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• Web Scraper via Web Service API?

  - by 001

  How would I go about doing the following... I want to build a web service for my application to grab a piece of data from an external website, that requires the user to login. The website has no public API , hence the reason for the scrapper. Is there a library to perform the following functions? or what do I do? automate fill-in form, auto click Automate submit button check which URL the user has landed on, and redirect user to URL Grab data from label. EDIT: what im asking for is there a web service, library etc to make it easier to perform screen scrapping/automation functions???

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• Simplifying const Overloading?

  - by templatetypedef

  Hello all- I've been teaching a C++ programming class for many years now and one of the trickiest things to explain to students is const overloading. I commonly use the example of a vector-like class and its operator[] function: template <typename T> class Vector { public: T& operator[] (size_t index); const T& operator[] (size_t index) const; }; I have little to no trouble explaining why it is that two versions of the operator[] function are needed, but in trying to explain how to unify the two implementations together I often find myself wasting a lot of time with language arcana. The problem is that the only good, reliable way that I know how to implement one of these functions in terms of the other is with the const_cast/static_cast trick: template <typename T> const T& Vector<T>::operator[] (size_t index) const { /* ... your implementation here ... */ } template <typename T> T& Vector<T>::operator[] (size_t index) { return const_cast<T&>(static_cast<const Vector&>(*this)[index]); } The problem with this setup is that it's extremely tricky to explain and not at all intuitively obvious. When you explain it as "cast to const, then call the const version, then strip off constness" it's a little easier to understand, but the actual syntax is frightening,. Explaining what const_cast is, why it's appropriate here, and why it's almost universally inappropriate elsewhere usually takes me five to ten minutes of lecture time, and making sense of this whole expression often requires more effort than the difference between const T* and T* const. I feel that students need to know about const-overloading and how to do it without needlessly duplicating the code in the two functions, but this trick seems a bit excessive in an introductory C++ programming course. My question is this - is there a simpler way to implement const-overloaded functions in terms of one another? Or is there a simpler way of explaining this existing trick to students? Thanks so much!

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• How to convert from integer to unsigned char in C, given integers larger than 256?

  - by Alf_InPogform

  As part of my CS course I've been given some functions to use. One of these functions takes a pointer to unsigned chars to write some data to a file (I have to use this function, so I can't just make my own purpose built function that works differently BTW). I need to write an array of integers whose values can be up to 4095 using this function (that only takes unsigned chars). However am I right in thinking that an unsigned char can only have a max value of 256 because it is 1 byte long? I therefore need to use 4 unsigned chars for every integer? But casting doesn't seem to work with larger values for the integer. Does anyone have any idea how best to convert an array of integers to unsigned chars?

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• Function return type style

  - by JB

  I'm learning c++0x, at least the parts supported by the Visual C++ Express 2010 Beta. This is a question about style rather than how it works. Perhaps it's too early for style and good practice to have evolved yet for a standard that isn't even released yet... In c++0x you can define the return type of a method using - type at the end of the function instead of putting the type at the start. I believe this change in syntax is required due to lambdas and some use cases of the new decltype keyword, but you can use it anywhere as far as I know. // Old style int add1(int a, int b) { return a + b; } // New style return type auto add2(int a, int b) -> int { return a + b; } My question really then, is given that some functions will need to be defined in the new way is it considered good style to define all functions in this way for consistency? Or should I stick to only using it when necessary?

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• Compiler reordering around mutex boundaries?

  - by shojtsy

  Suppose I have my own non-inline functions LockMutex and UnlockMutex, which are using some proper mutex - such as boost - inside. How will the compiler know not to reorder other operations with regard to calls to the LockMutex and UnlockMutex? It can not possibly know how will I implement these functions in some other compilation unit. void SomeClass::store(int i) { LockMutex(_m); _field = i; // could the compiler move this around? UnlockMutex(_m); } ps: One is supposed to use instances of classes for holding locks to guarantee unlocking. I have left this out to simplify the example.

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• Windows equivalent of inb(), outb(), low level i/o

  - by Sebastian Dwornik

  I have some Linux code that monitors our hardware by collecting temperatures, voltages, and fan speeds, from the motherboard using inb(), outb(), inl(), etc. low level i/o functions. My challenge is to port that code over to run under Windows as a simple console app. But am puzzled in what functions Win32 (or .NET) provide that allow me permission to access direct memory mapped ports. I don't want to code a system driver either. My Windows tool preference is VS2008. (fyi) Is this possible?

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• Making links clickable from comments in php

  - by neat

  im trying to create functions that will give my chat clickable links.... here are the functions i've created <?php //makes links starting with http clickable function makehttpclickable($text){ return preg_replace('!(((f|ht)tp://)[-a-zA-Z?-??-?()0-9@:%_+.~#?&;//=]+)!i', '<a href="$1">$1</a>', $text); } //makes links starting www. http clickable function clickywww($www){ return preg_replace('!((www)[-a-zA-Z?-??-?()0-9@:%_+.~#?&;//=]+)!i', '<a href="$1">$1</a>', $www); } /function that gives me an error! function clickydotcom($noob){ return preg_replace('!([-a-zA-Z?-??-?()0-9@:%_+.~#?&;//=]+)(\.com)!i'.'!([-a-zA-Z?-??-?()0-9@:%_+.~#?&;//=]+)(\.com)!f', '<a href="$1.com$f">$1.com</a>', $noob); } I've been getting an unkown modifier error. Warning: preg_replace() [function.preg-replace]: Unknown modifier '!' So Anyways any help would be nice on how i can make all types of links clickable

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• Override l() function in Drupal

  - by Marco

  I'm currently working on a Drupal site (6.*), which when in production mode will be accessed through some kind of http proxy, which means I will have to rewrite all the links for my custom theme if the $_SERVER['HTTP_X_FORWARDED_SERVER'] variable is set to the domain people will access the site from. The site has a lot of internal linking, mostly through Views. My thought is that the easiest way to solve this would be to hook into the url() and/or the l() functions and post process the url before returning it if HTTP_X_FORWARDED_SERVER is set. My problem is that I can't figure out how to hook into these functions, or if it's even possible without touching the core, has anyone had to do this? How did you solve it?

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• Will C++1x support __stdcall or extern "C" capture-nothing lambdas?

  - by Daniel Trebbien

  Yesterday I was thinking about whether it would be possible to use the convenience of C++1x lambda functions to write callbacks for Windows API functions. For example, what if I wanted to use a lambda as an EnumChildProc with EnumChildWindows? Something like: EnumChildWindows(hTrayWnd, CALLBACK [](HWND hWnd, LPARAM lParam) { // ... return static_cast<BOOL>(TRUE); // continue enumerating }, reinterpret_cast<LPARAM>(&myData)); Another use would be to write extern "C" callbacks for C routines. E.g.: my_class *pRes = static_cast<my_class*>(bsearch(&key, myClassObjectsArr, myClassObjectsArr_size, sizeof(my_class), extern "C" [](const void *pV1, const void *pV2) { const my_class& o1 = *static_cast<const my_class*>(pV1); const my_class& o2 = *static_cast<const my_class*>(pV2); int res; // ... return res; })); Is this possible?

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• tool to generate C++ wrapper over java class

  - by Vardhan Varma

  From what I understand, SWIG is to wrap C++/C to make it appear in Java, and javah is to implement certain java functions in C++ ( aka native functions ). Is there a tool which can create a C++ wrapper over a java class, so that the caller. of this c++ wrapper doesn't have to worry about java, for example Input Java is class hw { public void hi() { System.out.println("Hello World"); } } Tools outputs hw.hh ( and some. c++ files ), which can be used as: hw *h = new hw(/*JEnv */ env); h-hi(); Is there a tool available which can do this ?

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• How to get function's name from function's pointer in C?

  - by Daniel Silveira

  How to get function's name from function's pointer in C? Edit: The real case is: I'm writing a linux kernel module and I'm calling kernel functions. Some of these functions are pointers and I want to inspect the code of that function in the kernel source. But I don't know which function it is pointing to. I thought it could be done because, when the system fails (kernel panic) it prints out in the screen the current callstack with function's names. But, I guess I was wrong... am I?

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• Forced naming of parameters in python

  - by Mark Mayo

  In python you may have a function definition: def info(object, spacing=10, collapse=1) which could be called in any of the following ways: info(odbchelper) info(odbchelper, 12) info(odbchelper, collapse=0) info(spacing=15, object=odbchelper) thanks to python's allowing of any-order arguments, so long as they're named. The problem we're having is as some of our larger functions grow, people might be adding parameters between spacing and collapse, meaning that the wrong values may be going to parameters that aren't named. In addition sometimes it's not always clear as to what needs to go in. We're after a way to force people to name certain parameters - not just a coding standard, but ideally a flag or pydev plugin? so that in the above 4 examples, only the last would pass the check as all the parameters are named. Odds are we'll only turn it on for certain functions, but any suggestions as to how to implement this - or if it's even possible would be appreciated.

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• Why does PHP 5.2 disallow abstract static class methods?

  - by Artem Russakovskii

  After enabling strict warnings in PHP 5.2, I saw a load of strict standards warnings from a project that was originally written without strict warnings: Strict Standards: Static function Program::getSelectSQL() should not be abstract in Program.class.inc The function in question belongs to an abstract parent class Program and is declared abstract static because it should be implemented in its child classes, such as TVProgram. I did find references to this change here: Dropped abstract static class functions. Due to an oversight, PHP 5.0.x and 5.1.x allowed abstract static functions in classes. As of PHP 5.2.x, only interfaces can have them. My question is: can someone explain in a clear way why there shouldn't be an abstract static function in PHP?

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• Importing a DllMain winapi .dll into Visual Studio project C++

  - by Bad Man

  I have the .def file, .lib file, the .dll, the source files. It's using WINAPI DllMain, all its functions follow that. It's like this: BOOL APIENTRY DllMain( HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved ) { return TRUE; } extern "C" { int WINAPI DoSomething() { return -1; } int WINAPI DOSOMETHIGNELSE!() { return 202020; } }; IN the project settings linker I added the .lib file. There is no header file for the actual functions in the extern "C" part. I include windows.h try to call DoSomething() but doesnt know what it is.

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• Need some explanation about MS Ajax using PageMethods

  - by Ahmed Said

  I have a project that uses PageMethods to call functions on the server. The server functions (written in C#) return the values as array of strings, without doing any kind of serialization and in the client side (from Js) the accessing of the return values is by using static variable called arguments. I found that sometimes for some users (cases are not repro) sometimes an exception occured "WebServiceFailedException the server method 'Foo' returned invalid data. the 'd' property is missing from JSON." Some searching on google I found that people are serializing the return values using DataContractJsonSerializer class and in js accessing the return value using one of the callback function Example: function OnRequestComplete(result, userContext, methodName) { var Person = eval('(' + result + ')'); alert(Person.Forename); alert(Person.Surname); } So is the first technique is correct? or what?

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• How to store and access JSON data for a site?

  - by Callmeed

  I'm buiding an HTML/jQuery site where almost all the content comes from remote JSON data. I'm having trouble coming up with a good way to store and access the data in the future (scope-wise). Currently, I've written a jQuery plugin that gets the JSONP data when the site loads. But I have other functions and jQuery plugins that need to access this data. Where should this data be stored so other functions and plugins can access it? Should it be a global variable? If it matters, this site will only run on the iPad and the back-end of the site is in Rails.

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• Identifying a function call in a python script line in runtime

  - by Dani

  I have a python script that I run with 'exec'. The script's string has calls to functions. When a function is called, I would like it to know the line number and offset in line for that call in the script (in the string I fed exec with). Here is an example. If my script is: foo1(); foo2(); foo1() foo3() And if I have code that prints (line,offset) in every function, I should get (0,0), (0,8), (0,16), (1,0) In most cases this can be easily done by getting the stack frame, because it contains the line number and the function name. The only problem is when there are two functions with the same name in a certain line. Unfortunately this is a common case for me. Any ideas?

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• javascript - how to call a function newly added from ajax

  - by strike_noir

  I have a coding difficulty which have been asked in this forum before: Calling a JavaScript function returned from a Ajax response But I didn't find the answers quite satisfying. To be more precise of the problem I'm dealing, here is the details: I dynamically load a document (HTML and javascript) using jquery var url = 'document.php'; $('#container').load(url); And then I want to call the functions from that document.php. Due to my requirement, I don't want to call the function after the documents' loaded, but rather to call it later when I need it. Because it was dynamically loaded, the DOM doesn't recognize the functions. How to properly call this function? Thank you

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• Does program need additional symbols from .so shared library except those declared in header file?

  - by solotim

  In C programming, I thought that a object file can be successfully linked with a .so file as long as the .so file offers all symbols which have been declared in the header file. Suppose I have foo.c, bar.h and two libraries libbar.so.1 and libbar.so.2. The implementation of libbar.so.1 and libbar.so.2 is totally different, but I think it's OK as long as they both offers functions declared in bar.h. I linked foo.o with libbar.so.1 and produced an executable: foo.bin. This executable worked when libbar.so.1 is in LD_LIBRARY_PATH.(of course a symbolic link is made as libbar.so) However, when I change the symbolic link to libbar.so.2, foo.bin could not run and complainted this: undefined symbol: _ZSt4cerr I found this symbol type is 'B' and it does not appear in libbar.so.2. Obviously this symbol has nothing to do with those functions I decared in bar.h. What's wrong here?

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• Call methods on native Javascript types without wrapping with ()

  - by Anurag

  In Javascript, we can call methods on string literals directly without enclosing it within round brackets. But not for other types such as numbers, or functions. It is a syntax error, but is there a reason as to why the Javascript lexer needs these other types to be enclosed in round brackets? For example, if we extend Number, String, and Function with an alert method and try calling this method on the literals, it's a SyntaxError for Number and Function, while it works for a String. function alertValue() { alert(this); } Number.prototype.alert = alertValue; String.prototype.alert = alertValue; Function.prototype.alert = alertValue; We can call alert directly on a string object: "someStringLiteral".alert() // alerts someStringLiteral but it's a SyntaxError on numbers, and functions. 7.alert(); function() {}.alert(); To work with these types, we have to enclose it within brackets: (7).alert(); // alerts "7" (function() {}).alert(); // alerts "function() {}"

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• Device drivers and Windows

  - by b-gen-jack-o-neill

  Hi, I am trying to complete the picture of how the PC and the OS interacts together. And I am at point, where I am little out of guess when it comes to device drivers. Please, don´t write things like its too complicated, or you don´t need to know when using high programming laguage and winapi functions. I want to know, it´s for study purposes. So, the very basic structure of how OS and PC (by PC I mean of course HW) is how I see it is that all other than direct CPU commands, which can CPU do on itself (arithmetic operation, its registers access and memory access) must pass thru OS. Mainly becouse from ring level 3 you cannot use in and out intructions which are used for acesing other HW. I know that there is MMIO,but it must be set by port comunication first. It was not like this all the time. Even I am bit young to remember MSDOS, I know you could access HW directly, becouse there ws no limitation, no ring mode. So you could to write string to diplay use wheather DOS function, or directly acess video card memory and write it by yourself. But as OS developed, there is no longer this possibility. But it is fine, since OS now handles all the HW comunication, and frankly it more convinient and much more safe (I would say the only option) in multitasking environment. So nowdays you instead of using int instructions to use BIOS mapped function or DOS function you call dll which internally than handles everything you don´t need to know about. I understand this. I also undrstand that device drivers is the piece of code that runs in ring level 0, so it can do all the HW interactions. But what I don´t understand is connection between OS and device driver. Let´s take a example - I want to make a sound card make a sound. So I call windows API to acess sound card, but what happens than? Does windows call device drivers to do so? But if it does call device driver, does it mean, that all device drivers which can be called by winAPI function, must have routines named in some specific way? I mean, when I have new sound card, must its drivers have functions named same as the old one? So Windows can actually call the same function from its perspective? But if Windows have predefined sets of functions requored by device drivers, that it cannot use new drivers that doesent existed before last version of OS came out. Please, help me understand this mess. I am really getting mad. Thanks.

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• virtual function

  - by saha

  what are virtual functions? what is pure virtual function? please explain with example

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• Javascript/jQuery: Varying parameters on a custom function

  - by dclowd9901

  I'm writing a plugin that will allow parameters to 'set it up.' But I predict the user won't always want to set up every aspect of the function. function This_Function(a,b,c,d); For instance, maybe they'll only want to set up a and c, but not b and d (they'll just prefer to leave those as defaults). How do I write the function (or the parameters for that matter) so that the user can customize which functions they would prefer to pass? I have a feeling it involves parsing input, but I've seen many other functions with this capability. Thanks in advance for the help.

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• How To Refactor If-else Code Segment?

  - by LostInLib

  I'm developing win8(metro style) application with Html5-js-jquery. I have this code segment; GetBoutiqueDetail: function (boutiqueId, options) { if (IsUserLogin()) { //different job A } else { ShowLoginPanel(undefined); } }, GetProductDetail: function (boutiqueId, productId, options) { if (IsUserLogin()) { //different job B } else { ShowLoginPanel(undefined); } }, AddBasket: function (productId, productVariantId, quantity, options) { if (IsUserLogin()) { //different job C } else { ShowLoginPanel(undefined); } },.... .And ~20 functions should check if user login or not. I should call functions like similar to "Library.GetBoutiqueDetail();" So my question is simple, how can I refactor that code to remove these if-else sections ?

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• Hashing a python function to regenerate output when the function is modified

  - by Seth Johnson

  I have a python function that has a deterministic result. It takes a long time to run and generates a large output: def time_consuming_function(): # lots_of_computing_time to come up with the_result return the_result I modify time_consuming_function from time to time, but I would like to avoid having it run again while it's unchanged. [time_consuming_function only depends on functions that are immutable for the purposes considered here; i.e. it might have functions from Python libraries but not from other pieces of my code that I'd change.] The solution that suggests itself to me is to cache the output and also cache some "hash" of the function. If the hash changes, the function will have been modified, and we have to re-generate the output. Is this possible or ridiculous? Updated: based on the answers, it looks like what I want to do is to "memoize" time_consuming_function, except instead of (or in addition to) arguments passed into an invariant function, I want to account for a function that itself will change.

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