metaprogramming

问题 I've encountered a Groovy meta-programming problem which I'm unable to solve. When adding the static method foo() to the class FooBar, then FooBar.foo() works as expected: FooBar.metaClass.static.foo = { println "hello" } FooBar.foo() However, I instead add the same static method foo() to the class Object, then FooBar.foo() fails with an MissingMethodException: Object.metaClass.static.foo = { println "hello" } FooBar.foo() // groovy.lang.MissingMethodException: // No signature of method:

问题 I am trying to dynamically create a class using the eval method. It is working fine except for one small problem. As my code shows I am creating the Browser class inside the BrowserFactory class. When I do this the Browser class has an added namespace of BrowserFactory. Is there anyway to evaluate the Browser class from a string without the BrowserFactory namespace being attached? class BrowserFactory def self.create_browser(browser) super_class = nil case browser when 'IE' require 'watir'

问题 Say I make a class with a method in it. class A def test puts 'test' end end I want to know what goes on inside of test . I want to literally output: def test puts 'test' end Is there any way to output the source of a method in a string? 回答1: You can use Pry to view methods # myfile.rb require 'pry' class A def test return 'test' end end puts Pry::Method(A.new.method(:test)).source #(1) # or as suggested in the comments puts Pry::Method.from_str("A#test").source #(2) # uses less cpu cycles

问题 I did a little experiments with Ruby class dynamic loading/unloading/updating as implementing plugins infrastructure. I found a few points: If loading new version of same class without first unloading it, the new one essentially 'top' or 'merge' with previous version. All existent objects created with previous version would get their class definition 'updated'. Unloading a class does not affect existent objects created with this class. Existent objects stay with whatever version just unloaded

问题 In Python 3 one can use super() instead of super(MyClass, self) , but this only works in methods that were defined inside the class. As described in Michele Simionato's article the following example does not work: def __init__(self): print('calling __init__') super().__init__() class C(object): __init__ = __init__ if __name__ == '__main__': c = C() It fails because super() looks for a __class__ cell, which is not defined in this case. Is it possible to set this cell manually after the

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . I want to do some metaprogramming in a statically typed language, where both my programs and my meta-programs will be typed. I mean

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 6 years ago . I want to do some metaprogramming in a statically typed language, where both my programs and my meta-programs will be typed. I mean

问题 I am exploring different ways to wrap an aggregation function (but really it could be any type of function) using data.table (one dplyr example is also provided) and was wondering on best practices for functional programming / metaprogramming with respect to performance (does the implementation matter with respect to potential optimization that data.table may apply) readability (is there a commonly agreed standard e.g. in most packages utilizing data.table) ease of generalization (are there

问题 I read this term a lot in blogs about haskell and functional programming (specially in sigfpe's blog) but I don't have a clue about what it means. I get away with not knowing it most of the times, but I probably would have understood the texts a lot better if I knew. Google didn't help me. I get lost in the technical stuff. Also the non-technical meaning of the world ("turning the abstract concrete") doesn't help me understand what it practically means to reify something in code. I'm kinda

问题 I read this term a lot in blogs about haskell and functional programming (specially in sigfpe's blog) but I don't have a clue about what it means. I get away with not knowing it most of the times, but I probably would have understood the texts a lot better if I knew. Google didn't help me. I get lost in the technical stuff. Also the non-technical meaning of the world ("turning the abstract concrete") doesn't help me understand what it practically means to reify something in code. I'm kinda