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  • Passing variables, creating instances, self, The mechanics and usage of classes: need explenation

    - by Baf
    I've been sitting over this the whole day and Im a little tired already so please excuse me being brief. Im new to python. I just rewrrote a working program, into a bunch of functions in a class and everzthings messed up. I dont know if its me but Im very surprised i couldn t find a beginners tutorial on how to handle classes on the web so I have a few questions. First of all, in the init section of the class i have declared a bunch of variables with self.variable=something. Is it correct that i should be able to access/modify these variables in every function of the class by using self.variable in that function? In other words by declaring self.variable i have made these variables, global variables in the scope of the class right? If not how do i handle self. ? Secondly how do i correctly pass arguments to the class? some example code would be cool. thirdly how do i call a function of the class outside of the class scope? some example code would be cool. fouthly how do I create an Instance of the class INITIALCLASS in another class OTHERCLASS, passing variables from OTHERCLASS to INITIALCLASS? some example code would be cool. I Want to call a function from OTHERCLASS with arguments from INITIALCLASS. What Ive done so far is. class OTHERCLASS(): def __init__(self,variable1,variable2,variable3): self.variable1=variable1 self.variable2=variable2 self.variable3=variable3 def someotherfunction(self): something=somecode(using self.variable3) self.variable2.append(something) print self.variable2 def somemorefunctions(self): self.variable2.append(variable1) class INITIALCLASS(): def __init__(self): self.variable1=value1 self.variable2=[] self.variable3='' self.DoIt=OTHERCLASS(variable1,variable2,variable3) def somefunction(self): variable3=Somecode #tried this self.DoIt.someotherfunctions() #and this DoIt.someotherfunctions() I clearly havent understood how to pass variables to classes or how to handle self, when to use it and when not, I probably also havent understood how to properly create an isntance of a class. In general i havent udnerstood the mechanics of classes So please help me and explain it to me like i have no Idea( which i dont it seems). Or point me to a thorough video, or readable tutorial. All i find on the web is super simple examples, that didnt help me much. Or just very short definitions of classes and class methods instances etc. I can send you my original code if you guys want, but its quite long. Thanks for the Help Much appreciated!

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  • Is this a problem typically solved with IOC?

    - by Dirk
    My current application allows users to define custom web forms through a set of admin screens. it's essentially an EAV type application. As such, I can't hard code HTML or ASP.NET markup to render a given page. Instead, the UI requests an instance of a Form object from the service layer, which in turn constructs one using a several RDMBS tables. Form contains the kind of classes you would expect to see in such a context: Form= IEnumerable<FormSections>=IEnumerable<FormFields> Here's what the service layer looks like: public class MyFormService: IFormService{ public Form OpenForm(int formId){ //construct and return a concrete implementation of Form } } Everything works splendidly (for a while). The UI is none the wiser about what sections/fields exist in a given form: It happily renders the Form object it receives into a functional ASP.NET page. A few weeks later, I get a new requirement from the business: When viewing a non-editable (i.e. read-only) versions of a form, certain field values should be merged together and other contrived/calculated fields should are added. No problem I say. Simply amend my service class so that its methods are more explicit: public class MyFormService: IFormService{ public Form OpenFormForEditing(int formId){ //construct and return a concrete implementation of Form } public Form OpenFormForViewing(int formId){ //construct and a concrete implementation of Form //apply additional transformations to the form } } Again everything works great and balance has been restored to the force. The UI continues to be agnostic as to what is in the Form, and our separation of concerns is achieved. Only a few short weeks later, however, the business puts out a new requirement: in certain scenarios, we should apply only some of the form transformations I referenced above. At this point, it feels like the "explicit method" approach has reached a dead end, unless I want to end up with an explosion of methods (OpenFormViewingScenario1, OpenFormViewingScenario2, etc). Instead, I introduce another level of indirection: public interface IFormViewCreator{ void CreateView(Form form); } public class MyFormService: IFormService{ public Form OpenFormForEditing(int formId){ //construct and return a concrete implementation of Form } public Form OpenFormForViewing(int formId, IFormViewCreator formViewCreator){ //construct a concrete implementation of Form //apply transformations to the dynamic field list return formViewCreator.CreateView(form); } } On the surface, this seems like acceptable approach and yet there is a certain smell. Namely, the UI, which had been living in ignorant bliss about the implementation details of OpenFormForViewing, must possess knowledge of and create an instance of IFormViewCreator. My questions are twofold: Is there a better way to achieve the composability I'm after? (perhaps by using an IoC container or a home rolled factory to create the concrete IFormViewCreator)? Did I fundamentally screw up the abstraction here?

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  • I always get stuck here... Divs not behaving properly (alignment issues)

    - by user345501
    Hi, I don't know why, after encountering this problem dozens of times, the answer always seems different and I can't seem to work my way through the problem-solving process, but here I am again with misaligned divs. I've got 3rows encasing columns. each row is to have (at least) 3 columns (and probably some nested divs down the line, but I'm not even there yet). I'm trying to make a fluid chunk in the center ultimately, with pretty corners. However, my top row is already showing signs of misbehaving. .O Please help with my silly questions! Cheers and thanks in advance! <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Untitled Document</title> </head> <style type="text/css"> #wrap { margin:auto; width:80%; height:75%; border: solid #066 1px;} #row1 { width:100%; height:10%; background:#F20; } #r1c1 { float:left; width:05%;} #r1c2 { float:left; width:80%} #r1c3 { clear:both; width:05%; } #row2 { float:none; width:100%; background:#0C6; } #r2c1 {} #r2c2 {} #r2c3 {} #row3 { width:100%; height:15%; background:#00F; clear:both; } #r3c1 {} #r3c2 {} #r3c3 {} </style> <body> <div id="wrap"> <div id="row1"> <div id="r1c1">LEFT</div> <div id="r1c2">CENT</div> <div id="r1c3">RIGHT</div> </div> <div id="row2"> MIDDLE </div> <div id="row3"> BOTTOM </div> </div> </body> </html>

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  • MySQL Query to find consecutive available times of variable lenth

    - by Armaconn
    I have an events table that has user_id, date ('2013-10-01'), time ('04:15:00'), and status_id; What I am looking to find is a solution similar to http://stackoverflow.com/questions/2665574/find-consecutive-rows-calculate-duration but I need I need two additional components: 1) Take date into consideration, so 10/1/2013 at 11:00 PM - 10/2/2013 at 3:00AM. Feel free to just put in a fake date range (like '2013-10-01' to '2013-10-31') 2) Limit output to only include when there are 4+ consecutive times (each event is 15 minutes and I want it to display minimum blocks of an hour, but would also like to be able to switch this restriction to 1.5 hours or some other duration if possible). SUMMARY - Looking for a query that provides the start and end times for a set of events that have the same user_id, status_id, and are in a continuous series based on date and time. For which I can restrict results based on date range and minimum series duration. So the output should have: user_id, date_start, time_start, date_end, time_end, status_id, duration CREATE TABLE `events` ( `event_id` int(11) NOT NULL auto_increment COMMENT 'ID', `user_id` int(11) NOT NULL, `date` date NOT NULL, `time` time NOT NULL, `status_id` int(11) default NULL, PRIMARY KEY (`event_id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1568 ; INSERT INTO `events` VALUES(1, 101, '2013-08-14', '23:00:00', 2); INSERT INTO `events` VALUES(2, 101, '2013-08-14', '23:15:00', 2); INSERT INTO `events` VALUES(3, 101, '2013-08-14', '23:30:00', 2); INSERT INTO `events` VALUES(4, 101, '2013-08-14', '23:45:00', 2); INSERT INTO `events` VALUES(5, 101, '2013-08-15', '00:00:00', 2); INSERT INTO `events` VALUES(6, 101, '2013-08-15', '00:15:00', 1); INSERT INTO `events` VALUES(7, 500, '2013-08-14', '23:45:00', 1); INSERT INTO `events` VALUES(8, 500, '2013-08-15', '00:00:00', 1); INSERT INTO `events` VALUES(9, 500, '2013-08-15', '00:15:00', 2); INSERT INTO `events` VALUES(10, 500, '2013-08-15', '00:30:00', 2); INSERT INTO `events` VALUES(11, 500, '2013-08-15', '00:45:00', 1); Desired output row |user_id | date_start | time_start | date_end | time_end | status_id | duration 1 |101 |'2013-08-14'| '23:00:00' |'2013-08-15'|'00:15:00'| 2 | 5 2 |101 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:30:00'| 1 | 1 3 |500 |'2013-08-14'| '00:23:45' |'2013-08-15'|'00:15:00'| 1 | 2 4 |500 |'2013-08-15'| '00:00:15' |'2013-08-15'|'00:45:00'| 2 | 2 5 |500 |'2013-08-15'| '00:00:45' |'2013-08-15'|'01:00:00'| 2 | 1 *except that rows 2 and 5 wouldn't appear if duration had to be greater than 30 minutes Thanks for any help that you can provide! And please let me know if there is anything I can further clarify!!

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  • Inbreeding-immune database structure

    - by Nick Savage
    I have an application that requires a "simple" family tree. I would like to be able to perform queries that will give me data for an entire family given one id from a member in the family. I say simple because it does not need to take into account adoption or any other obscurities. The requirements for the application are as follows: Any two people will not be able to breed if they're from the same genetic line Needs to allow for the addition of new family lines (new people with no previous family) Need to be able to pull siblings, parents separately through queries I'm having trouble coming up with the proper structure for the database. So far I've come up with two solutions but they're not very reliable and will probably get out of hand quite quickly. Solution 1 involves placing a family_ids field on the people table and storing a list of unique family ids. Each time two people breed the lists are checked against each other to make sure no ids match and if everything checks out will merge the two lists and set that as the child's family_ids field. Example: Father (family_ids: (null)) breeds with Mother (family_ids: (213, 519)) -> Child (family_ids: (213, 519)) breeds with Random Person (family_ids: (813, 712, 122, 767)) -> Grandchild (family_ids: (213, 519, 813, 712, 122, 767)) And so on and so forth... The problem I see with this is the lists becoming unreasonably large as time goes on. Solution 2 uses cakephp's associations to declare: public $belongsTo = array( 'Father' => array( 'className' => 'User', 'foreignKey' => 'father_id' ), 'Mother' => array( 'className' => 'User', 'foreignKey' => 'mother_id' ) ); Now setting recursive to 2 will fetch the results of the mother and father, along with their mother and father, and so on and so forth all the way down the line. The problem with this route is that the data is in nested arrays and I'm unsure of how to efficiently work through the code. If anyone would be able to steer me in the direction of the most efficient way to handle what I want to achieve that would be tremendously helpful. Any and all help is greatly appreciated and I'll gladly answer any questions anyone has. Thanks a lot.

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  • Yet another Memory Leak Issue (memory is still gone when program terminates)- C program on SLES

    - by user1426181
    I run my C program on Suse Linux Enterprise that compresses several thousand large files (between 10MB and 100MB in size), and the program gets slower and slower as the program runs (it's running multi-threaded with 32 threads on a Intel Sandy Bridge board). When the program completes, and it's run again, it's still very slow. When I watch the program running, I see that the memory is being depleted while the program runs, which you would think is just a classic memory leak problem. But, with a normal malloc()/free() mismatch, I would expect all the memory to return when the program terminates. But, most of the memory doesn't get reclaimed when the program completes. The free or top command shows Mem: 63996M total, 63724M used, 272M free when the program is slowed down to a halt, but, after the termination, the free memory only grows back to about 3660M. When the program is rerun, the free memory is quickly used up. The top program only shows that the program, while running, is using at most 4% or so of the memory. I thought that it might be a memory fragmentation problem, but, I built a small test program that simulates all the memory allocation activity in the program (many randomized aspects were built in - size/quantity), and it always returns all the memory upon completion. So, I don't think that's it. Questions: Can there be a malloc()/free() mismatch that will lose memory permanently, i.e. even after the process completes? What other things in a C program (not C++) can cause permanent memory loss, i.e. after the program completes, and even the terminal window closes? Only a reboot brings the memory back. I've read other posts about files not being closed causing problems, but, I don't think I have that problem. Is it valid to be looking at top and free for the memory statistics, i.e. do they accurately describe the memory situation? They do seem to correspond to the slowness of the program. If the program only shows a 4% memory usage, will something like valgrind find this problem?

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  • Android - dialer icon gets placed in recently used apps after finish()

    - by Donal Rafferty
    In my application I detect the out going call when a call is dialled from the dialer or contacts. This works fine and I then pop up a dialog saying I have detected the call and then the user presses a button to close the dialog which calls finish() on that activity. It all works fine except that when I then hold the home key to bring up the recently used apps the dialer icon is there. And when it is clicked the dialog is brought back into focus in the foreground when the dialog activity should be dead and gone and not be able to be brought back to the foreground. Here is a picture of what I mean. So two questions arise, why would the dialer icon be getting placed there and why would it be recalling my activity to the foreground? Here is the code for that Activity which has a dialog theme: public class CallDialogActivity extends Activity{ boolean isRecording; AudioManager audio_service; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.dialog); audio_service = (AudioManager) getSystemService(Context.AUDIO_SERVICE); getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND); Bundle b = this.getIntent().getExtras(); String number = b.getString("com.networks.NUMBER"); String name = b.getString("com.networks.NAME"); TextView tv = (TextView) findViewById(R.id.voip) ; tv.setText(name); Intent service = new Intent(CallAudio.CICERO_CALL_SERVICE); startService(service); final Button stop_Call_Button = (Button) findViewById(R.id.widget35); this.setVolumeControlStream(AudioManager.STREAM_VOICE_CALL); stop_Call_Button.setOnClickListener(new View.OnClickListener(){ public void onClick(View v){ Intent service = new Intent(CallAudio._CALL_SERVICE); //this is for Android 1.5 (sets speaker going for a few seconds before shutting down) stopService(service); Intent setIntent = new Intent(Intent.ACTION_MAIN); setIntent.addCategory(Intent.CATEGORY_HOME); setIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); startActivity(setIntent); finish(); isRecording = false; } }); final Button speaker_Button = (Button) findViewById(R.id.widget36); speaker_Button.setOnClickListener(new View.OnClickListener(){ public void onClick(View v){ if(true){ audio_service.setSpeakerphoneOn(false); } else{ audio_service.setSpeakerphoneOn(true); } } }); } @Override protected void onResume() { super.onResume(); } @Override protected void onPause() { super.onPause(); } public void onCofigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); } } It calls a service that uses AudioRecord to record from the Mic and AudioTrack to play it out the earpiece, nothing in the service to do with the dialler. Has anyone any idea why this might be happening?

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  • Architectural Design for a Data-Driven Silverlight WP7 app

    - by Rosarch
    I have a Silverlight Windows Phone 7 app that pulls data from a public API. I find myself doing much of the same thing over and over again: In the UI, set a loading message or loading progress bar in place of where the content is Get the content, which may be already in memory, cached in isolated file storage, or require an HTTP request If the content can not be acquired (no network connection, etc), display an error message If the content is acquired, display it in the UI Keep the content in main memory for subsequent queries The content that is displayed to the user can be taken directly from a data source, such as an ObservableCollection, or it may be a query on a data source. I would like to factor out this repetitive process into a framework where ideally only the following needs to be specified: Where to display the content in the UI The UI elements to show while loading, on failure, and on success The URI of the HTTP request How to parse the HTTP response into the data structure that will kept in memory The location of the file in isolated storage, if it exists How to parse the file contents into the data structure that will be kept in memory It may sound like a lot, but two strings, three FrameworkElements, and two methods is less than the overhead that I currently have. Also, this needs to work for however the data is maintained in memory, and needs to work for direct collections and queries on those collections. My questions are: Has something like this already been implemented? Are my thoughts about the topic above fundamentally wrong in some way? Here is a design I'm thinking of: There are two components, a View and a Model. The View is given the FrameworkElements for loading, failure, and success. It is also given a reference to the corresponding Model. The View is a UserControl that is placed somewhere in the UI. The Model a class that is given the URI for the data, a method of how to parse the data, and optionally a filename and how to parse the file. It is responsible for retrieving the data and notifying the View whenever the current status (loading/fail/success) changes. If the data downloaded from the network is different from the cache, the network data takes precedence. When the app closes or is tombstoned, the model writes the data to the cache. How does that sound?

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  • JQuery Ajax Updating MySQL Database, But Not Running Success Function

    - by myrmidon16
    I am currently using the JQuery ajax function to call an exterior PHP file, in which I select and add data in a database. Once this is done, I run a success function in JavaScript. What's weird is that the database is updating successfully when ajax is called, however the success function is not running. Here is my code: <!DOCTYPE html> <head> <script type="text/javascript" src="jquery-1.6.4.js"></script> </head> <body> <div onclick="addtask();" style="width:400px; height:200px; background:#000000;"></div> <script> function addtask() { var tid = (Math.floor(Math.random() * 3)) + 1; var tsk = (Math.floor(Math.random() * 10)) + 1; if(tsk !== 1) { $.ajax({ type: "POST", url: "taskcheck.php", dataType: "json", data: {taskid:tid}, success: function(task) {alert(task.name);} }); } } </script> </body> </html> And the PHP file: session_start(); $connect = mysql_connect('x', 'x', 'x') or die('Not Connecting'); mysql_select_db('x') or die ('No Database Selected'); $task = $_REQUEST['taskid']; $uid = $_SESSION['user_id']; $q = "SELECT task_id, taskname FROM tasks WHERE task_id=" .$task. " LIMIT 1"; $gettask = mysql_fetch_assoc(mysql_query($q)); $q = "INSERT INTO user_tasks (ut_id, user_id, task_id, taskstatus, taskactive) VALUES (null, " .$uid. ", '{$gettask['task_id']}', 0, 1)"; $puttask = mysql_fetch_assoc(mysql_query($q)); $json = array( "name" => $gettask['taskname'] ); $output = json_encode($json); echo $output; Let me know if you have any questions or comments, thanks.

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  • Fastest way to copy a set (100+) of related SQLAlchemy objects and change attribute on each one

    - by rebus
    I am developing an app that keeps track of items going in and out of factory. For example, lets say you have 3 kinds of plastic coming in, they are mixed in various ratios and then sent out as a new product. So to keep track of this I've created following database structure: This is very simplified overview of my SQLAlchemy models: IN <- RATIO <- OUT <- REPORT ITEMS -> REPORT IN are products coming in, RATIO is various information on measurements, and OUT is a final product. REPORT is basically a header model which has a lot of REPORT ITEMS attached to it, which in turn relate it to OUT products. This would all work perfectly, but IN and RATION values can change. These changes ultimately change the OUT product which would mean the REPORT values would change. So in order to change an attribute on IN object for example I should copy that object with that attribute changed. I would think this is basically a question about database normalization, because i didn't want to duplicate all the IN, RATIO and OUT information by writing it in REPORT ITEMS table for example, but I've came across this problem (well not really a problem but rather a feature I'd like for a user to have). When the attribute on IN object is changed I want related objects (RATIO and OUT) automatically copied and related to a new IN object. So I was thinking something like: Take an existing instance of model IN that needs to change (call it old_in) Create a new one out of it with some attributes changed (call it new_in) Collect all the RATIO objects that are related to old_in Copy each RATIO and relate them to a new_in Collect all the OUT objects that are related to old RATIO Copy each OUT and relate them to a new RATIO Few questions pop to mind when i look at this problem: Should i just duplicate the data, does all this copying even make sense? If it does, should i rather do it in plain SQL? If no what would be the best approach to do it with Python and SQLAlchemy? Any general answer would suffice really, at least a pointer in right direction. I really want to free then end user for hassle of having create new ratios and out products.

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  • Controlling the USB from Windows

    - by b-gen-jack-o-neill
    Hi, I know this probably is not the easiest thing to do, but I am trying to connect Microcontroller and PC using USB. I dont want to use internal USART of Microcontroller or USB to RS232 converted, its project indended to help me understand various principles. So, getting the communication done from the Microcontroller side is piece of cake - I mean, when I know he protocol, its relativelly easy to implement it on Micro, becouse I am in direct control of evrything, even precise timing. But this is not the case of PC. I am not very familiar with concept of Windows handling the devices connected. In one of my previous question I ask about how Windows works with devices thru drivers. I understood that for internal use of Windows, drivers must have some default set of functions available to OS. I mean, when OS wants to access HDD, it calls HDD driver (which is probably internal in OS), with specific "questions" so that means that HDD driver has to be written to cooperate with Windows, to have write function in the proper place to be called by the OS. Something similiar is for GPU, Even DirectX, I mean DirectX must call specific functions from drivers, so drivers must be written to work with DX. I know, many functions from WinAPI works on their own, but even "simple" window must be in the end written into framebuffer, using MMIO to adress specified by drivers. Am I right? So, I expected that Windows have internal functions, parts of WinAPI designed to work with certain comonly used things. To call manufacturer-designed drivers. But this seems to not be entirely true becouse Windows has no way to communicate thru Paralel port. I mean, there is no function in the WinAPI to work with serial port, but there are funcions to work with HDD,GPU and so. But now there comes the part I am getting very lost at. So, I think Windows must have some built-in functions to communicate thru USB, becouse for example it handles USB flash memory. So, is there any WinAPI function designed to let user to operate USB thru that function, or when I want to use USB myself, do I have to call desired USB-driver function myself? Becouse all you need to send to USB controller is device adress and the infromation right? I mean, I don´t have to write any new drivers, am I right? Just to call WinAPI function if there is such, or directly call original USB driver. Does any of this make some sense?

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  • How to pipe two CORE::system commands in a cross-platform way

    - by Pedro Silva
    I'm writing a System::Wrapper module to abstract away from CORE::system and the qx operator. I have a serial method that attempts to connect command1's output to command2's input. I've made some progress using named pipes, but POSIX::mkfifo is not cross-platform. Here's part of what I have so far (the run method at the bottom basically calls system): package main; my $obj1 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{''}], input => ['input.txt'], description => 'Concatenate input.txt to STDOUT', ); my $obj2 = System::Wrapper->new( interpreter => 'perl', arguments => [-pe => q{'$_ = reverse $_}'}], description => 'Reverse lines of input input', output => { '>' => 'output' }, ); $obj1->serial( $obj2 ); package System::Wrapper; #... sub serial { my ($self, @commands) = @_; eval { require POSIX; POSIX->import(); require threads; }; my $tmp_dir = File::Spec->tmpdir(); my $last = $self; my @threads; push @commands, $self; for my $command (@commands) { croak sprintf "%s::serial: type of args to serial must be '%s', not '%s'", ref $self, ref $self, ref $command || $command unless ref $command eq ref $self; my $named_pipe = File::Spec->catfile( $tmp_dir, int \$command ); POSIX::mkfifo( $named_pipe, 0777 ) or croak sprintf "%s::serial: couldn't create named pipe %s: %s", ref $self, $named_pipe, $!; $last->output( { '>' => $named_pipe } ); $command->input( $named_pipe ); push @threads, threads->new( sub{ $last->run } ); $last = $command; } $_->join for @threads; } #... My specific questions: Is there an alternative to POSIX::mkfifo that is cross-platform? Win32 named pipes don't work, as you can't open those as regular files, neither do sockets, for the same reasons. The above doesn't quite work; the two threads get spawned correctly, but nothing flows across the pipe. I suppose that might have something to do with pipe deadlocking or output buffering. What throws me off is that when I run those two commands in the actual shell, everything works as expected.

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  • Performance - FunctionCall vs Event vs Action vs Delegate

    - by hwcverwe
    Currently I am using Microsoft Sync Framework to synchronize databases. I need to gather information per record which is inserted/updated/deleted by Microsoft Sync Framework and do something with this information. The sync speed can go over 50.000 records per minute. So that means my additional code need to be very lightweight otherwise it will be a huge performance penalty. Microsoft Sync Framework raises an SyncProgress event for each record. I am subscribed to that code like this: // Assembly1 SyncProvider.SyncProgress += OnSyncProgress; // .... private void OnSyncProgress(object sender, DbSyncProgressEventArgs e) { switch (args.Stage) { case DbSyncStage.ApplyingInserts: // MethodCall/Delegate/Action<>/EventHandler<> => HandleInsertedRecordInformation // Do something with inserted record info break; case DbSyncStage.ApplyingUpdates: // MethodCall/Delegate/Action<>/EventHandler<> => HandleUpdatedRecordInformation // Do something with updated record info break; case DbSyncStage.ApplyingDeletes: // MethodCall/Delegate/Action<>/EventHandler<> => HandleDeletedRecordInformation // Do something with deleted record info break; } } Somewhere else in another assembly I have three methods: // Assembly2 public class SyncInformation { public void HandleInsertedRecordInformation(...) {...} public void HandleUpdatedRecordInformation(...) {...} public void HandleInsertedRecordInformation(...) {...} } Assembly2 has a reference to Assembly1. So Assembly1 does not know anything about the existence of the SyncInformation class which need to handle the gathered information. So I have the following options to trigger this code: use events and subscribe on it in Assembly2 1.1. EventHandler< 1.2. Action< 1.3. Delegates using dependency injection: public class Assembly2.SyncInformation : Assembly1.ISyncInformation Other? I know the performance depends on: OnSyncProgress switch using a method call, delegate, Action< or EventHandler< Implementation of SyncInformation class I currently don't care about the implementation of the SyncInformation class. I am mainly focused on the OnSyncProgress method and how to call the SyncInformation methods. So my questions are: What is the most efficient approach? What is the most in-efficient approach? Is there a better way than using a switch in OnSyncProgress?

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  • How can I represent a line of music notes in a way that allows fast insertion at any index?

    - by chairbender
    For "fun", and to learn functional programming, I'm developing a program in Clojure that does algorithmic composition using ideas from this theory of music called "Westergaardian Theory". It generates lines of music (where a line is just a single staff consisting of a sequence of notes, each with pitches and durations). It basically works like this: Start with a line consisting of three notes (the specifics of how these are chosen are not important). Randomly perform one of several "operations" on this line. The operation picks randomly from all pairs of adjacent notes that meet a certain criteria (for each pair, the criteria only depends on the pair and is independent of the other notes in the line). It inserts 1 or several notes (depending on the operation) between the chosen pair. Each operation has its own unique criteria. Continue randomly performing these operations on the line until the line is the desired length. The issue I've run into is that my implementation of this is quite slow, and I suspect it could be made faster. I'm new to Clojure and functional programming in general (though I'm experienced with OO), so I'm hoping someone with more experience can point out if I'm not thinking in a functional paradigm or missing out on some FP technique. My current implementation is that each line is a vector containing maps. Each map has a :note and a :dur. :note's value is a keyword representing a musical note like :A4 or :C#3. :dur's value is a fraction, representing the duration of the note (1 is a whole note, 1/4 is a quarter note, etc...). So, for example, a line representing the C major scale starting on C3 would look like this: [ {:note :C3 :dur 1} {:note :D3 :dur 1} {:note :E3 :dur 1} {:note :F3 :dur 1} {:note :G3 :dur 1} {:note :A4 :dur 1} {:note :B4 :dur 1} ] This is a problematic representation because there's not really a quick way to insert into an arbitrary index of a vector. But insertion is the most frequently performed operation on these lines. My current terrible function for inserting notes into a line basically splits the vector using subvec at the point of insertion, uses conj to join the first part + notes + last part, then uses flatten and vec to make them all be in a one-dimensional vector. For example if I want to insert C3 and D3 into the the C major scale at index 3 (where the F3 is), it would do this (I'll use the note name in place of the :note and :dur maps): (conj [C3 D3 E3] [C3 D3] [F3 G3 A4 B4]), which creates [C3 D3 E3 [C3 D3] [F3 G3 A4 B4]] (vec (flatten previous-vector)) which gives [C3 D3 E3 C3 D3 F3 G3 A4 B4] The run time of that is O(n), AFAIK. I'm looking for a way to make this insertion faster. I've searched for information on Clojure data structures that have fast insertion but haven't found anything that would work. I found "finger trees" but they only allow fast insertion at the start or end of the list. Edit: I split this into two questions. The other part is here.

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  • c++ multithread array

    - by user1731972
    i'm doing something for fun, trying to learn multithreading Problems passing array by reference to threads but Arno pointed out that my threading via process.h wasn't going to be multi-threaded. What I'm hoping to do is something where I have an array of 100 (or 10,000, doesn't really matter I don't think), and split up the assignment of values to each thread. Example, 4 threads = 250 values per thread to be assigned. Then I can use this filled array for further calculations. Here's some code I was working on (which doesn't work) #include <process.h> #include <windows.h> #include <iostream> #include <fstream> #include <time.h> //#include <thread> using namespace std; void myThread (void *dummy ); CRITICAL_SECTION cs1,cs2; // global int main() { ofstream myfile; myfile.open ("coinToss.csv"); int rNum; long numRuns; long count = 0; int divisor = 1; float holder = 0; int counter = 0; float percent = 0.0; HANDLE hThread[1000]; int array[10000]; srand ( time(NULL) ); printf ("Runs (use multiple of 10)? "); cin >> numRuns; for (int i = 0; i < numRuns; i++) { //_beginthread( myThread, 0, (void *) (array1) ); //??? //hThread[i * 2] = _beginthread( myThread, 0, (void *) (array1) ); hThread[i*2] = _beginthread( myThread, 0, (void *) (array) ); } //WaitForMultipleObjects(numRuns * 2, hThread, TRUE, INFINITE); WaitForMultipleObjects(numRuns, hThread, TRUE, INFINITE); } void myThread (void *param ) { //thanks goes to stockoverflow //http://stackoverflow.com/questions/12801862/problems-passing-array-by-reference-to-threads int *i = (int *)param; for (int x = 0; x < 1000000; x++) { //param[x] = rand() % 2 + 1; i[x] = rand() % 2 + 1; } } Can anyone explain why it isn't working?

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  • Learning C, would appreciate input on why this solution works.

    - by Keifer
    This is literally the first thing I've ever written in C, so please feel free to point out all it's flaws. :) My issue, however is this: if I write the program the way I feel is cleanest, I get a broken program: #include <sys/queue.h> #include <stdlib.h> #include <stdio.h> #include <string.h> /* Removed prototypes and non related code for brevity */ int main() { char *cmd = NULL; unsigned int acct = 0; int amount = 0; int done = 0; while (done==0) { scanf ("%s %u %i", cmd, &acct, &amount); if (strcmp (cmd, "exit") == 0) done = 1; else if ((strcmp (cmd, "dep") == 0) || (strcmp (cmd, "deb") == 0)) debit (acct, amount); else if ((strcmp (cmd, "wd") == 0) || (strcmp (cmd, "cred") == 0)) credit (acct, amount); else if (strcmp (cmd, "fee") == 0) service_fee(acct, amount); else printf("Invalid input!\n"); } return(0); } void credit(unsigned int acct, int amount) { } void debit(unsigned int acct, int amount) { } void service_fee(unsigned int acct, int amount) { } As it stands, the above generates no errors at compile, but gives me a segfault when ran. I can fix this by changing the program to pass cmd by reference when calling scanf and strcmp. The segfault goes away and is replaced by warnings for each use of strcmp at compile time. Despite the warnings, the affected code works. warning: passing arg 1 of 'strcmp' from incompatible pointer type As an added bonus, modifying the scanf and strcmp calls allows the program to progress far enough to execute return(0), at which point the thing crashes with an Abort trap. If I swap out return(0) for exit(0) then everything works as expected. This leaves me with two questions: why was the original program wrong? How can I fix it better than I have? The bit about needing to use exit instead of return has me especially baffled.

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  • sed multiline pygmentize

    - by dasickis
    I would like to take the html piece and pass it to pygmentize to colorize it accordingly. I'm wondering how I could use sed or some other cli tool to get that accomplished. I tried a bunch of sed one-liners and tried to use the following SO questions: Sed multiline replacement question Using or in multiline sed replacement sed or awk multiline replace I have the following log: 2012-03-26 18:04:27,385 9372 [main] ERROR web.commons.exception.ServiceInvocationException - Response from server cannot be decoded to JSON, responsePayload = <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"/> <title>Error 404 Not Found</title> </head> <body><h2>HTTP ERROR 404</h2> <p>Problem accessing jetty-url. Reason: <pre> Not Found</pre></p><hr /><i><small>Powered by Jetty://</small></i><br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> <br/> </body> </html> org.codehaus.jackson.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null') at [Source: java.io.StringReader@369133f6; line: 1, column: 2] UPDATE I'm adding this to a longer command: mvn -U test | (while read line; do echo ${line} | sed -e "s/.*ERROR.*/`echo -e '\e[91m&\e[0m'`/g" -e "s/.*\(WARN|INFO\).*/`echo -e '\e[93m&\e[0m'`/g"; done)

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  • Java Flow Control Problem

    - by Kyle_Solo
    I am programming a simple 2d game engine. I've decided how I'd like the engine to function: it will be composed of objects containing "events" that my main game loop will trigger when appropriate. A little more about the structure: Every GameObject has an updateEvent method. objectList is a list of all the objects that will receive update events. Only objects on this list have their updateEvent method called by the game loop. I’m trying to implement this method in the GameObject class (This specification is what I’d like the method to achieve): /** * This method removes a GameObject from objectList. The GameObject * should immediately stop executing code, that is, absolutely no more * code inside update events will be executed for the removed game object. * If necessary, control should transfer to the game loop. * @param go The GameObject to be removed */ public void remove(GameObject go) So if an object tries to remove itself inside of an update event, control should transfer back to the game engine: public void updateEvent() { //object's update event remove(this); System.out.println("Should never reach here!"); } Here’s what I have so far. It works, but the more I read about using exceptions for flow control the less I like it, so I want to see if there are alternatives. Remove Method public void remove(GameObject go) { //add to removedList //flag as removed //throw an exception if removing self from inside an updateEvent } Game Loop for(GameObject go : objectList) { try { if (!go.removed) { go.updateEvent(); } else { //object is scheduled to be removed, do nothing } } catch(ObjectRemovedException e) { //control has been transferred back to the game loop //no need to do anything here } } // now remove the objects that are in removedList from objectList 2 questions: Am I correct in assuming that the only way to implement the stop-right-away part of the remove method as described above is by throwing a custom exception and catching it in the game loop? (I know, using exceptions for flow control is like goto, which is bad. I just can’t think of another way to do what I want!) For the removal from the list itself, it is possible for one object to remove one that is farther down on the list. Currently I’m checking a removed flag before executing any code, and at the end of each pass removing the objects to avoid concurrent modification. Is there a better, preferably instant/non-polling way to do this?

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  • Representation of a DateTime as the local to remote user

    - by TwoSecondsBefore
    Hello! I was confused in the problem of time zones. I am writing a web application that will contain some news with dates of publication, and I want the client to see the date of publication of the news in the form of corresponding local time. However, I do not know in which time zone the client is located. I have three questions. I have to ask just in case: does DateTimeOffset.UtcNow always returns the correct UTC date and time, regardless of whether the server is dependent on daylight savings time? For example, if the first time I get the value of this property for two minutes before daylight savings time (or before the transition from daylight saving time back) and the second time in 2 minutes after the transfer, whether the value of properties in all cases differ by only 4 minutes? Or here require any further logic? (Question #1) Please see the following example and tell me what you think. I posted the news on the site. I assume that DateTimeOffset.UtcNow takes into account the time zone of the server and the daylight savings time, and so I immediately get the correct UTC server time when pressing the button "Submit". I write this value to a MS SQL database in the field of type datetime2(0). Then the user opens a page with news and no matter how long after publication. This may occur even after many years. I did not ask him to enter his time zone. Instead, I get the offset of his current local time from UTC using the javascript function following way: function GetUserTimezoneOffset() { var offset = new Date().getTimezoneOffset(); return offset; } Next I make the calculation of the date and time of publication, which will show the user: public static DateTime Get_Publication_Date_In_User_Local_DateTime( DateTime Publication_Utc_Date_Time_From_DataBase, int User_Time_Zone_Offset_Returned_by_Javascript) { int userTimezoneOffset = User_Time_Zone_Offset_Returned_by_Javascript; // For // example Javascript returns a value equal to -300, which means the // current user's time differs from UTC to 300 minutes. Ie offset // is UTC +6. In this case, it may be the time zone UTC +5 which // currently operates summer time or UTC +6 which currently operates the // standard time. // Right? (Question #2) DateTimeOffset utcPublicationDateTime = new DateTimeOffset(Publication_Utc_Date_Time_From_DataBase, new TimeSpan(0)); // get an instance of type DateTimeOffset for the // date and time of publication for further calculations DateTimeOffset publication_DateTime_In_User_Local_DateTime = utcPublicationDateTime.ToOffset(new TimeSpan(0, - userTimezoneOffset, 0)); return publication_DateTime_In_User_Local_DateTime.DateTime;// return to user } Is the value obtained correct? Is this the right approach to solving this problem? (Question #3)

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  • template; Point<2, double>; Point<3, double>

    - by Oops
    Hi, I want to create my own Point struct it is only for purposes of learning C++. I have the following code: template <int dims, typename T> struct Point { T X[dims]; Point(){} Point( T X0, T X1 ) { X[0] = X0; X[1] = X1; } Point( T X0, T X1, T X2 ) { X[0] = X0; X[1] = X1; X[2] = X2; } Point<dims, int> toint() { //how to distinguish between 2D and 3D ??? Point<dims, int> ret = Point<dims, int>( (int)X[0], (int)X[1]); return ret; } std::string str(){ //how to distinguish between 2D and 3D ??? std::stringstream s; s << "{ X0: " << X[0] << " | X1: " << X[1] << " }"; return s.str(); } }; int main(void) { Point<2, double> p2d = Point<2, double>( 12.3, 45.6 ); Point<3, double> p3d = Point<3, double>( 12.3, 45.6, 78.9 ); Point<2, int> p2i = p2d.toint(); //OK Point<3, int> p3i = p3d.toint(); //m??? std::cout << p2d.str() << std::endl; //OK std::cout << p3d.str() << std::endl; //m??? std::cout << p2i.str() << std::endl; //m??? std::cout << p3i.str() << std::endl; //m??? char c; std::cin >> c; return 0; } of couse until now the output is not what I want. my questions is: how to take care of the dimensions of the Point (2D or 3D) in member functions of the Point? many thanks in advance Oops

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  • Inlining an array of non-default constructible objects in a C++ class

    - by porgarmingduod
    C++ doesn't allow a class containing an array of items that are not default constructible: class Gordian { public: int member; Gordian(int must_have_variable) : member(must_have_variable) {} }; class Knot { Gordian* pointer_array[8]; // Sure, this works. Gordian inlined_array[8]; // Won't compile. Can't be initialized. }; As even beginner C++ users know, the language guarantees that all members are initialized when constructing a class. And it doesn't trust the user to initialize everything in the constructor - one has to provide valid arguments to the constructors of all members before the body of the constructor even starts. Generally, that's a great idea as far as I'm concerned, but I've come across a situation where it would be a lot easier if I could actually have an array of non-default constructible objects. The obvious solution: Have an array of pointers to the objects. This is not optimal in my case, as I am using shared memory. It would force me to do extra allocation from an already contended resource (that is, the shared memory). The entire reason I want to have the array inlined in the object is to reduce the number of allocations. This is a situation where I would be willing to use a hack, even an ugly one, provided it works. One possible hack I am thinking about would be: class Knot { public: struct dummy { char padding[sizeof(Gordian)]; }; dummy inlined_array[8]; Gordian* get(int index) { return reinterpret_cast<Gordian*>(&inlined_array[index]); } Knot() { for (int x = 0; x != 8; x++) { new (get(x)) Gordian(x*x); } } }; Sure, it compiles, but I'm not exactly an experienced C++ programmer. That is, I couldn't possibly trust my hacks less. So, the questions: 1) Does the hack I came up with seem workable? What are the issues? (I'm mainly concerned with C++0x on newer versions of GCC). 2) Is there a better way to inline an array of non-default constructible objects in a class?

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  • Accesing server control from withing app_code class

    - by OverSeven
    My question is about how to acces a server control (listbox) that is located in default.aspx. I wish to acces this control in Functions.cs (this class is located in the App_Code folder). My page structures: - 1 masterpage with 1 content holder - Default.aspx (all the controls are within the content place holder) - Functions.cs (located in App_Code) Now when i try to fill up the listbox elements i get the error "object reference not set to an instance of an object." What i have tried to gain acces to this control: (this code is located in Functions.cs in App_Code). This is basicly showing some items in the listbox that are located in the xml file private static string file = HttpContext.Current.Server.MapPath("~/App_Data/Questions.xml"); public static void ListItems() { XmlDocument XMLDoc = new XmlDocument(); XMLDoc.Load(file); XPathNavigator nav = XMLDoc.CreateNavigator(); XPathExpression expr; expr = nav.Compile("/root/file/naam"); XPathNodeIterator iterator = nav.Select(expr); //ATTEMPT to get acces to ServerControl(listbox) Page page = (Page)HttpContext.Current.Handler; ListBox test = (ListBox)page.FindControl("lbTest"); //control is called lbTest in Default.aspx test.Items.Clear(); while (iterator.MoveNext()) { test.Items.Add(iterator.Current.Value); } } Code from the default.apx file <%@ Page Title="" Language="C#" MasterPageFile="~/MasterFile.master" AutoEventWireup="true" CodeFile="default.aspx.cs" Inherits="default" Debug="true" %> <%@ MasterType TypeName="Master" %> <asp:Content ID="Content1" ContentPlaceHolderID="cphContent" Runat="Server" > <asp:MultiView ID="mvTest" runat="server" > <asp:View ID="vCollection" runat="server"> <asp:ListBox ID="lbTest" runat="server" CssClass="listbox" ></asp:ListBox> </asp:View> </asp:MultiView> </asp:Content> The masterfile itself just has 1 placeholder. Then i call upon the funcion ListItems in the Default.aspx.cs file protected void Page_Load(object sender, EventArgs e) { Functions.ListItems(); } Regards.

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  • ODBC: when is the best time to create my database?

    - by mawg
    I have a windows program which generates PGP forms which will be filled in later. Those PHP forms will populate a database. It looks very much like MySql, but I can't be certain, so let's call it ODBC. And, yes, it does have to be a windows program. There will also be PHP forms which query the database - examine which tables and fields it contains and then generates forms which can be used to search the database (e.g, it finds a table with fields "employee_name", etc and generates a form which lets you search based on employee name. Let's call that design time and run time. At design time, some manager or IT guy or similar gets to define the nature of the database and at runtime 1) a worker fills in the form daily and 2) management can extract reports. Here's my question: given that the database is defined at "design time" (and populated at run time), where and how is best to do so? 1 I could use an ODBC interface from the windows program, but I am having difficulty finding something good to work with Delphi. Things like ADO and firebird tend to expect you to already have a database and allow you to manipulate it, but I can find no code example of how to create a database and some tables, so ... 2 I could used DOS commands from Delphi in my windows program. I just tried and got a response to MySql --version, but am not sure if MySql etc are more interactive. That is, can I use a script file or a very long stacked command with semicolons and returns separating? e.g 'CREATE DATABASE db; CREATE TABLE t1;' 3) Since the best way to work with databases seems to be PHP, perhaps my windows program could spit out a PHP page which would, when run in a browser, create the database. I have tried to make this as uncomplicated as I can, but please feel free to ask questions. It may be that there are several valid ways, but there is probably one 'better' solution in terms of ease of implementation or maintenance. Better scratch option 3. What if the user later wants to come back and have the windows program change the input form? It needs to update the database too.

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  • Using a large list of terms, search through page text and replace words with links

    - by dunc
    A while ago I posted this question asking if it's possible to convert text to HTML links if they match a list of terms from my database. I have a fairly huge list of terms - around 6000. The accepted answer on that question was superb, but having never used XPath, I was at a loss when problems started occurring. At one point, after fiddling with code, I somehow managed to add over 40,000 random characters to our database - the majority of which required manual removal. Since then I've lost faith in that idea and the more simple PHP solutions simply weren't efficient enough to deal with the amount of data and the quantity of terms. My next attempt at a solution is to write a JS script which, once the page has loaded, retrieves the terms and matches them against the text on a page. This answer has an idea which I'd like to attempt. I would use AJAX to retrieve the terms from the database, to build an object such as this: var words = [ { word: 'Something', link: 'http://www.something.com' }, { word: 'Something Else', link: 'http://www.something.com/else' } ]; When the object has been built, I'd use this kind of code: //for each array element $.each(words, function() { //store it ("this" is gonna become the dom element in the next function) var search = this; $('.message').each( function() { //if it's exactly the same if ($(this).text() === search.word) { //do your magic tricks $(this).html('<a href="' + search.link + '">' + search.link + '</a>'); } } ); } ); Now, at first sight, there is a major issue here: with 6,000 terms, will this code be in any way efficient enough to do what I'm trying to do?. One option would possibly be to perform some of the overhead within the PHP script that the AJAX communicates with. For instance, I could send the ID of the post and then the PHP script could use SQL statements to retrieve all of the information from the post and match it against all 6,000 terms.. then the return call to the JavaScript could simply be the matching terms, which would significantly reduce the number of matches the above jQuery would make (around 50 at most). I have no problem with the script taking a few seconds to "load" on the user's browser, as long as it isn't impacting their CPU usage or anything like that. So, two questions in one: Can I make this work? What steps can I take to make it as efficient as possible? Thanks in advance,

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  • Should an object be fully complete before injected as a dependency?

    - by Hans
    This is an extension of this question: http://stackoverflow.com/questions/3027082/understanding-how-to-inject-object-dependencies. Since it is a bit different, I wanted to separate them, to make it, hopefully, easier to answer. Also, this is not a real system, just a simplified example that I thought we'd all be familiar with. TIA. : DB threads: thread_id, thread_name, etc posts: post_id, thread_id, post_name, post_contents, post_date, post_user_id, etc Overview Basically I'm looking at the most maintainable way to load $post_id and have it cascade and load the other things I want to know about and I'm trying to keep the controller skinny. BUT: I'm ending up with too many dependencies to inject I'm passing in initialized but empty objects I want to limit how many parameters I am passing around I could inject $post(-many) into $thread(one<-), but on that page I'm not looking at a thread, I'm looking at a post I could combine/inject them into a new object Detail If I am injecting an object into another, is it best to have it fully created first? I'm trying to limit how many parameters I have to pass in to a page, but I end up with a circle. // 1, empty object injected via constructor $thread = new Thread; $post = new Post($thread); // $thread is just an empty object $post->load($post_id); // I could now do something like $post->get('thread_id') to get everything I want in $post // 2, complete object injected via constructor $thread = new Thread; $thread->load($thread_id); // this page would have to have passed in a $thread_id, too $post = new Post($thread); // thread is a complete object, with the data I need, like thread name $post->load($post_id); // 3, inject $post into $thread, but this makes less sense to me, since I'm looking at a post page, not a thread page $post = new Post(); $post->load($post_id); $thread = new Thread($post); $thread->load(); // would load based on the $post->get('post_id') and combine. Now I have all the data I want, but it's non-intuitive to be heirarchially Thread->Post instead of Post-with-thread-info // Or, I could inject $post into $thread, but if I'm on a post page, // having an object with a top level of Thread instead of // Post-which-contains-thread-info, makes less sense to me. // to go with example 1 class post { public function __construct(&$thread) { $this->thread=$thread; } public function load($id) { // ... here I would load all the post data based on $id // now include the thread data $this->thread->load($this->get('thread_id')); return $this; } } // I don't want to do $thread = new Thread; $post = new Post; $post->load($post_id); $thread->load($post->get('post_id')); Or, I could create a new object and inject both $post and $thread into it, but then I have object with an increasing number of dependencies.

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