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• Another sound not working post

  - by Thomas Smart

  Tried all the other "sound not working" posts i think, lost count. purge/reinstall alsa and pulse, reboot, add user to audio group, various lines in the alsa config file such as "options snd-hda-intel model=" then tried different options like generic, auto, basic, default, etc. tried pulseaudio -k && sudo alsa force-reload a few times, with and without rebooting. Hardware: 16gb ram, core I7-4790, Intel Haswell mboard with onboard sound and graphics Multimedia: Audio Adapter: HDA-Intel-HDA Intel HDMI OS: Ubuntu server 14.04 with ubuntu-desktop installed. GUI sound settings lists only the dummy sound card alsamixer -c 0 ¦ Card: HDA Intel HDMI F1: Help ¦ ¦ Chip: Intel Haswell HDMI F2: System information ¦ ¦ View: F3:[Playback] F4: Capture F5: All F6: Select sound card ¦ ¦ Item: S/PDIF ¦ ¦ +--+ ¦ ¦ ¦OO¦ ¦ ¦ +--+ ¦ ¦ < S/PDIF > ¦ aplay -l **** List of PLAYBACK Hardware Devices **** card 0: HDMI [HDA Intel HDMI], device 3: HDMI 0 [HDMI 0] Subdevices: 1/1 Subdevice #0: subdevice #0 aplay -L default Playback/recording through the PulseAudio sound server null Discard all samples (playback) or generate zero samples (capture) pulse PulseAudio Sound Server hdmi:CARD=HDMI,DEV=0 HDA Intel HDMI, HDMI 0 HDMI Audio Output dmix:CARD=HDMI,DEV=3 HDA Intel HDMI, HDMI 0 Direct sample mixing device dsnoop:CARD=HDMI,DEV=3 HDA Intel HDMI, HDMI 0 Direct sample snooping device hw:CARD=HDMI,DEV=3 HDA Intel HDMI, HDMI 0 Direct hardware device without any conversions plughw:CARD=HDMI,DEV=3 HDA Intel HDMI, HDMI 0 Hardware device with all software conversions cat /proc/asound/cards 0 [HDMI ]: HDA-Intel - HDA Intel HDMI HDA Intel HDMI at 0xf7d14000 irq 46 cat /proc/asound/devices 1: : sequencer 2: [ 0- 3]: digital audio playback 3: [ 0- 0]: hardware dependent 4: [ 0] : control 33: : timer mplayer -ao alsa:device=hdmi /usr/share/sounds/ubuntu/stereo/system-ready.ogg MPlayer 1.1-4.8 (C) 2000-2012 MPlayer Team mplayer: could not connect to socket mplayer: No such file or directory Failed to open LIRC support. You will not be able to use your remote control. Playing /usr/share/sounds/ubuntu/stereo/system-ready.ogg. libavformat version 54.20.4 (external) Mismatching header version 54.20.3 libavformat file format detected. [lavf] stream 0: audio (vorbis), -aid 0 Load subtitles in /usr/share/sounds/ubuntu/stereo/ ========================================================================== Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders libavcodec version 54.35.0 (external) AUDIO: 44100 Hz, 1 ch, floatle, 80.0 kbit/5.67% (ratio: 10000->176400) Selected audio codec: [ffvorbis] afm: ffmpeg (FFmpeg Vorbis) ========================================================================== [AO_ALSA] alsa-lib: confmisc.c:768:(parse_card) cannot find card '1' [AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory [AO_ALSA] alsa-lib: confmisc.c:392:(snd_func_concat) error evaluating strings [AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory [AO_ALSA] alsa-lib: confmisc.c:1251:(snd_func_refer) error evaluating name [AO_ALSA] alsa-lib: conf.c:4248:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory [AO_ALSA] alsa-lib: conf.c:4727:(snd_config_expand) Evaluate error: No such file or directory [AO_ALSA] alsa-lib: pcm.c:2239:(snd_pcm_open_noupdate) Unknown PCM hdmi [AO_ALSA] Playback open error: No such file or directory Failed to initialize audio driver 'alsa:device=hdmi' Could not open/initialize audio device -> no sound. Audio: no sound Video: no video Exiting... (End of file) mplayer -ao alsa:device=hw=0.3 /usr/share/sounds/ubuntu/stereo/system-ready.ogg MPlayer 1.1-4.8 (C) 2000-2012 MPlayer Team mplayer: could not connect to socket mplayer: No such file or directory Failed to open LIRC support. You will not be able to use your remote control. Playing /usr/share/sounds/ubuntu/stereo/system-ready.ogg. libavformat version 54.20.4 (external) Mismatching header version 54.20.3 libavformat file format detected. [lavf] stream 0: audio (vorbis), -aid 0 Load subtitles in /usr/share/sounds/ubuntu/stereo/ ========================================================================== Opening audio decoder: [ffmpeg] FFmpeg/libavcodec audio decoders libavcodec version 54.35.0 (external) AUDIO: 44100 Hz, 1 ch, floatle, 80.0 kbit/5.67% (ratio: 10000->176400) Selected audio codec: [ffvorbis] afm: ffmpeg (FFmpeg Vorbis) ========================================================================== [AO_ALSA] Format floatle is not supported by hardware, trying default. AO: [alsa] 44100Hz 2ch s16le (2 bytes per sample) Video: no video Starting playback... A: 0.4 (00.4) of 0.8 (00.7) 0.1% Exiting... (End of file) Thank you for your time and help :)

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• Introducing functional programming constructs in non-functional programming languages

  - by Giorgio

  This question has been going through my mind quite a lot lately and since I haven't found a convincing answer to it I would like to know if other users of this site have thought about it as well. In the recent years, even though OOP is still the most popular programming paradigm, functional programming is getting a lot of attention. I have only used OOP languages for my work (C++ and Java) but I am trying to learn some FP in my free time because I find it very interesting. So, I started learning Haskell three years ago and Scala last summer. I plan to learn some SML and Caml as well, and to brush up my (little) knowledge of Scheme. Well, a lot of plans (too ambitious?) but I hope I will find the time to learn at least the basics of FP during the next few years. What is important for me is how functional programming works and how / whether I can use it for some real projects. I have already developed small tools in Haskell. In spite of my strong interest for FP, I find it difficult to understand why functional programming constructs are being added to languages like C#, Java, C++, and so on. As a developer interested in FP, I find it more natural to use, say, Scala or Haskell, instead of waiting for the next FP feature to be added to my favourite non-FP language. In other words, why would I want to have only some FP in my originally non-FP language instead of looking for a language that has a better support for FP? For example, why should I be interested to have lambdas in Java if I can switch to Scala where I have much more FP concepts and access all the Java libraries anyway? Similarly: why do some FP in C# instead of using F# (to my knowledge, C# and F# can work together)? Java was designed to be OO. Fine. I can do OOP in Java (and I would like to keep using Java in that way). Scala was designed to support OOP + FP. Fine: I can use a mix of OOP and FP in Scala. Haskell was designed for FP: I can do FP in Haskell. If I need to tune the performance of a particular module, I can interface Haskell with some external routines in C. But why would I want to do OOP with just some basic FP in Java? So, my main point is: why are non-functional programming languages being extended with some functional concept? Shouldn't it be more comfortable (interesting, exciting, productive) to program in a language that has been designed from the very beginning to be functional or multi-paradigm? Don't different programming paradigms integrate better in a language that was designed for it than in a language in which one paradigm was only added later? The first explanation I could think of is that, since FP is a new concept (it isn't new at all, but it is new for many developers), it needs to be introduced gradually. However, I remember my switch from imperative to OOP: when I started to program in C++ (coming from Pascal and C) I really had to rethink the way in which I was coding, and to do it pretty fast. It was not gradual. So, this does not seem to be a good explanation to me. Or can it be that many non-FP programmers are not really interested in understanding and using functional programming, but they find it practically convenient to adopt certain FP-idioms in their non-FP language? IMPORTANT NOTE Just in case (because I have seen several language wars on this site): I mentioned the languages I know better, this question is in no way meant to start comparisons between different programming languages to decide which is better / worse. Also, I am not interested in a comparison of OOP versus FP (pros and cons). The point I am interested in is to understand why FP is being introduced one bit at a time into existing languages that were not designed for it even though there exist languages that were / are specifically designed to support FP.

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• Functional programming constructs in non-functional programming languages

  - by Giorgio

  This question has been going through my mind quite a lot lately and since I haven't found a convincing answer to it I would like to know if other users of this site have thought about it as well. In the recent years, even though OOP is still the most popular programming paradigm, functional programming is getting a lot of attention. I have only used OOP languages for my work (C++ and Java) but I am trying to learn some FP in my free time because I find it very interesting. So, I started learning Haskell three years ago and Scala last summer. I plan to learn some SML and Caml as well, and to brush up my (little) knowledge of Scheme. Well, a lot of plans (too ambitious?) but I hope I will find the time to learn at least the basics of FP during the next few years. What is important for me is how functional programming works and how / whether I can use it for some real projects. I have already developed small tools in Haskell. In spite of my strong interest for FP, I find it difficult to understand why functional programming constructs are being added to languages like C#, Java, C++, and so on. As a developer interested in FP, I find it more natural to use, say, Scala or Haskell, instead of waiting for the next FP feature to be added to my favourite non-FP language. In other words, why would I want to have only some FP in my originally non-FP language instead of looking for a language that has a better support for FP? For example, why should I be interested to have lambdas in Java if I can switch to Scala where I have much more FP concepts and access all the Java libraries anyway? Similarly: why do some FP in C# instead of using F# (to my knowledge, C# and F# can work together)? Java was designed to be OO. Fine. I can do OOP in Java (and I would like to keep using Java in that way). Scala was designed to support OOP + FP. Fine: I can use a mix of OOP and FP in Scala. Haskell was designed for FP: I can do FP in Haskell. If I need to tune the performance of a particular module, I can interface Haskell with some external routines in C. But why would I want to do OOP with just some basic FP in Java? So, my main point is: why are non-functional programming languages being extended with some functional concept? Shouldn't it be more comfortable (interesting, exciting, productive) to program in a language that has been designed from the very beginning to be functional or multi-paradigm? Don't different programming paradigms integrate better in a language that was designed for it than in a language in which one paradigm was only added later? The first explanation I could think of is that, since FP is a new concept (it isn't new at all, but it is new for many developers), it needs to be introduced gradually. However, I remember my switch from imperative to OOP: when I started to program in C++ (coming from Pascal and C) I really had to rethink the way in which I was coding, and to do it pretty fast. It was not gradual. So, this does not seem to be a good explanation to me. Also, I asked myself if my impression is just plainly wrong due to lack of knowledge. E.g., do C# and C++11 support FP as extensively as, say, Scala or Caml do? In this case, my question would be simply non-existent. Or can it be that many non-FP programmers are not really interested in using functional programming, but they find it practically convenient to adopt certain FP-idioms in their non-FP language? IMPORTANT NOTE Just in case (because I have seen several language wars on this site): I mentioned the languages I know better, this question is in no way meant to start comparisons between different programming languages to decide which is better / worse. Also, I am not interested in a comparison of OOP versus FP (pros and cons). The point I am interested in is to understand why FP is being introduced one bit at a time into existing languages that were not designed for it even though there exist languages that were / are specifically designed to support FP.

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• Project structure: where to put business logic

  - by Mister Smith

  First of all, I'm not asking where does business logic belong. This has been asked before and most answers I've read agree in that it belongs in the model: Where to put business logic in MVC design? How much business logic should be allowed to exist in the controller layer? How accurate is "Business logic should be in a service, not in a model"? Why put the business logic in the model? What happens when I have multiple types of storage? However people disagree in the way this logic should be distributed across classes. There seem to exist three major currents of thought: Fat model with business logic inside entity classes. Anemic model and business logic in "Service" classes. It depends. I find all of them problematic. The first option is what most Fowlerites stick to. The problem with a fat model is that sometimes a business logic funtion is not only related to a class, and instead uses a bunch of other classes. If, for example, we are developing a web store, there should be a function that calcs an order's total. We could think of putting this function inside the Order class, but what actually happens is that the logic needs to use different classes, not only data contained in the Order class, but also in the User class, the Session class, and maybe the Tax class, Country class, or Giftcard, Payment, etc. Some of these classes could be composed inside the Order class, but some others not. Sorry if the example is not very good, but I hope you understand what I mean. Putting such a function inside the Order class would break the single responsibility principle, adding unnecesary dependences. The business logic would be scattered across entity classes, making it hard to find. The second option is the one I usually follow, but after many projects I'm still in doubt about how to name the class or classes holding the business logic. In my company we usually develop apps with offline capabilities. The user is able to perform entire transactions offline, so all validation and business rules should be implemented in the client, and then there's usually a background thread that syncs with the server. So we usually have the following classes/packages in every project: Data model (DTOs) Data Access Layer (Persistence) Web Services layer (Usually one class per WS, and one method per WS method). Now for the business logic, what is the standard approach? A single class holding all the logic? Multiple classes? (if so, what criteria is used to distribute the logic across them?). And how should we name them? FooManager? FooService? (I know the last one is common, but in our case it is bad naming because the WS layer usually has classes named FooWebService). The third option is probably the right one, but it is also devoid of any useful info. To sum up: I don't like the first approach, but I accept that I might have been unable to fully understand the Zen of it. So if you advocate for fat models as the only and universal solution you are welcome to post links explaining how to do it the right way. I'd like to know what is the standard design and naming conventions for the second approach in OO languages. Class names and package structure, in particular. It would also be helpful too if you could include links to Open Source projects showing how it is done. Thanks in advance.

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• Thoughts on C# Extension Methods

  - by Damon

  I'm not a huge fan of extension methods.  When they first came out, I remember seeing a method on an object that was fairly useful, but when I went to use it another piece of code that method wasn't available.  Turns out it was an extension method and I hadn't included the appropriate assembly and imports statement in my code to use it.  I remember being a bit confused at first about how the heck that could happen (hey, extension methods were new, cut me some slack) and it took a bit of time to track down exactly what it was that I needed to include to get that method back.  I just imagined a new developer trying to figure out why a method was missing and fruitlessly searching on MSDN for a method that didn't exist and it just didn't sit well with me. I am of the opinion that if you have an object, then you shouldn't have to include additional assemblies to get additional instance level methods out of that object.  That opinion applies to namespaces as well - I do not like it when the contents of a namespace are split out into multiple assemblies.  I prefer to have static utility classes instead of extension methods to keep things nicely packaged into a cohesive unit.  It also makes it abundantly clear where utility methods are used in code.  I will concede, however, that it can make code a bit more verbose and lengthy.  There is always a trade-off. Some people harp on extension methods because it breaks the tenants of object oriented development and allows you to add methods to sealed classes.  Whatever.  Extension methods are just utility methods that you can tack onto an object after the fact.  Extension methods do not give you any more access to an object than the developer of that object allows, so I say that those who cry OO foul on extension methods really don't have much of an argument on which to stand.  In fact, I have to concede that my dislike of them is really more about style than anything of great substance. One interesting thing that I found regarding extension methods is that you can call them on null objects. Take a look at this extension method: namespace ExtensionMethods {   public static class StringUtility   {     public static int WordCount(this string str)     {       if(str == null) return 0;       return str.Split(new char[] { ' ', '.', '?' },         StringSplitOptions.RemoveEmptyEntries).Length;     }   }   } Notice that the extension method checks to see if the incoming string parameter is null.  I was worried that the runtime would perform a check on the object instance to make sure it was not null before calling an extension method, but that is apparently not the case.  So, if you call the following code it runs just fine. string s = null; int words = s.WordCount(); I am a big fan of things working, but this seems to go against everything I've come to know about instance level methods.  However, an extension method is really a static method masquerading as an instance-level method, so I suppose it would be far more frustrating if it failed since there is really no reason it shouldn't succeed. Although I'm not a fan of extension methods, I will say that if you ever find yourself at an impasse with a die-hard fan of either the utility class or extension method approach, then there is a common ground.  Extension methods are defined in static classes, and you call them from those static classes as well as directly from the objects they extend.  So if you build your utility classes using extension methods, then you can have it your way and they can have it theirs. 

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• Surviving MATLAB and R as a Hardcore Programmer

  - by dsimcha

  I love programming in languages that seem geared towards hardcore programmers. (My favorites are Python and D.) MATLAB is geared towards engineers and R is geared towards statisticians, and it seems like these languages were designed by people who aren't hardcore programmers and don't think like hardcore programmers. I always find them somewhat awkward to use, and to some extent I can't put my finger on why. Here are some issues I have managed to identify: (Both): The extreme emphasis on vectors and matrices to the extent that there are no true primitives. (Both): The difficulty of basic string manipulation. (Both): Lack of or awkwardness in support for basic data structures like hash tables and "real", i.e. type-parametric and nestable, arrays. (Both): They're really, really slow even by interpreted language standards, unless you bend over backwards to vectorize your code. (Both): They seem to not be designed to interact with the outside world. For example, both are fairly bulky programs that take a while to launch and seem to not be designed to make simple text filter programs easy to write. Furthermore, the lack of good string processing makes file I/O in anything but very standard forms near impossible. (Both): Object orientation seems to have a very bolted-on feel. Yes, you can do it, but it doesn't feel much more idiomatic than OO in C. (Both): No obvious, simple way to get a reference type. No pointers or class references. For example, I have no idea how you roll your own linked list in either of these languages. (MATLAB): You can't put multiple top level functions in a single file, encouraging very long functions and cut-and-paste coding. (MATLAB): Integers apparently don't exist as a first class type. (R): The basic builtin data structures seem way too high level and poorly documented, and never seem to do quite what I expect given my experience with similar but lower level data structures. (R): The documentation is spread all over the place and virtually impossible to browse or search. Even D, which is often knocked for bad documentation and is still fairly alpha-ish, is substantially better as far as I can tell. (R): At least as far as I'm aware, there's no good IDE for it. Again, even D, a fairly alpha-ish language with a small community, does better. In general, I also feel like MATLAB and R could be easily replaced by plain old libraries in more general-purpose langauges, if sufficiently comprehensive libraries existed. This is especially true in newer general purpose languages that include lots of features for library writers. Why do R and MATLAB seem so weird to me? Are there any other major issues that you've noticed that may make these languages come off as strange to hardcore programmers? When their use is necessary, what are some good survival tips? Edit: I'm seeing one issue from some of the answers I've gotten. I have a strong personal preference, when I analyze data, to have one script that incorporates the whole pipeline. This implies that a general purpose language needs to be used. I hate having to write a script to "clean up" the data and spit it out, then another to read it back in a completely different environment, etc. I find the friction of using MATLAB/R for some of my work and a completely different language with a completely different address space and way of thinking for the rest to be a huge source of friction. Furthermore, I know there are glue layers that exist, but they always seem to be horribly complicated and a source of friction.

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• Educational, well-written FOSS projects to read, study or discuss

  - by Godot

  Before you say it: yes, this "question" has been asked other times. However, I could not fine many of such questions and not that easily, and those I found had similar results. What I'm trying to say that there are no comprehensive lists of well written Open Source projects, so I decided to set some requirements for the entries (one or possibly more): Idiomatic use of the language in which they are written The project should be lightweight. Not as in "a few kbs", as in "clean" and possibly following the UNIX philosophy, making an efficient use of resources and performing its duty and nothing more. No code bloat, most importantly. Projects like Firefox and GNOME wouldn't qualify, for example. Minimal reliance on external, non-standard libraries, with exceptions for some common FOSS libraries (curses, Xlib, OpenGL and possibly "usual suspects" like gtk+, webkit and Boost). Reliance on well-written libraries is welcome. No reliance on proprietary software - for obvious reasons (programs that rely on XNA, DirectX, Cocoa and similar, for example). Well-documented code is welcome. Include link to web interfaces to their repositories if possible. Here are some sample projects that often pop up in these threads: Operating Systems Plan 9 from Bell Labs: More or less, the official "sequel" to UNIX. Written in C by the same people who invented C! NetBSD: The most portable BSD implementation, written in C and also a good example of portable and organized code. Network and Databases Sqlite: Extremely lightweight and extremely efficient, one of the best pieces of C software I've seen. Count the lines yourself! Lighttpd: A small but pretty reliable web server written in C. Programming languages and VMs Lua: extremely lightweight multi-paradigm programming language. Written in C. Tiny C Compiler: Really tiny C compiler. Not really comparable to GCC or Clang but does its job. PyPy: A Python implementation written in Python. Pharo: OK, I admit it, I'm not really a Smalltalk expert but Pharo is a fork of Squeak and looked rather interesting. Stackless Python - An implementation of Python that doesn't rely on the C call stack - written in C (with some parts in Python) Games and 3D: Angband: One of the most accessible roguelike codebases around here, written in C. Ogre3D: Cross-platform 3D engine. Gets bloated if you don't skip the platform-specific implementation code, otherwise is a pretty solid example of good C++ OO. Simon Tatham's Portable Puzzle Collection: Title says it all. Other - dwm: Lightweight window manager. Written in C. Emulation and Reverse Engineering - Bochs: x86 emulator, written in C++ and tiny enough. - MAME: If you want to see C at one of its lowest levels, MAME is for you. May not be as clean as the other projects but it can teach you A LOT. Before you ask: I didn't mention Linux because it has become quite bloated in the last few years, Linus has also confirmed it. Nonetheless, it'd be a great educational read the same, even if for other reasons. Same for GCC. Feel free to edit or wikify my post. I hope you won't lock my question, I'm only trying to organize a little community effort for the good of all those people who want to enhance their coding skills.

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• Independence Day for Software Components &ndash; Loosening Coupling by Reducing Connascence

  - by Brian Schroer

  Today is Independence Day in the USA, which got me thinking about loosely-coupled “independent” software components. I was reminded of a video I bookmarked quite a while ago of Jim Weirich’s “Grand Unified Theory of Software Design” talk at MountainWest RubyConf 2009. I finally watched that video this morning. I highly recommend it. In the video, Jim talks about software connascence. The dictionary definition of connascence (con-NAY-sense) is: 1. The common birth of two or more at the same time 2. That which is born or produced with another. 3. The act of growing together. The brief Wikipedia page about Connascent Software Components says that: Two software components are connascent if a change in one would require the other to be modified in order to maintain the overall correctness of the system. Connascence is a way to characterize and reason about certain types of complexity in software systems. The term was introduced to the software world in Meilir Page-Jones’ 1996 book “What Every Programmer Should Know About Object-Oriented Design”. The middle third of that book is the author’s proposed graphical notation for describing OO designs. UML became the standard about a year later, so a revised version of the book was published in 1999 as “Fundamentals of Object-Oriented Design in UML”. Weirich says that the third part of the book, in which Page-Jones introduces the concept of connascence “is worth the price of the entire book”. (The price of the entire book, by the way, is not much – I just bought a used copy on Amazon for $1.36, so that was a pretty low-risk investment. I’m looking forward to getting the book and learning about connascence from the original source.) Meanwhile, here’s my summary of Weirich’s summary of Page-Jones writings about connascence: The stronger the form of connascence, the more difficult and costly it is to change the elements in the relationship. Some of the connascence types, ordered from weak to strong are: Connascence of Name Connascence of name is when multiple components must agree on the name of an entity. If you change the name of a method or property, then you need to change all references to that method or property. Duh. Connascence of name is unavoidable, assuming your objects are actually used. My main takeaway about connascence of name is that it emphasizes the importance of giving things good names so you don’t need to go changing them later. Connascence of Type Connascence of type is when multiple components must agree on the type of an entity. I assume this is more of a problem for languages without compilers (especially when used in apps without tests). I know it’s an issue with evil JavaScript type coercion. Connascence of Meaning Connascence of meaning is when multiple components must agree on the meaning of particular values, e.g that “1” means normal customer and “2” means preferred customer. The solution to this is to use constants or enums instead of “magic” strings or numbers, which reduces the coupling by changing the connascence form from “meaning” to “name”. Connascence of Position Connascence of positions is when multiple components must agree on the order of values. This refers to methods with multiple parameters, e.g.: eMailer.Send("[email protected]", "[email protected]", "Your order is complete", "Order completion notification"); The more parameters there are, the stronger the connascence of position is between the component and its callers. In the example above, it’s not immediately clear when reading the code which email addresses are sender and receiver, and which of the final two strings are subject vs. body. Connascence of position could be improved to connascence of type by replacing the parameter list with a struct or class. This “introduce parameter object” refactoring might be overkill for a method with 2 parameters, but would definitely be an improvement for a method with 10 parameters. This points out two “rules” of connascence:  The Rule of Degree: The acceptability of connascence is related to the degree of its occurrence. The Rule of Locality: Stronger forms of connascence are more acceptable if the elements involved are closely related. For example, positional arguments in private methods are less problematic than in public methods. Connascence of Algorithm Connascence of algorithm is when multiple components must agree on a particular algorithm. Be DRY – Don’t Repeat Yourself. If you have “cloned” code in multiple locations, refactor it into a common function.   Those are the “static” forms of connascence. There are also “dynamic” forms, including… Connascence of Execution Connascence of execution is when the order of execution of multiple components is important. Consumers of your class shouldn’t have to know that they have to call an .Initialize method before it’s safe to call a .DoSomething method. Connascence of Timing Connascence of timing is when the timing of the execution of multiple components is important. I’ll have to read up on this one when I get the book, but assume it’s largely about threading. Connascence of Identity Connascence of identity is when multiple components must reference the entity. The example Weirich gives is when you have two instances of the “Bob” Employee class and you call the .RaiseSalary method on one and then the .Pay method on the other does the payment use the updated salary?   Again, this is my summary of a summary, so please be forgiving if I misunderstood anything. Once I get/read the book, I’ll make corrections if necessary and share any other useful information I might learn.   See Also: Gregory Brown: Ruby Best Practices Issue #24: Connascence as a Software Design Metric (That link is failing at the time I write this, so I had to go to the Google cache of the page.)

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• Talking JavaOne with Rock Star Martijn Verburg

  - by Janice J. Heiss

  JavaOne Rock Stars, conceived in 2005, are the top-rated speakers at each JavaOne Conference. They are awarded by their peers, who, through conference surveys, recognize them for their outstanding sessions and speaking ability. Over the years many of the world’s leading Java developers have been so recognized. Martijn Verburg has, in recent years, established himself as an important mover and shaker in the Java community. His “Diabolical Developer” session at the JavaOne 2011 Conference got people’s attention by identifying some of the worst practices Java developers are prone to engage in. Among other things, he is co-leader and organizer of the thriving London Java User Group (JUG) which has more than 2,500 members, co-represents the London JUG on the Executive Committee of the Java Community Process, and leads the global effort for the Java User Group “Adopt a JSR” and “Adopt OpenJDK” programs. Career highlights include overhauling technology stacks and SDLC practices at Mizuho International, mentoring Oracle on technical community management, and running off shore development teams for AIG. He is currently CTO at jClarity, a start-up focusing on automating optimization for Java/JVM related technologies, and Product Advisor at ZeroTurnaround. He co-authored, with Ben Evans, "The Well-Grounded Java Developer" published by Manning and, as a leading authority on technical team optimization, he is in high demand at major software conferences.Verburg is participating in five sessions, a busy man indeed. Here they are: CON6152 - Modern Software Development Antipatterns (with Ben Evans) UGF10434 - JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group (with Csaba Toth) BOF4047 - OpenJDK Building and Testing: Case Study—Java User Group OpenJDK Bugathon (with Ben Evans and Cecilia Borg) BOF6283 - 101 Ways to Improve Java: Why Developer Participation Matters (with Bruno Souza and Heather Vancura-Chilson) HOL6500 - Finding and Solving Java Deadlocks (with Heinz Kabutz, Kirk Pepperdine, Ellen Kraffmiller and Henri Tremblay) When I asked Verburg about the biggest mistakes Java developers tend to make, he listed three: A lack of communication -- Software development is far more a social activity than a technical one; most projects fail because of communication issues and social dynamics, not because of a bad technical decision. Sadly, many developers never learn this lesson. No source control -- Developers simply storing code in local filesystems and emailing code in order to integrate Design-driven Design -- The need for some developers to cram every design pattern from the Gang of Four (GoF) book into their source code All of which raises the question: If these practices are so bad, why do developers engage in them? “I've seen a wide gamut of reasons,” said Verburg, who lists them as: * They were never taught at high school/university that their bad habits were harmful.* They weren't mentored in their first professional roles.* They've lost passion for their craft.* They're being deliberately malicious!* They think software development is a technical activity and not a social one.* They think that they'll be able to tidy it up later.A couple of key confusions and misconceptions beset Java developers, according to Verburg. “With Java and the JVM in particular I've seen a couple of trends,” he remarked. “One is that developers think that the JVM is a magic box that will clean up their memory, make their code run fast, as well as make them cups of coffee. The JVM does help in a lot of cases, but bad code can and will still lead to terrible results! The other trend is to try and force Java (the language) to do something it's not very good at, such as rapid web development. So you get a proliferation of overly complex frameworks, libraries and techniques trying to get around the fact that Java is a monolithic, statically typed, compiled, OO environment. It's not a Golden Hammer!”I asked him about the keys to running a good Java User Group. “You need to have a ‘Why,’” he observed. “Many user groups know what they do (typically, events) and how they do it (the logistics), but what really drives users to join your group and to stay is to give them a purpose. For example, within the LJC we constantly talk about the ‘Why,’ which in our case is several whys:* Re-ignite the passion that developers have for their craft* Raise the bar of Java developers in London* We want developers to have a voice in deciding the future of Java* We want to inspire the next generation of tech leaders* To bring the disparate tech groups in London together* So we could learn from each other* We believe that the Java ecosystem forms a cornerstone of our society today -- we want to protect that for the futureLooking ahead to Java 8 Verburg expressed excitement about Lambdas. “I cannot wait for Lambdas,” he enthused. “Brian Goetz and his group are doing a great job, especially given some of the backwards compatibility that they have to maintain. It's going to remove a lot of boiler plate and yet maintain readability, plus enable massive scaling.”Check out Martijn Verburg at JavaOne if you get a chance, and, stay tuned for a longer interview yours truly did with Martijn to be publish on otn/java some time after JavaOne. Originally published on blogs.oracle.com/javaone.

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• Talking JavaOne with Rock Star Martijn Verburg

  - by Janice J. Heiss

  JavaOne Rock Stars, conceived in 2005, are the top-rated speakers at each JavaOne Conference. They are awarded by their peers, who, through conference surveys, recognize them for their outstanding sessions and speaking ability. Over the years many of the world’s leading Java developers have been so recognized. Martijn Verburg has, in recent years, established himself as an important mover and shaker in the Java community. His “Diabolical Developer” session at the JavaOne 2011 Conference got people’s attention by identifying some of the worst practices Java developers are prone to engage in. Among other things, he is co-leader and organizer of the thriving London Java User Group (JUG) which has more than 2,500 members, co-represents the London JUG on the Executive Committee of the Java Community Process, and leads the global effort for the Java User Group “Adopt a JSR” and “Adopt OpenJDK” programs. Career highlights include overhauling technology stacks and SDLC practices at Mizuho International, mentoring Oracle on technical community management, and running off shore development teams for AIG. He is currently CTO at jClarity, a start-up focusing on automating optimization for Java/JVM related technologies, and Product Advisor at ZeroTurnaround. He co-authored, with Ben Evans, "The Well-Grounded Java Developer" published by Manning and, as a leading authority on technical team optimization, he is in high demand at major software conferences.Verburg is participating in five sessions, a busy man indeed. Here they are: CON6152 - Modern Software Development Antipatterns (with Ben Evans) UGF10434 - JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group (with Csaba Toth) BOF4047 - OpenJDK Building and Testing: Case Study—Java User Group OpenJDK Bugathon (with Ben Evans and Cecilia Borg) BOF6283 - 101 Ways to Improve Java: Why Developer Participation Matters (with Bruno Souza and Heather Vancura-Chilson) HOL6500 - Finding and Solving Java Deadlocks (with Heinz Kabutz, Kirk Pepperdine, Ellen Kraffmiller and Henri Tremblay) When I asked Verburg about the biggest mistakes Java developers tend to make, he listed three: A lack of communication -- Software development is far more a social activity than a technical one; most projects fail because of communication issues and social dynamics, not because of a bad technical decision. Sadly, many developers never learn this lesson. No source control -- Developers simply storing code in local filesystems and emailing code in order to integrate Design-driven Design -- The need for some developers to cram every design pattern from the Gang of Four (GoF) book into their source code All of which raises the question: If these practices are so bad, why do developers engage in them? “I've seen a wide gamut of reasons,” said Verburg, who lists them as: * They were never taught at high school/university that their bad habits were harmful.* They weren't mentored in their first professional roles.* They've lost passion for their craft.* They're being deliberately malicious!* They think software development is a technical activity and not a social one.* They think that they'll be able to tidy it up later.A couple of key confusions and misconceptions beset Java developers, according to Verburg. “With Java and the JVM in particular I've seen a couple of trends,” he remarked. “One is that developers think that the JVM is a magic box that will clean up their memory, make their code run fast, as well as make them cups of coffee. The JVM does help in a lot of cases, but bad code can and will still lead to terrible results! The other trend is to try and force Java (the language) to do something it's not very good at, such as rapid web development. So you get a proliferation of overly complex frameworks, libraries and techniques trying to get around the fact that Java is a monolithic, statically typed, compiled, OO environment. It's not a Golden Hammer!”I asked him about the keys to running a good Java User Group. “You need to have a ‘Why,’” he observed. “Many user groups know what they do (typically, events) and how they do it (the logistics), but what really drives users to join your group and to stay is to give them a purpose. For example, within the LJC we constantly talk about the ‘Why,’ which in our case is several whys:* Re-ignite the passion that developers have for their craft* Raise the bar of Java developers in London* We want developers to have a voice in deciding the future of Java* We want to inspire the next generation of tech leaders* To bring the disparate tech groups in London together* So we could learn from each other* We believe that the Java ecosystem forms a cornerstone of our society today -- we want to protect that for the futureLooking ahead to Java 8 Verburg expressed excitement about Lambdas. “I cannot wait for Lambdas,” he enthused. “Brian Goetz and his group are doing a great job, especially given some of the backwards compatibility that they have to maintain. It's going to remove a lot of boiler plate and yet maintain readability, plus enable massive scaling.”Check out Martijn Verburg at JavaOne if you get a chance, and, stay tuned for a longer interview yours truly did with Martijn to be publish on otn/java some time after JavaOne.

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• How to get sound on macbook pro 4,1

  - by Thomas

  I have just installed Xubuntu 12.04.2. My soundcard is detected: thomas@thomas-pc:~$ sudo aplay -l **** List of PLAYBACK Hardware Devices **** Home directory /home/thomas not ours. card 0: Intel [HDA Intel], device 0: ALC889A Analog [ALC889A Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 1: ALC889A Digital [ALC889A Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 Everything is put to max in alsamixer and nothing is muted (all the sliders are on OO. My speakers do not work, but when I plug in a headphone I hear it very soft. When I connect my stereo and put the sound VERY loud (3-blocks-of-complaining-neighbours loud) I hear it on a normal level but crackling. I added options snd-hda-intel model=mbp5 amixer set IEC958 off to at the end of /etc/modprobe.d/alsa-base.conf. When it's still not working I tried everything here: https://help.ubuntu.com/community/SoundTroubleshooting 1 >>> list-sinks 1 sink(s) available. * index: 0 name: <alsa_output.pci-0000_00_1b.0.analog-stereo> driver: <module-alsa-card.c> flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY state: SUSPENDED suspend cause: IDLE priority: 9959 volume: 0: 100% 1: 100% 0: 0.00 dB 1: 0.00 dB balance 0.00 base volume: 100% 0.00 dB volume steps: 65537 muted: no current latency: 0.00 ms max request: 0 KiB max rewind: 0 KiB monitor source: 0 sample spec: s16le 2ch 44100Hz channel map: front-left,front-right Stereo used by: 0 linked by: 0 configured latency: 0.00 ms; range is 0.50 .. 371.52 ms card: 0 <alsa_card.pci-0000_00_1b.0> module: 4 properties: alsa.resolution_bits = "16" device.api = "alsa" device.class = "sound" alsa.class = "generic" alsa.subclass = "generic-mix" alsa.name = "ALC889A Analog" alsa.id = "ALC889A Analog" alsa.subdevice = "0" alsa.subdevice_name = "subdevice #0" alsa.device = "0" alsa.card = "0" alsa.card_name = "HDA Intel" alsa.long_card_name = "HDA Intel at 0x9b500000 irq 46" alsa.driver_name = "snd_hda_intel" device.bus_path = "pci-0000:00:1b.0" sysfs.path = "/devices/pci0000:00/0000:00:1b.0/sound/card0" device.bus = "pci" device.vendor.id = "8086" device.vendor.name = "Intel Corporation" device.product.name = "82801H (ICH8 Family) HD Audio Controller" device.form_factor = "internal" device.string = "front:0" device.buffering.buffer_size = "65536" device.buffering.fragment_size = "32768" device.access_mode = "mmap+timer" device.profile.name = "analog-stereo" device.profile.description = "Analog Stereo" device.description = "Built-in Audio Analog Stereo" alsa.mixer_name = "Realtek ALC889A" alsa.components = "HDA:10ec0885,106b3a00,00100103" module-udev-detect.discovered = "1" device.icon_name = "audio-card-pci" ports: analog-output-speaker: Speakers (priority 10000, available: unknown) properties: analog-output-headphones: Headphones (priority 9000, available: no) properties: active port: <analog-output-speaker> 2 and 3: Doesn't seem an permission issue, the sound is very far away (See opening paragraph). 4 thomas@thomas-pc:~$ sudo aplay -l **** List of PLAYBACK Hardware Devices **** Home directory /home/thomas not ours. card 0: Intel [HDA Intel], device 0: ALC889A Analog [ALC889A Analog] Subdevices: 1/1 Subdevice #0: subdevice #0 card 0: Intel [HDA Intel], device 1: ALC889A Digital [ALC889A Digital] Subdevices: 1/1 Subdevice #0: subdevice #0 5 thomas@thomas-pc:~$ find /lib/modules/`uname -r` | grep snd /lib/modules/3.2.0-48-generic/kernel/sound/core/snd-hwdep.ko /lib/modules/3.2.0-48-generic/kernel/sound/core/snd-pcm.ko [.. huge lists continues ..] /lib/modules/3.2.0-48-generic/kernel/sound/pcmcia/pdaudiocf/snd-pdaudiocf.ko /lib/modules/3.2.0-48-generic/kernel/sound/pcmcia/vx/snd-vxpocket.ko thomas@thomas-pc:~$ 6 thomas@thomas-pc:~$ lspci -v | grep -A7 -i "audio" 00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 03) Subsystem: Apple Inc. Device 00a4 Flags: bus master, fast devsel, latency 0, IRQ 46 Memory at 9b500000 (64-bit, non-prefetchable) [size=16K] Capabilities: <access denied> Kernel driver in use: snd_hda_intel Kernel modules: snd-hda-intel 7 I guess it's supported. Linux mint and Xubuntu 13.04 had no trouble with sounds. Everything worked out of the box Thanks in advance Edit: alsa-info.sh output: WARNING: /etc/modprobe.d/alsa-base.conf line 45: ignoring bad line starting with 'amixer' ALSA Information Script v 0.4.62 -------------------------------- This script visits the following commands/files to collect diagnostic information about your ALSA installation and sound related hardware. dmesg lspci lsmod aplay amixer alsactl /proc/asound/ /sys/class/sound/ ~/.asoundrc (etc.) See './alsa-info.sh --help' for command line options. WARNING: /etc/modprobe.d/alsa-base.conf line 45: ignoring bad line starting with 'amixer' Automatically upload ALSA information to www.alsa-project.org? [y/N] : y Uploading information to www.alsa-project.org ... Done! Your ALSA information is located at http://www.alsa-project.org/db/?f=6cffc584284d4c0b266eb53249824ef83d6c4e3e Please inform the person helping you. thomas@thomas-pc:~$

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• Functional Adaptation

  - by Charles Courchaine

  In real life and OO programming we’re often faced with using adapters, DVI to VGA, 1/4” to 1/8” audio connections, 110V to 220V, wrapping an incompatible interface with a new one, and so on.  Where the adapter pattern is generally considered for interfaces and classes a similar technique can be applied to method signatures.  To be fair, this adaptation is generally used to reduce the number of parameters but I’m sure there are other clever possibilities to be had.  As Jan questioned in the last post, how can we use a common method to execute an action if the action has a differing number of parameters, going back to the greeting example it was suggested having an AddName method that takes a first and last name as parameters.  This is exactly what we’ll address in this post. Let’s set the stage with some review and some code changes.  First, our method that handles the setup/tear-down infrastructure for our WCF service: 1: private static TResult ExecuteGreetingFunc<TResult>(Func<IGreeting, TResult> theGreetingFunc) 2: { 3: IGreeting aGreetingService = null; 4: try 5: { 6: aGreetingService = GetGreetingChannel(); 7: return theGreetingFunc(aGreetingService); 8: } 9: finally 10: { 11: CloseWCFChannel((IChannel)aGreetingService); 12: } 13: } Our original AddName method: 1: private static string AddName(string theName) 2: { 3: return ExecuteGreetingFunc<string>(theGreetingService => theGreetingService.AddName(theName)); 4: } Our new AddName method: 1: private static int AddName(string firstName, string lastName) 2: { 3: return ExecuteGreetingFunc<int>(theGreetingService => theGreetingService.AddName(firstName, lastName)); 4: } Let’s change the AddName method, just a little bit more for this example and have it take the greeting service as a parameter. 1: private static int AddName(IGreeting greetingService, string firstName, string lastName) 2: { 3: return greetingService.AddName(firstName, lastName); 4: } The new signature of AddName using the Func delegate is now Func<IGreeting, string, string, int>, which can’t be used with ExecuteGreetingFunc as is because it expects Func<IGreeting, TResult>.  Somehow we have to eliminate the two string parameters before we can use this with our existing method.  This is where we need to adapt AddName to match what ExecuteGreetingFunc expects, and we’ll do so in the following progression. 1: Func<IGreeting, string, string, int> -> Func<IGreeting, string, int> 2: Func<IGreeting, string, int> -> Func<IGreeting, int>   For the first step, we’ll create a method using the lambda syntax that will “eliminate” the last name parameter: 1: string lastNameToAdd = "Smith"; 2: //Func<IGreeting, string, string, int> -> Func<IGreeting, string, int> 3: Func<IGreeting, string, int> addName = (greetingService, firstName) => AddName(greetingService, firstName, lastNameToAdd); The new addName method gets us one step close to the signature we need.  Let’s say we’re going to call this in a loop to add several names, we’ll take the final step from Func<IGreeting, string, int> -> Func<IGreeting, int> in line as a lambda passed to ExecuteGreetingFunc like so: 1: List<string> firstNames = new List<string>() { "Bob", "John" }; 2: int aID; 3: foreach (string firstName in firstNames) 4: { 5: //Func<IGreeting, string, int> -> Func<IGreeting, int> 6: aID = ExecuteGreetingFunc<int>(greetingService => addName(greetingService, firstName)); 7: Console.WriteLine(GetGreeting(aID)); 8: } If for some reason you needed to break out the lambda on line 6 you could replace it with 1: aID = ExecuteGreetingFunc<int>(ApplyAddName(addName, firstName)); and use this method: 1: private static Func<IGreeting, int> ApplyAddName(Func<IGreeting, string, int> addName, string lastName) 2: { 3: return greetingService => addName(greetingService, lastName); 4: } Splitting out a lambda into its own method is useful both in this style of coding as well as LINQ queries to improve the debugging experience.  It is not strictly necessary to break apart the steps & functions as was shown above; the lambda in line 6 (of the foreach example) could include both the last name and first name instead of being composed of two functions.  The process demonstrated above is one of partially applying functions, this could have also been done with Currying (also see Dustin Campbell’s excellent post on Currying for the canonical curried add example).  Matthew Podwysocki also has some good posts explaining both Currying and partial application and a follow up post that further clarifies the difference between Currying and partial application.  In either technique the ultimate goal is to reduce the number of parameters passed to a function.  Currying makes it a single parameter passed at each step, where partial application allows one to use multiple parameters at a time as we’ve done here.  This technique isn’t for everyone or every problem, but can be extremely handy when you need to adapt a call to something you don’t control.

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• Why not .NET-style delegates rather than closures in Java?

  - by h2g2java

  OK, this is going to be my beating a dying horse for the 3rd time. However, this question is different from my earlier two about closures/delegates, which asks about plans for delegates and what are the projected specs and implementation for closures. This question is about - why is the Java community struggling to define 3 different types of closures when we could simply steal the whole concept of delegates lock, stock and barrel from our beloved and friendly neighbour - Microsoft. There are two non-technical conclusions I would be very tempted to jump into: The Java community should hold up its pride, at the cost of needing to go thro convoluted efforts, by not succumbing to borrowing any Microsoft concepts or otherwise vindicate Microsoft's brilliance. Delegates is a Microsoft patented technology. Alright, besides the above two possibilities, Q1. Is there any weakness or inadequacy in msft-styled delegates that the three (or more) forms of closures would be addressing? Q2. I am asking this while shifting between java and c# and it intrigues me that c# delegates does exactly what I needed. Are there features that would be implemented in closures that are not currently available in C# delegates? If so what are they because I cannot see what I need more than what C# delegates has adequately provided me? Q3. I know that one of the concerns about implementing closures/delegates in java is the reduction of orthogonality of the language, where more than one way is exposed to perform a particular task. Is it worth the level convolution and time spent to avoid delegates just to ensure java retains its level of orthogonality? In SQL, we know that it is advisable to break orthogonality by frequently adequately satisfying only the 2nd normal form. Why can't java be subjected to reduction of orthogonality and OO-ness for the sake of simplicity? Q4. The architecture of JVM is technically constrained from implementing .NET-styled delegates. If this reason WERE (subjunctive to emphasize unlikelihood) true, then why can't the three closures proposals be hidden behind a simple delegate keyword or annotation: if we don't like to use @delegate, we could use @method. I cannot see how delegate statement format is more complex than the three closure proposals.

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• When should I use Perl's AUTOLOAD?

  - by Robert S. Barnes

  In "Perl Best Practices" the very first line in the section on AUTOLOAD is: Don't use AUTOLOAD However all the cases he describes are dealing with OO or Modules. I have a stand alone script in which some command line switches control which versions of particular functions get defined. Now I know I could just take the conditionals and the evals and stick them naked at the top of my file before everything else, but I find it convenient and cleaner to put them in AUTOLOAD at the end of the file. Is this bad practice / style? If you think so why, and is there a another way to do it? As per brian's request I'm basically using this to do conditional compilation based on command line switches. I don't mind some constructive criticism. sub AUTOLOAD { our $AUTOLOAD; (my $method = $AUTOLOAD) =~ s/.*:://s; # remove package name if ($method eq 'tcpdump' && $tcpdump) { eval q( sub tcpdump { my $msg = shift; warn gf_time()." Thread ".threads->tid().": $msg\n"; } ); } elsif ($method eq 'loginfo' && $debug) { eval q( sub loginfo { my $msg = shift; $msg =~ s/$CRLF/\n/g; print gf_time()." Thread ".threads->tid().": $msg\n"; } ); } elsif ($method eq 'build_get') { if ($pipelining) { eval q( sub build_get { my $url = shift; my $base = shift; $url = "http://".$url unless $url =~ /^http/; return "GET $url HTTP/1.1${CRLF}Host: $base$CRLF$CRLF"; } ); } else { eval q( sub build_get { my $url = shift; my $base = shift; $url = "http://".$url unless $url =~ /^http/; return "GET $url HTTP/1.1${CRLF}Host: $base${CRLF}Connection: close$CRLF$CRLF"; } ); } } elsif ($method eq 'grow') { eval q{ require Convert::Scalar qw(grow); }; if ($@) { eval q( sub grow {} ); } goto &$method; } else { eval "sub $method {}"; return; } die $@ if $@; goto &$method; }

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• Haskell newbie on types

  - by garulfo

  I'm completely new to Haskell (and more generally to functional programming), so forgive me if this is really basic stuff. To get more than a taste, I try to implement in Haskell some algorithmic stuff I'm working on. I have a simple module Interval that implements intervals on the line. It contains the type data Interval t = Interval t t the helper function makeInterval :: (Ord t) => t -> t -> Interval t makeInterval l r | l <= r = Interval l r | otherwise = error "bad interval" and some utility functions about intervals. Here, my interest lies in multidimensional intervals (d-intervals), those objects that are composed of d intervals. I want to separately consider d-intervals that are the union of d disjoint intervals on the line (multiple interval) from those that are the union of d interval on d separate lines (track interval). With distinct algorithmic treatments in mind, I think it would be nice to have two distinct types (even if both are lists of intervals here) such as import qualified Interval as I -- Multilple interval newtype MInterval t = MInterval [I.Interval t] -- Track interval newtype TInterval t = TInterval [I.Interval t] to allow for distinct sanity checks, e.g. makeMInterval :: (Ord t) => [I.Interval t] -> MInterval t makeMInterval is = if foldr (&&) True [I.precedes i i' | (i, i') <- zip is (tail is)] then (MInterval is) else error "bad multiple interval" makeTInterval :: (Ord t) => [I.Interval t] -> TInterval t makeTInterval = TInterval I now get to the point, at last! But some functions are naturally concerned with both multiple intervals and track intervals. For example, a function order would return the number of intervals in a multiple interval or a track interval. What can I do? Adding -- Dimensional interval data DInterval t = MIntervalStuff (MInterval t) | TIntervalStuff (TInterval t) does not help much, since, if I understand well (correct me if I'm wrong), I would have to write order :: DInterval t -> Int order (MIntervalStuff (MInterval is)) = length is order (TIntervalStuff (TInterval is)) = length is and call order as order (MIntervalStuff is) or order (TIntervalStuff is) when is is a MInterval or a TInterval. Not that great, it looks odd. Neither I want to duplicate the function (I have many functions that are concerned with both multiple and track intevals, and some other d-interval definitions such as equal length multiple and track intervals). I'm left with the feeling that I'm completely wrong and have missed some important point about types in Haskell (and/or can't forget enough here about OO programming). So, quite a newbie question, what would be the best way in Haskell to deal with such a situation? Do I have to forget about introducing MInterval and TInterval and go with one type only? Thanks a lot for your help, Garulfo

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• Becoming a professional programmer / software engineer

  - by Matt

  This isn't strictly about programming, more about being a programmer, so I'm sorry if its not the right kind of question to ask on this forum (mod, please delete if it isn't) I'm a computer tech in the US Army, and once I'm out I'll have eight years on the job. I'm about to start a degree through an online school (the only way I can get the army to pay for it while I'm still in), and I'm seriously looking at getting a computer science degree. I'm great with computers. I can take one apart and put it back together with my eyes closed. I'm A+ and Network+ certified and I'm getting a couple other CompTIA certs before I get out. I can work Windows as well as anyone on this planet and I'm not terrible with Linux. A job in computers is something I've always wanted. But, aside from being a computer technician, it seems that every job in the field requires programming ability. I like programming as a hobby. I programmed TI BASIC in high school and I'm teaching myself Python, but that's as far as my experience goes. That sort of brings me to my questions: I've always heard that the first language is the most difficult, and once you learn it well then all the others sort of fall into place for you. Is that true? Like, if I spend the next eight months mastering Python, will I pretty much be able to pick up at least fair proficiency in any other OO language within a month of studying it or whatever? How easy is it to burn out? the biggest thing I'm afraid of is just burning out on programming. I can go all day long if I'm programming strictly for my own personal desire, but I can imagine it being really easy to burn out after a few years of programming to deadlines and certain specifications. Especially if its a big project involving a dozen different designers. From what I told you about myself, would I already be qualified to work as a regular technician (geek squad type or maybe running a computer repair shop). Is Python a good base to learn from? I've heard that it makes you hate other languages because they feel more convoluted when learning, but also that its a great beginner language. If you're a professional programmer, did you have any of the same fears? Would you recommend that I stick to computer repair and Python rather than try to get into corporate programming? (just from what you've read in this thread, anyway) Thanks for taking the time to read all this and answer (if you did)

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• Arguments for moving from LINQtoSQL to Nhibernate?

  - by sah302

  Backstory: Hi all, I just spent a lot of time reading many of the LINQ vs Nhibernate threads here and on other sites. I work in a small development team of 4 people and we don't even have really any super experienced developers. We work for a small company that has a lot of technical needs but not enough developers to implement them (and hiring more is out of the question right now). Typically our projects (which individually are fairly small) have been coded separately and weren't really layered in anyway, code wasn't re-used, no class libraries, and we just use the LINQtoSQL .dbml files for our pojects, we really don't even use objects but pass around values and stuff, the only time we use objects is when inserting to a database (heck not even querying since you don't need to assign it to a type and can just bind to gridview). Despite all this as I said our company has a lot of technical needs, no one could come to us for a year and we would have plenty of work to implement requested features. Well I have decided to change that a bit first by creating class libraries and actually adding layers to our applications. I am trying to meet these guys halfway by still using LINQtoSQL as the ORM yet and still use VB as the language. However I am finding it a b***h of a time dealing with so many thing in LINQtoSQL that I found easy in Nhibernate (automatic handling of the session, criteria creation easier than expression trees, generic an dynamic querying easier etc.) So... Question: How can I convince my lead developers and other senior programmers that switching to Nhibernate is a good thing? That being in control of our domain objects is a good thing? That being able to implement interfaces is a good? I've tried exlpaining the advantages of this before but it's not understood by them because they've never programmed in a true OO & layered way. Also one of the counter arguments to this I can see is sqlMetal generates those classes automatically and therefore it saves a lot of time. I can't really counter that other than saying spending more time on infrastructure to make it more scalable and flexible is good, but they can't see how. Again, I know the features and advantages (somewhat enough I believe) of each, but I need arguments applicable to my context, hence why I provided the context. I just am not a very good arguer I guess. (Caveat: For all the LINQtoSQL lovers, I may just not be super proficient as LINQ, but I find it very cumbersome that you are required to download some extra library for dynamic queries which don't by default support guid comparisons, and I also find the way of updating entitites to be cumbersome as well in terms of data context managing, so it could just be that I suck hehe.)

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• Is it a oop good design ?

  - by remi bourgarel

  Hi all, I'd like to know what you think about this part of our program is realized : We have in our database a list of campsite. Partners call us to get all the campsites near a GPS location or all the campsites which provide a bar (we call it a service). So how I realized it ? Here is our database : Campsite - ID - NAME - GPS_latitude - GPS_longitude CampsiteServices -Campsite_ID -Services_ID So my code (c# but it's not relevant, let say it's an OO language) looks like this public class SqlCodeCampsiteFilter{ public string SqlCode; public Dictionary<string, object> Parameters; } interface ISQLCampsiteFilter{ SqlCodeEngineCore CreateSQLCode(); } public class GpsLocationFilter : ISQLCampsiteFilter{ public float? GpsLatitude; public float? GpsLongitude; public SqlCodeEngineCore CreateSQLCode() { --return an sql code to filter on the gps location like dbo.getDistance(@gpsLat,@gpsLong,campsite.GPS_latitude,campsite.GPS_longitude) with the parameters } } public class ServiceFilter : : ISQLCampsiteFilter{ public int[] RequiredServicesID; public SqlCodeEngineCore CreateSQLCode() { --return an sql code to filter on the services "where ID IN (select CampsiteServices.Service_ID FROm CampsiteServices WHERE Service_ID in ...) } } So in my webservice code : List<ISQLFilterEngineCore> filters = new List<ISQLFilterEngineCore>(); if(gps_latitude.hasvalue && gps_longitude.hasvalue){ filters.Add (new GpsLocationFilter (gps_latitude.value,gps_longitude.value)); } if(required_services_id != null){ filters.Add (new ServiceFilter (required_services_id )); } string sql = "SELECT ID,NAME FROM campsite where 1=1" foreach(ISQLFilterEngineCore aFilter in filters){ SqlCodeCampsiteFilter code = aFilter.CreateSQLCode(); sql += code.SqlCode; mySqlCommand.AddParameters(code.Parameters);//add all the parameters to the sql command } return mySqlCommand.GetResults(); 1/ I don't use ORM for the simple reason that the system exists since 10 years and the only dev who is here since the beginning is starting to learn about difference between public and private. 2/ I don't like SP because : we can do override, and t-sql is not so funny to use :) So what do you think ? Is it clear ? Do you have any pattern that I should have a look to ? If something is not clear please ask

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• Design Technique: How to design a complex system for processing orders, products and units.

  - by Shyam

  Hi, Programming is fun: I learned that by trying out simple challenges, reading up some books and following some tutorials. I am able to grasp the concepts of writing with OO (I do so in Ruby), and write a bit of code myself. What bugs me though is that I feel re-inventing the wheel: I haven't followed an education or found a book (a free one that is) that explains me the why's instead of the how's, and I've learned from the A-team that it is the plan that makes it come together. So, armed with my nuby Ruby skills, I decided I wanted to program a virtual store. I figured out the following: My virtual Store will have: Products and Services Inventories Orders and Shipping Customers Now this isn't complex at all. With the help of some cool tools (CMapTools), I drew out some concepts, but quickly enough (thanks to my inferior experience in designing), my design started to bite me. My very first product-line were virtual "laptops". So, I created a class (Ruby): class Product attr_accessor :name, :price def initialize(name, price) @name = name @price = price end end which can be instantiated by doing (IRb) x = Product.new("Banana Pro", 250) Since I want my virtual customers to be able to purchase more than one product, or various types, I figured out I needed some kind of "Order" mechanism. class Order def initialize(order_no) @order_no = order_no @line_items = [] end def add_product(myproduct) @line_items << myproduct end def show_order() puts @order_no @line_items.each do |x| puts x.name.to_s + "\t" + x.price.to_s end end end that can be instantiated by doing (IRb) z = Order.new(1234) z.add_product(x) z.show_order Splendid, I have now a very simple ordering system that allows me to add products to an order. But, here comes my real question. What if I have three models of my product (economy, business, showoff)? Or have my products be composed out of separate units (bigger screen, nicer keyboard, different OS)? Surely I could make them three separate products, or add complexity to my product class, but I am looking for are best practices to design a flexible product object that can be used in the real world, to facilitate a complex system. My apologies if my grammar and my spelling are with error, as english is not my first language and I took the time to check as far I could understand and translate properly! Thank you for your answers, comments and feedback!

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• Implementing a scalable and high-performing web app

  - by Christopher McCann

  I have asked a few questions on here before about various things relating to this but this is more of a consolidation question as I would like to check I have got the gist of everything. I am in the middle of developing a social media web app and although I have a lot of experience coding in Java and in PHP I am trying things a bit different this time. I have modularised each component of the application. So for example one component of the application allows users to private message each other and I have split this off into its own private messaging service. I have also created a user data service the purpose of which is to return data about the user for example their name, address, age etc etc from the database. Their is also another service, the friends service, which will work off the neo4j database to create a social graph. My reason for doing all this is to allow me up to update seperate modules when I need to - so while they mostly all run off MySQL right now I could move one to Cassandra later if I thought it approriate. The actual code of the web app is really just used for the final construction. The modules behind it dont really follow any strict REST or SOAP protocol. Basically each method on our API is turned into a PHP procedural script. This then may make calls to other back-end code which tends to be OO. The web app makes CURL requests to these pages and POSTs data to them or GETs data from them. These pages then return JSON where data is required. I'm still a little mixed up about how I actually identify which user is logged in at that moment. Do I just use sessions for that? Like if we called the get-messages.php script which equates to the getMessages() method for that user - returning all the private messages for that user - how would the back-end code know which user it is as posting the users ID to the script would not be secure. Anyone could do that and get all the messages. So I thought I would use sessions for it. Am I correct on this? Can anyone spot any other problems with what I am doing here? Thanks

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• Robust way to save/load objects with dependencies?

  - by mrteacup

  I'm writing an Android game in Java and I need a robust way to save and load application state quickly. The question seems to apply to most OO languages. To understand what I need to save: I'm using a Strategy pattern to control my game entities. The idea is I have a very general Entity class which e.g. stores the location of a bullet/player/enemy and I then attach a Behaviour class that tells the entity how to act: class Entiy { float x; float y; Behavior b; } abstract class Behavior { void update(Entity e); {} // Move about at a constant speed class MoveBehavior extends Behavior { float speed; void update ... } // Chase after another entity class ChaseBehavior extends Behavior { Entity target; void update ... } // Perform two behaviours in sequence class CombineBehavior extends Behavior { Behaviour a, b; void update ... } Essentially, Entity objects are easy to save but Behaviour objects can have a semi-complex graph of dependencies between other Entity objects and other Behaviour objects. I also have cases where a Behaviour object is shared between entities. I'm willing to change my design to make saving/loading state easier, but the above design works really well for structuring the game. Anyway, the options I've considered are: Use Java serialization. This is meant to be really slow in Android (I'll profile it sometime). I'm worried about robustness when changes are made between versions however. Use something like JSON or XML. I'm not sure how I would cope with storing the dependencies between objects however. Would I have to give each object a unique ID and then use these IDs on loading to link the right objects together? I thought I could e.g. change the ChaseBehaviour to store a ID to an entity, instead of a reference, that would be used to look up the Entity before performing the behaviour. I'd rather avoid having to write lots of loading/saving code myself as I find it really easy to make mistakes (e.g. forgetting to save something, reading things out in the wrong order). Can anyone give me any tips on good formats to save to or class designs that make saving state easier?

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• Sort a list of pointers.

  - by YuppieNetworking

  Hello all, Once again I find myself failing at some really simple task in C++. Sometimes I wish I could de-learn all I know from OO in java, since my problems usually start by thinking like Java. Anyways, I have a std::list<BaseObject*> that I want to sort. Let's say that BaseObject is: class BaseObject { protected: int id; public: BaseObject(int i) : id(i) {}; virtual ~BaseObject() {}; }; I can sort the list of pointer to BaseObject with a comparator struct: struct Comparator { bool operator()(const BaseObject* o1, const BaseObject* o2) const { return o1->id < o2->id; } }; And it would look like this: std::list<BaseObject*> mylist; mylist.push_back(new BaseObject(1)); mylist.push_back(new BaseObject(2)); // ... mylist.sort(Comparator()); // intentionally omitted deletes and exception handling Until here, everything is a-ok. However, I introduced some derived classes: class Child : public BaseObject { protected: int var; public: Child(int id1, int n) : BaseObject(id1), var(n) {}; virtual ~Child() {}; }; class GrandChild : public Child { public: GrandChild(int id1, int n) : Child(id1,n) {}; virtual ~GrandChild() {}; }; So now I would like to sort following the following rules: For any Child object c and BaseObject b, b<c To compare BaseObject objects, use its ids, as before. To compare Child objects, compare its vars. If they are equal, fallback to rule 2. GrandChild objects should fallback to the Child behavior (rule 3). I initially thought that I could probably do some casts in Comparator. However, this casts away constness. Then I thought that probably I could compare typeids, but then everything looked messy and it is not even correct. How could I implement this sort, still using list<BaseObject*>::sort ? Thank you

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• Refactoring Singleton Overuse

  - by drharris

  Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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• How can I represent a line of music notes in a way that allows fast insertion at any index?

  - by chairbender

  For "fun", and to learn functional programming, I'm developing a program in Clojure that does algorithmic composition using ideas from this theory of music called "Westergaardian Theory". It generates lines of music (where a line is just a single staff consisting of a sequence of notes, each with pitches and durations). It basically works like this: Start with a line consisting of three notes (the specifics of how these are chosen are not important). Randomly perform one of several "operations" on this line. The operation picks randomly from all pairs of adjacent notes that meet a certain criteria (for each pair, the criteria only depends on the pair and is independent of the other notes in the line). It inserts 1 or several notes (depending on the operation) between the chosen pair. Each operation has its own unique criteria. Continue randomly performing these operations on the line until the line is the desired length. The issue I've run into is that my implementation of this is quite slow, and I suspect it could be made faster. I'm new to Clojure and functional programming in general (though I'm experienced with OO), so I'm hoping someone with more experience can point out if I'm not thinking in a functional paradigm or missing out on some FP technique. My current implementation is that each line is a vector containing maps. Each map has a :note and a :dur. :note's value is a keyword representing a musical note like :A4 or :C#3. :dur's value is a fraction, representing the duration of the note (1 is a whole note, 1/4 is a quarter note, etc...). So, for example, a line representing the C major scale starting on C3 would look like this: [ {:note :C3 :dur 1} {:note :D3 :dur 1} {:note :E3 :dur 1} {:note :F3 :dur 1} {:note :G3 :dur 1} {:note :A4 :dur 1} {:note :B4 :dur 1} ] This is a problematic representation because there's not really a quick way to insert into an arbitrary index of a vector. But insertion is the most frequently performed operation on these lines. My current terrible function for inserting notes into a line basically splits the vector using subvec at the point of insertion, uses conj to join the first part + notes + last part, then uses flatten and vec to make them all be in a one-dimensional vector. For example if I want to insert C3 and D3 into the the C major scale at index 3 (where the F3 is), it would do this (I'll use the note name in place of the :note and :dur maps): (conj [C3 D3 E3] [C3 D3] [F3 G3 A4 B4]), which creates [C3 D3 E3 [C3 D3] [F3 G3 A4 B4]] (vec (flatten previous-vector)) which gives [C3 D3 E3 C3 D3 F3 G3 A4 B4] The run time of that is O(n), AFAIK. I'm looking for a way to make this insertion faster. I've searched for information on Clojure data structures that have fast insertion but haven't found anything that would work. I found "finger trees" but they only allow fast insertion at the start or end of the list. Edit: I split this into two questions. The other part is here.

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• Encapsulating a Windows.Forms.Button

  - by devoured elysium

  I want to define a special kind of button that only allows two possible labels: "ON" and "OFF". I decided to inherit from a Windows.Forms.Button to implement this but now I don't know I how should enforce this rule. Should I just override the Text property like this? public override string Text { set { throw new InvalidOperationException("Invalid operation on StartStopButton!"); } } The problem I see with this is that I am breaking the contract that all buttons should have. If any code tries something like foreach (Button button in myForm) { button.Text = "123"; } they will get an Exception if I have any of my special buttons on the form, which is something that isn't expectable. First, because people think of properties just as "public" variables, not methods, second, because they are used to using and setting whatever they want to buttons without having to worry with Exceptions. Should I instead just make the set property do nothing? That could also lead to awkward results: myButton.Text = "abc"; MessageBox.Show(abc); //not "abc"! The general idea from the OO world is to in this kind of cases use Composition instead of inheritance. public class MySpecialButton : <Some class from System.Windows.Forms that already knows how to draw itself on forms> private Button button = new Button(); //I'd just draw this button on this class //and I'd then only show the fields I consider //relevant to the outside world. ... } But to make the Button "live" on a form it must inherit from some special class. I've looked on Control, but it seems to already have the Text property defined. I guess the ideal situation would be to inherit from some kind of class that wouldn't even have the Text property defined, but that'd have position, size, etc properties available. Upper in the hierarchy, after Control, we have Component, but that looks like a really raw class. Any clue about how to achieve this? I know this was a long post :( Thanks

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