[Abs[#1 - #2]^2 &, {p1, p2}]) // Sqrt; test1 = {{1.`, 6.340196001221532`}, {1.`, 13.78779876355869`}, {1.045`, 6.2634018978377295`}, {1.045`, 13.754947081416544`}, {1.09`, 6.178367702583522`}, {1.09`, 13.72055251752498`}, {1.135`, 1.8183153704413153`}, {1.135`, 6.082497198000075`}, {1.135`, 13.684582525399742`}, {1.18`, 1.6809452373465104`}, {1.18`, 5.971583107298081`}, {1.18`, 13.646996905469383`}, {1.225`, 1.9480537697339537`}, {1.225`, 5.838386922625636`}, {1.225`, 13.607746407088161`}, {1.27`, 2.1183174369679234`}, {1.27`, 5.669799095595362`}, {1.27`, 13.566771130126131`}, {1.315`, 2.2572975468163463`}, {1.315`, 5.444014254828522`}, {1.315`, 13.523998701347882`}, {1.36`, 2.380307009155079`}, {1.36`, 5.153024664297602`}, {1.36`, 13.479342200528283`}, {1.405`, 2.4941312539733285`}, {1.405`, 4.861423833512566`}, {1.405`, 13.432697814928654`}, {1.45`, 2.6028066447609426`}, {1.45`, 4.619367407525507`}, {1.45`, 13.383942212133244`}}; DynamicModule[{p = {1.2, 10}, q = {1.3, 11}}, q := Dynamic@ First@test1[[ Ordering[{#, EuclideanDistanceMod[p, #, {1, .1}]} & /@ test1, 1, #1[[2]] < #2[[2]] &]]]; Grid[{{Show[{ListPlot[test1, Frame -> True, ImageSize -> 300], Graphics@Locator[Dynamic[p]], Graphics@ Locator[q, Appearance -> {Small}, Background -> Pink]}]}, {Dynamic@p}, {q},{q[[2]]}}]]

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• Code promotion: Enforcing the rules

  - by jbarker7

  So here is our problem: We have a small team of developers with their own ways of doing things-- I am trying to formalize a process in which we are required to promote our code in the following order: Local sandbox Dev UAT Staging Live Developers develop/test as they go on their own sandbox, Dev is its own box that we would use for continuous integration, UAT is another site in IIS on the dev box, which uses our dev database. We then promote to staging, which is a site in IIS on the Live box and using live data (just like the live, hence staging). Then, finally, we promote to live. Here are a few of my questions: 1.) Does this seem to be best practice? If not, what needs to be done differently? 2.) How do I enforce the rules to the developers? Often developers skip steps in order to save time... this should not be tolerated and would be great if it could be physically enforced. 3.) How do I enforce these rules to the business group? The business group just wants to get features out FAST. Do we promote only on certain days? Thanks! Josh

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