Inspetting a method's caller

[Alberto Santini]

Hello.
How can i know a function's caller method? E.g.

class A
def do_stg(n)
b = B.new
b.do_xyz(n)
end
end

class B
def do_xyz(n)
# -> Here i want to know that
# -> This method has been called
# -> From A#do_stg
n + 1
end
end

Kernel#caller does not help.. i don't care what file or line a function
has been called, and i couldn't find nothing helpful on ruby-doc nor by
searching google :|
Please keep in mind i'd like to know that do_xyz has been called by
do_stg -> WHICH IS A METHOD OF THE "A" CLASS <-

Thanks for your help

 

[mutahhir hayat]

I've always seen that whenever you need something like this, there's
always a better design choice that you can make. Like what would you
do in languages that didn't have caller etc etc.

Its still a hack, (because ideally you shouldn't be needing this IMO),
but you can make the caller send in an extra argument, putting its
description/ID/Name there.

MT

 

[Alberto Santini]

but you can make the caller send in an extra argument, putting its

description/ID/Name there.

Of course i can, i just *don't want* to do this. For example, imagine i
want to access a database table that (by -> convention <-) has the same
name of a class. Imagine i have a DBHelper class that contains a
DBHelper#find method used to find records on the database. if
DBHelper#find is called from a Ball object i want to lookup on the
"ball" table, it it's called from a Cube object i want to search the
"cube" table, etc. This is just the simplest usage that came to my mind,
but i guess there are hundreds. Obviously, i can implement DBHelper#find
in a way like this:

def find(table_name = "", criteria = {})
...
end

and call it like this:

find(self.class.to_s, {:id => 5})

It is just *not what i want to do*.

So, coming back to my question, is there a simple way to get the wanted
class name, without haveing to parse Kernel#caller?

Thanks.

 

[Benjamin Oakes]

Of course i can, i just *don't want* to do this. For example, imagine i
want to access a database table that (by -> convention <-) has the same
name of a class. Imagine i have a DBHelper class that contains a
DBHelper#find method used to find records on the database. if
DBHelper#find is called from a Ball object i want to lookup on the
"ball" table, it it's called from a Cube object i want to search the
"cube" table, etc. This is just the simplest usage that came to my mind,
but i guess there are hundreds. Obviously, i can implement DBHelper#find
in a way like this:

def find(table_name = "", criteria = {})
...
end

and call it like this:

find(self.class.to_s, {:id => 5})

It is just *not what i want to do*.

So, coming back to my question, is there a simple way to get the wanted
class name, without haveing to parse Kernel#caller?

Thanks.

There's something in Ruby Facets that seems related: Binding#called

http://facets.rubyforge.org/quick/rdoc/core/classes/Binding.html#M000221

I've only ever used it when I'm working with trace statements when a
debugger isn't available or doing the job I need it to.

-- Ben

 

[mutahhir hayat]

I don't know, but maybe you can implement the methods you *want* as a
module method, and use them in your classes that you need such
functionality built-into, which would ensure they'll be able to know
which class they're under whenever they're called.
like

module M
def foo
puts self.class
end
end

class A
include M
end

class B
include M
end

a= A.new
a.foo => A
b= B.new
b.foo => B

I might be completely off base here, but i'll still *try* to give you
a design based resolution, more often than not, that causes less
problems in the long run.

HTH
Mt.

 

[Alex Fenton]

Of course i can, i just *don't want* to do this. For example, imagine i
want to access a database table that (by -> convention <-) has the same
name of a class. Imagine i have a DBHelper class that contains a
DBHelper#find method used to find records on the database. if
DBHelper#find is called from a Ball object i want to lookup on the
"ball" table, it it's called from a Cube object i want to search the
"cube" table, etc.

Perhaps your DBHelper class would be better designed as a module that is
included in the Ball/Cube.etc classes, or extends its instances?

alex