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  • Good working habits to observe in project development?

    - by Will Marcouiller
    As my development experience grows, I see fit to stick to best practices from here and there to build somehow my own working practices while observing the conventions, etc. I'm currently working on a project which my goals is to graduate the security access model from an environment's Active Directory to another environment's automatically. I don't know for any of you, but as far as I'm concerned, I meet some real difficulties sticking to only one way, then develop. I mean, I learn something new everyday while visiting SO, and recently wanted to get acquainted with generics. On the other hand, I better know the Façade pattern which proved to be very practical in transactional programming in process systems. This seems to be less practical for desktop application as there are plenty of variables to consider in a desktop application that you don't have to care in transactional programming, as you're playing only with information data. As for my current project, I have: Groups; Organizational Units; Users. Which are all considered an entry in the Active Directory. This points out to be a good candidate for generics, as also approached this way by Bart de Smett's Linq to AD on CodePlex. He has a DirectorySource<T>, and to manage let's say groups, then he instantiate a source with the proper type: var groups = new DirectorySource<Group>(); This seems to be very a good way of doing. Despite, I seem to go from one pattern to another and I don't seem to be able to strictly stick to one. While I'm aware that one must not stay with only one way of doing, since each pattern statisfies certain advantages, while also illustrating disadvantages under some usage conditions, I seem to want to develop with both patterns having a singleton Façade class with the underlying factories which represent the sub systems: GroupsFactory; UsersFactory; OrganizationalUnitsFactory. Each of the factories offers the possible operations for their respective entity (group, user, OU). To make a very long story short, I often have plenty of ideas while developping and this causes me some trouble, as I go from an idea to another feeling completely lost after a while. Yet I understand the advantages and disavantages, I have no trouble choosing from one pattern to another depending on the situation. Nevertheless, when it comes to programming itself, if I'm not part of a team, I feel sometimes like I can't do anything good. That is, because I can't stand not doing something "perfect" the first time. The role I play within the project is both: the project manager and the programmer. I am more comfortable in the project manager role, architectural role, analytical role than the developer's. Has any of you some good habbits to observe in project development? Thanks to you all! =)

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  • Multiple infowindows - tearing my hair out

    - by thewinchester
    Ok, I'll admit I'm nowhere near the best programmer on the planet - and I'm used to the answer staring me right in the face but not making sense of it. Problem I need to display multiple markers on a map, each with their own infowindow. I have created the individual markers without a problem, but don't know how to create the infowindows for each. Steps so far I am generating a map using the V3 API within an ASP-based website, with markers being created from a set of DB records. The markers are created by looping through a rs and defining a marker() with the relevant variables: var myLatlng = new google.maps.LatLng(lat,long); var marker = new google.maps.Marker({ map: map, position: myLatlng, title: 'locationname', icon: 'http://google-maps-icons.googlecode.com/files/park.png' }); This is creating all the relevant markers in their correct locations. What I need to do now, and am not sure of how to achieve is give each of them their own unique infowindow which I can use to display information and links relevant to that marker. Source <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=false"></script> <script language="javascript"> $(document).ready(function() { //Google Maps var myOptions = { zoom: 5, center: new google.maps.LatLng(-26.66, 122.25), mapTypeControl: false, mapTypeId: google.maps.MapTypeId.ROADMAP, navigationControl: true, navigationControlOptions: { style: google.maps.NavigationControlStyle.SMALL } } var map = new google.maps.Map(document.getElementById("map_canvas"), myOptions); <!-- While locations_haslatlong not BOF.EOF --> <% While ((Repeat1__numRows <> 0) AND (NOT locations_haslatlong.EOF)) %> var myLatlng = new google.maps.LatLng(<%=(locations_haslatlong.Fields.Item("llat").Value)%>,<%=(locations_haslatlong.Fields.Item("llong").Value)%>); var marker = new google.maps.Marker({ map: map, position: myLatlng, title: '<%=(locations_haslatlong.Fields.Item("ldescription").Value)%>', icon: 'http://google-maps-icons.googlecode.com/files/park.png', clickable: true, }); <% Repeat1__index=Repeat1__index+1 Repeat1__numRows=Repeat1__numRows-1 locations_haslatlong.MoveNext() Wend %> <!-- End While locations_haslatlong not BOF.EOF --> google.maps.event.addListener(marker, 'click', function() { infowindow.open(map,marker); }); google.maps.event.addListener(marker, 'dblclick', function() { map.setZoom(14); }); });

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  • Autocomplete server-side implementation

    - by toluju
    What is a fast and efficient way to implement the server-side component for an autocomplete feature in an html input box? I am writing a service to autocomplete user queries in our web interface's main search box, and the completions are displayed in an ajax-powered dropdown. The data we are running queries against is simply a large table of concepts our system knows about, which matches roughly with the set of wikipedia page titles. For this service obviously speed is of utmost importance, as responsiveness of the web page is important to the user experience. The current implementation simply loads all concepts into memory in a sorted set, and performs a simple log(n) lookup on a user keystroke. The tailset is then used to provide additional matches beyond the closest match. The problem with this solution is that it does not scale. It currently is running up against the VM heap space limit (I've set -Xmx2g, which is about the most we can push on our 32 bit machines), and this prevents us from expanding our concept table or adding more functionality. Switching to 64-bit VMs on machines with more memory isn't an immediate option. I've been hesitant to start working on a disk-based solution as I am concerned that disk seek time will kill performance. Are there possible solutions that will let me scale better, either entirely in memory or with some fast disk-backed implementations? Edits: @Gandalf: For our use case it is important the the autocompletion is comprehensive and isn't just extra help for the user. As for what we are completing, it is a list of concept-type pairs. For example, possible entries are [("Microsoft", "Software Company"), ("Jeff Atwood", "Programmer"), ("StackOverflow.com", "Website")]. We are using Lucene for the full search once a user selects an item from the autocomplete list, but I am not yet sure Lucene would work well for the autocomplete itself. @Glen: No databases are being used here. When I'm talking about a table I just mean the structured representation of my data. @Jason Day: My original implementation to this problem was to use a Trie, but the memory bloat with that was actually worse than the sorted set due to needing a large number of object references. I'll read on the ternary search trees to see if it could be of use.

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  • Recommended textbook for machine-level programming?

    - by Norman Ramsey
    I'm looking at textbooks for an undergraduate course in machine-level programming. If the perfect book existed, this is what it would look like: Uses examples written in C or assembly language, or both. Covers machine-level operations such as two's-complement integer arithmetic, bitwise operations, and floating-point arithmetic. Explains how caches work and how they affect performance. Explains machine instructions or assembly instructions. Bonus if the example assembly language includes x86; triple bonus if it includes x86-64 (aka AMD64). Explains how C values and data structures are represented using hardware registers and memory. Explains how C control structures are translated into assembly language using conditional and unconditional branch instructions. Explains something about procedure calling conventions and how procedure calls are implemented at the machine level. Books I might be interested in would probably have the words "machine organization" or "computer architecture" in the title. Here are some books I'm considering but am not quite happy with: Computer Systems: A Programmer's Perspective by Randy Bryant and Dave O'Hallaron. This is quite a nice book, but it's a book for a broad, shallow course in systems programming, and it contains a great deal of material my students don't need. Also, it is just out in a second edition, which will make it expensive. Computer Organization and Design: The Hardware/Software Interface by Dave Patterson and John Hennessy. This is also a very nice book, but it contains way more information about how the hardware works than my students need. Also, the exercises look boring. Finally, it has a show-stopping bug: it is based very heavily on MIPS hardware and the use of a MIPS simulator. My students need to learn how to use DDD, and I can't see getting this to work on a simulator. Not to mention that I can't see them cross-compiling their code for the simulator, and so on and so forth. Another flaw is that the book mentions the x86 architecture only to sneer at it. I am entirely sympathetic to this point of view, but news flash! You guys lost! Write Great Code Vol I: Understanding the Machine by Randall Hyde. I haven't evaluated this book as thoroughly as the other two. It has a lot of what I need, but the translation from high-level language to assembler is deferred to Volume Two, which has mixed reviews. My students will be annoyed if I make them buy a two-volume series, even if the price of those two volumes is smaller than the price of other books. I would really welcome other suggestions of books that would help students in a class where they are to learn how C-language data structures and code are translated to machine-level data structures and code and where they learn how to think about performance, with an emphasis on the cache.

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  • USB windows xp final USB access issues

    - by Lex Dean
    I basically understand you C++ people, Please do not get distracted because I'm writing in Delphi. I have a stable USB Listing method that accesses all my USB devices I get the devicepath, and this structure: TSPDevInfoData = packed record Size: DWORD; ClassGuid: TGUID; DevInst: DWORD; // DEVINST handle Reserved: DWord; end; I get my ProductID and VenderID successfully from my DevicePath Lists all USB devices connected to the computer at the time That enables me to access the registry data to each device in a stable way. What I'm lacking is a little direction Is friendly name able to be written inside the connected USB Micro chips by the firmware programmer? (I'm thinking of this to identify the device even further, or is this to help identify Bulk data transfer devices like memory sticks and camera's) Can I use SPDRP_REMOVAL_POLICY_OVERRIDE to some how reset these polices What else can I do with the registry details. Identifying when some one unplugs a device The program is using (in windows XP standard) I used a documented windows event that did not respond. Can I read a registry value to identify if its still connected? using CreateFileA (DevicePath) to send and receive data I have read when some one unplugs in the middle of a data transfer its difficult clearing resources. what can IoCreateDevice do for me and how does one use it for that task This two way point of connection status and system lock up situations is very concerning. Has some one read anything about this subject recently? My objectives are to 1. list connected USB devices identify a in development Micro Controller from everything else send and receive data in a stable and fast way to the limits of the controller No lock up's transferring data Note I'm not using any service packs I understand everything USB is in ANSI when windows xp is not and .Net is all about ANSI (what a waste of memory) I plan to continue this project into a .net at a later date as an addition. MSDN gives me Structures and Functions and what should link to what ok but say little to what they get used for. What is available in my language Delphi is way over priced that it needs a major price drop.

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  • Function Point Analysis -- a seriously overestimating technique?

    - by kizzx2
    I know questions about FPA has been asked numerous times before, but this time I'm taking a more analytical angle at it, backed up with data. 1. First, some data This question is based on a tutorial. He had a "Sample Count" section where he demonstrated it step by step. You can see some screenshots of his sample application here. In the end, he calculated the unadjusted FP to be 99. There is another article on InformIT with industry data on typical hour/FP. It ranges from 2 hours/FP to 27.4 hours/FP. Let's try to stick with 2 for the moment (since SO readers are probably the more efficient crowd :p). 2. Reality check!? Now just check out the screenshots again. Do a little math here 99 * 2 = 198 hours 198 hours / 40 hours per week = 5 weeks Seriously? That sample application is going to take 5 weeks to implement? Is it just my feeling that it wouldn't take any decent programmer longer than one week (I"m not even saying weekend) to have it completed? Now let's try estimating the cost of the project. We'll use New York's minimum wage at the moment (Wikipedia), which is $7.25 198 * 7.25 = $1435.5 From what I could see from the screenshots, this application is a small excel-improvement app. I could have bought MS Office Pro for 200 bucks which gives me greater interoperability (.xls files) and flexibility (spreadsheets). (For the record, that same Web site has another article discussing productivity. It seems like they typically use 4.2 hours/FP, which gives us even more shocking stats: 99 * 4.2 = 415 hours = 10 weeks = almost 3 whopping months! 415 hours * $7.25 = $3000 zomg (That's even assuming that all our poor coders get the minimum wage!) 3. Am I missing something here? Right now, I could come up with several possible explanation: FPA is really only suited for bigger projects (1000+ FPs) so it becomes extremely inaccurate at smaller scale. The hours/FP metric fluctuates abruptly from team to team, project to project. For a small project like this, we could have used something like 0.5 hour/FP or something. (Now this kind of makes the whole estimation thing pointless, unless my firm does the same type of projects for several years with the same team, not really common.) From my experience with several software metrics, Function Point is really not a lightweight metric. If the hour/FP thing fluctuates so much, then what's the point, maybe I could have gone with User Story Points which is a lot faster to get and arguably almost as uncertain. What would be the FP experts' answers to this?

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  • Matching array elements to get an array element at another index

    - by bccarlso
    I have a PHP array that I'm using to generate an HTML form. The PHP array is this: <?php $vdb = array ( array( "Alabama", 275), array( "Alaska", 197), array( "Arizona", 3322)); ?> The PHP to generate the HTML form is below. I need to have the value be the name of the state, because there is some AJAX I'm using to display which states a user has chosen. <?php echo "<table border='1'><thead><tr><th></th><th>State</th><th>Contacts</th><th>Email</th></tr></thead>"; for ($row = 0; $row < 42; $row++) { echo "<tr><td class='input_button'><input type='checkbox' name='vdb[]' value='".$vdb[$row][0]."' title='".$vdb[$row][1]."' /></td>"; echo "<td>".$vdb[$row][0]."</td>"; echo "<td>".$vdb[$row][1]."</td>"; } echo "</table>"; ?> What I'm trying to do is, on submission of the form, with the states the user selected, loop through the PHP array and total the numbers from the selected states. So if I checked Alabama and Alaska, I'd want to add 275 + 197. This is what I thought would have worked, but it's not: <?php $vendors = array(); if (isset($_POST["vdb"])) { $vendors = $_POST["vdb"]; } $ven_i = 0; $ven_j = 0; $ven_total = 0; foreach ($vendors as $value) { foreach ($vdb as $vdb_value) { if ($vendors[$ven_i] == $vdb[$ven_j][0]) { $ven_total += $vdb[$ven_j][1]; } $ven_j++; } $ven_i++; } ?> and then $ven_total should be the total I'm looking for. However, $ven_total just ends up being the first checkbox selected, and it ignores the rest. I am doing this correctly with the AJAX, displaying the total on the front end, but I don't know how to pass that on to the form submission. I'd rather not using GET and URL variables, because a user could type something into the URL and modify the count. Any idea what I'm doing wrong, or a better way to approach this that I would be able to understand? (Very much a novice programmer.)

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  • help Implementing Object Oriented ansi-C approach??

    - by No Money
    Hey there, I am an Intermediate programmer in Java and know some of the basics in C++. I recently started to scam over "C language" [please note that i emphasized on C language and want to stick with C as i found it to be a perfect tool, so no need for suggestions focusing on why should i move back to C++ or Java]. Moving on, I code an Object Oriented approach in C but kindda scramble with the pointers part. Please understand that I am just a noob trying to extend my knowledge beyond what i learned in High School. Here is my code..... #include <stdio.h> typedef struct per{ int privateint; char *privateString; struct per (*New) (); void (*deleteperOBJ) (struct t_person *); void (*setperNumber) ((struct*) t_person,int); void (*setperString) ((struct*) t_person,char *); void (*dumpperState) ((struct*) t_person); }t_person; void setperNumber(t_person *const per,int num){ if(per==NULL) return; per->privateint=num; } void setperString(t_person *const per,char *string){ if(per==NULL) return; per->privateString=string; } void dumpperState(t_person *const per){ if(per==NULL) return; printf("value of private int==%d\n", per->privateint); printf("value of private string==%s\n", per->privateString); } void deleteperOBJ(struct t_person *const per){ free((void*)t_person->per); t_person ->per = NULL; } main(){ t_person *const per = (struct*) malloc(sizeof(t_person)); per = t_person -> struct per -> New(); per -> setperNumber (t_person *per, 123); per -> setperString(t_person *per, "No money"); dumpperState(t_person *per); deleteperOBJ(t_person *per); } Just to warn you, this program has several errors and since I am a beginner I couldn't help except to post this thread as a question. I am looking forward for assistance. Thanks in advance.

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  • How to check for palindrome using Python logic

    - by DrOnline
    My background is only a 6 month college class in basic C/C++, and I'm trying to convert to Python. I may be talking nonsense, but it seems to me C, at least at my level, is very for-loop intensive. I solve most problems with these loops. And it seems to me the biggest mistake people do when going from C to Python is trying to implement C logic using Python, which makes things run slowly, and it's just not making the most of the language. I see on this website: http://hyperpolyglot.org/scripting (serach for "c-style for", that Python doesn't have C-style for loops. Might be outdated, but I interpret it to mean Python has its own methods for this. I've tried looking around, I can't find much up to date (Python 3) advice for this. How can I solve a palindrome challenge in Python, without using the for loop? I've done this in C in class, but I want to do it in Python, on a personal basis. The problem is from the Euler Project, great site btw. def isPalindrome(n): lst = [int(n) for n in str(n)] l=len(lst) if l==0 || l==1: return True elif len(lst)%2==0: for k in range (l) ##### else: while (k<=((l-1)/2)): if (list[]): ##### for i in range (999, 100, -1): for j in range (999,100, -1): if isPalindrome(i*j): print(i*j) break I'm missing a lot of code here. The five hashes are just reminders for myself. Concrete questions: 1) In C, I would make a for loop comparing index 0 to index max, and then index 0+1 with max-1, until something something. How to best do this in Python? 2) My for loop (in in range (999, 100, -1), is this a bad way to do it in Python? 3) Does anybody have any good advice, or good websites or resources for people in my position? I'm not a programmer, I don't aspire to be one, I just want to learn enough so that when I write my bachelor's degree thesis (electrical engineering), I don't have to simultaneously LEARN an applicable programming language while trying to obtain good results in the project. "How to go from basic C to great application of Python", that sort of thing. 4) Any specific bits of code to make a great solution to this problem would also be appreciated, I need to learn good algorithms.. I am envisioning 3 situations. If the value is zero or single digit, if it is of odd length, and if it is of even length. I was planning to write for loops... PS: The problem is: Find the highest value product of two 3 digit integers that is also a palindrome.

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  • Need a fast programming language that can drive two printers

    - by Pete
    I have a rather unusual application that isn't working the way I need, and I hope someone here will have some suggestions or at least a direction to investigate. We have a museum exhibit that has a computer at the entrance driving two small receipt printers. There are two buttons on a console, wired to the left and right buttons of a disemboweled mouse. The two printers and associated buttons are for girls and boys, each button does a random selection from a database of names and prints a small ticket on the appropriate printer with a graphic image, a few words about the exhibit and the randomly chosen name. Conceptually all is well, but it hangs quite often. I got the project at the last minute, because the original designer got bogged down and couldn't deliver, so the exhibit's author asked me the day before opening, whether I could write something that would work. I did it in Word, since I am an experienced VBA programmer. Several other avenues I attempted first all lead to dead ends - one couldn't do graphics, another couldn't handle two printers, yet another couldn't change fonts and so on. The problem is that it simply isn't fast enough - Word can only drive one printer at a time and changing the active printer takes a long time. Not by office standards, where a second or two of delay before a printer starts working on your document is not an issue, but here I need more or less instant response. If kids press a button and nothing happens, they press it over and over until something does happen, resulting in maybe half a dozen commands being sent before the printer starts reacting. Sometimes it jams the program completely, since boys and girls will be pressing the two buttons simultaneously and Word locks up, and even when it doesn't jam, the printers then spit out a stream of tickets, making a mess. The kids start squabbling over which ticket is whose, pulling them out of the printers, snarling the paper tape, jamming the printer and generally making a mess of the whole affair, often necessitating the exhibit caretakers having to restart the computer and clear torn bits of paper out the printers. What I need is some sort of fast programming language that can drive two printers *-simultaneously-*, not the MSOffice claptrap of having to switch the active printer, that can react to both left and right mouse button click events, can print a small graphic image and can print in different font sizes and styles and. I don't need many, but it's not all in one typeface. Can anyone suggest what I might use for this? I don't even know if it's possible at all under Windows, whether the "single active printer" garbage is an Office artifact, or a Windows restriction. My little Commodore-64 twenty-five years ago had two printers attached to it and drove both simultaneously with no difficulties - it doesn't seem to me it should be such an impossible requirement today.

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  • Do You Really Know Your Programming Languages?

    - by Kristopher Johnson
    I am often amazed at how little some of my colleagues know or care about their craft. Something that constantly frustrates me is that people don't want to learn any more than they need to about the programming languages they use every day. Many programmers seem content to learn some pidgin sub-dialect, and stick with that. If they see a keyword or construct that they aren't familiar with, they'll complain that the code is "tricky." What would you think of a civil engineer who shied away from calculus because it had "all those tricky math symbols?" I'm not suggesting that we all need to become "language lawyers." But if you make your living as a programmer, and claim to be a competent user of language X, then I think at a minimum you should know the following: Do you know the keywords of the language and what they do? What are the valid syntactic forms? How are memory, files, and other operating system resources managed? Where is the official language specification and library reference for the language? The last one is the one that really gets me. Many programmers seem to have no idea that there is a "specification" or "standard" for any particular language. I still talk to people who think that Microsoft invented C++, and that if a program doesn't compile under VC6, it's not a valid C++ program. Programmers these days have it easy when it comes to obtaining specs. Newer languages like C#, Java, Python, Ruby, etc. all have their documentation available for free from the vendors' web sites. Older languages and platforms often have standards controlled by standards bodies that demand payment for specs, but even that shouldn't be a deterrent: the C++ standard is available from ISO for $30 (and why am I the only person I know who has a copy?). Programming is hard enough even when you do know the language. If you don't, I don't see how you have a chance. What do the rest of you think? Am I right, or should we all be content with the typical level of programming language expertise? Update: Several great comments here. Thanks. A couple of people hit on something that I didn't think about: What really irks me is not the lack of knowledge, but the lack of curiosity and willingness to learn. It seems some people don't have any time to hone their craft, but they have plenty of time to write lots of bad code. And I don't expect people to be able to recite a list of keywords or EBNF expressions, but I do expect that when they see some code, they should have some inkling of what it does. Few people have complete knowledge of every dark corner of their language or platform, but everyone should at least know enough that when they see something unfamiliar, they will know how to get whatever additional information they need to understand it.

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  • Chrome extension - Localstorage not working

    - by Bjarki Jonasson
    I'm writing a Chrome extension that uses a content script to modify certain parts of a website. The content script worked fine until I tried to add an options page to my extension. Right now I'm using an options.html file to save user preferences to localstorage, as you can see here: <html> <head><title>Options</title></head> <script type="text/javascript"> function save_options() { var select = document.getElementById("width"); var width = select.children[select.selectedIndex].value; localStorage["site_width"] = width; } function restore_options() { var fwidth = localStorage["site_width"]; if (!fwidth) { return; } var select = document.getElementById("width"); for (var i = 0; i < select.children.length; i++) { var child = select.children[i]; if (child.value == fwidth) { child.selected = "true"; break; } } } </script> <body onload="restore_options()"> Width: <select id="width"> <option value="100%">100%</option> <option value="90%">90%</option> <option value="80%">80%</option> <option value="70%">70%</option> </select> <br> <button onclick="save_options()">Save</button> </body> </html> I also have a background.html file to handle the communication between the content script and the localstorage: <html> <script type="text/javascript"> chrome.extension.onRequest.addListener(function(request, sender, sendResponse) { if (request.method == "siteWidth") sendResponse({status: localStorage["site_width"]}); else sendResponse({}); }); </script> </html> Then there's the actual content script that looks like this: var Width; chrome.extension.sendRequest({method: "siteWidth"}, function(response) { width = response.status; }); None of that code actually works. It looks solid enough to me but I'm not a very experienced programmer so I might be wrong. Could someone explain localstorage to me in layman's terms?

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  • Implementing Object Oriented: ansi-C approach

    - by No Money
    Hey there, I am an Intermediate programmer in Java and know some of the basics in C++. I recently started to scam over "C language" [please note that i emphasized on C language and want to stick with C as i found it to be a perfect tool, so no need for suggestions focusing on why should i move back to C++ or Java or any other crappy language (e.g: C#)]. Moving on, I code an Object Oriented approach in C but kindda scramble with the pointers part. Please understand that I am just a noob trying to extend my knowledge beyond what i learned in High School. Here is my code..... #include <stdio.h> typedef struct per{ int privateint; char *privateString; struct per (*New) (); void (*deleteperOBJ) (struct t_person *); void (*setperNumber) ((struct*) t_person,int); void (*setperString) ((struct*) t_person,char *); void (*dumpperState) ((struct*) t_person); }t_person; void setperNumber(t_person *const per,int num){ if(per==NULL) return; per->privateint=num; } void setperString(t_person *const per,char *string){ if(per==NULL) return; per->privateString=string; } void dumpperState(t_person *const per){ if(per==NULL) return; printf("value of private int==%d\n", per->privateint); printf("value of private string==%s\n", per->privateString); } void deleteperOBJ(struct t_person *const per){ free((void*)t_person->per); t_person ->per = NULL; } main(){ t_person *const per = (struct*) malloc(sizeof(t_person)); per = t_person -> struct per -> New(); per -> setperNumber (t_person *per, 123); per -> setperString(t_person *per, "No money"); dumpperState(t_person *per); deleteperOBJ(t_person *per); } Just to warn you, this program has several errors and since I am a beginner I couldn't help except to post this thread as a question. I am looking forward for assistance. Thanks in advance.

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  • C++ Class Access Specifier Verbosity

    - by PolyTex
    A "traditional" C++ class (just some random declarations) might resemble the following: class Foo { public: Foo(); explicit Foo(const std::string&); ~Foo(); enum FooState { Idle, Busy, Unknown }; FooState GetState() const; bool GetBar() const; void SetBaz(int); private: struct FooPartialImpl; void HelperFunction1(); void HelperFunction2(); void HelperFunction3(); FooPartialImpl* m_impl; // smart ptr FooState m_state; bool m_bar; int m_baz; }; I always found this type of access level specification ugly and difficult to follow if the original programmer didn't organize his "access regions" neatly. Taking a look at the same snippet in a Java/C# style, we get: class Foo { public: Foo(); public: explicit Foo(const std::string&); public: ~Foo(); public: enum FooState { Idle, Busy, Unknown }; public: FooState GetState() const; public: bool GetBar() const; public: void SetBaz(int); private: struct FooPartialImpl; private: void HelperFunction1(); private: void HelperFunction2(); private: void HelperFunction3(); private: FooPartialImpl* m_impl; // smart ptr private: FooState m_state; private: bool m_bar; private: int m_baz; }; In my opinion, this is much easier to read in a header because the access specifier is right next to the target, and not a bunch of lines away. I found this especially true when working with header-only template code that wasn't separated into the usual "*.hpp/*.inl" pair. In that scenario, the size of the function implementations overpowered this small but important information. My question is simple and stems from the fact that I've never seen anyone else actively do this in their C++ code. Assuming that I don't have a "Class View" capable IDE, are there any obvious drawbacks to using this level of verbosity? Any other style recommendations are welcome!

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  • Coping with feelings of technical mediocrity

    - by Karim
    As I've progressed as a programmer, I noticed more nuance and areas I could study in depth. In part, I've come to think of myself from, at one point, a "guru" to now much less, even mediocre or inadequate. Is this normal, or is it a sign of a destructive excessive ambition? Background I started to program when I was still a kid, I had about 10 or 11 years. I really enjoy my work and never get bored from it. It's amazing how somebody could be paid for what he really likes to do and would be doing it anyway even for free. When I first started to program, I was feeling proud of what I was doing, each application I built was for me a success and after 2-3 year I had a feeling that I'm a coding guru. It was a nice feeling. ;-) But the more I was in the field and the more types of software I started to develop, I was starting to have a feeling that I'm completely wrong in thinking I'm a guru. I felt that I'm not even a mediocre developer. Each new field I start to work on is giving me this feeling. Like when I once developed a device driver for a client, I saw how much I need to learn about device drivers. When I developed a video filter for an application, I saw how much do I still need to learn about DirectShow, Color Spaces, and all the theory behind that. The worst thing was when I started to learn algorithms. It was several years ago. I knew then the basic structures and algorithms like the sorting, some types of trees, some hashtables, strings, etc. and when I really wanted to learn a group of structures I learned about 5-6 new types and saw that in fact even this small group has several hundred subtypes of structures. It's depressing how little time people have in their lives to learn all this stuff. I'm now a software developer with about 10 years of experience and I still feel that I'm not a proficient developer when I think about things that others do in the industry.

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  • Java loading user-specified classes at runtime

    - by user349043
    I'm working on robot simulation in Java (a Swing application). I have an abstract class "Robot" from which different types of Robots are derived, e.g. public class StupidRobot extends Robot { int m_stupidness; int m_insanityLevel; ... } public class AngryRobot extends Robot { float m_aggression; ... } As you can see, each Robot subclass has a different set of parameters. What I would like to do is control the simulation setup in the initial UI. Choose the number and type of Robots, give it a name, fill in the parameters etc. This is one of those times where being such a dinosaur programmer, and new to Java, I wonder if there is some higher level stuff/thinking that could help me here. So here is what I've got: (1) User Interface Scrolling list of Robot types on the left. "Add " and "<< Remove" buttons in the middle. Default-named scrolling list of Robots on the right. "Set Parameters" button underneath. (So if you wanted an AngryRobot, you'd select AngryRobot on the left list, click "Add" and "AngryRobot1" would show up on the right.) When selecting a Robot on the right, click "Set Parameters..." button which would call yet another model dialog where you'd fill in the parameters. Different dialog called for each Robot type. (2) Data structures an implementation As an end-product I think a HashMap would be most convenient. The keys would be Robot types and the accompanying object would be all of the parameters. The initializer could just retrieve each item one and a time and instantiate. Here's what the data structures would look like: enum ROBOT_TYPE {STUPID, ANGRY, etc} public class RobotInitializer { public ROBOT_TYPE m_type; public string m_name; public int[] m_int_params; public float[] m_float_params; etc. The initializer's constructor would create the appropriate length parameter arrays based on the type: public RobotInitializer(ROBOT_TYPE type, int[] int_array, float[] float_array, etc){ switch (type){ case STUPID: m_int_params = new int[STUPID_INT_PARAM_LENGTH]; System.arraycopy(int_array,0,m_int_params,0,STUPID_INT_PARAM_LENGTH); etc. Once all the RobotInitializers are instantiated, they are added to the HashMap. Iterating through the HashMap, the simulation initializer takes items from the Hashmap and instantiates the appropriate Robots. Is this reasonable? If not, how can it be improved? Thanks

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  • A case-insensitive related implementation problem

    - by Robert
    Hi All, I am going through a final refinement posted by the client, which needs me to do a case-insesitive query. I will basically walk through how this simple program works. First of all, in my Java class, I did a fairly simple webpage parsing: title=(String)results.get("title"); doc = docBuilder.parse("http://" + server + ":" + port + "/exist/rest/db/wb/xql/media_lookup.xql?" + "&title=" + title); This Java statement references an XQuery file "media_lookup.xql" which is stored on localhost, and the only parameter we are passing is the string "title". Secondly, let's take at look at that XQuery file: $title := request:get-parameter('title',""), $mediaNodes := doc('/db/wb/portfolio/media_data.xml'), $query := $mediaNodes//media[contains(title,$title)], Then it will evaluate that query. This XQuery will get the "title" parameter that are passes from our Java class, and query the "media_data" xml file stored in the database, which contains a bunch of media nodes with a 'title' element node. As you may expect, this simple query will just match those media nodes whose 'title' element contains a substring of what the value of string 'title' is. So if our 'title' is "Chi", it will return media nodes whose title may be "Chicago" or "Chicken". The refinment request posted by the client is that there should be NO case-sensitivity. The very intuitive way is to modify the XQuery statement by using a lower-case funtion in it, like: $query := $mediaNodes//media[contains(lower-case(title/text(),lower-case($title))], However, the question comes: this modified query will run my machine into memory overflow. Since my "media_data.xml" is quite huge and contains thouands of millions of media nodes, I assume the lower-case() function will run on each of the entries, thus causing the machine to crash. I've talked with some experienced XQuery programmer, and they think I should use an index to solve this problem, and I will definitely research into that. But before that, I am just posting this problem here to get other ideas or any suggestions, do you think any other way may help? for example, could I tweak the Java parse statement to realize the case-insensitivity? Since I think I saw some people did some string concatination by using "contains." in Java before passing it to the server. Any idea or help is welcomed, thanks in advance.

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  • web design PSD to html -> more direct ways?

    - by Assembler
    At work I see one colleague designing a site in Photoshop/Fireworks, I see another taking this data, slicing it up and using Dreamweaver to rebuild the same from scratch. It seems like too much mucking around! I know that Photoshop can output a tables based HTML, and Fireworks will create divs with absolute positioning; neither appear to be very helpful. Admittedly, I haven't tried much of (DW/FW) (CS4/CS3) since becoming a programmer, so I don't know if new versions are addressing this work flow issue, but are we still double handling things? Can we attach some sort of layout metadata (this is a rollover button, this will be a SWF, this will be text, this logo will hide "xyz" <h1> text etc) to slices to aid in layout generation? are there some secret tools which assist in this conversion process? Or are we still restricted to doing things by hand? The frustration continues when said hand built page needs to be reworked again to fit Smarty Templates/Wordpress/generic CMS. I acknowledge that designers need to be free of systems to be able to do whatever, but most conventional sites have: a header with navigation a sidebar with more links the main content part maybe another sidebar a footer Given the similarity of a lot of components, shouldn't there be a more systematic approach to going from sliced designs to functional HTML? Or am I over-simplifying things? -edit- Mmmmm.... I suppose I will accept an answer, but they weren't really what I was looking for. It just seems like designing the DOM is a bit of holy grail ("It's only a model!"), and maybe with all the "groovy" things you can do with HTML and Javascript, it would be mighty hard work, but with a set of constraints (that 960 stuff looks interesting), some well designed reset style sheets and a bit of... fairy dust? we should be able to improve the work flow. Photoshop's tables by themselves are pretty much useless, I agree, but surely we can take this data, and then select a group of cells and say "right, this is a text div, overflow:auto" or "these cells are an image block, style it with the same height/width as the selected area". Admittedly here at work there are other elephants in the room that need to make their formal introductions to management, but some parts of the designpage workflow seem... uneducated at best.

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  • Why do we have reinterpret_cast in C++ when two chained static_cast can do it's job?

    - by Nawaz
    Say I want to cast A* to char* and vice-versa, we have two choices (I mean, many of us think we've two choices, because both seems to work! Hence the confusion!): struct A { int age; char name[128]; }; A a; char *buffer = static_cast<char*>(static_cast<void*>(&a)); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 Both work fine. //convert back A *pA = static_cast<A*>(static_cast<void*>(buffer)); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Even this works fine! So why do we have reinterpret_cast in C++ when two chained static_cast can do it's job? Some of you might think this topic is a duplicate of the previous topics such as listed at the bottom of this post, but it's not. Those topics discuss only theoretically, but none of them gives even a single example demonstrating why reintepret_cast is really needed, and two static_cast would surely fail. I agree, one static_cast would fail. But how about two? If the syntax of two chained static_cast looks cumbersome, then we can write a function template to make it more programmer-friendly: template<class To, class From> To any_cast(From v) { return static_cast<To>(static_cast<void*>(v)); } And then we can use this, as: char *buffer = any_cast<char*>(&a); //choice 1 char *buffer = reinterpret_cast<char*>(&a); //choice 2 //convert back A *pA = any_cast<A*>(buffer); //choice 1 A *pA = reinterpret_cast<A*>(buffer); //choice 2 Also, see this situation where any_cast can be useful: Proper casting for fstream read and write member functions. So my question basically is, Why do we have reinterpret_cast in C++? Please show me even a single example where two chained static_cast would surely fail to do the same job? Which cast to use; static_cast or reinterpret_cast? Cast from Void* to TYPE* : static_cast or reinterpret_cast

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  • Are there any platforms where using structure copy on an fd_set (for select() or pselect()) causes p

    - by Jonathan Leffler
    The select() and pselect() system calls modify their arguments (the 'struct fd_set *' arguments), so the input value tells the system which file descriptors to check and the return values tell the programmer which file descriptors are currently usable. If you are going to call them repeatedly for the same set of file descriptors, you need to ensure that you have a fresh copy of the descriptors for each call. The obvious way to do that is to use a structure copy: struct fd_set ref_set_rd; struct fd_set ref_set_wr; struct fd_set ref_set_er; ... ...code to set the reference fd_set_xx values... ... while (!done) { struct fd_set act_set_rd = ref_set_rd; struct fd_set act_set_wr = ref_set_wr; struct fd_set act_set_er = ref_set_er; int bits_set = select(max_fd, &act_set_rd, &act_set_wr, &act_set_er, &timeout); if (bits_set > 0) { ...process the output values of act_set_xx... } } My question: Are there any platforms where it is not safe to do a structure copy of the struct fd_set values as shown? I'm concerned lest there be hidden memory allocation or anything unexpected like that. (There are macros/functions FD_SET(), FD_CLR(), FD_ZERO() and FD_ISSET() to mask the internals from the application.) I can see that MacOS X (Darwin) is safe; other BSD-based systems are likely to be safe, therefore. You can help by documenting other systems that you know are safe in your answers. (I do have minor concerns about how well the struct fd_set would work with more than 8192 open file descriptors - the default maximum number of open files is only 256, but the maximum number is 'unlimited'. Also, since the structures are 1 KB, the copying code is not dreadfully efficient, but then running through a list of file descriptors to recreate the input mask on each cycle is not necessarily efficient either. Maybe you can't do select() when you have that many file descriptors open, though that is when you are most likely to need the functionality.) There's a related SO question - asking about 'poll() vs select()' which addresses a different set of issues from this question.

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  • Create a Counter within a For-Loop?

    - by Todd Hartman
    I am a novice programmer and apologize upfront for the complicated question. I am trying to create a lexical decision task for experimental research, in which respondents must decide if a series of letters presented on the screen make a "word" or "not a word". Everything works reasonably well except for the bit where I want to randomly select a word (category A) or nonword (category B) for each of 80 trials from a separate input file (input.txt). The randomization works, but some elements from each list (category A or B) are skipped because I have used "round.catIndex = j;" where "j" is a loop for each successive trial. Because some trials randomly select from Category A and other from Category B, "j" does not move successively down the list for each category. Instead, elements from the Category A list may be selected from something like 1, 2, 5, 8, 9, 10, and so on (it varies each time because of the randomization). To make a long story short(!), how do I create a counter that will work within the for-loop for each trial, so that every word and nonword from Category A and B, respectively, will be used for the lexical decision task? Everything I have tried thus far does not work properly or breaks the javascript entirely. Below is my code snippet and the full code is available at http://50.17.194.59/LDT/trunk/LDT.js. Also, the full lexical decision task can be accessed at http://50.17.194.59/LDT/trunk/LDT.php. Thanks! function initRounds() { numlst = []; for (var k = 0; k<numrounds; k++) { if (k % 2 == 0) numlst[k] = 0; else numlst[k] = 1; } numlst.sort(function() {return 0.5 - Math.random()}) for (var j = 0; j<numrounds; j++) { var round = new LDTround(); if (numlst[j] == 0) { round.category = input.catA.datalabel; } else if (numlst[j] == 1) { round.category = input.catB.datalabel; } // pick a category & stimulus if (round.category == input.catA.datalabel) { round.itemtype = input.catA.itemtype; round.correct = 1; round.catIndex = j; } else if (round.category == input.catB.datalabel) { round.itemtype = input.catB.itemtype; round.correct = 2; round.catIndex = j; } roundArray[i].push(round); } return roundArray; }

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  • How do I write object classes effectively when dealing with table joins?

    - by Chris
    I should start by saying I'm not now, nor do I have any delusions I'll ever be a professional programmer so most of my skills have been learned from experience very much as a hobby. I learned PHP as it seemed a good simple introduction in certain areas and it allowed me to design simple web applications. When I learned about objects, classes etc the tutor's basic examnples covered the idea that as a rule of thumb each database table should have its own class. While that worked well for the photo gallery project we wrote, as it had very simple mysql queries, it's not working so well now my projects are getting more complex. If I require data from two separate tables which require a table join I've instead been ignoring the class altogether and handling it on a case by case basis, OR, even worse been combining some of the data into the class and the rest as a separate entity and doing two queries, which to me seems inefficient. As an example, when viewing content on a forum I wrote, if you view a thread, I retrieve data from the threads table, the posts table and the user table. The queries from the user and posts table are retrieved via a join and not instantiated as an object, whereas the thread data is called using my Threads class. So how do I get from my current state of affairs to something a little less 'stupid', for want of a better word. Right now I have a DB class that deals with connection and escaping values etc, a parent db query class that deals with the common queries and methods, and all of the other classes (Thread, Upload, Session, Photo and ones thats aren't used Post, User etc ) are children of that. Do I make a big posts class that has the relevant extra attributes that I retrieve from the users (and potentially threads) table? Do I have separate classes that populate each of their relevant attributes with a single query? If so how do I do that? Because of the way my classes are written, based on what I was taught, my db update row method, or insert method both just take the attributes as an array and update all of that, if I have extra attributes from other db tables in each class then how do I rewrite those methods as obbiously updating automatically like that would result in errors? In short I think my understanding is limited right now and I'd like some pointers when it comes to the fundamentals of how to write more complex classes.

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  • Multiset container appears to stop sorting

    - by Sarah
    I would appreciate help debugging some strange behavior by a multiset container. Occasionally, the container appears to stop sorting. This is an infrequent error, apparent in only some simulations after a long time, and I'm short on ideas. (I'm an amateur programmer--suggestions of all kinds are welcome.) My container is a std::multiset that holds Event structs: typedef std::multiset< Event, std::less< Event > > EventPQ; with the Event structs sorted by their double time members: struct Event { public: explicit Event(double t) : time(t), eventID(), hostID(), s() {} Event(double t, int eid, int hid, int stype) : time(t), eventID( eid ), hostID( hid ), s(stype) {} bool operator < ( const Event & rhs ) const { return ( time < rhs.time ); } double time; ... }; The program iterates through periods of adding events with unordered times to EventPQ currentEvents and then pulling off events in order. Rarely, after some events have been added (with perfectly 'legal' times), events start getting executed out of order. What could make the events ever not get ordered properly? (Or what could mess up the iterator?) I have checked that all the added event times are legitimate (i.e., all exceed the current simulation time), and I have also confirmed that the error does not occur because two events happen to get scheduled for the same time. I'd love suggestions on how to work through this. The code for executing and adding events is below for the curious: double t = 0.0; double nextTimeStep = t + EPID_DELTA_T; EventPQ::iterator eventIter = currentEvents.begin(); while ( t < EPID_SIM_LENGTH ) { // Add some events to currentEvents while ( ( *eventIter ).time < nextTimeStep ) { Event thisEvent = *eventIter; t = thisEvent.time; executeEvent( thisEvent ); eventCtr++; currentEvents.erase( eventIter ); eventIter = currentEvents.begin(); } t = nextTimeStep; nextTimeStep += EPID_DELTA_T; } void Simulation::addEvent( double et, int eid, int hid, int s ) { assert( currentEvents.find( Event(et) ) == currentEvents.end() ); Event thisEvent( et, eid, hid, s ); currentEvents.insert( thisEvent ); }

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  • How should I handle the case in which a username is already in use?

    - by idealmachine
    I'm a JavaScript programmer and new to PHP and MySQL (want to get into server-side coding). Because I'm trying to learn PHP by building a simple online game (more specifically, correspondence chess), I'm starting by implementing a simple user accounts system. Of course, user registration comes first. What are the best practices for: How I should handle the (likely) possibility that when a user tries to register, the username he has chosen is already in use, particularly when it comes to function return values?($result === true is rather ugly, and I'm not sure whether checking the MySQL error code is the best way to do it either) How to cleanly handle varying page titles?($gPageTitle = '...'; require_once 'bgsheader.php'; is also rather ugly) Anything else I'm doing wrong? In some ways, PHP is rather different from JavaScript... Here is a (rather large) excerpt of the code I have written so far. Note that this is a work in progress and is missing security checks that I will add as my next step. function addUser( $username, $password ) { global $gDB, $gPasswordSalt; $stmt = $gDB->prepare( 'INSERT INTO user(user_name, user_password, user_registration) VALUES(?, ?, NOW())' ); $stmt || trigger_error( 'Failed to prepare statement: ' . htmlspecialchars( $gDB->error ) ); $hashedPassword = hash_hmac( 'sha256', $password, $gPasswordSalt, true ); $stmt->bind_param( 'ss', $username, $hashedPassword ); if( $stmt->execute() ) { return true; } elseif( $stmt->errno == 1062) { return 'exists'; } else { trigger_error( 'Failed to execute statement: ' . htmlspecialchars( $stmt->error ) ); } } $username = $_REQUEST['username']; $password = $_REQUEST['password']; $result = addUser( $username, $password ); if( $result === true ) { $gPageTitle = 'Registration successful'; require_once 'bgsheader.php'; echo '<p>You have successfully registered as ' . htmlspecialchars( $username ) . ' on this site.</p>'; } elseif( $result == 'exists' ) { $gPageTitle = 'Username already taken'; require_once 'bgsheader.php'; echo '<p>Someone is already using the username you have chosen. Please try using another one instead.'; } else { trigger_error('This should never happen'); } require_once 'bgsfooter.php';

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  • Custom cell in list in Flash AS3

    - by Stian Flatby
    I am no expert in Flash, and I need some quick help here, without needing to learn everything from scratch. Short story, I have to make a list where each cell contains an image, two labels, and a button. List/Cell example: img - label - label - button img - label - label - button As a Java-programmer, I have tried to quicly learn the syntax and visualness of Flash and AS3, but with no luck so far. I have fairly understood the basics of movie clips etc. I saw a tutorial on how to add a list, and add some text to it. So I dragged in a list, and in the code went list.addItem({label:"hello"}); , and that worked ofc. So i thought if I double-clicked the MC of the list, i would get to tweak some things. In there I have been wandering around different halls of cell-renderers etc. I have now come to the point that I entered the CellRenderer_skinUp or something, and customized it to my liking. When this was done, I expected i could use list.addItem(); and get an empty "version" of my cell, with the img, labels and the button. But AS3 expects an input in addItem. From my object-oriented view, I am thinking that i have to create an object of the cell i have made, but i have no luck reaching it.. I tried to go var test:CellRenderer = list.listItem; list.addItem(test); ..But with no luck. This is just for funsies, but I really want to make this work, however not so much that I am willing to read up on ALOT of Flash and AS3. I felt that I was closing in on the prize, but the compiler expected a semicolon after the variable (list.addItem({test:something});). Note: If possible, I do NOT want this: list.addItem({image:"src",label:"text",label"text",button:"text"}); Well.. It actually is what I want, but I would really like to custom-draw everything. Does anyone get what I am trying to do, and has any answers for me? Am I approaching this the wrong way? I have searched the interwebs for custom list-cells, but with no luck. Please, any guiding here is appreciated! Sti

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