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  • Use of infix operator hack in production code (Python)

    - by Casebash
    What is your opinion of using the infix operator hack in production code? Issues: The effect this will have on speed. The potential for a clashes with an object with these operators already defined. This seems particularly dangerous with generic code that is intended to handle objects of any type. It is a shame that this isn't built in - it really does improve readability

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  • PHP or Javascript or other - Draw simple shapes onto images?

    - by Tommo
    I basically have an image of a world map and i would like to place a pin image at a specified pixel co-ordinate ontop of this world map image. It's for a website, so ideally the solution should be in PHP or Javascript (i'm avoiding Java and Flash as i want it to be as simple as possible). I had a look at the processing.js library but it is way to big and bloated for just performing this simple task. Is there a pre-existing Javascript function which will allow me to do this? Or a more simple javascript library that i can use? (processing.js was a bit too advanced for me, i couldnt get it working lol) In terms of a PHP solution, i would prefer taking the load off the server and onto the client for this task, but i would still like to hear methods for doing it in PHP if they are suitable. Thanks!

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  • desing pattern for related inputs

    - by curiousMo
    My question is a design question : let's say i have a data entry web page with 4 drop down lists, each depending on the previous one, and a bunch of text boxes. country (ddl), state (ddl), city (ddl), boro (ddl), address (txtBox), zipcode(txtbox). and an object that represents a datarow with a value for each. naturally the country, state, city and boro values will be values of primary keys of some lookup tables. when the user chooses to edits that record, i would load it from database and load it into the page. the issue that I have is how to streamline loading the ddls. i have some code that would grab the object, look thru its values and move them to their corresponding input controls in one shot. but in this case i will have to load possible values of country, then assign values, then load values of state, then assign value ans so on. I guess i am looking for an elegant solution. i am using asp.net, but i think it is irrelevant to the question. i am looking more into a design pattern. thanks

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  • creating a wrapper around a 3rd party assembly - swap out and decouple

    - by mrblah
    I have an email component that I am integrating into my application, looking for some tips on how should build a wrapper around it so I can swap it out with another 3rd party component if needed. My approach right now is it: build an interface will the functionality I need. create a class that implements the interface, using my 3rd party component inside this class. any usage of this component will be via the interface so like: IPop3 pop3 = new AcmeIncePop3Wrapper(); pop3.connect(); and inside AcmeIncePop3Wrapper will be: public void connect() { AcmeIncePop3 pop = new AcmeIncePop3(); pop.connect(); } Is that a good approach? I could probably add another abstraction by using ninject so I could swap out implementations, but really this seems to be all I need as i don't expect to be changing 3rd party assemblies every day, just don't want to make things so tightly coupled.

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  • Assembly wide multicast attributes. Are they evil?

    - by HeavyWave
    I am working on a project where we have several attributes in AssemblyInfo.cs, that are being multicast to a methods of a particular class. [assembly: Repeatable( AspectPriority = 2, AttributeTargetAssemblies = "MyNamespace", AttributeTargetTypes = "MyNamespace.MyClass", AttributeTargetMemberAttributes = MulticastAttributes.Public, AttributeTargetMembers = "*Impl", Prefix = "Cls")] What I don't like about this, is that it puts a piece of login into AssemblyInfo (Info, mind you!), which for starters should not contain any logic at all. The worst part of it, is that the actual MyClass.cs does not have the attribute anywhere in the file, and it is completely unclear that methods of this class might have them. From my perspective it greatly hurts readability of the code (not to mention that overuse of PostSharp can make debugging a nightmare). Especially when you have multiple multicast attributes. What is the best practice here? Is anyone out there is using PostSharp attributes like this?

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  • ASP.NET MVC null ViewResult

    - by David Neale
    How should one deal with an MVC controller returning a null ViewResult? As an example I am creating a simple edit view: public ActionResult Edit(int id) { var person = (from p in context.SWLiftShare_Persons where p.id == id select p).SingleOrDefault(); if (person != null) { return View(person); } else return View(); } I guess in reality there's no point in checking for a null result in the controller because the view picks out properties from the model: <h2>Edit - <%= Html.Encode(Model.Name) %></h2> <%= Html.ValidationSummary("Edit was unsuccessful. Please correct the errors and try again.") %> <% using (Html.BeginForm()) {%> <fieldset> <legend>Fields</legend> <p> <label for="id">id: <%= Html.Encode(Model.id) %></label> </p> <p> <label for="CollarNumber">CollarNumber:</label> <%= Html.TextBox("CollarNumber", Model.CollarNumber)%> <%= Html.ValidationMessage("CollarNumber", "*") %> </p> <p> <label for="Name">Name:</label> <%= Html.TextBox("Name", Model.Name)%> <%= Html.ValidationMessage("Name", "*") %> </p> <p> <label for="EmailAddress">EmailAddress:</label> <%= Html.TextBox("EmailAddress", Model.EmailAddress, new { style = "width:300px" })%> <%= Html.ValidationMessage("EmailAddress", "*") %> </p> <p> <input type="submit" value="Save" /> </p> </fieldset> <% } %> I could just wrap everything in a <% if(Model != null) { //render edit markup... etc. but that seems rather unelegant. Is there a better way to deal with this?

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  • System.Drawing.Image for Images in Business Objects?

    - by Mudu
    Hi Folks I'd like to store an image in a business object. In MSDN I saw that the System.Drawing-namespace provides lots of GDI+-features, etc. Is it okay to store an Image in an System.Drawing.Image class in business layer (which is a class library "only"), and thus including a reference to System.Drawing too? I slightly feel just kind of bad doing that, 'cause it seems like I have UI-specific references in business code. Moreover, the code could become unnecessarily platform-dependant (though this is only a problem in theory, because we do not develop for multiple platforms). If it isn't right that way, which type would fit best? Thank you for any response! Matthias

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  • Multi-level shop, xml or sql. best practice?

    - by danrichardson
    Hello, i have a general "best practice" question regarding building a multi-level shop, which i hope doesn't get marked down/deleted as i personally think it's quite a good "subjective" question. I am a developer in charge (in most part) of maintaining and evolving a cms system and associated front-end functionality. Over the past half year i have developed a multiple level shop system so that an infinite level of categories may exist down into a product level and all works fine. However over the last week or so i have questioned by own methods in front-end development and the best way to show the multi-level data structure. I currently use a sql server database (2000) and pull out all the shop levels and then process them into an enumerable typed list with child enumerable typed lists, so that all levels are sorted. This in my head seems quite process heavy, but we're not talking about thousands of rows, generally only 1-500 rows maybe. I have been toying with the idea recently of storing the structure in an XML document (as well as the database) and then sending last modified headers when serving/requesting the document for, which would then be processed as/when nessecary with an xsl(t) document - which would be processed server side. This is quite a handy, reusable method of storing the data but does it have more overheads in the fact im opening and closing files? And also the xml will require a bit of processing to pull out blocks of xml if for instance i wanted to show two level mid way through the tree for a side menu. I use the above method for sitemap purposes so there is currently already code i have built which does what i require, but unsure what the best process is to go about. Maybe a hybrid method which pulls out the data, sorts it and then makes an xml document/stream (XDocument/XmlDocument) for xsl processing is a good way? - This is the way i currently make the cms work for the shop. So really (and thanks for sticking with me on this), i am just wandering which methods other people use or recommend as being the best/most logical way of doing things. Thanks Dan

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  • Spring online repository for Maven

    - by Fortyrunner
    I've just installed Maven2 for the first time. By default it pulls down a few useful jars into a local project: jakarta-commons, junit etc. I wanted to pull in the latest Spring release (2.5.6 at the time of writing). But the online repositories I looked at (iBiblio and Maven) only had much older versions of Spring libraries. Are there any other repositories that are kept up to date? What is the best practice here; can we maintain them ourselves? I would be prepared to help out maintaining this stuff!

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  • Has anyone ever encountered a Monad Transformer in the wild?

    - by martingw
    In my area of business - back office IT for a financial institution - it is very common for a software component to carry a global configuration around, to log it's progress, to have some kind of error handling / computation short circuit... Things that can be modelled nicely by Reader-, Writer-, Maybe-monads and the like in Haskell and composed together with monad transformers. But there seem to some drawbacks: The concept behind monad transformers is quite tricky and hard to understand, monad transformers lead to very complex type signatures, and they inflict some performance penalty. So I'm wondering: Are monad transformers best practice when dealing with those common tasks mentioned above?

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  • How 'terse' is too terse? -- Practical guidelines for expressing as much intent in as few characters

    - by Christopher Altman
    First, I love writing as little code as possible. I think, and please correct me, one of the golden rules of programming is to express your code in as few of character as possible while maintaining human readability. But I can get a little carried away. I can pack three or four lines into one statement, something like $startDate = $dateTime > time() ? mktime(0,0,0,date('m',time()-86400),date('d',time()*2),2011) : time(); (Note: this is a notional example) I can comprehend the above code when reading it. I prefer 'mushing' it all together because having less lines per page is a good thing to me. So my question: When writing code and thinking about how compact or terse you can express yourself, what are some guidelines you use? Do you write multiple lines because you think it helps other people? Do you write as little as possible, but use comments? Or do you always look for the way to write as little code as possible and enjoy the rewards of compact statements? (Just one slightly off topic comment: I love the Perl one-liners, but that is not what I am talking about here)

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  • Are GUIDs the ultimate ID?

    - by mafutrct
    I noticed some people don't bother having the usual incremented number as ID but instead simply generate a GUID. The advantages include: Quick and easy No need to keep track of previous IDs Guaranteed to be unique even across machines without knowledge of each other Some disadvantages are: Possibly performance bottleneck Uses a large number of bytes My understanding is that using a GUID is beneficial in most cases, except if optimization for time or space is an issue. Did I miss something? Or do you agree with this idea?

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  • Using static variable in function vs passing variable from caller

    - by Patrick
    I have a function which spawns various types of threads, one of the thread types needs to be spawned every x seconds. I currently have it like this: bool isTime( Time t ) { return t >= now(); } void spawner() { while( 1 ) { Time t = now(); if( isTime( t ) )//is time is called in more than one place in the real function { launchthread() t = now() + offset; } } } but I'm thinking of changing it to: bool isTime() { static Time t = now(); if( t >= now() ) { t = now() + offset; return true; } return false; } void spawner() { if( isTime() ) launchthread(); } I think the second way is neater but I generally avoid statics in much the same way I avoid global data; anyone have any thoughts on the different styles?

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  • Repository organization for Hadoop project

    - by Alex N.
    I am starting on a new Hadoop project that will have multiple hadoop jobs(and hence multiple jar files). Using mercurial for source control, I was wondering what would be optimal way of organizing the repository structure? Should each job live in separate repo or would it be more efficient to keep them in the same, but break down into folders?

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  • State pattern: Why doesn't the context class implement or inherit the State abstract interface/class

    - by Ricket
    I'm reading about the State pattern. I have only just begun, so of course I begin by reading the entire Wikipedia article on it. I noticed that both of the examples in the article have some base abstract class or Java interface for a generic State's methods/functions. Then there are some states which inherit from the base and implement those methods/functions in different ways. Then there's a Context class which has a private member of type State and which, at any time, can be equal to an instance of one of the implementations. That context class also implements the same methods, and passes them onto the current state instance, and then has an additional method to change the state (or depending on design I understand the change of state could be a reaction to one of the implemented methods). Why doesn't this context class specifically "extend" or "implement" the generic State base class/interface?

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  • In JSF - What is the correct way to do this? Two dropdown lists with dependency.

    - by Ben
    Hi, I'm making two dropdown lists in JSF which are dependent. Specifically, one list has all the languages and the second list contains values that are displayed in the currently selected language. I've implemented this by having the second list use information from a Hash and rebuilding that Hash in the setter of the currently selected language. JSF Code Bit: <rich:dropDownMenu value="#{bean.currentlySelectedLanguage}" id="languageSelector"> ... (binding to languages hash) ... <rich:dropDownMenu value="#{bean.currentlySelectedScript}" id="ScriptPullDown"> ... (binding to scripts hash) ... Backing Bean Code Bit: setCurrentlySelectedLanguage(String lang){ this.currentlySelectedLanguage = lang; rebuildScriptNames(lang); } I'm wondering if that's a good way of doing this or if theres a better method that I am not aware of. Thank you! EDIT - Adding info.. I used a a4j:support that with event="onchange" and ReRender="ScriptPullDown" to rerender the script pull down. I could probably add an action expression to run a method when the value changes. But is there a benefit to doing this over using code in the setter function?

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  • Can this PHP version of SPICE be improved?

    - by Noctis Skytower
    I do not know much about PHP's standard library of functions and was wondering if the following code can be improved in any way. The implementation should yield the same results, the API should remain as it is, but ways to make is more PHP-ish would be greatly appreciated. This is a custom encryption library. Code <?php /*************************************** Create random major and minor SPICE key. ***************************************/ function crypt_major() { $all = range("\x00", "\xFF"); shuffle($all); $major_key = implode("", $all); return $major_key; } function crypt_minor() { $sample = array(); do { array_push($sample, 0, 1, 2, 3); } while (count($sample) != 256); shuffle($sample); $list = array(); for ($index = 0; $index < 64; $index++) { $b12 = $sample[$index * 4] << 6; $b34 = $sample[$index * 4 + 1] << 4; $b56 = $sample[$index * 4 + 2] << 2; $b78 = $sample[$index * 4 + 3]; array_push($list, $b12 + $b34 + $b56 + $b78); } $minor_key = implode("", array_map("chr", $list)); return $minor_key; } /*************************************** Create the SPICE key via the given name. ***************************************/ function named_major($name) { srand(crc32($name)); return crypt_major(); } function named_minor($name) { srand(crc32($name)); return crypt_minor(); } /*************************************** Check validity for major and minor keys. ***************************************/ function _check_major($key) { if (is_string($key) && strlen($key) == 256) { foreach (range("\x00", "\xFF") as $char) { if (substr_count($key, $char) == 0) { return FALSE; } } return TRUE; } return FALSE; } function _check_minor($key) { if (is_string($key) && strlen($key) == 64) { $indexs = array(); foreach (array_map("ord", str_split($key)) as $byte) { foreach (range(6, 0, 2) as $shift) { array_push($indexs, ($byte >> $shift) & 3); } } $dict = array_count_values($indexs); foreach (range(0, 3) as $index) { if ($dict[$index] != 64) { return FALSE; } } return TRUE; } return FALSE; } /*************************************** Create encode maps for encode functions. ***************************************/ function _encode_map_1($major) { return array_map("ord", str_split($major)); } function _encode_map_2($minor) { $map_2 = array(array(), array(), array(), array()); $list = array(); foreach (array_map("ord", str_split($minor)) as $byte) { foreach (range(6, 0, 2) as $shift) { array_push($list, ($byte >> $shift) & 3); } } for ($byte = 0; $byte < 256; $byte++) { array_push($map_2[$list[$byte]], chr($byte)); } return $map_2; } /*************************************** Create decode maps for decode functions. ***************************************/ function _decode_map_1($minor) { $map_1 = array(); foreach (array_map("ord", str_split($minor)) as $byte) { foreach (range(6, 0, 2) as $shift) { array_push($map_1, ($byte >> $shift) & 3); } } return $map_1; }function _decode_map_2($major) { $map_2 = array(); $temp = array_map("ord", str_split($major)); for ($byte = 0; $byte < 256; $byte++) { $map_2[$temp[$byte]] = chr($byte); } return $map_2; } /*************************************** Encrypt or decrypt the string with maps. ***************************************/ function _encode($string, $map_1, $map_2) { $cache = ""; foreach (str_split($string) as $char) { $byte = $map_1[ord($char)]; foreach (range(6, 0, 2) as $shift) { $cache .= $map_2[($byte >> $shift) & 3][mt_rand(0, 63)]; } } return $cache; } function _decode($string, $map_1, $map_2) { $cache = ""; $temp = str_split($string); for ($iter = 0; $iter < strlen($string) / 4; $iter++) { $b12 = $map_1[ord($temp[$iter * 4])] << 6; $b34 = $map_1[ord($temp[$iter * 4 + 1])] << 4; $b56 = $map_1[ord($temp[$iter * 4 + 2])] << 2; $b78 = $map_1[ord($temp[$iter * 4 + 3])]; $cache .= $map_2[$b12 + $b34 + $b56 + $b78]; } return $cache; } /*************************************** This is the public interface for coding. ***************************************/ function encode_string($string, $major, $minor) { if (is_string($string)) { if (_check_major($major) && _check_minor($minor)) { $map_1 = _encode_map_1($major); $map_2 = _encode_map_2($minor); return _encode($string, $map_1, $map_2); } } return FALSE; } function decode_string($string, $major, $minor) { if (is_string($string) && strlen($string) % 4 == 0) { if (_check_major($major) && _check_minor($minor)) { $map_1 = _decode_map_1($minor); $map_2 = _decode_map_2($major); return _decode($string, $map_1, $map_2); } } return FALSE; } ?> This is a sample showing how the code is being used. Hex editors may be of help with the input / output. Example <?php # get and process all of the form data @ $input = htmlspecialchars($_POST["input"]); @ $majorname = htmlspecialchars($_POST["majorname"]); @ $minorname = htmlspecialchars($_POST["minorname"]); @ $majorkey = htmlspecialchars($_POST["majorkey"]); @ $minorkey = htmlspecialchars($_POST["minorkey"]); @ $output = htmlspecialchars($_POST["output"]); # process the submissions by operation # CREATE @ $operation = $_POST["operation"]; if ($operation == "Create") { if (strlen($_POST["majorname"]) == 0) { $majorkey = bin2hex(crypt_major()); } if (strlen($_POST["minorname"]) == 0) { $minorkey = bin2hex(crypt_minor()); } if (strlen($_POST["majorname"]) != 0) { $majorkey = bin2hex(named_major($_POST["majorname"])); } if (strlen($_POST["minorname"]) != 0) { $minorkey = bin2hex(named_minor($_POST["minorname"])); } } # ENCRYPT or DECRYPT function is_hex($char) { if ($char == "0"): return TRUE; elseif ($char == "1"): return TRUE; elseif ($char == "2"): return TRUE; elseif ($char == "3"): return TRUE; elseif ($char == "4"): return TRUE; elseif ($char == "5"): return TRUE; elseif ($char == "6"): return TRUE; elseif ($char == "7"): return TRUE; elseif ($char == "8"): return TRUE; elseif ($char == "9"): return TRUE; elseif ($char == "a"): return TRUE; elseif ($char == "b"): return TRUE; elseif ($char == "c"): return TRUE; elseif ($char == "d"): return TRUE; elseif ($char == "e"): return TRUE; elseif ($char == "f"): return TRUE; else: return FALSE; endif; } function hex2bin($str) { if (strlen($str) % 2 == 0): $string = strtolower($str); else: $string = strtolower("0" . $str); endif; $cache = ""; $temp = str_split($str); for ($index = 0; $index < count($temp) / 2; $index++) { $h1 = $temp[$index * 2]; if (is_hex($h1)) { $h2 = $temp[$index * 2 + 1]; if (is_hex($h2)) { $cache .= chr(hexdec($h1 . $h2)); } else { return FALSE; } } else { return FALSE; } } return $cache; } if ($operation == "Encrypt" || $operation == "Decrypt") { # CHECK FOR ANY ERROR $errors = array(); if (strlen($_POST["input"]) == 0) { $output = ""; } $binmajor = hex2bin($_POST["majorkey"]); if (strlen($_POST["majorkey"]) == 0) { array_push($errors, "There must be a major key."); } elseif ($binmajor == FALSE) { array_push($errors, "The major key must be in hex."); } elseif (_check_major($binmajor) == FALSE) { array_push($errors, "The major key is corrupt."); } $binminor = hex2bin($_POST["minorkey"]); if (strlen($_POST["minorkey"]) == 0) { array_push($errors, "There must be a minor key."); } elseif ($binminor == FALSE) { array_push($errors, "The minor key must be in hex."); } elseif (_check_minor($binminor) == FALSE) { array_push($errors, "The minor key is corrupt."); } if ($_POST["operation"] == "Decrypt") { $bininput = hex2bin(str_replace("\r", "", str_replace("\n", "", $_POST["input"]))); if ($bininput == FALSE) { if (strlen($_POST["input"]) != 0) { array_push($errors, "The input data must be in hex."); } } elseif (strlen($bininput) % 4 != 0) { array_push($errors, "The input data is corrupt."); } } if (count($errors) != 0) { # ERRORS ARE FOUND $output = "ERROR:"; foreach ($errors as $error) { $output .= "\n" . $error; } } elseif (strlen($_POST["input"]) != 0) { # CONTINUE WORKING if ($_POST["operation"] == "Encrypt") { # ENCRYPT $output = substr(chunk_split(bin2hex(encode_string($_POST["input"], $binmajor, $binminor)), 58), 0, -2); } else { # DECRYPT $output = htmlspecialchars(decode_string($bininput, $binmajor, $binminor)); } } } # echo the form with the values filled echo "<P><TEXTAREA class=maintextarea name=input rows=25 cols=25>" . $input . "</TEXTAREA></P>\n"; echo "<P>Major Name:</P>\n"; echo "<P><INPUT id=textbox1 name=majorname value=\"" . $majorname . "\"></P>\n"; echo "<P>Minor Name:</P>\n"; echo "<P><INPUT id=textbox1 name=minorname value=\"" . $minorname . "\"></P>\n"; echo "<DIV style=\"TEXT-ALIGN: center\"><INPUT class=submit type=submit value=Create name=operation>\n"; echo "</DIV>\n"; echo "<P>Major Key:</P>\n"; echo "<P><INPUT id=textbox1 name=majorkey value=\"" . $majorkey . "\"></P>\n"; echo "<P>Minor Key:</P>\n"; echo "<P><INPUT id=textbox1 name=minorkey value=\"" . $minorkey . "\"></P>\n"; echo "<DIV style=\"TEXT-ALIGN: center\"><INPUT class=submit type=submit value=Encrypt name=operation> \n"; echo "<INPUT class=submit type=submit value=Decrypt name=operation> </DIV>\n"; echo "<P>Result:</P>\n"; echo "<P><TEXTAREA class=maintextarea name=output rows=25 readOnly cols=25>" . $output . "</TEXTAREA></P></DIV></FORM>\n"; ?>

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  • Java library class to handle scheduled execution of "callbacks"?

    - by Hanno Fietz
    My program has a component - dubbed the Scheduler - that lets other components register points in time at which they want to be called back. This should work much like the Unix cron service, i. e. you tell the Scheduler "notify me at ten minutes past every full hour". I realize there are no real callbacks in Java. Here's my approach, is there a library which already does this stuff? Feel free to suggest improvements, too. Register call to Scheduler passes: a time specification containing hour, minute, second, year month, dom, dow, where each item may be unspecified, meaning "execute it every hour / minute etc." (just like crontabs) an object containing data that will tell the calling object what to do when it is notified by the Scheduler. The Scheduler does not process this data, just stores it and passes it back upon notification. a reference to the calling object Upon startup, or after a new registration request, the Scheduler starts with a Calendar object of the current system time and checks if there are any entries in the database that match this point in time. If there are, they are executed and the process starts over. If there aren't, the time in the Calendar object is incremented by one second and the entreis are rechecked. This repeats until there is one entry or more that match(es). (Discrete Event Simulation) The Scheduler will then remember that timestamp, sleep and wake every second to check if it is already there. If it happens to wake up and the time has already passed, it starts over, likewise if the time has come and the jobs have been executed. Edit: Thanks for pointing me to Quartz. I'm looking for something much smaller, however.

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