Is this potentially a problem?

ruby-talk
1

"DaZoner" <nobody@nowhere.com> writes:

I've defined a class I use that strips methods off of a class (specified by
a string representing the class name). I use it maybe 30 times during my
application run. However I'm concerned because it does an
ObjectSpace.each(Class) call to make sure the specified class exists before
trying to remove any methods. Will this call get slow as a few arrays
containing perhaps a million FixNums get defined by the application in
between calls? The array's data stays around as the calls to my class are
made. I've included the source of the class below. If anyone knows an
efficient way to determine if a class exists given its name in String form
I'd sure appreciate seeing it.

Something like:

  Object.const_defined?(name) && Object.const_get(name).is_a?(Class)

You'd need to tweak it a bit to support nested class names like
C::D::E (in that case you'd need to call C::D.const_defined?('E'),
e.g.).

2

"George Ogata" <g_ogata@optushome.com.au> schrieb im Newsbeitrag
news:87d61xwbct.fsf@optushome.com.au...

"DaZoner" <nobody@nowhere.com> writes:

> I've defined a class I use that strips methods off of a class

(specified by

> a string representing the class name). I use it maybe 30 times during

my

> application run. However I'm concerned because it does an
> ObjectSpace.each(Class) call to make sure the specified class exists

before

> trying to remove any methods. Will this call get slow as a few arrays
> containing perhaps a million FixNums get defined by the application in
> between calls? The array's data stays around as the calls to my class

are

> made. I've included the source of the class below. If anyone knows an
> efficient way to determine if a class exists given its name in String

form

> I'd sure appreciate seeing it.
>

Something like:

  Object.const_defined?(name) && Object.const_get(name).is_a?(Class)

You'd need to tweak it a bit to support nested class names like
C::D::E (in that case you'd need to call C::D.const_defined?('E'),
e.g.).

For example like this:

module Kernel
  private

  # raises NameError if it's undefined
  # raises TypeError if it's not a class
  # returns the class instance otherwise
  def get_class(class_name)
    c = class_name.split(/::|\./).inject(Object) do |cl, name|
      cl.const_get name
    end
    raise TypeError, "Not a class: #{class_name}" unless Class === c
    c
  end
end

get_class "String"

=> String

get_class "StringX"

NameError: uninitialized constant StringX
        from (irb):27:in `const_get'
        from (irb):27:in `get_class'
        from (irb):26:in `inject'
        from (irb):26:in `each'
        from (irb):26:in `inject'
        from (irb):26:in `get_class'
        from (irb):35

get_class "File::Stat"

=> File::Stat

get_class "Enumerable"

TypeError: Not a class: Enumerable
        from (irb):29:in `get_class'
        from (irb):37

You probable want to include modules as well. Just change to

    raise TypeError, "Not a class: #{class_name}" unless Class === c ||
Module === c

get_class "Enumerable"

=> Enumerable

Regards

    robert