Catching attr_accessor with set_trace_func

[Wilson Bilkovich]

Code using attr_accessor:

class User
attr_accessor :something
def initialize
@something = 0
end
end

@user = User.new

set_trace_func(lambda {|*trace| STDERR.puts trace.inspect})
@user.something

#########
prints this to STDERR:
["line", "trace_func.rb", 11, nil, #<Binding:0x2946df0>, false]
#########

Functionally equivalent code with a hand-written method, instead of
attr_accessor:

class User
def something
@something
end
def initialize
@something = 0
end
end

@user = User.new

set_trace_func(lambda {|*trace| STDERR.puts trace.inspect})
@user.something


#########
prints this to STDERR:
["line", "trace_func.rb", 13, nil, #<Binding:0x2946d78>, false]
["call", "trace_func.rb", 2, :something, #<Binding:0x2946c10>, User]
["line", "trace_func.rb", 3, :something, #<Binding:0x2946bc8>, User]
["return", "trace_func.rb", 4, :something, #<Binding:0x2946aa8>, User]
#########


How can I capture the fact that the 'something' accessor was called in
the first example?

 

[Wilson Bilkovich]

Hi,

At Thu, 16 Nov 2006 16:52:07 +0900,
Nobuyoshi Nakada wrote in [ruby-talk:225257]:

--- eval.c 7 Nov 2006 09:38:12 -0000 1.958
+++ eval.c 16 Nov 2006 07:32:05 -0000

Sorry, it was wrong.

Thank you. That explains why it wasn't traceable.

While I have you here, perhaps you have an idea about the problem I am
trying to solve.

Given:
@user.something.trace_me

..I am trying to 'unwind' the calling order, so that the 'trace_me'
method can get a reference to @user and :something.
I need to do this in a general way, where the name of the object
(@user), and the last message it was sent something) are not known
in advance.

Is set_trace_func the only way to do that? Kernel#caller doesn't seem
like enough.

 

[Nobuyoshi Nakada]

Hi,

At Fri, 17 Nov 2006 00:01:43 +0900,
Wilson Bilkovich wrote in [ruby-talk:225298]:

Given:
@user.something.trace_me

..I am trying to 'unwind' the calling order, so that the 'trace_me'
method can get a reference to @user and :something.
I need to do this in a general way, where the name of the object
(@user), and the last message it was sent something) are not known
in advance.

What do you expect when the receiver isn't assigned to any
variable?

 

[Wilson Bilkovich]

Hi,

At Fri, 17 Nov 2006 00:01:43 +0900,
Wilson Bilkovich wrote in [ruby-talk:225298]:

Given:
@user.something.trace_me

..I am trying to 'unwind' the calling order, so that the 'trace_me'
method can get a reference to @user and :something.
I need to do this in a general way, where the name of the object
(@user), and the last message it was sent something) are not known
in advance.

What do you expect when the receiver isn't assigned to any
variable?

Something indicating that would be fine. I don't need a handle on
'intermediate' objects, just ones that have a real lexical existence
in source code.