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• What are Class methods in Python for?

  - by Dave Webb

  I'm teaching myself Python and my most recent lesson was that Python is not Java, and so I've just spent a while turning all my Class methods into functions. I now realise that I don't need to use Class methods for what I would done with static methods in Java, but now I'm not sure when I would use them. All the advice I can find about Python Class methods is along the lines of newbies like me should steer clear of them, and the standard documentation is at its most opaque when discussing them. Does anyone have a good example of using a Class method in Python or at least can someone tell me when Class methods can be sensibly used?

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• Can PHP Perform Magic Instantiation?

  - by Aiden Bell

  Despite PHP being a pretty poor language and ad-hoc set of libraries ... of which the mix of functions and objects, random argument orders and generally ill-thought out semantics mean constant WTF moments.... ... I will admit, it is quite fun to program in and is fairly ubiquitous. (waiting for Server-side JavaScript to flesh out though) question: Given a class class RandomName extends CommonAppBase {} is there any way to automatically create an instance of any class extending CommonAppBase without explicitly using new? As a rule there will only be one class definition per PHP file. And appending new RandomName() to the end of all files is something I would like to eliminate. The extending class has no constructor; only CommonAppBase's constructor is called. Strange question, but would be nice if anyone knows a solution. Thanks in advance, Aiden (btw, my PHP version is 5.3.2) Please state version restrictions with any answer.

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• python: strange behavior about exec statement

  - by ifocus

  exec statement: exec code [ in globals[, locals]] When I execute the following code in python, the result really confused me. Some of the variables were setup into the globals, some were setup into the locals. s = """ # test var define int_v1 = 1 list_v1 = [1, 2, 3] dict_v1 = {1: 'hello', 2:'world', 3:'!'} # test built-in function list_v2 = [float(x) for x in list_v1] len_list_v1 = len(list_v1) # test function define def func(): global g_var, list_v1, dict_v1 print 'access var in globals:' print g_var print 'access var in locals:' for x in list_v1: print dict_v1[x] """ g = {'__builtins__': __builtins__, 'g_var': 'global'} l = {} exec s in g, l print 'globals:', g print 'locals:', l exec 'func()' in g, l the result in python2.6.5: globals: {'__builtins__': <module '__builtin__' (built-in)>, 'dict_v1': {1: 'hello', 2: 'world', 3: '!'}, 'g_var': 'global', 'list_v1': [1, 2, 3]} locals: {'int_v1': 1, 'func': <function func at 0x00ACA270>, 'x': 3, 'len_list_v1': 3, 'list_v2': [1.0, 2.0, 3.0]} access var in globals: global access var in locals: hello world ! And if I want to setup all variables and functions into the locals, and keep the rights of accessing the globals. How to do ?

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• Style of if: to nest or not to nest

  - by Marco

  A colleague of mine and me had a discussion about the following best-practice issue. Most functions/methods start with some parameter checking. I advocate the following style, which avoids nesting. if (parameter one is ugly) return ERROR; if (parameter two is nonsense || it is raining) return ERROR; // do the useful stuff return result; He, who comes from a more functional/logic programming background, prefers the following, because it reduces the number of exit points from the function. if (parameter one is ok) { if (parameter two is ok && the sun is shining) { // do the useful stuff return result } } return ERROR; Which one would you prefer and why?

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• Dealing with passwords securely

  - by Krt_Malta

  Hi I have a Java web service and a Java web client making use of this service. One of the functions is to create a new user account. My two concerns are: How will I send the user's password securely from the client. How will I store the user's password securely on the server. How can I achieve these? I know the theory basically behind security, security algorithms etc but can anyone give me some advice on how I should go about in coding? Could anyone point me to some good (and if possible not complicated) examples to follow since I found some examples on the Internet very contorted? Thanks a lot and regards, Krt_Malta

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• In Python, how to use a C++ function which returns an allocated array of structs via a ** parameter?

  - by Jon-Eric

  I'd like to use some existing C++ code, NvTriStrip, in a Python tool. SWIG easily handles the functions with simple parameters, but the main function, GenerateStrips, is much more complicated. What do I need to put in the SWIG interface file to indicate that primGroups is really an output parameter and that it must be cleaned up with delete[]? /////////////////////////////////////////////////////////////////////////// // GenerateStrips() // // in_indices: input index list, the indices you would use to render // in_numIndices: number of entries in in_indices // primGroups: array of optimized/stripified PrimitiveGroups // numGroups: number of groups returned // // Be sure to call delete[] on the returned primGroups to avoid leaking mem // bool GenerateStrips( const unsigned short* in_indices, const unsigned int in_numIndices, PrimitiveGroup** primGroups, unsigned short* numGroups, bool validateEnabled = false ); FYI, here is the PrimitiveGroup declaration: enum PrimType { PT_LIST, PT_STRIP, PT_FAN }; struct PrimitiveGroup { PrimType type; unsigned int numIndices; unsigned short* indices; PrimitiveGroup() : type(PT_STRIP), numIndices(0), indices(NULL) {} ~PrimitiveGroup() { if(indices) delete[] indices; indices = NULL; } };

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• Install driver by using C++

  - by user296359

  Hi, This is a question about installing driver. I have the following files : aaa.cat aaa.inf x86\ttt.sys I can install this driver by clicking "update driver" in device manager. But now I need to install this driver on Windows (XP, Vista and Win7) by using C++. How could I do this? On the other hand, I can't use install shield or other tool to do the job. That is why I am asking this question. Thanks in advance. I have found this page, which mentioned SetupInstallFile and SetupInstallFileEx functions. Is this the answer? http://msdn.microsoft.com/en-us/library/aa376958%28VS.85%29.aspx

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• Autorelease for CGMutablePathRef?

  - by huggie

  Hi, I am developing for iphone. I want to creating a mutable path via CGPathCreateMutable(), and I want to return it out of the function which creates it. I'm suppose to call a CGPathRelease() when I'm done with it. But since I'm returning it I wish to autorelease it. Since Quartz path is a C code (and doesn't look like an objective C object), is it correct that I cannot call autorelease on it? Edit: For others who stumble upon this question, the below advise is for C functions returning Core foundation objects only. For objective C methods returning Core foundation objects, see http://stackoverflow.com/questions/2901942/ownership-regarding-to-returned-quartz-objects

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• Can I make valgrind ignore glibc libraries?

  - by Jack

  Is it possible to tell valgrind to ignore some set of libraries? Specifically glibc libraries.. Actual Problem: I have some code that runs fine in normal execution. No leaks etc. When I try to run it through valgrind, I get core dumps and program restarts/stops. Core usually points to glibc functions (usually fseek, mutex etc). I understand that there might be some issue with incompatible glibc / valgrind version. I tried various valgrind releases and glibc versions but no luck. Any suggestions?

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• What is the most useful R trick?

  - by Dirk Eddelbuettel

  In order to share some more tips and tricks for R, what is you single-most useful feature or trick? Clever vectorization? Data input/output? Visualization and graphics? Statistical analysis? Special functions? The interactive environment itself? One item per post, and we will see if we get a winner by means of votes. [Edit 25-Aug 2008]: So after one week, it seems that the simple str() won the poll. As I like to recommend that one myself, it is an easy answer to accept.

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• "Ambiguous template specialization" problem

  - by Setien

  I'm currently porting a heap of code that has previously only been compiled with Visual Studio 2008. In this code, there's an arrangement like this: template <typename T> T convert( const char * s ) { // slow catch-all std::istringstream is( s ); T ret; is >> ret; return ret; } template <> inline int convert<int>( const char * s ) { return (int)atoi( s ); } Generally, there are a lot of specializations of the templated function with different return types that are invoked like this: int i = convert<int>( szInt ); The problem is, that these template specializations result in "Ambiguous template specialization". If it was something besides the return type that differentiated these function specializations, I could obviously just use overloads, but that's not an option. How do I solve this without having to change all the places the convert functions are called?

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• How to integrate access control with my ORM in a .net windows form application?

  - by Ying

  I am developing a general database query tools, a .Net 3.5 Windows Form application. In order to make the presentation layer is independent of the database layer. I use an ORM framework, XPO from DevExpress. But, I have no access control function built in. I surfed Internet and I found in WCF Data Services, there is an interesting concept, Interceptor, which is following AOP(Aspect Oriented Programming). I am wondering who has such an experience to build access control in ORM. My basic requirement is : It should be a general method and controlled by users in runtime. So any hard coding is not acceptable. It could be based on attribute, database table, or even an external assembly. I am willing to buy a ready solution. According to the idea of AOP, an access control function can be integrated with existing functions easily and nearly not knowingly to the previous developer;) Any suggestions are welcome.

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• What does static linking against a library actually do?

  - by Salgar

  Say I had a library called libfoo which contained a class, a few static variables, possibly something with 'C' linkage, and a few other functions. Now I have a main program which looks like this: int main() { return 5+5; } When I compile and link this, I link against libfoo. Will this have any effect? Will my executable increase in size? If so, why? Do the static variables or their addresses get copied into my executable? Apologies if there is a similar question to this or if I'm being particularly stupid in any way.

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• Best practices for handling string in VC++?

  - by Hiren Gujarati

  As I am new to Visual C++, there are so many types for handling string. When I use some type and go ahead with coding but on next step, there are in-build functions that use other types & it always require to convert one type of string to other. I found so many blogs but so confused when see so many answers & try but some are working & some are not. Please give your answer or links that gives ultimate solution for handling different types of strings in visual c++.

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• Generator speed in python 3

  - by Will

  Hello all, I am going through a link about generators that someone posted. In the beginning he compares the two functions below. On his setup he showed a speed increase of 5% with the generator. I'm running windows XP, python 3.1.1, and cannot seem to duplicate the results. I keep showing the "old way"(logs1) as being slightly faster when tested with the provided logs and up to 1GB of duplicated data. Can someone help me understand whats happening differently? Thanks! def logs1(): wwwlog = open("big-access-log") total = 0 for line in wwwlog: bytestr = line.rsplit(None,1)[1] if bytestr != '-': total += int(bytestr) return total def logs2(): wwwlog = open("big-access-log") bytecolumn = (line.rsplit(None,1)[1] for line in wwwlog) getbytes = (int(x) for x in bytecolumn if x != '-') return sum(getbytes)

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• Why the macros in Objective-C / Cocoa?

  - by Joe

  I'm coming from a place without macros (Java/Python/C#/Scala) so perhaps my perspective is distorted but... Why are macros used in Cocoa? Two that spring to mind are NSLocalizedString and NSAssert (and STAssert). Would it be so hard / unsuitable to make them functions (which could be inlined)? I suppose I find them a little bizarre as an unnecessary throw-back to C (and yes, I am familiar with the pedigree of Obj-C). Is it just something that was done back in the day or is there a specific reason?

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• Looking for a C# code parser

  - by Blindy

  I'm looking for a set of classes (preferably in the .net framework) that will parse C# code and return a list of functions with parameters, classes with their methods, properties etc. Ideally it would provide all that's needed to build my own intellisense. I have a feeling something like this should be in the .net framework, given all the reflection stuff they offer, but if not then an open source alternative is good enough. What I'm trying to build is basically something like Snippet Compiler, but with a twist. I'm trying to figure out how to get the code dom first. I tried googling for this but I'm not sure what the correct term for this is so I came up empty.

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• Perl passing argument into eval

  - by ehretf

  I'm facing an issue using eval function. Indeed I have some function name inside a SQL database, my goal is to execute those functions within perl (after retrieve in SQL). Here is what I'm doing, considering that $RssSource-{$k}{Proceed} contains "&test" as a string retrieved from SQL: my $str2 = "ABCD"; eval "$RssSource->{$k}{Proceed}";warn if $@; sub test { my $arg = shift; print "fct TEST -> ", $row, "\n"; } This is working correctly and display: fct TEST -> However I would like to be able to pass $str2 as an argument to $RssSource-{$k}{Proceed} but I don't know how, every syntax I tried return an error: eval "$RssSource->{$k}{Proceed}$str2" eval "$RssSource->{$k}{Proceed}($str2)" eval "$RssSource->{$k}{Proceed}"$str2 eval "$RssSource->{$k}{Proceed}"($str2) May someone tell me how to properly pass an argument to the evaluated function? Thanks a lot for your help Regards. Florent

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• Best solution for language documentation.

  - by Simone Margaritelli

  I'm developing a new object oriented scripting language and the project itself is quite ready for audience now, so i'm starting to think about a serious (not as "drafty" as it is right now) way of document its grammar, functions from standard library and standard library classes. I've looked a bit around and almost every language hash its own web application for the documentation, Python uses Sphinx for instance. Which is the best PHP (don't have the time/will to install mod_who_knows_what on my server) application to accomplish this? I've used mediawiki a bit but i found its tag system a little bit hard to use in this context. Thanks for your answers.

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• why do i lose my hidden field value?

  - by user517406

  Hi, I have some hidden fields on my page, all of which work fine apart from one. I am setting the value in document.ready, before calling buildGrid() : $(document).ready(function() { $.ajax( { type: "POST", url: "/CDServices.asmx/GetWeekEndingDates", data: "{}", dataType: "json", contentType: "application/json; charset=utf-8", success: function(msg) { //store default dates in hidden fields $("#<%=hdnCurrentDate.ClientID%>").val(msg.d.CurrentDate); $("#<%=hdnLastWeekEndingDate.ClientID%>").val(msg.d.LastWeekEndingDate); } }); buildGrid(); }); Yet in buildGrid, the value in the hidden field is empty : function buildGrid() { alert($("#<%=hdnLastWeekEndingDate.ClientID%>").val()); I call other functions on button clicks where the hidden field value is picked up fine, why does the value disappear here?

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• Why my print current date time (C language) gives different answer

  - by vodkhang

  I want to get the current date (day, mon and year). I found out there are some functions in C to do that like ctime (get the string of time), localtime and gmtime. I tried with following code but the output are different. I get this output: The date and time is Tue Apr 20 2010 (which is correct) The year is : 110 The year is : 110. Does anybody know why? int main(int argc, char** argv) { time_t now; if((now = time(NULL)) == (time_t)-1) { puts("Failure in getting time"); } else { printf("The date and time is: %s\n", ctime(&now)); printf("The year is: %ld\n", localtime(&now)->tm_year); printf("The year is: %ld\n", gmtime(&now)->tm_year); } getchar(); }

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• Other SecurityManager implementations available?

  - by mhaller

  Is there any other implementation (e.g. in an OSS project) of a Java SecurityManager available which has more features than the one in the JDK? I'm looking for features like configurable at runtime policies updateable at runtime, read from other data sources than a security.policy file Thread-aware, e.g. different policies per Thread Higher-level policies, e.g. "Disable network functions, but allow JDBC traffic" Common predefined policies, e.g. "Allow read-access to usual system properties like file.encoding or line.separator, but disallow read-access to user.home" Monitoring and audit trace logging, e.g. "Log all file access, log all network access going NOT to knownhost.example.org" Blocking jobs "requesting" a permission until an administrator grants permission, letting the thread/job continue ... I'm pretty sure that application servers (at least the commercial ones) have their own SecurityManager implementation or at least their own policy configuration. I'm wondering if there is any free project with similar requirements.

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• Building an http packet in libnet(tcp packet), Please help us as soon as posible. we are stuck!

  - by Hila

  we are building a NAT program,we change each packet that comes from our internal subnet, change it's source IP address by libnet functions.( catch the packet with libpcap, put it sniff structures and build the new packet with libnet) over TCP, the syn/ack packets are good after the change, and when a HTTP-GET request is coming, we can see by wireshark that there is an error on the checksum field.. all the other fields are exactly the same as the original packet. Is anyone knows what can cause this problem? the new checksum in other packets is calculated as it should be.. but in the HTTP packet it doesn't..

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• fHow can I get Opera speed-dial and password management features in other browsers?

  - by Howard Guo

  I heavily rely on Opera's speed dial and password management features. Lack of these two features is really stopping me from switching to another web browser such as Chrome or Firefox. Opera's password management has two unique characteristics which I rely on heavily: It saves passwords on all pages, (apparently) despite the page's meta data asking not to save passwords. It offers keyboard shortcut and button to automatically fill in username/passwords and all other fields in a login form, then automatically submit the form. How can I get those functions in other browsers? Thank you!

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• How do Ruby and Python implement their interactive consoles?

  - by sxa

  When implementing the interpreter for my programming language I first thought of a simple console window which allows the user to enter some code which is then executed as a standalone program as a shell. But there are severe problems: If every line of code the user enters is handled as a standalone program, it has to go through the tokenizer and parser and is then just executed by the interpreter - what about functions then? How can the Python/Ruby interactive consoles (IDLE, irb) "share" the code? How is the code entered handled? Example: >> def x: >> print("Blah") >> >> x() Where is the function stored so it can be called at any time again? How can the interactive console take everything entered as obviously one program without executing everything over and over again?

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