From: Thomas Mueller <thomasmueller76@...>
Date: 2008-03-05T09:56:21+09:00
Subject: Re: Inspecting a block given to a method

Thanks for your quick reply. If I understand you correctly that would
result in something like this being executed:

bc.find_all(search_specs) do |record|
  activate("field1")  # this is what the proxy object would do
  record["field1"] = "some value"
  activate("field2")  # this is what the proxy object would do
  puts record["field2"]
end

That wouldn't work because the fields need to be activated before I
query the data, basically before or at the beginning of the find_all()
method.

When I query for data in Siebel it issues SQL statements to the
database and only includes activated fields. Activating fields just
before accessing them doesn't work - they need to be activated before
querying the database.

My find_all() looks something like this:

def find_all
  self.clear_to_query()
  self.set_search_spec(...) # several of those, based on arguments to find_all()
  self.execute_query()

  begin
    yield self
  end while self.next_record() if self.first_record()
end

The fields need to be activated before the execute_query() call.

Thomas


2008/3/5, Christopher Dicely <cmdicely@gmail.com>:
> On Tue, Mar 4, 2008 at 3:00 PM, Thomas Mueller
>  <thomasmueller76@googlemail.com> wrote:
>  > Hi,
>  >
>  >  I am using JRuby to access data in some business application (Siebel,
>  >  if anybody is interested).
>  >  In Siebel I need to activate fields if I want to access them later:
>  >
>  >  bc.activate_field(name)
>  >  bc.query(search_specs)
>  >  do stuff
>  >
>  >  I've written methods that do the query and then yield each record to a
>  >  given block, so I can write something like:
>  >
>  >  bc.activate_field("field1")
>  >  bc.activate_field("field2")
>  >  bc.find_all(search_specs) do |record|
>  >   record["field1"] = "some value"
>  >   puts record["field2"]
>  >  end
>  >
>  >  I would like to do the activate_field() calls automatically, based on
>  >  which fields are being accessed inside the block.
>  >  Is it possible to look into the block and find out which fields are
>  >  being accessed? In the above example that would include the fields
>  >  "field1" and "field2".
>  >  Basically, can I access the code inside the block and inspect it?
>
>
>
> I don't know of any way to do that. But I don't think you need to:
>  you can yield a proxy object to the block that intercepts the
>  references (the []= methods on the record object, or anything else
>  that requires activation) and activates fields as necessary, before
>  passing the call on to the object that does the real work, I think.
>
>