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  • Chart for deciphering terms in different programming languages

    - by Nathan Adams
    This has been bugging me every since I started to use Python - in PHP you have this ability to use a string as a key in an array. PHP calls these associative arrays. Python calls these dictionaries. Does anyone know of a premade chart that will let me see what the different terminology is in different languages. For example: PHP             | Python Assosicative array | Dictionary

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  • Web application architecture, and application servers?

    - by seanieb
    Hi, I'm building a web application, and I need to use an architecture that allows me to run it on two servers. The application scrapes information from other sites periodically, and on input from the end user. To do this I'm using Php+curl to scrape the information, Php or python to parse it and store the results in a MySQLDB. Then I will use Python to run some algorithms on the data, this will happen both periodically and on input from the end user. I'm going to cache some of the results in the MySQL DB and sometimes if it is specific to the user, skip storing the data and serve it to the user. I'm think of using Php for the website front end on a separate web server, running the Php spider, MySQL DB and python on another server. As you can see I'm fairly clueless. I'm familiar with using Php, MySQL and the basics of Python, but bringing this all together using something more complex than a cron job is new to me. How do go about implementing this? What frame work(s) should I use? Is MVC a good architecture for this? (I'm new to MVC, architectures etc.) Is Cakephp a good solution? If so will I be able to control and monitor the Python code using it?

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  • When/Why ( if ever ) should i think about doing Generic Programming/Meta Programming

    - by hotadvice
    Hi there IMHO to me OOPS, design patterns make sense and i have been able to apply them practically. But when it comes to "generic programming /meta programming" of the Modern C++ kind, i am left confused. -- Is it a new programming/design paradigm ? -- Is it just limited to "library development"? If not, What design/coding situations call for using meta programming/generic programming. -- Does using templates mean i am doing generic programming? I have googled a lot on this topic but do not grasp the BIG PICTURE fully. Also see this post. After reading dicussions here under, up till now, I am sure ( might still not be correct): a) Generic programming and meta programming are two different concepts.

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  • Help me choose a web development framework/platform that will make me learn something

    - by Sergio Tapia
    I'm having a bit of an overload of information these past two days. I'm planning to start my own website that will allow local businesses to list their items on sale, and then users can come in and search for "Abercrombie t-shirt" and the stores that sell them will be listed. It's a neat little project I'm really excited for and I'm sure it'll take off, but I'm having problems from the get go. Sure I could use ASP.Net for it, I'm a bit familiar with it and the IDE for ASP.Net pages is bar-none, but I feel this is a great chance for me to learn something new to branch out a bit and not regurgitate .NET like a robot. I've been looking and asking around but it's all just noise and I can't make an educated decision. Can you help me choose a framework/platform that will make me learn something that's a nice thing to know in the job market, but also nice for me to grow as a professional? So far I've looked at: Ruby on Rails Kohana CakePHP CodeIgniter Symfony But they are all very esoteric to me, and I have trouble even finding out which IDE to use to that will let me use auto-complete for the proprietary keywords/methods. Thank you for your time.

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  • Where can I find a good tutorial for py2exe?

    - by Manzabar
    Can somebody point me at a good tutorial for py2exe? I've read over the official tutorial but it is rather light on details, compared to all the options one can use when building an executable out of a python script. For the record, my python script uses Python 2.5.2, wxPython/wxWidgets 2.8 and MySQLdb 1.2.2; so if you have specific tips for py2exe with those packages that would be much appreciated (and yes, I've seen the Py2EXE and wxPython page).

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  • alias_method and class_methods don't mix?

    - by Daniel
    Greetings, I've been trying to tinker with a global Cache module, but I can't figure out why this isn't working. Does anyone have any suggestions? This is the error produced for the below code: NameError: undefined method get' for moduleCache' from (irb):21:in `alias_method' module Cache def self.get puts "original" end end module Cache def self.get_modified puts "New get" end end def peek_a_boo Cache.module_eval do # make :get_not_modified alias_method :get_not_modified, :get alias_method :get, :get_modified end Cache.get Cache.module_eval do alias_method :get, :get_not_modified end end # test first round peek_a_boo # test second round peek_a_boo TIA! -daniel

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  • How to add django modules to pydiction dictionary?

    - by speck
    I'm trying to use pydiction to autocomplete Python/Django statements in VIM Editor. When I try to add django modules to complete-dic using this: python pydiction.py /usr/lib/pymodules/python2.6/django or: python pydiction.py /usr/lib/pymodules/python2.6/django/__init__.py I receive this error: Couldn't import: (...). Import by filename is not supported. Thanks! Pydiction: http://www.vim.org/scripts/script.php?script_id=850

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  • Windows 7 - pydoc from cmd

    - by Random_Person
    Okay, I'm having one of those moments that makes me question my ability to use a computer. This is not the sort of question I imagined asking as my first SO post, but here goes. Started on Zed's new "Learn Python the Hard Way" since I've been looking to get back into programming after a 10 year hiatus and python was always what I wanted. This book has really spoken to me. That being said, I'm having a serious issue with pydoc from the command. I've got all the directories in c:/python26 in my system path and I can execute pydoc from the command line just fine regardless of pwd - but it accepts no arguments. Doesn't matter what I type, I just get the standard pydoc output telling me the acceptable arguments. Any ideas? For what it's worth, I installed ActivePython as per Zed's suggestion. C:\Users\Chevee>pydoc file pydoc - the Python documentation tool pydoc.py <name> ... Show text documentation on something. <name> may be the name of a Python keyword, topic, function, module, or package, or a dotted reference to a class or function within a module or module in a package. If <name> contains a '\', it is used as the path to a Python source file to document. If name is 'keywords', 'topics', or 'modules', a listing of these things is displayed. pydoc.py -k <keyword> Search for a keyword in the synopsis lines of all available modules. pydoc.py -p <port> Start an HTTP server on the given port on the local machine. pydoc.py -g Pop up a graphical interface for finding and serving documentation. pydoc.py -w <name> ... Write out the HTML documentation for a module to a file in the current directory. If <name> contains a '\', it is treated as a filename; if it names a directory, documentation is written for all the contents. C:\Users\Chevee> EDIT: New information, pydoc works just fine in PowerShell. As a linux user, I have no idea why I'm trying to use cmd anyways--but I'd still love to figure out what's up with pydoc and cmd. EDIT 2: More new information. In cmd... c:\>python c:/python26/lib/pydoc.py file ...works just fine. Everything works just fine with just pydoc in PowerShell without me worrying about pwd, or extensions or paths.

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  • Building a ctypes-"based" C library with distutils

    - by Robie Basak
    Following this recommendation, I have written a native C extension library to optimise part of a Python module via ctypes. I chose ctypes over writing a CPython-native library because it was quicker and easier (just a few functions with all tight loops inside). I've now hit a snag. If I want my work to be easily installable using distutils using python setup.py install, then distutils needs to be able to build my shared library and install it (presumably into /usr/lib/myproject). However, this not a Python extension module, and so as far as I can tell, distutils cannot do this. I've found a few references to people other people with this problem: Someone on numpy-discussion with a hack back in 2006. Somebody asking on distutils-sig and not getting an answer. Somebody asking on the main python list and being pointed to the innards of an existing project. I am aware that I can do something native and not use distutils for the shared library, or indeed use my distribution's packaging system. My concern is that this will limit usability as not everyone will be able to install it easily. So my question is: what is the current best way of distributing a shared library with distutils that will be used by ctypes but otherwise is OS-native and not a Python extension module? Feel free to answer with one of the hacks linked to above if you can expand on it and justify why that is the best way. If there is nothing better, at least all the information will be in one place.

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  • Why is partial specialziation of a nested class template allowed, while complete isn't?

    - by drhirsch
    template<int x> struct A { template<int y> struct B {};. template<int y, int unused> struct C {}; }; template<int x> template<> struct A<x>::B<x> {}; // error: enclosing class templates are not explicitly specialized template<int x> template<int unused> struct A<x>::C<x, unused> {}; // ok So why is the explicit specialization of a inner, nested class (or function) not allowed, if the outer class isn't specialiced too? Strange enough, I can work around this behaviour if I only partially specialize the inner class with simply adding a dummy template parameter. Makes things uglier and more complex, but it works. Note: I need this feature for recursive templates of the inner class for a set of the outer class. To make things even more complicate, in reality I only need a template function instead of the inner class. But partial specialization of functions is generally disallowed somewhere else in the standard ^^

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  • Dynamically defined setter methods using define_method?

    - by nicosuria
    I use a lot of iterations to define convenience methods in my models, stuff like: PET_NAMES.each do |pn| define_method(pn) do ... ... end but I've never been able to dynamically define setter methods, ie: def pet_name=(name) ... end using define_method like so: define_method("pet_name=(name)") do ... end Any ideas? Thanks in advance.

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  • How do I temporarily monkey with a global module constant?

    - by Daniel
    Greetings, I want to tinker with the global memcache object, and I found the following problems. Cache is a constant Cache is a module I only want to modify the behavior of Cache globally for a small section of code for a possible major performance gain. Since Cache is a module, I can't re-assign it, or encapsulate it. I Would Like To Do This: Deep in a controller method... code code code... old_cache = Cache Cache = MyCache.new code code code... Cache = old_cache code code code... However, since Cache is a constant I'm forbidden to change it. Threading is not an issue at the moment. :) Would it be "good manners" for me to just alias_method the special code I need just for a small section of code and then later unalias it again? That doesn't pass the smell test IMHO. Does anyone have any ideas? TIA, -daniel

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  • Ruby - print the variable name and then its value

    - by tyndall
    What is the best way to write a function (or something DSLish) that will allow me to write this code in Ruby. How would I construct the function write_pair? username = "tyndall" write_pair username # where write_pair username outputs username: tyndall Is it possible to do? Looking for the most simple way to do this.

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  • Counting entries in a list of dictionaries: for loop vs. list comprehension with map(itemgetter)

    - by Dennis Williamson
    In a Python program I'm writing I've compared using a for loop and increment variables versus list comprehension with map(itemgetter) and len() when counting entries in dictionaries which are in a list. It takes the same time using a each method. Am I doing something wrong or is there a better approach? Here is a greatly simplified and shortened data structure: list = [ {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'biscuits and gravy'}, {'key1': False, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'peaches and cream'}, {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': False, 'filenotfound': 'Abbott and Costello'}, {'key1': False, 'dontcare': False, 'ignoreme': True, 'key2': False, 'filenotfound': 'over and under'}, {'key1': True, 'dontcare': True, 'ignoreme': False, 'key2': True, 'filenotfound': 'Scotch and... well... neat, thanks'} ] Here is the for loop version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True key1 = key2 = 0 for dictionary in list: if dictionary["key1"]: key1 += 1 if dictionary["key2"]: key2 += 1 print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above: Counts: key1: 3, subset key2: 2 Here is the other, perhaps more Pythonic, version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True from operator import itemgetter KEY1 = 0 KEY2 = 1 getentries = itemgetter("key1", "key2") entries = map(getentries, list) key1 = len([x for x in entries if x[KEY1]]) key2 = len([x for x in entries if x[KEY1] and x[KEY2]]) print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above (same as before): Counts: key1: 3, subset key2: 2 I'm a tiny bit surprised these take the same amount of time. I wonder if there's something faster. I'm sure I'm overlooking something simple. One alternative I've considered is loading the data into a database and doing SQL queries, but the data doesn't need to persist and I'd have to profile the overhead of the data transfer, etc., and a database may not always be available. I have no control over the original form of the data. The code above is not going for style points.

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  • Macports and virtualenv site-packages Fallback

    - by Streeter
    I've installed django and python as this link suggested with macports. However, I'd like to use virtualenv to install more packages. My understanding is that if I do not pass in the --no-site-packages to virtualenv, I should get the currently installed packages in addition to whatever packages I install into the virtual environment. Is this correct? As an example, I've installed django through macports and then create a virtual environment, but I cannot import django from within that virtual environment: [streeter@mordecai]:~$ mkvirtualenv django-test New python executable in django-test/bin/python Installing setuptools............done. ... (django-test)[streeter@mordecai]:~$ pip install django-debug-toolbar Downloading/unpacking django-debug-toolbar Downloading django-debug-toolbar-0.8.4.tar.gz (80Kb): 80Kb downloaded Running setup.py egg_info for package django-debug-toolbar Installing collected packages: django-debug-toolbar Running setup.py install for django-debug-toolbar Successfully installed django-debug-toolbar Cleaning up... (django-test)[streeter@mordecai]:~$ python Python 2.6.1 (r261:67515, Jun 24 2010, 21:47:49) [GCC 4.2.1 (Apple Inc. build 5646)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import django Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: No module named django >>> So I can install packages into the virtual environment, but it isn't picking up the global site-packages. Or am I not doing something correctly / missing something / misunderstanding how virtualenv works? I've got Mac OS 10.6 (Snow Leopard), have updated my macports packages and am using macports' python26 (via python_select python26).

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  • Disable logging during manage.py test?

    - by Eric Palakovich Carr
    I utilize the standard python logging module. When I call python manage.py test I'd like to disable logging before all the tests are ran. Is there a signal or some other kind of hook I could use to call logging.disable? Or is there some other way to disable logging when python manage.py test is ran?

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  • C++ Declarative Parsing Serialization

    - by Martin York
    Looking at Java and C# they manage to do some wicked processing based on special languaged based anotation (forgive me if that is the incorrect name). In C++ we have two problems with this: 1) There is no way to annotate a class with type information that is accessable at runtime. 2) Parsing the source to generate stuff is way to complex. But I was thinking that this could be done with some template meta-programming to achieve the same basic affect as anotations (still just thinking about it). Like char_traits that are specialised for the different types an xml_traits template could be used in a declaritive way. This traits class could be used to define how a class is serialised/deserialized by specializing the traits for the class you are trying to serialize. Example Thoughs: template<typename T> struct XML_traits { typedef XML_Empty Children; }; template<> struct XML_traits<Car> { typedef boost::mpl::vector<Body,Wheels,Engine> Children; }; template<typename T> std::ostream& Serialize(T const&) { // my template foo is not that strong. // but somthing like this. boost::mpl::for_each<typename XML_Traits<T>::Children,Serialize>(data); } template<> std::ostream& Serialize<XML_Empty>(T const&) { /* Do Nothing */ } My question is: Has anybody seen any projects/decumentation (not just XML) out there that uses techniques like this (template meta-programming) to emulate the concept of annotation used in languges like Java and C# that can then be used in code generation (to effectively automate the task by using a declaritive style). At this point in my research I am looking for more reading material and examples.

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  • Looking for Programming Language that allows you to change true and false.

    - by Maushu
    For my curiosity sake I'm looking for a dynamic object oriented language that allows you to change true to false and vice versa. Something like this: true = false, false = true; This should also affect any conditional statements, therefore 42 == 42 should return False. Basically, with this premise, nothing in the language would be safe from the programmer. Is there any language like this?

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  • How do I fix this Django error "Exception Type: OperationalError Exception Value: no such table?"

    - by user319045
    I've finally installed all the requirements (so i think!) of a Django project, and I'm trying to get a local install running on my Mac (OSX 10.4). I'm getting the following error: Blockquote OperationalError at / no such table: django_content_type Request Method: GET Request URL: http://127.0.0.1:8000/ Exception Type: OperationalError Exception Value: no such table: django_content_type Exception Location: /Users/Diesel/Desktop/DjangoWork/pinax-ev/lib/python2.5/site-packages/django/db/backends/sqlite3/base.py in execute, line 170 Python Executable: /Users/Diesel/Desktop/DjangoWork/pinax-ev/bin/python Python Version: 2.5.1

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  • Stepping into Ruby Meta-Programming: Generating proxy methods for multiple internal methods

    - by mstksg
    Hi all; I've multiply heard Ruby touted for its super spectacular meta-programming capabilities, and I was wondering if anyone could help me get started with this problem. I have a class that works as an "archive" of sorts, with internal methods that process and output data based on an input. However, the items in the archive in the class itself are represented and processed with integers, for performance purposes. The actual items outside of the archive are known by their string representation, which is simply number_representation.to_s(36). Because of this, I have hooked up each internal method with a "proxy method" that converts the input into the integer form that the archive recognizes, runs the internal method, and converts the output (either a single other item, or a collection of them) back into strings. The naming convention is this: internal methods are represented by _method_name; their corresponding proxy method is represented by method_name, with no leading underscore. For example: class Archive ## PROXY METHODS ## ## input: string representation of id's ## output: string representation of id's def do_something_with id result = _do_something_with id.to_i(36) return nil if result == nil return result.to_s(36) end def do_something_with_pair id_1,id_2 result = _do_something_with_pair id_1.to_i(36), id_2.to_i(36) return nil if result == nil return result.to_s(36) end def do_something_with_these ids result = _do_something_with_these ids.map { |n| n.to_i(36) } return nil if result == nil return result.to_s(36) end def get_many_from id result = _get_many_from id return nil if result == nil # no sparse arrays returned return result.map { |n| n.to_s(36) } end ## INTERNAL METHODS ## ## input: integer representation of id's ## output: integer representation of id's def _do_something_with id # does something with one integer-represented id, # returning an id represented as an integer end def do_something_with_pair id_1,id_2 # does something with two integer-represented id's, # returning an id represented as an integer end def _do_something_with_these ids # does something with multiple integer ids, # returning an id represented as an integer end def _get_many_from id # does something with one integer-represented id, # returns a collection of id's represented as integers end end There are a couple of reasons why I can't just convert them if id.class == String at the beginning of the internal methods: These internal methods are somewhat computationally-intensive recursive functions, and I don't want the overhead of checking multiple times at every step There is no way, without adding an extra parameter, to tell whether or not to re-convert at the end I want to think of this as an exercise in understanding ruby meta-programming Does anyone have any ideas? edit The solution I'd like would preferably be able to take an array of method names @@PROXY_METHODS = [:do_something_with, :do_something_with_pair, :do_something_with_these, :get_many_from] iterate through them, and in each iteration, put out the proxy method. I'm not sure what would be done with the arguments, but is there a way to test for arguments of a method? If not, then simple duck typing/analogous concept would do as well.

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  • In MAYA 2009, is it possible to capture the cube rotate event?

    - by Rahul2047
    I need to call a function ( Maya-Python ) based on cube rotationX. For that I have to capture the event, programmatically. I tried using while loop but It stucks in the loop, Nothing can be done in that time. I tried theading (python), still same. Can it be done this or other way? If yes, How? Maya 2009 in Windows XP Some failed code references: import maya.cmds as cmds while (count < 90): lock = cmds.getAttr('pCube1.rotateX',lock=False) print lock count = count + 1 Here Python wise: #!/usr/bin/python import thread import time # Define a function for the thread def cubeRotateX( threadName, delay): count = 0 while count < 5: time.sleep(delay) count += 1 try: thread.start_new_thread( cubeRotateX, ("Thread-1", 2, ) ) except: print "Error: unable to start thread" while 1: pass

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  • Odd C++ template behaviour with static member vars

    - by jon hanson
    This piece of code is supposed to calculate an approximation to e (i.e. the mathematical constant ~ 2.71828183) at compile-time, using the following approach; e1 = 2 / 1 e2 = (2 * 2 + 1) / (2 * 1) = 5 / 2 = 2.5 e3 = (3 * 5 + 1) / (3 * 2) = 16 / 6 ~ 2.67 e4 = (4 * 16 + 1) / (4 * 6) = 65 / 24 ~ 2.708 ... e(i) = (e(i-1).numer * i + 1) / (e(i-1).denom * i) The computation is returned via the result static member however, after 2 iterations it yields zero instead of the expected value. I've added a static member function f() to compute the same value and that doesn't exhibit the same problem. #include <iostream> #include <iomanip> // Recursive case. template<int ITERS, int NUMERATOR = 2, int DENOMINATOR = 1, int I = 2> struct CalcE { static const double result; static double f () {return CalcE<ITERS, NUMERATOR * I + 1, DENOMINATOR * I, I + 1>::f ();} }; template<int ITERS, int NUMERATOR, int DENOMINATOR, int I> const double CalcE<ITERS, NUMERATOR, DENOMINATOR, I>::result = CalcE<ITERS, NUMERATOR * I + 1, DENOMINATOR * I, I + 1>::result; // Base case. template<int ITERS, int NUMERATOR, int DENOMINATOR> struct CalcE<ITERS, NUMERATOR, DENOMINATOR, ITERS> { static const double result; static double f () {return result;} }; template<int ITERS, int NUMERATOR, int DENOMINATOR> const double CalcE<ITERS, NUMERATOR, DENOMINATOR, ITERS>::result = static_cast<double>(NUMERATOR) / DENOMINATOR; // Test it. int main (int argc, char* argv[]) { std::cout << std::setprecision (8); std::cout << "e2 ~ " << CalcE<2>::result << std::endl; std::cout << "e3 ~ " << CalcE<3>::result << std::endl; std::cout << "e4 ~ " << CalcE<4>::result << std::endl; std::cout << "e5 ~ " << CalcE<5>::result << std::endl; std::cout << std::endl; std::cout << "e2 ~ " << CalcE<2>::f () << std::endl; std::cout << "e3 ~ " << CalcE<3>::f () << std::endl; std::cout << "e4 ~ " << CalcE<4>::f () << std::endl; std::cout << "e5 ~ " << CalcE<5>::f () << std::endl; return 0; } I've tested this with VS 2008 and VS 2010, and get the same results in each case: e2 ~ 2 e3 ~ 2.5 e4 ~ 0 e5 ~ 0 e2 ~ 2 e3 ~ 2.5 e4 ~ 2.6666667 e5 ~ 2.7083333 Why does result not yield the expected values whereas f() does? According to Rotsor's comment below, this does work with GCC, so I guess the question is, am i relying on some type of undefined behaviour with regards to static initialisation order, or is this a bug with Visual Studio?

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  • C# - Silverlight - Dynamically calling a method

    - by cmaduro
    Is there anyway in C# to call a method based on a Enum and/or class? Say if I were to call Controller<Actions.OnEdit, Customer>(customer); Could I do something like this then? public void Controller<TAction, TParam>(TParam object) { Action<TParam> action = FindLocalMethodName(TAction); action(object); } private Action<T> FindLocalMethodName(Enum method) { //Use reflection to find a metode with //the name corresponding to method.ToString() //which accepts a parameters type T. }

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  • C++ meta-splat function

    - by aaa
    hello. Is there an existing function (in boost mpl or fusion) to splat meta-vector to variadic template arguments? for example: splat<vector<T1, T2, ...>, function>::type same as function<T1, T2, ...> my search have not found one, and I do not want to reinvent one if it already exists. edit: after some tinkering, apparently it's next to impossible to accomplish this in general way, as it would require declaring full template template parameter list for all possible cases. only reasonable solution is to use macro: #define splat(name, function) \ template<class T, ...> struct name; \ template<class T> \ struct name<T,typename boost::enable_if_c< \ result_of::size<T>::value == 1>::type> { \ typedef function< \ typename result_of::value_at_c<T,0>::type \ > type; \ }; Oh well. thank you

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