define_class and get_class

[Mushtaq Ahmed]

Methods can be defined and called dynamically using define_method and
send/method respectively. Shouldn't there be similar alternatives for
class creation and invocation? Maybe like this:

name = "A"
define_class(name) do
def say_hi
p "hi"
end

 

[Robert Klemme]

Methods can be defined and called dynamically using define_method and
send/method respectively. Shouldn't there be similar alternatives for
class creation and invocation? Maybe like this:

name = "A"
define_class(name) do
def say_hi
p "hi"
end
.
.
end
get_class(name).new.say_hi


I would like the above syntax better than the current way of doing it.

name = "A"
eval "class #{name}; end"
klass = Object.const_get(name)
klass.class_eval do
def say_hi
p "hi"
end
.
.
end
klass.new.say_hi

-Mushtaq

cl = Class.new do
def say_hi() puts "hi!" end
end
hi!
=> nil=> "A"

Does that help?

Kind regards

robert

 

[Trans]

A = Class.new {
# ...
}

T.

 

[Paul Brannan]

name = "A"
eval "class #{name}; end"
klass = Object.const_get(name)
klass.class_eval do
def say_hi
p "hi"
end
.
.
end
klass.new.say_hi

This is unnecessary.

A = Class.new
A.class_eval do
def say_hi
p "hi"
end
end

And as of 1.8, we can now also write:

A = Class.new do
def say_hi
p "hi"
end
end

Paul

 

[daz]

Methods can be defined and called dynamically using define_method and
send/method respectively. Shouldn't there be similar alternatives for
class creation and invocation? Maybe like this:

name = "A"
define_class(name) do
def say_hi
p "hi"
end
.
.
end
get_class(name).new.say_hi


I would like the above syntax better than the current way of doing it.

module Kernel
def define_class(name, &blk)
klass = self.class.const_set(name, Class.new(&blk))
end

def get_class(name)
self.class.const_get(name)
end
end



name = 'D'

klass = define_class(name) do
def say_hi
p "hi #{self.class.name}"
end
end

get_class(name).new.say_hi #-> "hi D"


daz

 

[Mushtaq Ahmed]

A = Class.new {
# ...
}

T.

Not the same thing. I want to decide the class name at runtime. It could
be A, B, C or whatever.

-Mushtaq

 

[Robert Klemme]

Not the same thing. I want to decide the class name at runtime. It
could be A, B, C or whatever.

cl = Class.new do
def foo() "bar" end
end

Object.const_set("AnyName", cl)
....

robert