On 02/04/2011 04:33 PM, Jacob Carlborg wrote:
On 2011-02-04 04:29, Robert Jacques wrote:
On Thu, 03 Feb 2011 08:49:54 -0500, Jacob Carlborg <[email protected]> wrote:
Well, opDispatch does exactly that. __reflect, on the other hand, was
designed as a quasi-backend function primarily for a) internal use
(hence the double underscore), b) scripting language
interfacing/implementing and c) user-extension. So efficiency was of key
importance. And the reflection system is extensible, as Variant knows to
call __reflect on user defined types. This makes things like prototype
style objects possible. (There's even a beta implementation of a
prototype object in the library) But this requires that the use
__reflect methods not be templated.
I'm not well versed in dynamic reflection and its use cases, so when I
considered the combination of a runtime method name and compile-time
argument type information, I classed it as 'rare in practice'. But if
that's not the case, I'd like to know and would greatly appreciate a use
case/unit test.
I recommend looking at Ruby, it has very good support for runtime reflection.
ActiveRecord in Rails is hevaly based on runtime reflection. For example, given
the following Ruby class:
class Post < ActiveRecord::Base
end
The class "Post" maps to the database table "posts", no configuration is
necessary. Then you can use the column names in the table as fields to set and
get data, like this:
post = Post.new
post.title = "some title"
post.body = "the body"
post.save # will update the database
All this is done using runtime reflection. Then you can query the database,
also using runtime reflection:
Post.find_by_name_and_body("some title", "the body")
Will find the first row where "title" and "body" matches the given values.
FWIW, python example of "Calling method by name" (using no exotic feature):
class C:
def __init__(self, x):
self.x = x
def write (self, thing):
print "%s == %s ? %s" \
%(self.x,thing, self.x==thing)
def runMethodWithArgs (object, name, *args):
method = getattr(object, name)
method(*args)
c= C(1.11)
runMethodWithArgs(c, "write", 2.22)
# --> 1.11 == 2.22 ? False
(Explanations if needed.)
Denis
--
_________________
vita es estrany
spir.wikidot.com
