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  • How do I use a Rails ActiveRecord migration to insert a primary key into a MySQL database?

    - by Terry Lorber
    I need to create an AR migration for a table of image files. The images are being checked into the source tree, and should act like attachment_fu files. That being the case, I'm creating a hierarchy for them under /public/system. Because of the way attachment_fu generates links, I need to use the directory naming convention to insert primary key values. How do I override the auto-increment in MySQL as well as any Rails magic so that I can do something like this: image = Image.create(:id => 42, :filename => "foo.jpg") image.id #=> 42

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  • SQL Server insert performance with and without primary key

    - by Eric
    Summary: I have a table populated via the following: insert into the_table (...) select ... from some_other_table Running the above query with no primary key on the_table is ~15x faster than running it with a primary key, and I don't understand why. The details: I think this is best explained through code examples. I have a table: create table the_table ( a int not null, b smallint not null, c tinyint not null ); If I add a primary key, this insert query is terribly slow: alter table the_table add constraint PK_the_table primary key(a, b); -- Inserting ~880,000 rows insert into the_table (a,b,c) select a,b,c from some_view; Without the primary key, the same insert query is about 15x faster. However, after populating the_table without a primary key, I can add the primary key constraint and that only takes a few seconds. This one really makes no sense to me. More info: The estimated execution plan shows 0% total query time spent on the clustered index insert SQL Server 2008 R2 Developer edition, 10.50.1600 Any ideas?

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  • Making a tab key on the right side of a full sized mac keyboard

    - by StoneBreaker
    I use mac OSX with a full sized keyboard (F1-F19, number pad arrow keys and FN, Home, End, Page UP/Down delete mini pad above the arrow keys). My mouse is on the left side of the keyboard. This allows use of the return key, the arrow keys and the number pad etc. with my right hand. I would like to assign a key or key combination on the right side of the keyboard to operate the same as the tab key. I am thinking a Function key or the Home key, or FN+?? I have QuickKeys and could use that if someone knows how. If there is no way to make a key the equivalent of the tab key, then at the least I would like to make some equivalent to Cmd+Tab that I can use with my right hand. Thanks for any help and ideas.

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  • SSH as root using public key still prompts for password on RHEL 6.1

    - by Dean Schulze
    I've generated rsa keys with cygwin ssh-keygen and copied them to the server with ssh-copy-id -i id_rsa.pub [email protected] I've got the following settings in my /etc/ssh/sshd_config file RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys PermitRootLogin yes When I ssh [email protected] it still prompts for a password. The output below from /usr/sbin/sshd -d says that a matching keys was found in the .ssh/authorized_keys file, but it still requires a password from the client. I've read a bunch of web postings about permissions on files and directories, but nothing works. Is it possible to ssh with keys in RHEL 6.1 or is this forbidden? The debug output from ssh and sshd is below. $ ssh -v [email protected] OpenSSH_6.1p1, OpenSSL 1.0.1c 10 May 2012 debug1: Connecting to my.ip.address [my.ip.address] port 22. debug1: Connection established. debug1: identity file /home/dschulze/.ssh/id_rsa type 1 debug1: identity file /home/dschulze/.ssh/id_rsa-cert type -1 debug1: identity file /home/dschulze/.ssh/id_dsa type 2 debug1: identity file /home/dschulze/.ssh/id_dsa-cert type -1 debug1: identity file /home/dschulze/.ssh/id_ecdsa type -1 debug1: identity file /home/dschulze/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3 debug1: match: OpenSSH_5.3 pat OpenSSH_5* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA 9f:00:e0:1e:a2:cd:05:53:c8:21:d5:69:25:80:39:92 debug1: Host 'my.ip.address' is known and matches the RSA host key. debug1: Found key in /home/dschulze/.ssh/known_hosts:3 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/dschulze/.ssh/id_rsa debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Offering DSA public key: /home/dschulze/.ssh/id_dsa debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Trying private key: /home/dschulze/.ssh/id_ecdsa debug1: Next authentication method: password Here is the server output from /usr/sbin/sshd -d [root@ga2-lab .ssh]# /usr/sbin/sshd -d debug1: sshd version OpenSSH_5.3p1 debug1: read PEM private key done: type RSA debug1: private host key: #0 type 1 RSA debug1: read PEM private key done: type DSA debug1: private host key: #1 type 2 DSA debug1: rexec_argv[0]='/usr/sbin/sshd' debug1: rexec_argv[1]='-d' debug1: Bind to port 22 on 0.0.0.0. Server listening on 0.0.0.0 port 22. debug1: Bind to port 22 on ::. Server listening on :: port 22. debug1: Server will not fork when running in debugging mode. debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8 debug1: inetd sockets after dupping: 3, 3 Connection from 172.60.254.24 port 53401 debug1: Client protocol version 2.0; client software version OpenSSH_6.1 debug1: match: OpenSSH_6.1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.3 debug1: permanently_set_uid: 74/74 debug1: list_hostkey_types: ssh-rsa,ssh-dss debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: client->server aes128-ctr hmac-md5 none debug1: kex: server->client aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST received debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: KEX done debug1: userauth-request for user root service ssh-connection method none debug1: attempt 0 failures 0 debug1: PAM: initializing for "root" debug1: userauth-request for user root service ssh-connection method publickey debug1: attempt 1 failures 0 debug1: test whether pkalg/pkblob are acceptable debug1: PAM: setting PAM_RHOST to "172.60.254.24" debug1: PAM: setting PAM_TTY to "ssh" debug1: temporarily_use_uid: 0/0 (e=0/0) debug1: trying public key file /root/.ssh/authorized_keys debug1: fd 4 clearing O_NONBLOCK debug1: matching key found: file /root/.ssh/authorized_keys, line 1 Found matching RSA key: db:b3:b9:b1:c9:df:6d:e1:03:5b:57:d3:d9:c4:4e:5c debug1: restore_uid: 0/0 Postponed publickey for root from 172.60.254.24 port 53401 ssh2 debug1: userauth-request for user root service ssh-connection method publickey debug1: attempt 2 failures 0 debug1: temporarily_use_uid: 0/0 (e=0/0) debug1: trying public key file /root/.ssh/authorized_keys debug1: fd 4 clearing O_NONBLOCK debug1: matching key found: file /root/.ssh/authorized_keys, line 1 Found matching RSA key: db:b3:b9:b1:c9:df:6d:e1:03:5b:57:d3:d9:c4:4e:5c debug1: restore_uid: 0/0 debug1: ssh_rsa_verify: signature correct debug1: do_pam_account: called Accepted publickey for root from 172.60.254.24 port 53401 ssh2 debug1: monitor_child_preauth: root has been authenticated by privileged process debug1: temporarily_use_uid: 0/0 (e=0/0) debug1: ssh_gssapi_storecreds: Not a GSSAPI mechanism debug1: restore_uid: 0/0 debug1: SELinux support enabled debug1: PAM: establishing credentials PAM: pam_open_session(): Authentication failure debug1: Entering interactive session for SSH2. debug1: server_init_dispatch_20 debug1: server_input_channel_open: ctype session rchan 0 win 1048576 max 16384 debug1: input_session_request debug1: channel 0: new [server-session] debug1: session_new: session 0 debug1: session_open: channel 0 debug1: session_open: session 0: link with channel 0 debug1: server_input_channel_open: confirm session debug1: server_input_global_request: rtype [email protected] want_reply 0 debug1: server_input_channel_req: channel 0 request pty-req reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req pty-req debug1: Allocating pty. debug1: session_pty_req: session 0 alloc /dev/pts/1 ssh_selinux_setup_pty: security_compute_relabel: Invalid argument debug1: server_input_channel_req: channel 0 request shell reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req shell debug1: Setting controlling tty using TIOCSCTTY. debug1: Received SIGCHLD. debug1: session_by_pid: pid 17323 debug1: session_exit_message: session 0 channel 0 pid 17323 debug1: session_exit_message: release channel 0 debug1: session_pty_cleanup: session 0 release /dev/pts/1 debug1: session_by_channel: session 0 channel 0 debug1: session_close_by_channel: channel 0 child 0 debug1: session_close: session 0 pid 0 debug1: channel 0: free: server-session, nchannels 1 Received disconnect from 172.60.254.24: 11: disconnected by user debug1: do_cleanup debug1: PAM: cleanup debug1: PAM: deleting credentials

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  • Is it ok to share private key file between multiple computers/services?

    - by Behrang
    So we all know how to use public key/private keys using SSH, etc. But what's the best way to use/reuse them? Should I keep them in a safe place forever? I mean, I needed a pair of keys for accessing GitHub. I created a pair from scratch and used that for some time to access GitHub. Then I formatted my HDD and lost that pair. Big deal, I created a new pair and configured GitHub to use my new pair. Or is it something that I don't want to lose? I also needed a pair of public key/private keys to access our company systems. Our admin asked me for my public key and I generated a new pair and gave it to him. Is it generally better to create a new pair for access to different systems or is it better to have one pair and reuse it to access different systems? Similarly, is it better to create two different pairs and use one to access our companies systems from home and the other one to access the systems from work, or is it better to just have one pair and use it from both places?

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  • Sagem Router Wifi Key Issue

    - by user23392
    Hi I have a multiservices sagem router which supports wifi as well, the pack came up with a default wifi configuration key and a WEP Key in the label of the package like this: WIFI Configuration key: abcd1234 WEP Key: C4H2F167C10263AEB98V52920E Now, when i execute the wifi usb wizard in the official cd, it asks me for the WIFI key, i put the abcd1234 & it says it's incorrect, i try the long WEP key and it says that the key should only have 8 characters. When i go to the control panel of the router in the wifi config, i see that: Open Authentification System WEP 128 Bit Passphrase: C4H2F167C10263AEB98V52920E Now since the wizard only accepts 8 characters, i try to change the 128bit to 64bit and put some 8 characters and it ends up saying that the new key should be 5 or 13, or 10-26 hex numbers. What to do? Thanks

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  • DATE function does not support all the dates in DAX by design #powerpivot #tabular #dax

    - by Marco Russo (SQLBI)
    The DATE function in DAX has this simple syntax: DATE( <year>, <month>, <day> ) If you are like me, you never read the BOL notes that says in a clear way that it supports dates beginning with March 1, 1900. In fact, I was wrongly assuming that it would have supported any date that can be represented in a Date data type in Data Models, so all the dates beginning with January 1, 1900. The funny thing is that in some of the BOL documentation you will find that Date data type supports dates after March 1, 1900 (which seems not including that date, but this is a detail…). But we should not digress. The real issue is that if you try to call the DATE function passing values between January 1 and February 28, 1900, you will see a different day as a result. evaluate row ( "x", DATE( 1900, 1, 1 ) ) -- return WRONG result -- [x] 12/31/1899 12:00:00 AM   evaluate row ( "x", DATE( 1901, 2, 29 ) ) -- return WRONG result -- [x] 2/28/1900 12:00:00 AM   evaluate row ( "x", DATE( 1900, 3, 1 ) ) -- return CORRECT result -- [x] 3/1/1900 12:00:00 AM As usual, this is not a bug. It is “by design”. The DATE function works in this way in Excel. And also in Excel it was “by design”. In this case the design is having the same bug of Lotus 1-2-3 that handled 1900 a leap year, even though it isn’t. The first release of Lotus 1-2-3 is dated 1983. I hope many of my readers are younger than that. I tried to open a bug in Connect. Please vote it. I would like if Microsoft changed this type of items from “by design” (as we can expect) to “by genetic disease”. Or by “historical respect”, in order to be more politically correct.

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  • Oracle Fusion Applications Design Patterns Now Available

    - by Frank Nimphius
    "The Oracle Fusion Applications user experience design patterns are published! These new, reusable usability solutions and best-practices, which will join Oracle dashboard patterns and guidelines that are already available online, are used by Oracle to artfully bring to life a new standard in the user experience, or UX, of enterprise applications. Now, the Oracle applications development community can benefit from the science behind the Oracle Fusion Applications user experience, too.These Oracle Fusion Applications UX Design Patterns, or blueprints, enable Oracle applications developers and system implementers everywhere to leverage professional usability insight when [...]  designing exciting, new, highly usable applications -- in the cloud or on-premise.  Based on the Oracle Application Development Framework (ADF) components, the Oracle Fusion Applications patterns and guidelines are proven with real users and in the Applications UX usability labs, so you can get right to work coding productivity-enhancing designs that provide an advantage for your entire business.  What’s the best way to get started? We’ve made that easy, too. The Design Filter Tool (DeFT) selects the best pattern for your user type and task. Simply adapt your selection for your own task flow and content, and you’re on your way to a really great applications user experience. More Oracle applications design patterns and training are coming your way in the future. To provide feedback on the sets that are currently available, let us know in the comments section or use the contact form provided."

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  • design in agile process

    - by ying
    Recently I had an interview with dev team in a company. The team uses agile + TDD. The code exercise implements a video rental store which generates statement to calc total rental fee for each type of video (new release, children, etc) for a customer. The existing code use object like: Statement to generate statement and calc fee where big switch statement sits to use enum to determine how to calc rental fee customer holds a list of rentals movie base class and derived class for each type of movie (NEW, CHILDREN, ACTION, etc) The code originally doesn't compile as the owner was assumed to be hit by a bus. So here is what I did: outlined the improvement over object model to have better responsibility for each class. use strategy pattern to replace switch statement and weave them in config But the team says it's waste of time because there is no requirement for it and UAT test suite works and is the only guideline goes into architecture decision. The underlying story is just to get pricing feature out and not saying anything about how to do it. So the discussion is focused on why should time be spent on refactor the switch statement. In my understanding, agile methodology doesn't mean zero design upfront and such code smell should be avoided at the beginning. Also any unit/UAT test suite won't detect such code smell, otherwise sonar, findbugs won't exist. Here I want to ask: is there such a thing called agile design in the agile methodology? Just like agile documentation. how to define agile design upfront? how to know enough is enough? In my understanding, ballpark architecture and data contract among components should be defined before/when starting project, not the details. Am I right? anyone can explain what the team is really looking for in this kind of setup? is it design aspect or agile aspect? how to implement minimum viable product concept in the agile process in the real world project? Is it must that you feel embarrassed to be MVP?

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  • MVC repository pattern design decision

    - by bradjive
    I have an asp .net MVC application and recently started implementing the repository pattern with a service validation layer, much like this. I've been creating one repository/service for each model that I create. Is this overkill? Instead, should I create one repository/service for each logical business area that provides CRUD for many different models? To me, it seems like I'm either cluttering the project tree with many files or cluttering a class with many methods. 6 one way half dozen the other. Can you think of any good arguments either way?

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  • OO design - car rental

    - by gkid123
    AnHow would you implement the following car hierarchy along with the accessor functions and a CarRental class which contains the container to store them? A car rental company wants to keep track of its cars. Each vehicle has a license plate and a brand. Currently the company has SUV and Sedans. SUV have an optional third row seat, sedan’s have an optional sport package. Each car can be queried to inquire the number of passengers it can carry.

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  • Fiscal year handling strategies in database design

    - by Sapphire
    By fiscal year I mean all the data in the database (in all tables) that occurred in the particular year. Lets say that we are building an application that allows user to choose from different years. What way of implementing this would you prefer, and why: Separate fiscal year data based on multiple separate database instances (for example, on every fiscal year start you could create a new instance with no data) Have everything in one database, but with logic that automatically separates records from different years. Personally, I have "seen" both methods, and I would choose the second. The only argument I can think of for the first method is to have less records in case that these are really big databases - but still, you could "archive" old records by joining them in summaries or by some other way. What do you think?

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  • Database design for summarized data

    - by holden
    I have a new table I'm going to add to a bunch of other summarized data, basically to take some of the load off by calculating weekly avgs. My question is whether I would be better off with one model over the other. One model with days of the week as a column with an additional column for price or another model as a series of fields for the DOW each taking a price. I'd like to know which would save me in speed and/or headaches? Or at least the trade off. IE. ID OBJECT_ID MON TUE WED THU FRI SAT SUN SOURCE OR ID OBJECT_ID DAYOFWEEK PRICE SOURCE

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  • XNA Class Design with Structs

    - by Nate Bross
    I'm wondering how you'd recommend designin a class, given the fact that XNA Framework uses Struct all over the place? For example, a spite class, which may require a Vector2 and a Rectangle (both defined as Struct) to be accessed outside of the class. The issue come in when you try to write code like this: class Item { public Vetor2 Position {get; set;} public Item() { Position = new Vector2(5,5); } } Item i = new Item(); i.Positon.X = 20; // fails with error 'Cannot modify the return value of Item because it is not a variable.' // you must write code like this var pos = i.Position; pos.X++; i.Position = pos; The second option compiles and works, but it is just butt ugly. Is there a better way?

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  • Web-design / UI advice

    - by Damian
    I'm working on a website on a Fmylife style. Now the homepage is the page showing the list of the latest posts. But I think there is a problem with that: The most "interesting" page is the one showing the top posts of the last days, but that page has very few visits compared to the main page. I suppose that's only because the main page is the "default" one. So, I've been thinking of making a home page that shows no posts (only one at the top of the page) but 4 big buttons showing the visitors what are the options to browse the content. But I'm also afraid that most users will not click any option and leave the site having seen no posts. So I don't know what to do. Obviously I have no idea of what will be good from a usability/efficiency point of view. Maybe a mix of the two options will be the best, but I don't know how to mix them. Any advice or idea will be greatly appreciated. The current home page looks like this: http://soquestion.latest.secretsapp.appspot.com/latest The new home page would look like this: http://soquestion.latest.secretsapp.appspot.com/

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  • Fluent interface design and code smell

    - by Jiho Han
    public class StepClause { public NamedStepClause Action1() {} public NamedStepClause Action2() {} } public class NamedStepClause : StepClause { public StepClause Step(string name) {} } Basically, I want to be able to do something like this: var workflow = new Workflow().Configure() .Action1() .Step("abc").Action2() .Action2() .Step("def").Action1(); So, some "steps" are named and some are not. The thing I do not like is that the StepClause has knowledge of its derived class NamedStepClause. I tried a couple of things to make this sit better with me. I tried to move things out to interfaces but then the problem just moved from the concrete to the interfaces - INamedStepClause still need to derive from IStepClause and IStepClause needs to return INamedStepClause to be able to call Step(). I could also make Step() part of a completely separate type. Then we do not have this problem and we'd have: var workflow = new Workflow().Configure() .Step().Action1() .Step("abc").Action2() .Step().Action2() .Step("def").Action1(); Which is ok but I'd like to make the step-naming optional if possible. I found this other post on SO here which looks interesting and promising. What are your opinions? I'd think the original solution is completely unacceptable or is it? By the way, those action methods will take predicates and functors and I don't think I want to take an additional parameter for naming the step there. The point of it all is, for me, is to only define these action methods in one place and one place only. So the solutions from the referenced link using generics and extension methods seem to be the best approaches so far.

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  • MVVM Good Design. DataSet or a RowViewModel

    - by LnDCobra
    I have just started learning MVVM and having a dilemna. If I have a a main ViewModel and inside this model I have a number of datasets. Now should I be creating a new ViewModel for each row inside the dataset? Or expose the DataSet itself as a DependencyProperty? For now the dataset has about 20 rows inside it, and the thought of iterating through each row to create a ViewModel binding to each row.... might not be the best option for performance reasons and memory reasons in the future, like when there are 1000+ rows. Should I still go ahead and create a RowViewModel and iterate through the dataset? And have an ObservableCollection of it or just expose the dataset? Any help would be greatly appreciated.

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  • Language Design: Combining Gotos and Functions

    - by sub
    I'm designing and currently rethinking a low-level interpreted programming language with similarities to assembler. I very soon came across the functions/loops/gotos decision problem and thought that while loops like while and for would be too high-level and unfitting, gotos would be too low level, unmaintainable and generally evil again. Functions like you know them from most languages that have return values and arguments aren't fitting in the language's concept either. So I tried to figure out something between a function and a goto which is capable of Recursion Efficient loops After some thinking I came up with the idea of subroutines: They have a beginning and an end like a function They have a name but no arguments like a goto You can go into one with jump and go out of it again before its end with return (doesn't give back any result, only stops the subroutine) Handled just like normal code - Global scope like goto So I wanted to know: Is the idea above good? What are the (dis)advantages? Would there be a better combination of function and goto or even a completely new idea?

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  • Python class design - Splitting up big classes into multiple ones to group functionality

    - by Ivo Wetzel
    OK I've got 2 really big classes 1k lines each that I currently have split up into multiple ones. They then get recombined using multiple inheritance. Now I'm wondering, if there is any cleaner/better more pythonic way of doing this. Completely factoring them out would result in endless amounts of self.otherself.do_something calls, which I don't think is the way it should be done. To make things clear here's what it currently looks like: from gui_events import GUIEvents # event handlers from gui_helpers import GUIHelpers # helper methods that don't directly modify the GUI # GUI.py class GUI(gtk.Window, GUIEvents, GUIHelpers): # general stuff here stuff here One problem that is result of this is Pylint complaining giving me trillions of "init not called" / "undefined attribute" / "attribute accessed before definition" warnings.

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  • Another design-related C++ question

    - by Kotti
    Hi! I am trying to find some optimal solutions in C++ coding patterns, and this is one of my game engine - related questions. Take a look at the game object declaration (I removed almost everything, that has no connection with the question). // Abstract representation of a game object class Object : public Entity, IRenderable, ISerializable { // Object parameters // Other not really important stuff public: // @note Rendering template will never change while // the object 'lives' Object(RenderTemplate& render_template, /* params */) : /*...*/ { } private: // Object rendering template RenderTemplate render_template; public: /** * Default object render method * Draws rendering template data at (X, Y) with (Width, Height) dimensions * * @note If no appropriate rendering method overload is specified * for any derived class, this method is called * * @param Backend & b * @return void * @see */ virtual void Render(Backend& backend) const { // Render sprite from object's // rendering template structure backend.RenderFromTemplate( render_template, x, y, width, height ); } }; Here is also the IRenderable interface declaration: // Objects that can be rendered interface IRenderable { /** * Abstract method to render current object * * @param Backend & b * @return void * @see */ virtual void Render(Backend& b) const = 0; } and a sample of a real object that is derived from Object (with severe simplifications :) // Ball object class Ball : public Object { // Ball params public: virtual void Render(Backend& b) const { b.RenderEllipse(/*params*/); } }; What I wanted to get is the ability to have some sort of standard function, that would draw sprite for an object (this is Object::Render) if there is no appropriate overload. So, one can have objects without Render(...) method, and if you try to render them, this default sprite-rendering stuff is invoked. And, one can have specialized objects, that define their own way of being rendered. I think, this way of doing things is quite good, but what I can't figure out - is there any way to split the objects' "normal" methods (like Resize(...) or Rotate(...)) implementation from their rendering implementation? Because if everything is done the way described earlier, a common .cpp file, that implements any type of object would generally mix the Resize(...), etc methods implementation and this virtual Render(...) method and this seems to be a mess. I actually want to have rendering procedures for the objects in one place and their "logic implementation" - in another. Is there a way this can be done (maybe alternative pattern or trick or hint) or this is where all this polymorphic and virtual stuff sucks in terms of code placement?

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  • Query Object Pattern (Design Pattern)

    - by The Elite Gentleman
    Hi Guys, I need to implement a Query Object Pattern in Java for my customizable search interface (of a webapp I'm writing). Does anybody know where I can get an example/tutorial of Query Object Pattern (Martin Fowler's QoP)? Thanks in Advance ADDITION How to add a Query Pattern to an existing DAO pattern?

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  • Design by contract: predict methods needed, discipline yourself and deal with code that comes to min

    - by fireeyedboy
    I like the idea of designing by contract a lot (at least, as far as I understand the principal). I believe it means you define intefaces first before you start implementing actual code, right? However, from my limited experience (3 OOP years now) I usually can't resist the urge to start coding pretty early, for several reasons: because my limited experience has shown me I am unable to predict what methods I will be needing in the interface, so I might as well start coding right away. or because I am simply too impatient to write out the whole interfaces first. or when I do try it, I still wind up implementing bits of code already, because I fear I might forget this or that imporant bit of code, that springs to mind when I am designing the interfaces. As you see, especially with the last two points, this leads to a very disorderly way of doing thing. Tasks get mixed up. I should draw a clear line between designing interfaces and actual coding. If you, unlike me, are a good/disciplined planner, as intended above, how do you: ...know the majority of methods you will be needing up front so well? Especially if it's components that implement stuff you are not familiar with yet. ...keep yourself from resisting the urge to start coding right away? ...deal with code that comes to mind when you are designing the intefaces?

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  • Android: ListActivity design - changing the content of the List Adapter

    - by Rob
    Hi, I would like to write a rather simple content application which displays a list of textual items (along with a small pic). I have a standard menu in which each menu item represents a different category of textual items (news, sports, leisure etc.). Pressing a menu item will display a list of textual items of this category. Now, having a separate ListActivity for each category seems like an overkill (or does it?..) Naturally, it makes much more sense to use one ListActivity and replace the data of its adapter when each category is loaded. My concern is when "back" is pressed. The adapter is loaded with items of the current category and now I need to display list of the previous category (and enable clicking on list items too...). Since I have only one activity - I thought of backup and load mechanism in onPause() and onResume() functions as well as making some distinction whether these function are invoked as a result of a "new" event (menu item selected) or by a "back" press. This seems very cumbersome for such a trivial usage... Am I missing something here? Thanks, Rob

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