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  • Javascript syntax for abbreviating repeated access to same identifier

    - by yongjieli
    Hi all I wanted to ask if there is a formal way of describing the following code, whereby we can access the same object repeatedly without re-typing the object's identifier: myObj.render(1).render(2).print(); I didn't know how to describe it when trying to form a question; I wanted to know whether or not something like this is possible in javascript, I know that I can do it in VB: myObj.render(1) if(foo == 'bar') .render(2) .print(); Thanks!

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  • Why cant i use the field user in SQL Server 8?

    - by acidzombie24
    Maybe not literally but the query below gets an error near user. If i change it to userZ it works. WHY can i not use that name? Is there a way to specific its a field instead of a keyword? (or whatever it is) create table Post2 ( id INTEGER PRIMARY KEY NOT NULL, title nvarchar(max) NOT NULL, body nvarchar(max) NOT NULL, user integer REFERENCES Post1(id));

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  • What does @@variable mean in Ruby?

    - by Andrew
    What are Ruby variables preceded with double at signs (@@)? My understanding of a variable preceded with an at sign is that it is an instance variable, like this in PHP: PHP version class Person { public $name; public function setName($name) { $this->name = $name; } public function getName() { return $this->name; } } Ruby equivalent class Person def set_name(name) @name = name end def get_name() @name end end What does the double at sign @@ mean, and how does it differ from a single at sign?

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  • jQuery extend $.fn and calling method syntax

    - by MBax
    I understand that you call a method like this when you are extending $.fn. ( $ == jQuery ) //$("div").myMethod(); $.fn.extend({ myMethod: function(){...} }); And like this when you extend the jQuery Object: //$.myMethod2(); $.extend({ myMethod2: function(){...} }); But I don't quite understand what the $() is doing here: $().functionName({ something: 'something' }).myMethod(); Does it have to do with the fact the method is being called including the function name? Thanks in advance and hope this makes sense.

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  • Regular Expressions Quick Reference

    - by Jan Goyvaerts
    The Regular-Expressions.info website has a new quick reference to regular expressions that lists all of the regex syntax in one single table along with a link to the tutorial section that explains the syntax. The quick reference is ordered by syntax whereas the full reference tables are ordered by feature. There are multiple entries for some of the syntax as different regex flavors may use the same syntax for different features. Use the quick reference if you’ve seen some syntax in somebody else’s regex and you have no idea what feature that syntax is for. Use the full reference tables if you already know the feature you want but forgot which syntax to use. Of course, an even quicker reference is to paste your regex into RegexBuddy, select the application you’re working with, and click on the part of the regex you don’t understand. RegexBuddy then selects the corresponding node in its regex tree which summarizes exactly what the syntax you clicked on does in your regex. If you need more information, press F1 or click the Explain Token button to open the relevant page in the regex tutorial in RegexBuddy’s help file.

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  • Newbie database index question

    - by RenderIn
    I have a table with multiple indexes, several of which duplicate the same columns: Index 1 columns: X, B, C, D Index 2 columns: Y, B, C, D Index 3 columns: Z, B, C, D I'm not very knowledgeable on indexing in practice, so I'm wondering if somebody can explain why X, Y and Z were paired with these same columns. B is an effective date. C is a semi-unique key ID for this table for a specific effective date B. D is a sequence that identifies the priority of this record for the identifier C. Why not just create 6 indexes, one for each X, Y, Z, B, C, D? I want to add an index to another column T, but in some contexts I'll only be querying on T alone while in others I will also be specifying the B, C and D columns... so should I create just one index like above or should I create one for T and one for (T, B, C, D)? I've not had as much luck as expected when googling for comprehensive coverage of indexing. Any resources where I can get a through explanation and lots of examples of B-tree indexing?

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  • Out of Core Implementation of a Quadtree

    - by Nima
    Hi, I am trying to build a Quadtree data structure(or let's just say a tree) on the secondary memory(Hard Disk). I have a C++ program to do so and I use fopen to create the files. Also, I am using tesseral coding to store each cell in a file named with its corresponding code to store it on the disk in one directory. The problem is that after creating about 1,100 files, fopen just returns NULL and stops creating new files. I can create further files manually in that directory, but using C++ it can not create any further files. I know about max limit of inode on ext3 filesystem which is (from Wikipedia) 32,000 but mine is way less than that, also note that I can create files manually on the disk; just not through fopen. Also, I really appreciate any idea regarding the best way to store a very dynamic quadtree on disk(I need the nodes to be in separate files and the quadtree might have a depth of 50). Using nested directories is one idea, but I think it will slow down the performance because of following the links on the filesystem to access the file. Thanks, Nima

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  • Installing sfJqueryTreeDoctrineManagerPlugin to Symfony 1.4

    - by Christine Q.
    I have faced serious difficulties while installing sfJqueryTreeDoctrineManagerPlugin to Symfony 1.4 w/ Doctrine ORM. The installation directly from the server did not work out like with previous plugins that I have installed: C:\pathsymfony plugin:install sfJqueryTreeDoctrineManagerPlugin plugin installing plugin "sfJqueryTreeDoctrineManagerPlugin" No release available for plugin "sfJqueryTreeDoctrineManagerPlugin" This is why I needed to install the plugin by downloading the tgz-archive and install it manually like this: C:\pathsymfony plugin:install "C:\path\to\downloads\sfJqueryTreeDoctrineManagerPlugin-1.2.4.tgz" plugin installing plugin "C:\path\to\downloads\sfJqueryTreeDoctrineManagerPlugin-1.2.4.tgz" sfSymfonyPluginManager Installing web data for plugin I guess everything should be fine this far? After that I edited \apps\admin\config\settings.yml like instructed in the plugins readme file. all: .settings: enabled_modules: [default, sfJqueryTreeDoctrineManager] I also checked that the plugin was enabled in \config\ProjectConfiguration.class.php like this: $this->enablePlugins(array( // other plugins, 'sfJqueryTreeDoctrineManagerPlugin' )); I published assets and cleared cache: C:\pathsymfony plugin:publish-assets >> plugin Configuring plugin - sfJqueryTreeDoctrineManagerPlugin C:\pathsymfony cc Finally I added the required helper to the newly created apps\admin\modules\category\templates\indexSuccess.php <?php use_helper("sfJqueryTreeDoctrine"); echo get_nested_set_manager("Category", "name"); When loading the page I unfortunately get the following error: 500 | Internal Server Error | InvalidArgumentException Unable to load "sfJqueryTreeDoctrineHelper.php" helper in: SF_ROOT_DIR\apps\admin\modules/businessunitgroup/lib/helper, SF_ROOT_DIR\apps\admin\lib/helper, SF_ROOT_DIR\lib/helper, SF_SYMFONY_LIB_DIR/helper. The file sfJqueryTreeDoctrineHelper.php exists indeed but not in any previously mentioned folder. The file can only be found in the folder \plugins\sfJqueryTreeDoctrineManagerPlugin\lib\helper. I guess that Symfony doesn't look to that folder while finding helpers? I have tried to move the helper file to one of the previously mentioned folders. As expected, that changes the error. Now I get: 500 | Internal Server Error | sfConfigurationException The component does not exist: "sfJqueryTreeDoctrineManager", "manager". Unfortunately I can't figure out how should I be able to retrieve the "missing" component from the correct folder. I would be very grateful for any advice to help me forward. By the way, I am aware that there are other nested-set / tree plugins available for Symfony (like sfDoctrineTreePlugin and caPropelTreePlugin) but unluckily those are either uncompatible or too limited for my needs.

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  • Generic unit test scheduling

    - by Raphink
    Hello, I'm (re)writing a program that does generic unit test scheduling. The current program is a mono-threaded Perl program, but I'm willing to modularize it and parallelize the tests. I'm also considering rewriting it in Python. Here is what I need to do: I have a list of tests, with the following attributes: uri: a URI to test (could be HTTP/HTTPS/SSH/local) ; depends: an associative array of tests/values that this test depends on ; join: a list of DB joints to be added when selecting items to process in this test ; depends_db: additional conditions to add to the DB request when selecting items to process in this test. The program builds a dependency tree, beginning with the tests that have no dependencies ; for each test: a list of items is selected from the database using the conditions (results of depending tests, joints and depends_db) ; the list of items is sent to the URI (using POST or stdin) ; the result is retrived as a YAML file listing the state and comments for the test for each tested item ; the results are stored in the DB ; the test returns, allowing depending tests to be performed. the program generates reports (CSV, DB, graphviz) of the performed tests. The primary use of this program currently is to test a fleet of machines against services such as backup, DNS, etc. The tests can then be: - backup: hosted on the backup machine(s), called through HTTP, checks if the machines' backup went well ; - DNS: hosted on the local machine, called via stdin, checks if the machines' fqdn have a valid DNS entry. Does such a tool/module already exist? What would be the best implementation to achieve this (using Perl or Python)?

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  • Syncing two separate structures to the same master data

    - by Mike Burton
    I've got multiple structures to maintain in my application. All link to the same records, and one of them could be considered the "master" in that it reflects actual relationships held in files on disk. The other structures are used to "call out" elements of the main design for purchase and work orders. I'm struggling to come up with a pattern that deals appropriately with changes to the master data. As an example, the following trees might refer to the same data: A |_ B |_ C |_ D |_ E |_ B |_ C |_ D A |_ B E C |_ D A |_ B C D E These secondary structures follow internal rules, but their overall structure is usually user-determined. In all cases (including the master), any element can be used in multiple locations and in multiple trees. When I add a child to any element in the tree, I want to either automatically build the secondary structure for each instance of the "master" element or at least advertise the situation to the user and allow them to manually generate the data required for the secondary trees. Is there any pattern which might apply to this situation? I've been treating it as a view problem, but it turns out to be more complicated than that when you look at the initial generation of the data.

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  • Checking inherited attributes in an 'ancestry' based SQL table

    - by Brendon Muir
    I'm using the ancestry gem to help organise my app's tree structure in the database. It basically writes a childs ancestor information to a special column called 'ancestry'. The ancestry column for a particular child might look like '1/34/87' where the parent of this child is 87, and then 87's parent is 34 and 34's is 1. It seems possible that we could select rows from this table each with a subquery that checks all the ancestors to see if a certain attribute it set. E.g. in my app you can hide an item and its children just by setting the parent element's visibility column to 0. I want to be able to find all the items where none of their ancestors are hidden. I tried converting the slashes to comma's with the REPLACE command but IN required a set of comma separated integers rather than one string with comma separated string numbers. It's funny, because I can do this query in two steps, e.g. retrieve the row, then take its ancestry column, split out the id's and make another query that checks that the id is IN that set of id's and that visibility isn't ever 0 and whala! But joining these into one query seems to be quite a task. Much searching has shown a few answers but none really do what I want. SELECT * FROM t1 WHERE id = 99; 99's ancestry column reads '1/34/87' SELECT * FROM t1 WHERE visibility = 0 AND id IN (1,34,87); kind of backwards, but if this returns no rows then the item is visible. Has anyone come across this before and come up with a solution. I don't really want to go the stored procedure route. It's for a rails app.

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  • Any software for pattern-matching and -rewriting source code?

    - by Steven A. Lowe
    I have some old software (in a language that's not dead but is dead to me ;-)) that implements a basic pattern-matching and -rewriting system for source code. I am considering resurrecting this code, translating it into a modern language, and open-sourcing the project as a refactoring power-tool. Before I go much further, I want to know if anything like this exists already (my google-fu is fanning air on this tonight). Here's how it works: the pattern-matching part matches source-code patterns spanning multiple lines of code using a template with binding variables, the pattern-rewriting part uses a template to rewrite the matched code, inserting the contents of the bound variables from the matching template matching and rewriting templates are associated (1:1) by a simple (unconditional) rewrite rule the software operates on the abstract syntax tree (AST) of the input application, and outputs a modified AST which can then be regenerated into new source code for example, suppose we find a bunch of while-loops that really should be for-loops. The following template will match the while-loop pattern: Template oldLoopPtrn int @cnt@ = 0; while (@cnt@ < @max@) { … @body@ ++@cnt@; } End_Template while the following template will specify the output rewrite pattern: Template newLoopPtrn for(int @cnt@ = 0; @cnt@ < @max@; @cnt@++) { @body@ } End_Template and a simple rule to associate them Rule oldLoopPtrn --> newLoopPtrn so code that looks like this int i=0; while(i<arrlen) { printf("element %d: %f\n",i,arr[i]); ++i; } gets automatically rewritten to look like this for(int i = 0; i < arrlen; i++) { printf("element %d: %f\n",i,arr[i]); } The closest thing I've seen like this is some of the code-refactoring tools, but they seem to be geared towards interactive rewriting of selected snippets, not wholesale automated changes. I believe that this kind of tool could supercharge refactoring, and would work on multiple languages (even HTML/CSS). I also believe that converting and polishing the code base would be a huge project that I simply cannot do alone in any reasonable amount of time. So, anything like this out there already? If not, any obvious features (besides rewrite-rule conditions) to consider? EDIT: The one feature of this system that I like very much is that the template patterns are fairly obvious and easy to read because they're written in the same language as the target source code, not in some esoteric mutated regex/BNF format.

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