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  • StrcutureMap Wiring - Sanity Check Please

    - by Steve Ward
    Hi - Im new to IOC and StructureMap and have an n-level application and am looking at how to setup the wirings (ForRequestedType ...) and just want to check with people with more experience that this is the best way of doing it! I dont want my UI application object to reference my persistence layer directly so am not able to wire everything up in this UI project. I now have it working by defining a Registry class in each project which wires up the types in the project as needed. The layer above registers its types and also calls the assembly below and looks for registries so that all types are registered throught the hierrachy. E.g. I have UI, Service, Domain, and Persistence libraries. In my service layer the registry looks like Scan(x => { x.Assembly("MyPersistenceProject"); x.LookForRegistries(); }); ForRequestedType<IService>().TheDefault.Is.OfConcreteType<MyService>(); Is this a recommended way of doing this in a setup such as this? Are there better ways and what are the advantages / disadvantages of these approaches in this case?

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  • Newbie question: When to use extern "C" { //code } ?

    - by Russel
    Hello, Maybe I'm not understanding the differences between C and C++, but when and why do we need to use: extern "C" { ? Apparently its a "linkage convention"? I read about it briefly and noticed that all the .h header files included with MSVS surround their code with it. What type of code exactly is "C code" and NOT "C++ code"? I thought C++ included all C code? I'm guessing that this is not the case and that C++ is different and that standard features/functions exist in one or the other but not both (ie: printf is C and cout is C++), but that C++ is backwards compatible though the extern "C" declaration. Is this correct? My next question depends on the answer to the first, but I'll ask it here anyway: Since MSVS header files that are written in C are surrounded by extern "C" { ... }, when would you ever need to use this yourself in your own code? If your code is C code and you are trying to compile it in a C++ compiler, shouldn't it work without problem because all the standard h files you include will already have the extern "C" thing in them with the C++ compiler? Do you have to use this when compiling in C++ but linking to alteady built C libraries or something? Please help clarify this for me... Thanks! --Keith

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  • How best to associate code with events in jQuery?

    - by Ned Batchelder
    Suppose I have a <select> element on my HTML page, and I want to run some Javascript when the selection is changed. I'm using jQuery. I have two ways to associate the code with the element. Method 1: jQuery .change() <select id='the_select'> <option value='opt1'>One</option> <option value='opt2'>Two</option> </select> <script> $('#the_select').change(function() { alert('Changed!'); }); </script> Method 2: onChange attribute <select id='the_select' onchange='selectChanged();'> <option value='opt1'>One</option> <option value='opt2'>Two</option> </select> <script> function selectChanged() { alert('Changed!'); } </script> I understand the different modularity here: for example, method 1 keeps code references out of the HTML, but method 2 doesn't need to mention HTML ids in the code. What I don't understand is: are there operational differences between these two that would make me prefer one over the other? For example, are there edge-case browsers where one of these works and the other doesn't? Is the integration with jQuery better for either? Does the late-binding of the code to the event make a difference in the behavior of the page? Which do you pick and why?

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  • 'Fixed' for loop - what is more efficient?

    - by pimvdb
    I'm creating a tic-tac-toe game, and one of the functions has to iterate through each of the 9 fields (tic-tac-toe is played on a 3x3 grid). I was wondering what is more efficient (which one is perhaps faster, or what is the preferred way of scripting in such situation) - using two for nested loops like this: for(var i=0; i<3; i++) { for(var j=0; j<3; j++) { checkField(i, j); } } or hard-coding it like this: checkField(0, 0); checkField(0, 1); checkField(0, 2); checkField(1, 0); checkField(1, 1); checkField(1, 2); checkField(2, 0); checkField(2, 1); checkField(2, 2); As there are only 9 combinations, it would be perhaps overkill to use two nested for loops, but then again this is clearer to read. The for loop, however, will increment variables and check whether i and j are smaller than 3 every time as well. In this example, the time saving at least might be negligible, but what is the preferred way of coding in this case? Thanks.

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  • PHP compare two dimension array

    - by Jerry
    Hello guys I would like to know how to compare two two-dimension arrays value. First array Array 1 ( [0] => Array ( [0] => a ) [1] => Array ( [0] => b ) [2] => Array ( [0] => c ) } Second one Array 2 ( [0] => Array ( [0] => a ) [1] => Array ( [0] => d ) [2] => Array ( [0] => e ) } I need to know if my loop could compare the arrays to check the matched value. In my case, array1[0][0]=a matches array2[0][0]=a. If it matches, php will output some html. My foreach loop foreach ($array1 as $arrays){ foreach($arrays as $array){ //need to compare array2 here not sure how to do it. } } I would appreciate any helps. Thanks!

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  • Simplest distributed persistent key/value store that supports primary key range queries

    - by StaxMan
    I am looking for a properly distributed (i.e. not just sharded) and persisted (not bounded by available memory on single node, or cluster of nodes) key/value ("nosql") store that does support range queries by primary key. So far closest such system is Cassandra, which does above. However, it adds support for other features that are not essential for me. So while I like it (and will consider using it of course), I am trying to figure out if there might be other mature projects that implement what I need. Specifically, for me the only aspect of value I need is to access it as a blob. For key, however, I need range queries (as in, access values ordered, limited by start and/or end values). While values can have structures, there is no need to use that structure for anything on server side (can do client-side data binding, flexible value/content types etc). For added bonus, Cassandra style storage (journaled, all sequential writes) seems quite optimal for my use case. To help filter out answers, I have investigated some alternatives within general domain like: Voldemort (key/value, but no ordering) and CouchDB (just sharded, more batch-oriented); and am aware of systems that are not quite distributed while otherwise qualifying (bdb variants, tokyo cabinet itself (not sure if Tyrant might qualify), redis (in-memory store only)).

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  • How to access elements in a complex list?

    - by Martin
    Hi, it's me and the lists again. I have a nice list, which looks like this: tmp = NULL t = NULL tmp$resultitem$count = "1057230" tmp$resultitem$status = "Ok" tmp$resultitem$menu = "PubMed" tmp$resultitem$dbname = "pubmed" t$resultitem$count = "305215" t$resultitem$status = "Ok" t$resultitem$menu = "PMC" t$resultitem$dbname = "pmc" tmp = c(tmp, t) t = NULL t$resultitem$count = "1" t$resultitem$status = "Ok" t$resultitem$menu = "Journals" t$resultitem$dbname = "journals" tmp = c(tmp, t) Which produces: str(tmp) List of 3 $ resultitem:List of 4 ..$ count : chr "1057230" ..$ status: chr "Ok" ..$ menu : chr "PubMed" ..$ dbname: chr "pubmed" $ resultitem:List of 4 ..$ count : chr "305215" ..$ status: chr "Ok" ..$ menu : chr "PMC" ..$ dbname: chr "pmc" $ resultitem:List of 4 ..$ count : chr "1" ..$ status: chr "Ok" ..$ menu : chr "Journals" ..$ dbname: chr "journals" Now I want to search through the elements of each "resultitem". I want to know the "dbname" for every database, that has less then 10 "count" (example). In this case it is very easy, as this list only has 3 elements, but the real list is a little bit longer. This could be simply done with a for loop. But is there a way to do this with some other function of R (like rapply)? My problem with those apply functions is, that they only look at one element. If I do a grep to get all "dbname" elements, I can not get the count of each element. rapply(tmp, function(x) paste("Content: ", x))[grep("dbname", names(rapply(tmp, c)))] Does someone has a better idea than a for loop? Thanx, Martin

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  • Signable, streamable, "readable" archive format?

    - by alexvoda
    Is there any archive format that offers the following: be digitally sign-able with a digital certificate from a trusted source like Verisign - for preventing changes to the file (I am not referring to read only, but in case the file was changed it should no longer be signed telling the user this is not the original file) be stream-able - be able to be opened even if not all of the content has been transfered (also not strictly linearly) be "readable" - be able to read the data without extracting to a temporary folder (AFAIK if you open a file in a zip archive it is extracted first, and this stays true even for zip based formats like OOXML. This is not what I want) be portable - support on at least Windows, Linux and Mac OS X is a must, or at least future support be free of patents - Be open source - also preferably a license that allows commercial use(as far as i know GPL a share-alike licence so it doesn't allow comercial use, BSD on the other hand alows it) Note: Though it may come in handy eventually I can not think right now of a scenario that would require both point 1 and point 2 simultaneously. Or lets leave it a be able to check the signature only when the whole file was downloaded. I am not interested in: being able to be compressed being supported on legacy systems Does any existing archive format fit this description (tar evolutions like DAR and pax come to mind) ? If there is, are there programing libraries available for the above mentioned OSs? If not, would it be hard to create such a thing? EDIT: clarrified piont 5 EDIT 2: added a note to clarify point 1 and 2 P.S.: This is my first question on StackOverflow

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  • Serializing and deserializing a map with key as string

    - by Grace K
    Hi! I am intending to serialize and deserialize a hashmap whose key is a string. From Josh Bloch's Effective Java, I understand the following. P.222 "For example, consider the case of a harsh table. The physical representation is a sequence of hash buckets containing key-value entries. Which bucket an entry is placed in is a function of the hash code of the key, which is not, in general guaranteed to be the same from JVM implementation to JVM implementation. In fact, it isn't even guranteed to be the same from run to run on the same JVM implementation. Therefore accepting the default serialized form for a hash table would constitute a serious bug. Serializing and deserializing the hash table could yield an object whose invariants were seriously corrupt." My questions are: 1) In general, would overriding the equals and hashcode of the key class of the map resolve this issue and the map can be correctly restored? 2) If my key is a String and the String class is already overriding the hashCode() method, would I still have problem described above. (I am seeing a bug which makes me think this is probably still a problem even though the key is String with overriding hashCode.) 3)Previously, I get around this issue by serializing an array of entries (key, value) and when deserializing I would reconstruct the map. I am wondering if there is a better approach. 4) If the answers to question 1 and 2 are that I still can't be guaranteed. Could someone explain why? If the hashCodes are the same would they go to the same buckets across JVMs? Thanks, Grace

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  • How to parse XML with special characters?

    - by Snooze
    Whenever I try to parse XML with special characters such as o or ???? I get an error. The xml documents claims to use UTF-8 encoding but that does not seem to be the case. Here is what the troublesome text looks like when I view the XML in Firefox: Bleach: The Diamond Dust Rebellion - MÅ? Hitotsu no HyÅ?rinmaru; Bleach - The DiamondDust Rebellion - Mou Hitotsu no Hyourinmaru On the actual website, Å? is actually the character o. <br /> One day, Doraemon and his friends meet Professor Mangetsu (æº?æ??å??ç??, Professor Mangetsu?), who studies magic and magical beings such as goblins, and his daughter Miyoko (ç¾?å¤?å­?, Miyoko?), and are warned of the dangerous approximation of the &quot;star of the Underworld&quot; to the Earth&#039;s orbit.<br /> <br /> And once again, on the actual website, those characters appear as ???? and ???. The actual XML file is formatted properly other than those special characters, which certainly do not appear to be using the UTF-8 encoding. Is there a way to get NSXML to parse these XML files?

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  • Swapping content in a seperate div on hover

    - by Fuego DeBassi
    I feel like this should work: $(".module .one").hover(function() { $("#viewport #one").addClass('red'); }); Basically I am hiding all the .children of "#viewport on load, then when a seperate element is hovered, in this case .module .one I want to change something on the corresponding viewport ID #viewport #one. Basic idea is a variable content window, where when a thumbnail or whatever I put in the modules swaps the content shown in the viewport. Something I am doing wrong? Here is my full code: <script type="text/javascript"> $(document).ready(function() { $(".module .caption").hide(); $("#viewport").children().hide(); $(".module").hover(function() { $(this).find(".caption").slideDown().end().siblings('.module').addClass('under'); },function() { $(this).find(".caption").slideUp().end().siblings('.module').removeClass('under'); }); $(".module .one").hover(function() { $("#viewport #one").addClass('red'); }); }); </script> The bigger hover function in the middle is for some fancy rollover effects that the modules will perform themselves, but for these purposes I just want to figure out why I can't add a Class to a separate element when another is hovered. Would love some help/advice!

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  • Using Tcl DSL in Python

    - by Sridhar Ratnakumar
    I have a bunch of Python functions. Let's call them foo, bar and baz. They accept variable number of string arguments and does other sophisticated things (like accessing the network). I want the "user" (let's assume he is only familiar with Tcl) to write scripts in Tcl using those functions. Here's an example (taken from Macports) that user can come up with: post-configure { if {[variant_isset universal]} { set conflags "" foreach arch ${configure.universal_archs} { if {${arch} == "i386"} {append conflags "x86 "} else { if {${arch} == "ppc64"} {append conflags "ppc_64 "} else { append conflags ${arch} " " } } } set profiles [exec find ${worksrcpath} -name "*.pro"] foreach profile ${profiles} { reinplace -E "s|^(CONFIG\[ \\t].*)|\\1 ${conflags}|" ${profile} # Cures an isolated case system "cd ${worksrcpath}/designer && \ ${qt_dir}/bin/qmake -spec ${qt_dir}/mkspecs/macx-g++ -macx \ -o Makefile python.pro" } } } Here, variant_issset, reinplace are so on (other than Tcl builtins) are implemented as Python functions. if, foreach, set, etc.. are normal Tcl constructs. post-configure is a Python function that accepts, well, a Tcl code block that can later be executed (which in turns would obviously end up calling the above mentioned Python "functions"). Is this possible to do in Python? If so, how? from Tkinter import *; root= Tk(); root.tk.eval('puts [array get tcl_platform]') is the only integration I know of, which is obviously very limited (not to mention the fact that it starts up X11 server on mac).

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  • Overlapping 2 Flash objects and controlling z-index

    - by Magnus Smith
    I have two Flash objects on a webpage (call them A and B), and they overlap so one partially obscures the other. I don't seem to have any control over the z-index, to force B in front of A. Whatever I try, A always 'wins' and stays on the top! I have read many people's posts about problem with getting HTML to show over the top of Flash...but nothing about when your two overlapping items are both Flash objects. I have tried various combinations of wmode=opaque/transparent/window I have tried CSS position:absolute/relative and z-index:0/999 I have tried placing the HTML sections in a different order The problem is the same in IE6 and Firefox 2.0 I do not want to use jQuery in this case In my particular situation B must have position:absolute and wmode=transparent, and sit above A. A needs relative positioning and transparency is not required. However, I have been testing without these restrictions, and I still have no control over the overlap. Are some SWFs (ours are adverts sent by clients) created in such a way as to override any code control of z-index? Thanks for any advice you can give.

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  • Ruby on Rails Associations

    - by Eef
    Hey all, I am starting to create my sites in Ruby on Rails these days instead of PHP. I have picked up the language easily but still not 100% confident with associations :) I have this situation: User Model has_and_belongs_to_many :roles Roles Model has_and_belongs_to_many :users Journal Model has_and_belongs_to_many :roles So I have a roles_users table and a journals_roles table I can access the user roles like so: user = User.find(1) User.roles This gives me the roles assigned to the user, I can then access the journal model like so: journals = user.roles.first.journals This gets me the journals associated with the user based on the roles. I want to be able to access the journals like so user.journals In my user model I have tried this: def journals self.roles.collect { |role| role.journals }.flatten end This gets me the journals in a flatten array but unfortunately I am unable to access anything associated with journals in this case, e.g in the journals model it has: has_many :items When I try to access user.journals.items it does not work as it is a flatten array which I am trying to access the has_many association. Is it possible to get the user.journals another way other than the way I have shown above with the collect method? Hope you guys understand what I mean, if not let me know and ill try to explain it better. Cheers Eef

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  • .NET Regex - Replace multiple characters at once without overwriting?

    - by Everaldo Aguiar
    I'm implementing a c# program that should automatize a Mono-alphabetic substitution cipher. The functionality i'm working on at the moment is the simplest one: The user will provide a plain text and a cipher alphabet, for example: Plain text(input): THIS IS A TEST Cipher alphabet: A - Y, H - Z, I - K, S - L, E - J, T - Q Cipher Text(output): QZKL KL QJLQ I thought of using regular expressions since I've been programming in perl for a while, but I'm encountering some problems on c#. First I would like to know if someone would have a suggestion for a regular expression that would replace all occurrence of each letter by its corresponding cipher letter (provided by user) at once and without overwriting anything. Example: In this case, user provides plaintext "TEST", and on his cipher alphabet, he wishes to have all his T's replaced with E's, E's replaced with Y and S replaced with J. My first thought was to substitute each occurrence of a letter with an individual character and then replace that character by the cipherletter corresponding to the plaintext letter provided. Using the same example word "TEST", the steps taken by the program to provide an answer would be: 1 - replace T's with (lets say) @ 2 - replace E's with # 3 - replace S's with & 4 - Replace @ with E, # with Y, & with j 5 - Output = EYJE This solution doesn't seem to work for large texts. I would like to know if anyone can think of a single regular expression that would allow me to replace each letter in a given text by its corresponding letter in a 26-letter cipher alphabet without the need of splitting the task in an intermediate step as I mentioned. If it helps visualize the process, this is a print screen of my GUI for the program:

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  • How can I get this week's dates in Perl?

    - by ABach
    I have the following loop to calculate the dates of the current week and print them out. It works, but I am swimming in the amount of date/time possibilities in Perl and want to get your opinion on whether there is a better way. Here's the code I've written: #!/usr/bin/env perl use warnings; use strict; use DateTime; # Calculate numeric value of today and the # target day (Monday = 1, Sunday = 7); the # target, in this case, is Monday, since that's # when I want the week to start my $today_dt = DateTime->now; my $today = $today_dt->day_of_week; my $target = 1; # Create DateTime copies to act as the "bookends" # for the date range my ($start, $end) = ($today_dt->clone(), $today_dt->clone()); if ($today == $target) { # If today is the target, "start" is already set; # we simply need to set the end date $end->add( days => 6 ); } else { # Otherwise, we calculate the Monday preceeding today # and the Sunday following today my $delta = ($target - $today + 7) % 7; $start->add( days => $delta - 7 ); $end->add( days => $delta - 1 ); } # I clone the DateTime object again because, for some reason, # I'm wary of using $start directly... my $cur_date = $start->clone(); while ($cur_date <= $end) { my $date_ymd = $cur_date->ymd; print "$date_ymd\n"; $cur_date->add( days => 1 ); } As mentioned, this works, but is it the quickest or most efficient? I'm guessing that quickness and efficiency may not necessarily go together, but your feedback is very appreciated.

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  • Can I connect to SQL from JavaScript MVC?

    - by user54197
    I am populating a list of names that will be added to my Sql Database. In this simple case, how do I send the information to SQL server without my page being refreshed? <script type="text/javascript"> function addNewRow() { $('#displayPropertyTable tr:last').after('<tr><td style="font-size:smaller;" class="name"></td><td style="font-size:smaller;" class="address"></td></tr>'); var $tr = $('#displayPropertyTable tr:last'); var propertyCondition = $('#txtPropAddress').val(); if (propertyCondition != "") { $tr.find('.name').text($('#txtPropName').val()); $tr.find('.address').text($('#txtPropAddress').val()); } } </script> ... <table id="displayPropertyTable" width= "100%"> <tr> <td style="font-size:smaller;" class="name"></td> <td style="font-size:smaller;" class="address"></td> </tr> </table> ... <table> <tr> <td><b>Name</b></td> <td colspan="2"><input id="txtPropName" type="text" /></td> </tr> <tr> <td><b>Address</b></td> <td colspan="2"><input id="txtPropAddress" type="text" /></td> </tr> </table> ... <button onclick="addNewRow();">Add</button>

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  • How do calculators work with precision?

    - by zoul
    Hello! I wonder how calculators work with precision. For example the value of sin(M_PI) is not exactly zero when computed in double precision: #include <math.h> #include <stdio.h> int main() { double x = sin(M_PI); printf("%.20f\n", x); // 0.00000000000000012246 return 0; } Now I would certainly want to print zero when user enters sin(p). I can easily round somewhere on 1e–15 to make this particular case work, but that’s a hack, not a solution. When I start to round like this and the user enters something like 1e–20, they get a zero back (because of the rounding). The same thing happens when the user enters 1/10 and hits the = key repeatedly — when he reaches the rounding treshold, he gets zero. And yet some calculators return plain zero for sin(p) and at the same time they can work with expressions such as (1e–20)/10 comfortably. Where’s the trick?

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  • Building Stored Procedure to group data into ranges with roughly equal results in each bucket

    - by Len
    I am trying to build one procedure to take a large amount of data and create 5 range buckets to display the data. the buckets ranges will have to be set according to the results. Here is my existing SP GO /****** Object: StoredProcedure [dbo].[sp_GetRangeCounts] Script Date: 03/28/2010 19:50:45 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[sp_GetRangeCounts] @idMenu int AS declare @myMin decimal(19,2), @myMax decimal(19,2), @myDif decimal(19,2), @range1 decimal(19,2), @range2 decimal(19,2), @range3 decimal(19,2), @range4 decimal(19,2), @range5 decimal(19,2), @range6 decimal(19,2) SELECT @myMin=Min(modelpropvalue), @myMax=Max(modelpropvalue) FROM xmodelpropertyvalues where modelPropUnitDescriptionID=@idMenu set @myDif=(@myMax-@myMin)/5 set @range1=@myMin set @range2=@myMin+@myDif set @range3=@range2+@myDif set @range4=@range3+@myDif set @range5=@range4+@myDif set @range6=@range5+@myDif select @myMin,@myMax,@myDif,@range1,@range2,@range3,@range4,@range5,@range6 select t.range as myRange, count(*) as myCount from ( select case when modelpropvalue between @range1 and @range2 then 'range1' when modelpropvalue between @range2 and @range3 then 'range2' when modelpropvalue between @range3 and @range4 then 'range3' when modelpropvalue between @range4 and @range5 then 'range4' when modelpropvalue between @range5 and @range6 then 'range5' end as range from xmodelpropertyvalues where modelpropunitDescriptionID=@idmenu) t group by t.range order by t.range This calculates the min and max value from my table, works out the difference between the two and creates 5 buckets. The problem is that if there are a small amount of very high (or very low) values then the buckets will appear very distorted - as in these results... range1 2806 range2 296 range3 75 range5 1 Basically I want to rebuild the SP so it creates buckets with equal amounts of results in each. I have played around with some of the following approaches without quite nailing it... SELECT modelpropvalue, NTILE(5) OVER (ORDER BY modelpropvalue) FROM xmodelpropertyvalues - this creates a new column with either 1,2,3,4 or 5 in it ROW_NUMBER()OVER (ORDER BY modelpropvalue) between @range1 and @range2 ROW_NUMBER()OVER (ORDER BY modelpropvalue) between @range2 and @range3 or maybe i could allocate every record a row number then divide into ranges from this?

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  • Translation of a RoR view to Java

    - by mnml
    Hi, for some reasons I am trying to translate the following RoR view code to a GSP view: List<Object> objectscontains the data I want to display in 3 columns <% modulo_objects = @objects.length % 3 base = @objects.length / 3 base = base.ceil case modulo_objects when 0 cols = [base, base, base] when 1 cols = [base, base + 1, base] when 2 cols = [base + 1, base, base + 1] end counter = 0 %> <% 3.times do |i| %> <td width="220" align="center" style="padding-right: 15px;"> <% cols[i].times do %> <h1><a href="/objects/show/<%= @objects[counter].urlname %>" ><%= @objects[counter].name %></a></h1> <% counter = counter + 1 %> <% end %> </td> <% end %> This is what I got so far: #{extends 'main.html' /} %{ modulo_objects = objects.size() % 3 base = objects.size() / 3 base = Math.ceil(base) if(modulo_objects == 0) cols = [base, base, base] else if(modulo_objects == 1) cols = [base, base + 1, base] else if(modulo_objects == 2) cols = [base + 1, base, base + 1] endif counter = 0 }% #{list items:1..3, as:'i'} <td width="220" align="center" style="padding-right: 15px;"> #{list items:cols[i]} <a href="@{Objects.show(objects.get(counter).name.replaceAll(" ", "-"))}" >${objects.get(counter).name}</a> %{ counter = counter + 1 }% #{/list} </td> #{/list} The idea is to keep the items organised in 3 columns like 1|0|1 4|5|4 or 5|4|5 for example, I don't really understand if #{list items:cols[i]} will reproduce ruby's cols[i].times do. So far the Java view is does not display more than two elements.

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  • How to "reduce" a hash?

    - by Julien Lebosquain
    Suppose I have any "long" hash, like a 16 bytes MD5 or a 20 bytes SHA1. I want to reduce this hash to fit on 4 bytes, for GetHashCode() purposes. First, I'm perfectly aware that I'll get more collisions. That's totally fine in my case, but I'd still prefer to get the less possible collisions. There are several solutions to my problem: I could take the 4 first bytes of the hash. I could take the 4 last bytes of the hash. I could take 4 random bytes of the hash. I could generate a hash of the hash, involving classic prime numbers multiplications. Are there other solutons I didn't think about? And more importantly, what method will give me the most unique hash code? I'm currently supposing they're almost equivalent. Microsoft choose that the public key token of an assembly is the last 8 bytes of the SHA1 hash of its public key, so I'll probably go for this solution but I'd like to know why.

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  • F# and statically checked union cases

    - by Johan Jonasson
    Soon me and my brother-in-arms Joel will release version 0.9 of Wing Beats. It's an internal DSL written in F#. With it you can generate XHTML. One of the sources of inspiration have been the XHTML.M module of the Ocsigen framework. I'm not used to the OCaml syntax, but I do understand XHTML.M somehow statically check if attributes and children of an element are of valid types. We have not been able to statically check the same thing in F#, and now I wonder if someone have any idea of how to do it? My first naive approach was to represent each element type in XHTML as a union case. But unfortunately you cannot statically restrict which cases are valid as parameter values, as in XHTML.M. Then I tried to use interfaces (each element type implements an interface for each valid parent) and type constraints, but I didn't manage to make it work without the use of explicit casting in a way that made the solution cumbersome to use. And it didn't feel like an elegant solution anyway. Today I've been looking at Code Contracts, but it seems to be incompatible with F# Interactive. When I hit alt + enter it freezes. Just to make my question clearer. Here is a super simple artificial example of the same problem: type Letter = | Vowel of string | Consonant of string let writeVowel = function | Vowel str -> sprintf "%s is a vowel" str I want writeVowel to only accept Vowels statically, and not as above, check it at runtime. How can we accomplish this? Does anyone have any idea? There must be a clever way of doing it. If not with union cases, maybe with interfaces? I've struggled with this, but am trapped in the box and can't think outside of it.

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  • using an alternative string quotation syntax in python

    - by Cawas
    Just wondering... I find using escape characters too distracting. I'd rather do something like this: print ^'Let's begin and end with sets of unlikely 2 chars and bingo!'^ Let's begin and end with sets of unlikely 2 chars and bingo! Note the ' inside the string, and how this syntax would have no issue with it, or whatever else inside for basically all cases. Too bad markdown can't properly colorize it (yet), so I decided to <pre> it. Sure, the ^ could be any other char, I'm not sure what would look/work better. That sounds good enough to me, tho. Probably some other language already have a similar solution. And, just maybe, Python already have such a feature and I overlooked it. I hope this is the case. But if it isn't, would it be too hard to, somehow, change Python's interpreter and be able to select an arbitrary (or even standardized) syntax for notating the strings? I realize there are many ways to change statements and the whole syntax in general by using pre-compilators, but this is far more specific. And going any of those routes is what I call "too hard". I'm not really needing to do this so, again, I'm just wondering.

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  • How do I integrate GUI elements from different classes at runtime?

    - by thefourthdoctor
    I'm trying to "future-proof" an application that I'm writing by splitting out those elements that are likely to change over time. In my application I need to be able to adapt to changes in the output format (e.g. today I output to a CSV file, in the future I may need to output directly to a SQL Server database, or to a web service, etc.). I'm handling this by defining an abstract class ("OutputProvider") that I will subclass for each individual case. The one aspect of this that has me stumped is how to provide a configuration GUI that is specific to each concrete class. I have a settings dialog with a tab for output configuration. On that tab I intend to provide a drop-down to select the provider and a JPanel beneath it to hold the contents of the provider-specific GUI. How do I get the right GUI in that panel at runtime and have it behave correctly with respect to events? Also, a bonus would be if there was a way to do this such that in order to add support for new providers I could simply provide a new jar or class file to be dropped in a specific folder and the application could pick that up at startup. I'm using NetBeans and Swing.

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  • Initializing PHP class property declarations with simple expressions yields syntax error

    - by user171929
    According to the PHP docs, one can initialize properties in classes with the following restriction: "This declaration may include an initialization, but this initialization must be a constant value--that is, it must be able to be evaluated at compile time and must not depend on run-time information in order to be evaluated." I'm trying to initialize an array and having some issues. While this works fine: public $var = array( 1 => 4, 2 => 5, ); This creates a syntax error: public $var = array( 1 => 4, 2 => (4+1), ); Even this isn't accepted: public $var = 4+1; which suggests it's not a limitation of the array() language construct. Now, the last time I checked, "4+1" equated to a constant value that not only should be accepted, but should in fact be optimized away. In any case, it's certainly able to be evaluated at compile-time. So what's going on here? Is the limitation really along the lines of "cannot be any calculated expression at all", versus any expression "able to be evaluated at compile time"? The use of "evaluated" in the doc's language suggests that simple calculations are permitted, but alas.... If this is a bug in PHP, does anyone have a bug ID? I tried to find one but didn't have any luck.

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