Here's what I want to be able to type: class foo : public watchKeys<A, B, C> {}; //Or any list of keys Boost::mpl has sequences, which allow you to do this, but I don't want to have to do: class foo : public watchKeys<mpl::list<A, B, C> > {}; I don't mind it being "ugly" or verbose on the inside, but I want the way watchKeys is ult...
I am trying to get a string name of a class from the class object itself. // For instance [NSArray className]; // @"NSArray" I have found object_getClassName(id obj) but that requires an instance be passed to it, and in my case that is needless work. So how can I get a string from a class object, and not an instance? ...
I'm trying to write some metaprogramming code such that: Inheriting from some class foo<c1, c2, c3, ...> results in inheritance from key<c1>, key<c2>, key<c3>, ... The simplest approach doesn't quite work because you can't inherit from the same empty class more than once. Handling the "..." portion isn't pretty (since it's copy-pasta),...
Why does this print 42: $answer = 42; $variable = "answer"; print ${$variable} . "\n"; but this doesn't: my $answer = 42; my $variable = "answer"; print ${$variable} . "\n"; ...
Is it worth to write code like the following to copy array elements: #include <iostream> using namespace std; template<int START, int N> struct Repeat { static void copy (int * x, int * y) { x[START+N-1] = y[START+N-1]; Repeat<START, N-1>::copy(x,y); } }; template<int START> struct Repeat<START, 0> { static void copy ...
I wonder how to get something like this 1 write copy(a,b,2,3) 2 and then get, a[2]=b[2]; a[3]=b[3]; a[4]=b[4]; I know that C #defines can't be used recursively to get that effect, so I suppose that template meta-programming is in place. I know there is a boost library for that, but I only want that "simple" trick, and boost is ...
Is there a way to find out the number of digits of min/max values of an integral type at compile time so that it's suitable to be placed as a template parameter? Ideally, there will be an existing solution in, for example, Boost MPL. Failing that I'm looking for some pointers for a hand-coded solution. ...
i need an mpl::equal like procedure that supports recursion on types. namespace mpl = boost::mpl; BOOST_MPL_ASSERT(( mpl::equal< mpl::vector<int, char>, typename mpl::push_back<mpl::vector<int>, char>::type > )); // OK the above compiles fine, however if i use it in mpl::transform or mpl::fold, visual studio 2010 rc1 complains. ...
Isn't it possible to treat functions in Scheme as any other list? Basically, what I want do to is something like this: (define (foo) "hello") (cdr foo) ; or similar, should return the list ((foo) "hello") I've found a similar discussion about this, and I feel a bit disappointed if this is not possible with Scheme. If so, why is th...
I'll explain what i'm looking for in code as thats probably the most succinct: module Mixin def method puts "Foo" end end class Whatever include Mixin end w = Whatever.new w.method => "Foo" # some magic here w2 = Whatever.new w.method => NoMethodError I had tried just undefining the Mixin module using remove_const, but t...
As a follow up to http://stackoverflow.com/questions/2403057/how-can-i-reverse-rubys-include-function, which was well answered but turned out my simplification of the real problem mean't that the solution was not applicable. I'm now faced with this (names changed to protect identities!): module OldFormHelpers def foo puts "foo" ...
This works: >>> def bar(x, y): ... print x, y ... >>> bar(y=3, x=1) 1 3 And this works: >>> class Foo(object): ... def bar(self, x, y): ... print x, y ... >>> z = Foo() >>> z.bar(y=3, x=1) 1 3 And even this works: >>> Foo.bar(z, y=3, x=1) 1 3 But why doesn't this work? >>> Foo.bar(self=z, y=3, x=1) Traceback...
The following code tried to replace an existing method in a Groovy class: class A { void abc() { println "original" } } x= new A() x.abc() A.metaClass.abc={-> println "new" } x.abc() A.metaClass.methods.findAll{it.name=="abc"}.each { println "Method $it"} new A().abc() And it results in the following output: original or...
I'm stuck. I'm trying to dynamically define a class method and I can't wrap my head around the ruby metaclass model. Consider the following class: class Example def self.meta; (class << self; self; end); end def self.class_instance; self; end end Example.class_instance.class # => Class Example.meta.class # => Class Ex...
I find functools.partial to be extremely useful, but I would like to be able to freeze arguments out of order (the argument you want to freeze is not always the first one) and I'd like to be able to apply it to several methods on a class at once, to make a proxy object that has the same methods as the underlying object except with some o...
I have a template that creates a unique identifier for each type it is instanced. Here's a streamlined version of the template: template <typename T> class arType { static const arType Id; // this will be unique for every instantiation of arType<>. } // Address of Id is used for identification. #define PA_TYPE_TAG(T) (&arType<T >::Id...
Say you have a tuple and want to generate a new tuple by applying a metafunction on each type of the first one. What' the most efficient C++ metafuntion to accomplish to this task? Is it also possible to use C++0x variadic template to provide a better implementation? ...
Hi everyone, I want to add class atttributes to a superclass dynamically. Furthermore, I want to create classes that inherit from this superclass dynamically, and the name of those subclasses should depend on user input. There is a superclass "Unit", to which I can add attributes at runtime. This already works. def add_attr (cls, na...
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 sa...
I'm trying to programmatically create a parameter block for a function ( along the lines of this blog post ). I'm starting with a CommandMetadata object (from an existing function). I can create the ParameterMetadata object and set things like the ParameterType, the name, as well as some attributes. The problem I'm running into is t...