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  • C/C++ Control Structure Limitations?

    - by STingRaySC
    I have heard of a limitation in VC++ (not sure which version) on the number of nested if statements (somewhere in the ballpark of 300). The code was of the form: if (a) ... else if (b) ... else if (c) ... ... I was surprised to find out there is a limit to this sort of thing, and that the limit is so small. I'm not looking for comments about coding practice and why to avoid this sort of thing altogether. Here's a list of things that I'd imagine could have some limitation: Number of functions in a scope (global, class, or namespace). Number of expressions in a single statement (e.g., compound conditionals). Number of cases in a switch. Number of parameters to a function. Number of classes in a single hierarchy (either inheritance or containment). What other control structures/language features have limits such as this? Do the language standards say anything about these limits (perhaps minimum requirements for an implementation)? Has anyone run into a particular language limitation like this with a particular compiler/implementation? EDIT: Please note that the above form of if statements is indeed "nested." It is equivalent to: if (a) { //... } else { if (b) { //... } else { if (c) { //... } else { //... } } }

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  • Help with an RSS Feed

    - by Pete Herbert Penito
    Hi Everyone! I've spent ages on this, all I'm trying to do is extract the "title" contents from an rss feed, everything else can be ignored. I've looked into simplepie, magpie and all that stuff, but I feel its kind of overkill for what I need to do. I realise there are google gadgets that are made that can do this, but I didn't want all the google logo stuff, and I wanted to personally make this. theres a whole bunch of unneeded tags thats coming in from the rss feed all I need is the title tag, it looks like this <title> My Title 3.0 </title> My server has PHP 5+ so I know I can use some of these simple xml functions which look promising. so far I've got <?php $blogfeed = file_get_contents("http://myblog.blogspot.com/feeds/posts/default?alt=rss"); echo $blogfeed; ?> And it gives me all the data, I was thinking of running through it with strpos and searching for <title> but is there any easier way to do this?? Thanks alot!

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  • How to redirect registry access of a dll loaded by my program

    - by dummzeuch
    I have got a dll that I load in my program which reads and writes its settings to the registry (hkcu). My program changes these settings prior to loading the dll so it uses the settings my program wants it to use which works fine. Unfortunately I need to run several instances of my program with different settings for the dll. Now the approach I have used so far no longer works reliably because it is possible for one instance of the program to overwrite the settings that another instance just wrote before the dll has a chance to read them. I haven't got the source of the dll in question and I cannot ask the programmer who wrote it to change it. One idea I had, was to hook registry access functions and redirect them to a different branch of the registry which is specific to the instance of my program (e.g. use the process id as part of the path). I think this should work but maybe you have got a different / more elegant. In case it matters: I am using Delphi 2007 for my program, the dll is probably written in C or C++.

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  • Socket Read In Multi-Threaded Application Returns Zero Bytes or EINTR (-1)

    - by user309670
    Hi. Am a c-coder for a while now - neither a newbie nor an expert. Now, I have a certain daemoned application in C on a PPC Linux. I use PHP's socket_connect as a client to connect to this service locally. The server uses epoll for concurrent connections via a Unix socket. A user submitted string is parsed for certain characters/words using strstr() and if found, spawns 4 joinable threads to different websites simultaneously. I use socket, connect, write and read, to interact with the said webservers via TCP on port 80 in each thread. All connections and writes seems successful. Reads to the webserver sockets fail however, with either (A) all 3 threads seem to hang, and only one thread returns -1 and errno is set to 104. The responding thread takes like 10 minutes - an eternity long:-(. *I read somewhere that the 104 (is EINTR) suggests that ...'the connection was reset by peer', or (B) 0 bytes from 3 threads, and only 1 of the 4 threads actually returns some data. Isn't the socket read/write thread-safe? Otherwise, use thread-safe (and reentrant) libc functions such as strtok_r, gethostbyname_r, etc. *I doubt that the said webhosts are actually resetting the connection, because when I run a single-threaded standalone (everything else equal) all things works perfectly right. There's a second problem too (oops), I can't write back to the client who connect to my epoll-ed Unix socket. My daemon application will hang and hog CPU 100% for ever. Yet nothing is written to the clients end. Am sure the client (a very typical PHP socket application) hasn't closed the connection whenever this is happening - no error(s) detected either. I cannot figure-out whatever is wrong even with Valgrind or GDB

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  • Getting the data inside the C# web service from Jsonified string

    - by gnomixa
    In my JS I use Jquery's $ajax functions to call the web service and send the jsonified data to it. The data is in the following format: var countries = { "1A": { id: "1A", name: "Andorra" }, "2B": { id: 2B name: "Belgium" }, ..etc }; var jsonData = JSON.stringify({ data: data }); //then $ajax is called and it makes the call to the c# web service On the c# side the web service needs to unpack this data, currently it comes in as string[][] data type. How do I convert it to the format so I can refer to the properties such as .id and .name? Assuming I have a class called Sample with these properties? Thanks! EDIT: Here is my JS code: var jsonData = JSON.stringify(countries); $.ajax({ type: 'POST', url: 'http://localhost/MyService.asmx/Foo', contentType: 'application/json; charset=utf-8', data: jsonData, success: function (msg) { alert(msg.d); }, error: function (xhr, status) { switch (status) { case 404: alert('File not found'); break; case 500: alert('Server error'); break; case 0: alert('Request aborted'); break; default: alert('Unknown error ' + status); } } }); inside c# web service I have: using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Services; using System.Data; using System.Collections; using System.IO; using System.Web.Script.Services; [WebMethod] [ScriptMethod] public string Foo(IDictionary<string, Country> countries) { return "success"; }

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  • smlnj rephrased question for listdir(filename, directoryname)

    - by czy1985
    i am a newbie learning sml and the question i am thrown with involves IO functions that i have no idea how it works even after reading it. Here is the 2 questions that i really need help with to get me started, please provide me with codings and some explaination, i will be able to trial and error with the code given for the other questions. Q1) listdir(filename,directoryname), which given the name of a directory, list its contents in a text file. The listing is in a form that makes it easy to seperate filenames, dates and sizes from each other. (similar to what msdos does with "dir" but instead of just listing it out, it places all the files and details into a text file. Q2) readlist(filename) which reads a list of filenames (each of which were produced by listdir in (Q1) and combines them into one large list. (reads from the text file in Q1 and then assigning the contents into 1 big list containing all the information) Thing is, i only learned from the lecturer in school on the introduction section, there isnt even a system input or output example shown, not even the "use file" function is taught. if anyone that knows sml sees this, please help. Thanks to anyone who took the effort helping me. Thanks for the reply, current I am using SMLNJ to try and do this. Basically, Q1 requires me to list the directory's files of the "directoryname" provided into a text file in "filename". The Q2 requires me to read from the "filename" text file and then place the contents into one large list. Duplicate of: smlnj listdir

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  • Unity in C# for Platform Specific Implementations

    - by DxCK
    My program has heavy interaction with the operating system through Win32API functions. now i want to migrate my program to run under Mono under Linux (No wine), and this requires different implementations to the interaction with the operating system. I started designing a code that can have different implementation for difference platform and is extensible for new future platforms. public interface ISomeInterface { void SomePlatformSpecificOperation(); } [PlatformSpecific(PlatformID.Unix)] public class SomeImplementation : ISomeInterface { #region ISomeInterface Members public void SomePlatformSpecificOperation() { Console.WriteLine("From SomeImplementation"); } #endregion } public class PlatformSpecificAttribute : Attribute { private PlatformID _platform; public PlatformSpecificAttribute(PlatformID platform) { _platform = platform; } public PlatformID Platform { get { return _platform; } } } public static class PlatformSpecificUtils { public static IEnumerable<Type> GetImplementationTypes<T>() { foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies()) { foreach (Type type in assembly.GetTypes()) { if (typeof(T).IsAssignableFrom(type) && type != typeof(T) && IsPlatformMatch(type)) { yield return type; } } } } private static bool IsPlatformMatch(Type type) { return GetPlatforms(type).Any(platform => platform == Environment.OSVersion.Platform); } private static IEnumerable<PlatformID> GetPlatforms(Type type) { return type.GetCustomAttributes(typeof(PlatformSpecificAttribute), false) .Select(obj => ((PlatformSpecificAttribute)obj).Platform); } } class Program { static void Main(string[] args) { Type first = PlatformSpecificUtils.GetImplementationTypes<ISomeInterface>().FirstOrDefault(); } } I see two problems with this design: I can't force the implementations of ISomeInterface to have a PlatformSpecificAttribute. Multiple implementations can be marked with the same PlatformID, and i dont know witch to use in the Main. Using the first one is ummm ugly. How to solve those problems? Can you suggest another design?

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  • Creating a function in Postgresql that does not return composite values

    - by celenius
    I'm learning how to write functions in Postgresql. I've defined a function called _tmp_myfunction() which takes in an id and returns a table (I also define a table object type called _tmp_mytable) -- create object type to be returned CREATE TYPE _tmp_mytable AS ( id integer, cost double precision ); -- create function which returns query CREATE OR REPLACE FUNCTION _tmp_myfunction( id integer ) RETURNS SETOF _tmp_mytable AS $$ BEGIN RETURN QUERY SELECT id, cost FROM sales WHERE id = sales.id; END; $$ LANGUAGE plpgsql; This works fine when I use one id and call it using the following approach: SELECT * FROM _tmp_myfunction(402); What I would like to be able to do is to call it, but to use a column of values instead of just one value. However, if I use the following approach I end up with all values of the table in one column, separated by commas: -- call function using all values in a column SELECT _tmp_myfunction(t.id) FROM transactions as t; I understand that I can get the same result if I use SELECT _tmp_myfunction(402); instead of SELECT * FROM _tmp_myfunction(402); but I don't know how to construct my query in such a way that I can separate out the results.

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  • Where can a self-teacher learn general good programming habits and conventions?

    - by lucid
    A few mistakes and general childishness in early adulthood have left me in a situation where I work a menial job, with no possibility (in the near future) of attending school. I aspire to one day work in the programming field (gaming specifically), after proving myself on the indie end of things. I've gotten very confident in C++, java, and python, and I find I'm able to solve any problem I want either from previous experience, or from scouring the web for help. The solutions work, and with each attempt they become more readable, maintainable, and extensible. But this is because I'm learning from mistakes and bad programming and design habits I feel I might have avoided with actual schooling. General tips like: "if it's hard to read or getting long, or you're writing it twice, it should be in one or more functions." or "design all your classes before you start coding, so you don't have to rewrite classes later when you discover an unforeseen dependency" Is there a good book or website for learning general good programming practices and design habits? Also, naming and format conventions. I realize sometimes development houses have their own conventions, but things like "Classes in python usually have the first letter of each word capitalized". I'd like to be able to show some source code to a potential employer, and be prepared when for what's expected on a team. Is there some central database of naming and formatting conventions somewhere? Also, feel free to give any thoughts on whether or not the self-teach, garner some indie sales, use them as your resume' route is realistic

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  • Passing data between Drupal module callback, preprocess and template

    - by rob5408
    I've create a module called finder that I want to take parameters from a url, crunch them and then display results via a tpl file. here's the relevant functions... function finder_menu() { $items = array(); $items['finder'] = array( 'page callback' => 'finder_view', 'access callback' => TRUE, ); return $items; } function finder_theme($existing, $type, $theme, $path) { return array( 'finder_view' => array( 'variables' => array('providers' => null), 'template' => 'results', ), ); } function finder_preprocess_finder_view(&$variables) { // put my data into $variables } function finder_view($zipcode = null) { // Get Providers from Zipcode return theme('finder_view', $providers); } Now I know finder_view is being called. I also know finder_preprocess_finder_view is being called. Finally, I know that result.tpl.php is being used to output. But I cannot wrap my head around how to do meaningful work in the callback, somehow make that data available in the preprocessor to add to "variables" so that i can access in the tpl file. in a situation where you are using a tpl file is the callback even useful for anything? I've done this in the past where the callback does all the work and passes to a theming function, but i want to use a file for output instead this time. Thanks...

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  • How to use R's ellipsis feature when writing your own function?

    - by Ryan Thompson
    The R language has a nifty feature for defining functions that can take a variable number of arguments. For example, the function data.frame takes any number of arguments, and each argument becomes the data for a column in the resulting data table. Example usage: > data.frame(letters=c("a", "b", "c"), numbers=c(1,2,3), notes=c("do", "re", "mi")) letters numbers notes 1 a 1 do 2 b 2 re 3 c 3 mi The function's signature includes an ellipsis, like this: function (..., row.names = NULL, check.rows = FALSE, check.names = TRUE, stringsAsFactors = default.stringsAsFactors()) { [FUNCTION DEFINITION HERE] } I would like to write a function that does something similar, taking multiple values and consolidating them into a single return value (as well as doing some other processing). In order to do this, I need to figure out how to "unpack" the ... from the function's arguments within the function. I don't know how to do this. The relevant line in the function definition of data.frame is object <- as.list(substitute(list(...)))[-1L], which I can't make any sense of. So how can I convert the ellipsis from the function's signature into, for example, a list? To be more specific, how can I write get_list_from_ellipsis in the code below? my_ellipsis_function(...) { input_list <- get.list.from.ellipsis(...) output_list <- lapply(X=input_list, FUN=do_something_interesting) return(output_list) } my_ellipsis_function(a=1:10,b=11:20,c=21:30)

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  • Visual Studio project remains "stuck" when stopped

    - by Traveling Tech Guy
    Hi, Currently developing a connector DLL to HP's Quality Center. I'm using their (insert expelative) COM API to connect to the server. An Interop wrapper gets created automatically by VStudio. My solution has 2 projects: the DLL and a tester application - essentially a form with buttons that call functions in the DLL. Everything works well - I can create defects, update them and delete them. When I close the main form, the application stops nicely. But when I call a function that returns a list of all available projects (to fill a combo box), if I close the main form, VStudio still shows the solution as running and I have to stop it. I've managed to pinpoint a single function in my code that when I call, the solution remains "hung" and if I don't, it closes well. It's a call to a property in the TDC object get_VisibleProjects that returns a List (not the .Net one, but a type in the COM library) - I just iterate over it and return a proper list (that I later use to fill the combo box): public List<string> GetAvailableProjects() { List<string> projects = new List<string>(); foreach (string project in this.tdc.get_VisibleProjects(qcDomain)) { projects.Add(project); } return projects; } My assumption is that something gets retained in memory. If I run the EXE outside of VStudio it closes - but who knows what gets left behind in memory? My question is - how do I get rid of whatever calling this property returns? Shouldn't the GC handle this? Do I need to delve into pointers? Things I've tried: getting the list into a variable and setting it to null at the end of the function Adding a destructor to the class and nulling the tdc object Stepping through the tester function application all the way out, whne the form closes and the Main function ends - it closes, but VStudio still shows I'm running. Thanks for your assistance!

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  • JSLINT error: Move all 'var' declarations to the top of the function.

    - by Oleg Yaroshevych
    JSLINT site updated, and I cannot check JS scripts anymore. For me, this warning is not critical, and I don't want to go through thousands of lines to fix this, I want to find more critical problems. Does anybody know how to turn off this error, or use legacy JSLINT? UPDATE Example: function doSomethingWithNodes(nodes){ this.doSomething(); for (var i = 0; i < nodes.length; ++i){ this.doSomethingElse(nodes[i]); } doSomething(); // want to find this problem } jslint.com output: Error: Problem at line 4 character 8: Move all 'var' declarations to the top of the function. for (var i = 0; i < nodes.length; ++i){ Problem at line 4 character 8: Stopping, unable to continue. (44% scanned). Problem: Having variables on top of the functions is new requirement. I cannot use JSLINT to test code, because it stops scanning script on this error. I have a lot of code, and do not want to threat this warning as critical error.

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  • Plotting an Arc in Discrete Steps

    - by phobos51594
    Good afternoon, Background My question relates to the plotting of an arbitrary arc in space using discrete steps. It is unique, however, in that I am not drawing to a canvas in the typical sense. The firmware I am designing is for a gcode interpreter for a CNC mill that will translate commands into stepper motor movements. Now, I have already found a similar question on this very site, but the methodology suggested (Bresenham's Algorithm) appears to be incompatable for moving an object in space, as it only relies on the calculation of one octant of a circle which is then mirrored about the remaining axes of symmetry. Furthermore, the prescribed method of calculation an arc between two arbitrary angles relies on trigonometry (I am implementing on a microcontroller and would like to avoid costly trig functions, if possible) and simply not taking the steps that are out of the range. Finally, the algorithm only is designed to work in one rotational direction (e.g. counterclockwise). Question So, on to the actual question: Does anyone know of a general-purpose algorithm that can be used to "draw" an arbitrary arc in discrete steps while still giving respect to angular direction (CW / CCW)? The final implementation will be done in C, but the language for the purpose of the question is irrelevant. Thank you in advance. References S.O post on drawing a simple circle using Bresenham's Algorithm: "Drawing" an arc in discrete x-y steps Wiki page describing Bresenham's Algorithm for a circle http://en.wikipedia.org/wiki/Midpoint_circle_algorithm Gcode instructions to be implemented (see. G2 and G3) http://linuxcnc.org/docs/html/gcode.html

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  • Visual Studio and .NET programming

    - by Vit
    Hi, I just want to ask wheather I am right or not about .NET. So, .NET is new framework that enables you to easily implement new and old windows functions. It is similiar to java in the way that its also compiled into "bytecode", but its name is Common Language Infrastructure, or CLI. This language is interpreted by .NET Framework, so code generated by programming using .NET cannot be executed directly by CPU. Now, few languages can be compiled to CLI. First, it was Microsoft-developed C#, than J#, C++ others. I suspect that this is in general right, at least I hope I understand it right. But, what I am still missing is, can you write to machine code compiled code in C#? And, if using Visual Studio 2005, when I select Win32 project, it is compiled into machine code, so only thing you need to run this apps are windows dynamic-link libraries, since static libraries code is implemented into app durink linking phase. And those dynamic-link libraries are implemented in every windows installation, or provided by DirectX installations. But when I select CLR in Visual Studio 2005, than app is compiled into CLI code, and it first executes .NET framework, and than .NET framework executes that program, since its not in machine code. So, I am right? I ask becouse you can read these infos on the internet, but I have noone to tell me wheather I understand it right or not. Thanks.

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  • Coupling an MFC CListCtrl and CTreeCtrl to get a view of the whole tree, not just one node at a time

    - by omatai
    Consider Windows Explorer (or regedit or similar). To the left side, there is a tree view, and to the right, a list view. In all cases I know of, the contents of the right view reflect the attributes of the selected node from the left pane. This is all well and good... but just not what I want. The nodes of the tree I want to display have a very few attributes (2-3) associated with each node - a reasonable amount to display horizontally as a row in a table. Rather than waste all that list view space on a single node with very few properties, I would like to have my list view display a table of the whole tree's properties (as the part of the tree currently expanded). So the nth line in the left view (tree) will correspond directly to the nth line in the right view (list/table), and I will get a decent overview of the properties of my tree. Does anyone know of code that does this? I am guessing that slaving a CListCtrl to a CTreeCtrl would be the way to go, and somehow overriding the vertical scrolling functions so that they are locked together. I'm just not sure that it is possible to lock the scrolls together like this... among other things! All advice gratefully welcomed :-)

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  • Are there any libraries for parsing "number expressions" like 1,2-9,33- in Java

    - by mihi
    Hi, I don't think it is hard, just tedious to write: Some small free (as in beer) library where I can put in a String like 1,2-9,33- and it can tell me whether a given number matches that expression. Just like most programs have in their print range dialogs. Special functions for matching odd or even numbers only, or matching every number that is 2 mod 5 (or something like that) would be nice, but not needed. The only operation I have to perform on this list is whether the range contains a given (nonnegative) integer value; more operations like max/min value (if they exist) or an iterator would be nice, of course. What would be needed that it does not occupy lots of RAM if anyone enters 1-10000000 but the only number I will ever query is 12345 :-) (To implement it, I would parse a list into several (min/max/value/mod) pairs, like 1,10,0,1 for 1-10 or 11,33,1,2 for 1-33odd, or 12,62,2,10 for 12-62/10 (i. e. 12, 22, 32, ..., 62) and then check each number for all the intervals. Open intervals by using Integer.MaxValue etc. If there are no libs, any ideas to do it better/more efficient?)

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  • How to easily map c++ enums to strings

    - by Roddy
    I have a bunch of enum types in some library header files that I'm using, and I want to have a way of converting enum values to user strings - and vice-versa. RTTI won't do it for me, because the 'user strings' need to be a bit more readable than the enumerations. A brute force solution would be a bunch of functions like this, but I feel that's a bit too C-like. enum MyEnum {VAL1, VAL2,VAL3}; String getStringFromEnum(MyEnum e) { switch e { case VAL1: return "Value 1"; case VAL2: return "Value 2"; case VAL1: return "Value 3"; default: throw Exception("Bad MyEnum"); } } I have a gut feeling that there's an elegant solution using templates, but I can't quite get my head round it yet. UPDATE: Thanks for suggestions - I should have made clear that the enums are defined in a third-party library header, so I don't want to have to change the definition of them. My gut feeling now is to avoid templates and do something like this: char * MyGetValue(int v, char *tmp); // implementation is trivial #define ENUM_MAP(type, strings) char * getStringValue(const type &T) \ { \ return MyGetValue((int)T, strings); \ } ; enum eee {AA,BB,CC}; - exists in library header file ; enum fff {DD,GG,HH}; ENUM_MAP(eee,"AA|BB|CC") ENUM_MAP(fff,"DD|GG|HH") // To use... eee e; fff f; std::cout<< getStringValue(e); std::cout<< getStringValue(f);

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  • How to extract part of the path and the ending file name with Regex?

    - by brasofilo
    I need to build an associative array with the plugin name and the language file it uses in the following sequence: /whatever/path/length/public_html/wp-content/plugins/adminimize/languages/adminimize-en_US.mo /whatever/path/length/public_html/wp-content/plugins/audio-tube/lang/atp-en_US.mo /whatever/path/length/public_html/wp-content/languages/en_US.mo /whatever/path/length/public_html/wp-content/themes/twentyeleven/languages/en_US.mo Those are the language files WordPress is loading. They are all inside /wp-content/, but with variable server paths. I'm looking only for those inside the plugins folder, grab the plugin folder name and the filename. Hipothetical case in PHP, where reg_extract_* functions are the parts I'm missing: $plugins = array(); foreach( $big_array as $item ) { $folder = reg_extract_folder( $item ); if( 'plugin' == $folder ) { // "folder-name-after-plugins-folder" $plugin_name = reg_extract_pname( $item ); // "ending-mo-file.mo" $file_name = reg_extract_fname( $item ); $plugins[] = array( 'name' => $plugin_name, 'file' => $file_name ); } } [update] Ok, so I was missing quite a basic function, pathinfo... :/ No problem to detect if /plugins/ is contained in the array. But what about the plugin folder name?

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  • How Can I Find a List of All Exceptions That a Given Library Function Throws in Python?

    - by b14ck
    Sorry for the long title, but it seems most descriptive for my question. Basically, I'm having a difficult time finding exception information in the official python documentation. For example, in one program I'm currently writing, I'm using the shutil libary's move function: from shutil import move move('somefile.txt', '/tmp/somefile.txt') That works fine, as long as I have write access to /tmp/, there is enough diskspace, and if all other requirements are satisfied. However, when writing generic code, it is often difficult to guarantee those factors, so one usually uses exceptions: from shutil import move try: move('somefile.txt', '/tmp/somefile.txt') except: print 'Move failed for some reason.' I'd like to actually catch the appropriate exceptions thrown instead of just catching everything, but I simply can't find a list of exceptions thrown for most python modules. Is there a way for me to see which exceptions a given function can throw, and why? This way I can make appropriate cases for each exception, eg: from shutil import move try: move('somefile.txt', '/tmp/somefile.txt') except PermissionDenied: print 'No permission.' except DestinationDoesNotExist: print "/tmp/ doesn't exist" except NoDiskSpace: print 'No diskspace available.' Answer points go to whoever can either link me to some relevant documentation that I've somehow overlooked in the official docs, or provide a sure-fire way to figure out exactly which exceptions are thrown by which functions, and why. Thanks!

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  • Recursion in assembly?

    - by Davis
    I'm trying to get a better grasp of assembly, and I am a little confused about how to recursively call functions when I have to deal with registers, popping/pushing, etc. I am embedding x86 assembly in C++. Here I am trying to make a method which given an array of integers will build a linked list containing these integers in the order they appear in the array. I am doing this by calling a recursive function: insertElem (struct elem *head, struct elem *newElem, int data) -head: head of the list -data: the number that will be inserted at the end of a list -newElem: points to the location in memory where I will store the new element (data field) My problem is that I keep overwriting the registers instead of a typical linked list. For example, if I give it an array {2,3,1,8,3,9} my linked-list will return the first element (head) and only the last element, because the elements keep overwriting each other after head is no longer null. So here my linked list looks something like: 2--9 instead of 2--3--1--8--3--9 I feel like I don't have a grasp on how to organize and handle the registers. newElem is in EBX and just keeps getting rewritten. Thanks in advance!

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  • Trait, FunctionN, or trait-inheriting-FunctionN in Scala?

    - by Willis Blackburn
    I have a trait in Scala that has a single method. Call it Computable and the single method is compute(input: Int): Int. I can't figure out whether I should Leave it as a standalone trait with a single method. Inherit from (Int = Int) and rename "compute" to "apply." Just get rid of Computable and use (Int = Int). A factor in favor of it being a trait is that I could usefully add some additional methods. But of course if they were all implemented in terms of the compute method then I could just break them out into a separate object. A factor in favor of just using the function type is simplicity and the fact that the syntax for an anonymous function is more concise than that for an anonymous Computable instance. But then I've no way to distinguish objects that are actually Computable instances from other functions that map Int to Int but aren't meant to be used in the same context as Computable. How do other people approach this type of problem? No right or wrong answers here; I'm just looking for advice.

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  • php and mysql listing databases and looping through results

    - by Jacksta
    Beginner help needed :) I am doign an example form a php book which lists tables in databases. I am getting an error on line 36: $db_list .= "$table_list"; <?php //connect to database $connection = mysql_connect("localhost", "admin_cantsayno", "cantsayno") or die(mysql_error()); //list databases $dbs = @mysql_list_dbs($connection) or die(mysql_error()); //start first bullet list $db_list = "<ul>"; $db_num = 0; //loop through results of functions while ($db_num < mysql_num_rows($dbs)) { //get database names and make each a list point $db_names[$db_num] = mysql_tablename($dbs, $db_num); $db_list .= "<li>$db_names[$db_num]"; //get table names and make another list $tables = @mysql_list_tables($db_names[$db_num]) or die(mysql_error()); $table_list = "<ul>"; $table_num = 0; //loop through results of function while ($table_num < mysql_num_rows($tables)){ //get table names and make each bullet point $table_names[$table_num] = mysql_tablename($tables, $table_num); $table_list .= "<li>$table_names[$table_num]"; $table_num++; } //close inner bullet list and increment number to continue $table_list .= "</ul>" $db_list .= "$table_list"; $db_num++; } //close outer bullet list $db_list .= "</ul>"; ?> <html> <head> <title>MySQL Tables</title> </head> <body> <p><strong>Data bases and tables on local host</strong></p> <? echo "$db_list"; ?> </body>

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  • Initialize Static Array of Structs in C

    - by russell_h
    I implementing a card game in C. There are lots of types of cards and each has a bunch of information, including some actions that will need to be individually scripted associated with it. Given a struct like this (and I'm not certain I have the syntax right for the function pointer) struct CARD { int value; int cost; // This is a pointer to a function that carries out actions unique // to this card int (*do_actions) (struct GAME_STATE *state, int choice1, int choice2); }; I would like to initialize a static array of these, one for each card. I'm guessing this would look something like this int do_card0(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } int do_card1(struct GAME_STATE *state, int choice1, int choice2) { // Operate on state here } extern static struct cardDefinitions[] = { {0, 1, do_card0}, {1, 3, do_card1} }; Will this work, and am I going about this the right way at all? I'm trying to avoid huge numbers of switch statements. Do I need to define the 'do_cardN' functions ahead of time, or is there some way to define them inline in the initialization of the struct (something like a lambda function in python)? I'll need read-only access to cardDefinitions from a different file - is 'extern static' correct for that? I know this is a lot of questions rolled into one but I'm really a bit vague about how to go about this. Thanks.

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  • Partial template specialization for more than one typename

    - by Matt Joiner
    In the following code, I want to consider functions (Ops) that have void return to instead be considered to return true. The type Retval, and the return value of Op are always matching. I'm not able to discriminate using the type traits shown here, and attempts to create a partial template specialization based on Retval have failed due the presence of the other template variables, Op and Args. How do I specialize only some variables in a template specialization without getting errors? Is there any other way to alter behaviour based on the return type of Op? template <typename Retval, typename Op, typename... Args> Retval single_op_wrapper( Retval const failval, char const *const opname, Op const op, Cpfs &cpfs, Args... args) { try { CallContext callctx(cpfs, opname); Retval retval; if (std::is_same<bool, Retval>::value) { (callctx.*op)(args...); retval = true; } else { retval = (callctx.*op)(args...); } assert(retval != failval); callctx.commit(cpfs); return retval; } catch (CpfsError const &exc) { cpfs_errno_set(exc.fserrno); LOGF(Info, "Failed with %s", cpfs_errno_str(exc.fserrno)); } return failval; }

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