I just started playing with metaprogramming and I am working on different tasks just to explore the domain. One of these was to generate a unique integer and map it to type, like below: int myInt = TypeInt<AClass>::value; I want to know if this is at all possible, and in that case how. Because although I have learned much about explor...
I'm trying to do an instance_eval followed by a attr_accessor inside initialize, and I keep getting this: `initialize': undefined method 'attr_accessor'. Why isn't this working? The code looks kind of like this: class MyClass def initialize(*args) instance_eval "attr_accessor :#{sym}" end end ...
I'd like to port a little piece of code from Ruby to Groovy, and I'm stuck at this: def given(array,closure) { closure.delegate = array closure() } given([1,2,3,4]) { findAll { it > 4} } Right now it dies with this message: Exception thrown: Cannot compare ConsoleScript0$_run_closure1 with value 'ConsoleScript0$_run_closu...
I currently have a class hierarchy like MatrixBase -> DenseMatrix -> (other types of matrices) -> MatrixView -> TransposeView -> DiagonalView -> (other specialized views of matrices) MatrixBase is an abstract class which forces implementers to define operator()(in...
Basically, given a template class like this: template< class Value > class Holder { }; I would like to be able to discover the type Value for a given Holder class. I thought that I would be able to make a simple metafunction that takes a template template argument, like this: template< template< class Value > class Holder > class Ge...
Hi, in Pharo, how can I find the currently evaluating stack? ...
I have a python module. I want to populate some values to it at runtime, how do I do it. Eg. I have a list, ['A', 'B', 'C'] I am creating there classes with these names, and want them to available as if I created them normally for el in ['A', 'B', 'C']: type(el, (object,), {}) ...
Hi, I recently came across the term Polymorphic Code, and was wondering if anyone could suggest a legitimate (i.e. in legal and business appropriate software) reason to use it in a computer program? Links to real world examples would be appreciated! Before someone answers, telling us all about the benefits of polymorphism in object or...
Hi, I'm exploiting the behavior of the constructors of C++ global variables to run code at startup in a simple manner. It's a very easy concept but a little difficult to explain so let me just paste the code: struct _LuaVariableRegistration { template<class T> _LuaVariableRegistration(const char* lua_name, const T& c_name) { ...
I am using the acts_as_taggable_on gem and would like to add a method to one of the gem source files (tag.rb), but I do not want to change the gem source in any way. I have tried creating my own tag.rb file to in the /app/models directory or in the /lib directory, and then adding the desired method to that file expecting that ruby will ...
I'm currently dealing with a code base which contains several dozens of classes generated with SOAP::WSDL. However, having worked with Moose I now think that generating those classes at runtime at meta level (i.e. not to files on disk but directly to objects) might be a better idea (completely excluding performance reasons at this point)...
Would it be possible to translate the Ruby on Rails code base to Python? I think many people like Python more than Ruby, but find Ruby on Rails features better (as a whole) than the ones in Python web frameworks. So that, would it be possible? Or does Ruby on Rails utilize language-specific features that would be difficult to translate...
OK, I'll admit upfront this is a mega kludge and that I could definately implement this better. It's only morbid curiosity that's driving me to find out how I could do this. class SomeClass(object): def __init__(self): def __(self, arg): self.doStuff(arg) self.overLoaded = __ def doStuff(self, string)...
EDIT: Note that this is a REALLY BAD idea to do in production code. This was just an interesting thing for me. Don't do this at home! Is it possible to modify __metaclass__ variable for whole program (interpreter) in Python? This simple example is working: class ChattyType(type): def __init__(cls, name, bases, dct): print...
Hi, I've seen this recently and now I can't find it … How do you set the class of an object to something else? --Update: Well, in Pharo! Like: d:=Object new. d setClass: Dictionary. Only that it isn't actually setClass. How can you modify the class pointer of an object? ...
After reading C++ compile-time string hashing with Boost.MPL, and considering a problem I have, the following came to my mind. I have the base class: template<class Command> class Base { typedef Command CommandType; } It is supposed to be a utility base class for the Commands classes, so they don't need to typedef and declare some ...
I search around and tried overriding the "for" keyword but I found nothing. I am trying something like that: def for("maybe_arguments_go_here") print "Hello from function for!" end for i in 1..3 print "Hello from for" end ...
Some code. In [1]: A = type('B', (), {}) In [2]: a = A() In [3]: b = B() --------------------------------------------------------------------------- NameError Traceback (most recent call last) /home/shabda/<ipython console> in <module>() NameError: name 'B' is not defined What does first argument to...
Hi, does anybody know a library similar to boost::preprocessor (maybe not so advanced) that could be easily used/incorporated in plain C projects? Of course, the most (all ?) of boost::preprocessor is usable when writing in C but I would prefer a small library with only basic capabilities that doesn't depend on the monster like boost. ...
Is there high-level language out there for describing algorithms, that's geared towards specification, rather than implementation? The idea would be to have a machine-readable archive of standard algorithms, with machine-readable annotations on trade-offs, and variants. I'm thinking of something like CycL / OpenCyC, but for algorithms ...