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  • Rails :dependent => :destroy VS :dependent => :delete_all

    - by Sergey
    In rails guides it's described like this: "Objects will be in addition destroyed if they’re associated with :dependent = :destroy, and deleted if they’re associated with :dependent = :delete_all." Right, cool. But what's the difference between being destroyed and being deleted? I tried both and it seems to do the same thing.

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  • HTTPService resultFormat, how to choose

    - by tag
    HTTPService has a property resultFormat which can be set to any of the following: array e4x flashvars object text xml I looked at the documentation to understand the difference, but still couldn't understand when to use each. I'm looking for the lightest weight of all of them. P.S. I'm consuming output from my own server, so can change the output format as needed to make it compatible with each.

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  • MySQL SELECT Statment issue

    - by mouthpiec
    Hi, I have the following query which returns 2 tuples SELECT bar_id, bar_name, town_name, bar_telephone, subscription_type_id, type FROM towns, subscriptiontype, regions, bar LEFT JOIN barpictures bp ON bar.bar_id = bp.bar_id_fk WHERE town_id = town_id_fk AND bar.test_field = 0 AND subscription_type_id = subscription_type_id_fk AND region_id = region_id_fk AND (type like 'logo%' OR type IS NULL) The main difference between the tuples is that one has 'type' = logo and the other tuple has 'type' = logo_large. I need that instead of having two tuples, I need that I have 2 type attributes, one holding the "logo" and the other the "logo_large" eg bar_id, bar_name, town_name, bar_telephone, subscription_type_id, type1, type2 is this possible

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  • mod_wsgi daemon mode vs threaded fastcgi

    - by t0ster
    Can someone explain the difference between apache mod_wsgi in daemon mode and django fastcgi in threaded mode. They both use threads for concurrency I think. Supposing that I'm using nginx as front end to apache mod_wsgi. UPDATE: I'm comparing django built in fastcgi(./manage.py method=threaded maxchildren=15) and mod_wsgi in 'daemon' mode(WSGIDaemonProcess example threads=15). They both use threads and acquire GIL, am I right?

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  • Best way to test for a variable's existence in PHP; isset() is clearly broken

    - by chazomaticus
    From the isset() docs: isset() will return FALSE if testing a variable that has been set to NULL. Basically, isset() doesn't check for whether the variable is set at all, but whether it's set to anything but NULL. Given that, what's the best way to actually check for the existence of a variable? I tried something like: if(isset($v) || @is_null($v)) (the @ is necessary to avoid the warning when $v is not set) but is_null() has a similar problem to isset(): it returns TRUE on unset variables! It also appears that: @($v === NULL) works exactly like @is_null($v), so that's out, too. How are we supposed to reliably check for the existence of a variable in PHP? Edit: there is clearly a difference in PHP between variables that are not set, and variables that are set to NULL: <?php $a = array('b' => NULL); var_dump($a); PHP shows that $a['b'] exists, and has a NULL value. If you add: var_dump(isset($a['b'])); var_dump(isset($a['c'])); you can see the ambiguity I'm talking about with the isset() function. Here's the output of all three of these var_dump()s: array(1) { ["b"]=> NULL } bool(false) bool(false) Further edit: two things. One, a use case. An array being turned into the data of an SQL UPDATE statement, where the array's keys are the table's columns, and the array's values are the values to be applied to each column. Any of the table's columns can hold a NULL value, signified by passing a NULL value in the array. You need a way to differentiate between an array key not existing, and an array's value being set to NULL; that's the difference between not updating the column's value and updating the column's value to NULL. Second, Zoredache's answer, array_key_exists() works correctly, for my above use case and for any global variables: <?php $a = NULL; var_dump(array_key_exists('a', $GLOBALS)); var_dump(array_key_exists('b', $GLOBALS)); outputs: bool(true) bool(false) Since that properly handles just about everywhere I can see there being any ambiguity between variables that don't exist and variables that are set to NULL, I'm calling array_key_exists() the official easiest way in PHP to truly check for the existence of a variable. (Only other case I can think of is for class properties, for which there's property_exists(), which, according to its docs, works similarly to array_key_exists() in that it properly distinguishes between not being set and being set to NULL.)

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  • Indent or comment several text lines with VI

    - by Werner
    Hi, can vim or vim be used to comment or indent at the same time a number of lines? For instance: for item in Lista: ind = int(floor(1.0*(item-lmin)/width)) if ind==nintervals: ind=ind-1 print item,ind comment it to: #for item in Lista: #ind = int(floor(1.0*(item-lmin)/width)) #if ind==nintervals: #ind=ind-1 #print item,ind or indent it to: for item in Lista: ind = int(floor(1.0*(item-lmin)/width)) if ind==nintervals: ind=ind-1 print item,ind Thanks P.D. Is relevant the difference between VI and VIM?

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  • Is there some performance issue between leaving empty ListProperties or using dynamic (expando) prop

    - by indiehacker
    Is there a datastore performance difference between adding dynamic properties of the expando class when they are needed for an entity or the simpler (for me) framework of just setting up all possible properties I might need from the start even though most instances will just be left empty. In my specific case I would be having 5-8 empty ReferenceList properties as 'overhead' that will be empty when I skip using expando class.

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  • C programming doubt!!!

    - by aks
    Hi, I am having a programming doubt? Please have a look at the below mentioned code snippet and tell me the difference? int main() { struct sockaddr_in serv_addr, cli_addr; /* Initialize socket structure */ bzero((char *) &serv_addr, sizeof(serv_addr)); } Now, what if i do something similar without typecasting (char *), then also i feel it will do the same thing? Can someone clarify? /* Initialize socket structure */ bzero( &serv_addr, sizeof(serv_addr));

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  • When should I use temporary variables?

    - by Kyle
    Specifically, I'm wondering which of these I should write: shared_ptr<GuiContextMenu> subMenu = items[j].subMenu.lock(); if (subMenu) subMenu->setVisible(false); or: if (items[j].subMenu.lock() items[j].subMenu.lock()->setVisible(false); I am not required to follow any style guidelines. After optimization, I don't think either choice makes a difference in performance. What is generally the preferred style and why?

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  • == Operator and operands

    - by rahul
    I want to check whether a value is equal to 1. Is there any difference in the following lines of code Evaluated value == 1 1 == evaluated value in terms of the compiler execution

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  • c# object instantiation

    - by user1112111
    What's the difference between: Object o = new Object(); o.foo(); and new Object().foo(); (assuming I do not need the reference afterwards) ? Are there any reasons for using one instead of the other one (e.g. memory usage) ?

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  • viewstack vs. tab navigator

    - by donpal
    I'm new to flex and was looking at some of the components that ship with flex. Can someone tell me the difference between viewstack and tab navigator. They seem to be somewhat similar. When do you use one or the other?

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  • diff between tables

    - by www.yegorov-p.ru
    I have two tables, with the same structure, for example: table "first' with columns 'a','b','c' and table 'second' with the same columns. How to find difference betweet those two tables? Of course, I can make some script on python, that will make set(a)-set(b), but I think there is some way to do it in mysql.

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  • Split comma separated string to count duplicates

    - by josepv
    I have the following data in my database (comma separated strings): "word, test, hello" "test, lorem, word" "test" ... etc How can I transform this data into a Dictionary whereby each string is separated into each distinct word together with the number of times that it occurs, i.e. {"test", 3}, {"word", 2}, {"hello", 1}, {"lorem", 1} I will have approximately 3000 rows of data in case this makes a difference to any solution offered. Also I am using .NET 3.5 (and would be interested to see any solution using linq)

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  • How do I aggregate activerecord model data for a specific time period?

    - by gsiener
    I'm collecting data from a system every ~10s (this time difference varies due to communication time with networked devices). I'd like to calculate averages and sums of the stored values for this activerecord model on a daily basis. All records are stored in UTC. What's the correct way to sum and average values for, e.g., the previous day from midnight to midnight EST? I can do this in sql but don't know the "rails way" to make this calculation.

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  • Git aliases that are stored in origin

    - by jga
    I use git with a big development team and I'd like to have a set of aliases be common across every developer. They change every so often, so I'd like to store them in origin somehow. Is there any way to set that up in git? I'm using gitosis for the git server (not sure if that would make a difference).

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  • Licensing WPF application

    - by Macros
    Does anyone have any guidance on the best way to manage licensing for a WPF application? I would like to have different levels of licensing (Free, Trial and Professional). The app itself will probably be distributed with a WiX installer (if that makes any difference)

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  • How to run Red5 applications on a remote server?

    - by domi
    I've got a really nasty problem... I wrote a Red5 app and so on and it is running perfectly on my local computer. Now the problem occurs = How can I make this program work on a remote server? Local : Mac OS X 10.5 - Red5 0.63 Server: CentOS 5 - Red5 0.90 Maybe it's because of the version difference. But I can't test Red5 0.90 locally because it won't start up and I can't install the 0.63 version on the server because of missing dependencies (and broken links to them...)

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