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  • Approach for packing 2D shapes while minimizing total enclosing area

    - by Dennis
    Not sure on my tags for this question, but in short .... I need to solve a problem of packing industrial parts into crates while minimizing total containing area. These parts are motors, or pumps, or custom-made components, and they have quite unusual shapes. For some, it may be possible to assume that a part === rectangular cuboid, but some are not so simple, i.e. they assume a shape more of that of a hammer or letter T. With those, (assuming 2D shape), by alternating direction of top & bottom, one can pack more objects into the same space, than if all tops were in the same direction. Crude example below with letter "T"-shaped parts: ***** xxxxx ***** x ***** *** ooo * x vs * x vs * x vs * x o * x * xxxxx * x * x o xxxxx xxx Right now we are solving the problem by something like this: using CAD software, make actual models of how things fit in crate boxes make estimates of actual crate dimensions & write them into Excel file (1) is crazy amount of work and as the result we have just a limited amount of possible entries in (2), the Excel file. The good things is that programming this is relatively easy. Given a combination of products to go into crates, we do a lookup, and if entry exists in the Excel (or Database), we bring it out. If it doesn't, we say "sorry, no data!". I don't necessarily want to go full force on making up some crazy algorithm that given geometrical part description can align, rotate, and figure out best part packing into a crate, given its shape, but maybe I do.. Question Well, here is my question: assuming that I can represent my parts as 2D (to be determined how), and that some parts look like letter T, and some parts look like rectangles, which algorithm can I use to give me a good estimate on the dimensions of the encompassing area, while ensuring that the parts are packed in a minimal possible area, to minimize crating/shipping costs? Are there approximation algorithms? Seeing how this can get complex, is there an existing library I could use? My thought / Approach My naive approach would be to define a way to describe position of parts, and place the first part, compute total enclosing area & dimensions. Then place 2nd part in 0 degree orientation, repeat, place it at 180 degree orientation, repeat (for my case I don't think 90 degree rotations will be meaningful due to long lengths of parts). Proceed using brute force "tacking on" other parts to the enclosing area until all parts are processed. I may have to shift some parts a tad (see 3rd pictorial example above with letters T). This adds a layer of 2D complexity rather than 1D. I am not sure how to approach this. One idea I have is genetic algorithms, but I think those will take up too much processing power and time. I will need to look out for shape collisions, as well as adding extra padding space, since we are talking about real parts with irregularities rather than perfect imaginary blocks. I'm afraid this can get geometrically messy fairly fast, and I'd rather keep things simple, if I can. But what if the best (practical) solution is to pack things into different crate boxes rather than just one? This can get a bit more tricky. There is human element involved as well, i.e. like parts can go into same box and are thus a constraint to be considered. Some parts that are not the same are sometimes grouped together for shipping and can be considered as a common grouped item. Sometimes customers want things shipped their way, which adds human element to constraints. so there will have to be some customization.

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  • For a Javascript library, what is the best or standard way to support extensibility

    - by Michael Best
    Specifically, I want to support "plugins" that modify the behavior of parts of the library. I couldn't find much information on the web about this subject. But here are my ideas for how a library could be extensible. The library exports an object with both public and "protected" functions. A plugin can replace any of those functions, thus modifying the library's behavior. Advantages of this method are that it's simple and that the plugin's functions can have full access to the library's "protected" functions. Disadvantages are that the library may be harder to maintain with a larger set of exposed functions and it could be hard to debug if multiple plugins are involved (how to know which plugin modified which function?). The library provides an "add plugin" function that accepts an object with a specific interface. Internally, the library will use the plugin instead of it's own code if appropriate. With this method, the internals of the library can be rearranged more freely as long as it still supports the same plugin interface. This could also support having different plugin interfaces to modify different parts of the library. A disadvantage of this method is that the plugins may have to re-implement code that is already part of the library since the library's internal functions are not exported. The library provides a "set implementation" function that accepts an object inherited from a specific base object. The library's public API calls functions in the implementation object for any functionality that can be modified and the base implementation object includes the core functionality, with both external (to the API) and internal functions. A plugin creates a new implementation object, which inherits from the base object and replaces any functions it wants to modify. This combines advantages and disadvantages of both the other methods.

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  • Constructor overloading in Java - best practice

    - by errr
    There are a few topics similar to this, but I couldn't find one with a sufficient answer. I would like to know what is the best practice for constructor overloading in Java. I already have my own thoughts on the subject, but I'd like to hear more advice. I'm referring to both constructor overloading in a simple class and constructor overloading while inheriting an already overloaded class (meaning the base class has overloaded constructors). Thanks :)

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  • Best practices concerning view model and model updates with a subset of the fields

    - by Martin
    By picking MVC for developing our new site, I find myself in the midst of "best practices" being developed around me in apparent real time. Two weeks ago, NerdDinner was my guide but with the development of MVC 2, even it seems outdated. It's an thrilling experience and I feel privileged to be in close contact with intelligent programmers daily. Right now I've stumbled upon an issue I can't seem to get a straight answer on - from all the blogs anyway - and I'd like to get some insight from the community. It's about Editing (read: Edit action). The bulk of material out there, tutorials and blogs, deal with creating and view the model. So while this question may not spell out a question, I hope to get some discussion going, contributing to my decision about the path of development I'm to take. My model represents a user with several fields like name, address and email. All the names, in fact, on field each for first name, last name and middle name. The Details view displays all these fields but you can change only one set of fields at a time, for instance, your names. The user expands a form while the other fields are still visible above and below. So the form that is posted back contains a subset of the fields representing the model. While this is appealing to us and our layout concerns, for various reasons, it is to be shunned by serious MVC-developers. I've been reading about some patterns and best practices and it seems that this is not in key with the paradigm of viewmodel == view. Or have I got it wrong? Anyway, NerdDinner dictates using FormCollection och UpdateModel. All the null fields are happily ignored. Since then, the MVC-community has abandoned this approach to such a degree that a bug in MVC 2 was not discovered. UpdateModel does not work without a complete model in your formcollection. The view model pattern receiving most praise seems to be Dedicated view model that contains a custom view model entity and is the only one that my design issue could be made compatible with. It entails a tedious amount of mapping, albeit lightened by the use of AutoMapper and the ideas of Jimmy Bogard, that may or may not be worthwhile. He also proposes a 1:1 relationship between view and view model. In keeping with these design paradigms, I am to create a view and associated view for each of my expanding sets of fields. The view models would each be nearly identical, differing only in the fields which are read-only, the views also containing much repeated markup. This seems absurd to me. In future I may want to be able to display two, more or all sets of fields open simultaneously. I will most attentively read the discussion I hope to spark. Many thanks in advance.

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  • Best way to define an immutable class in Objective C

    - by Patrick Marty
    Hi, I am a newbie in Objective C and I was wondering what is the best way to define an immutable class in Objective-C (like NSString for example). I want to know what are the basic rules one has to follow to make a class immutable. I think that : setters shouldn't be provided if properties are used, they should be readonly accessInstanceVariablesDirectly must be override and return NO Did I forget something ? Thanks

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  • What are MEF best practices?

    - by Sorskoot
    What are some best practices for using MEF in your code? Are there any pitfalls to take into account when starting your extensible application? Did you run into anything you should have known earlier?

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  • LDAP Best Practices

    - by Vik Gamov
    Hi, there. I'm interesting in best practices of using LDAP authentication in java-based web application. In my app I don't want to store username\password, only some id. But, I want retrieve addition information (Name, Last name) if any exists on LDAP catalog.

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  • Best practices for custom http user-agent strings?

    - by Noufal Ibrahim
    I'm developing an application that communicates with an internal web service using HTTP. Are there any "best practices" for custom user-agent strings so that I can put a nice one in my app? It's a Python library and the lower transport is Python's own httplib. Should the user-agent string say that or something else?

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  • Best practices for model driven development using LiveCycle Data Services

    - by Adnan
    What are your advises on using model driven development in developing enterprise applications. Adobe's LiveCycle Data Services looks very promising, I have found numerous tutorials/videos that shows how fast an application can be build by having methods/functions auto-generated. What are the best-practices, is it good/bad to use those auto-generated methods, they can really save a lot of time. All suggestions are welcome, also if you know some existing blog/discussion please let me know.

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  • Cruise Control.Net best practices

    - by Nasser Hajloo
    I'm going to implement a CI process with CC.NET so I'm looking for best practices for CC.net implementation. I use SVN as source control and JIRA as an issue tracker (if it's a useful tip). Any recommandation or article suggestion will be appreciated. Note: I read this article by Martin Fowler.

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  • What are the best practices for avoid xss attacks in a PHP site

    - by rikh
    I have PHP configured so that magic quotes are on and register globals are off. I do my best to always call htmlentities() for anything I am outputing that is derived from user input. I also occasionally seach my database for common things used in xss attached such as... <script What else should I be doing and how can I make sure that the things I am trying to do are always done.

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  • Nested Functions in C - Best Practices

    - by Justin Ethier
    I just realized a function may be defined inside another function in C: void main(){ int foo(){ return 2; }; printf("%d\n", foo()); } Besides being a neat trick, the useful thing about this is that the inner function is private to the outer function. But... is that a good enough reason to do this in a "real-world" application? What are the best practices for using this syntax?

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  • PHP best practices for naming conventions

    - by alex
    I recently started these naming conventions.. all functions & variables = camelCase constants with define() = ALL_CAPS_AND_UNDERSCORES Now I see a lot of other people mix up camelCase and underscores and they seem to have some sort of convention to it... What do you use and what is best? I've heard that public and private functions should have underscores before some.. I assume private have 2 underscores as in __construct() ? Thank you!

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  • Best Practices - log in stored procedures?

    - by hgulyan
    If you have a long running SP, do you log somehow it's actions or just wait for this message? "Command(s) completed successfully." I assume, that there can be plenty solutions on this subject, but is there any best practice - a simple solution that is frequently used?

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  • Best practices for developing simple ASP.NET sites (built in controls or JQuery + scripts)

    - by Nix
    I was recently reviewing some code written by two different contractors, both were basic ASP.NET management sites. The sites allowed the user to view and edit data. Pretty much simple CRUD gateways. One group did their best to use built in ASP + AJAX Toolkit controls and did their best to use as many built in controls as possible. I found the code much easier to read and maintain. The other used jQuery and the code is heavily marked up with script blocks which are then used to build pages from javascript files. Which one is more common? The one that basically leveraged embedded HTML markup in scripts controled by javascript files screams readability and maintenance issues? Is this just the way of doing asp dev with jQuery? Assuming the second example happens a lot, are there tools that help facilitate jQuery development with visual studio? Do you think they generated the html somewhere else and just copied it in? Example Script block: <script id="HRPanel" type="text/html"> <table cellpadding='0' cellspacing='0' class="atable"><thead class="mHeader"><tr><th>Name</th><th>Description</th><th>Other</th></thead><tbody> <# for(var i=0; i < hrRows.length; i++) { var r = HRRows[i]; #> <tr><td><#=r.Name#></td><td><#=r.Description#></td><td class="taRight"><#=r.Other#></td></tr> <#}#> </tbody><tfoot><th></th><th></th><th></th></tfoot></table> </script> Then in a separate location (js file) you would see something like this. $("#HRPanel").html($("#HRPanel").parseTemplate({ HRRows: response.something.bah.bah }));

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  • Codeigniter Best Practices for Model functions

    - by user270797
    Say my application has a "Posts" model, and one of the function is add_post(), it might be something like: function add_post($data) { $this-db-insert('posts',$data); } Where $data is an array: $data = array ('datetime'='2010-10-10 01:11:11', 'title'='test','body'='testing'); Is this best practice? It means if you use that function you need to know the names of the database fields where as my understanding of OOP is that you shouldnt need to know how the method works etc etc

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  • Ajax message best practices

    - by hhj
    Say I need to use ajax to asynchronously ask the server for an xml file containing relevant data. What is the best practice on what this message should look like? Should it be a string like get_data or something similar? Should it be xml? I don't really need long polling since its a one-time (or close to it) request. Thanks.

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  • Best way to ensure accurate timing with C

    - by Paul
    I am a beginning C programmer (though not a beginning programmer) looking to dive into a project to teach myself C. My project is music-based, and because of this I am curious whether there are any 'best practices' per-se, when it comes to timing functions.

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