Is main an object or a method?

Ruby
1

I was surprised, while reading Satish T.'s ruby tutorial, to discover
that main is actually a method – at least, it is according to the Open
Classes section of the tutorial:

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To quote:

Please note that self.class refers to Object and self refers to method
main. Therefore while running this program you are executing the main
method of object Object.

Is that correct? I would have thought main was an instance of Object,
and thus was an object itself, not a method of class Object. Using
Object.methods within irb doesn’t list a main method, so I’m skeptical.

2

Hi Chad,

I stand corrected.

That was the impression I was carrying when I started learning Ruby (and
coming from a long Java background). I realized my folly a long time
back
and corrected my statement here -
http://sitekreator.com/satishtalim/first_program.html

but forgot to correct the same at the url you mention. Thanks for
pointing
it out - it’s now corrected.

Satish

3

indeed, main is a method of class Thread
check it with ri
ri main
gives you
Thread.main
which returns the main thread for the process.

self is the current object, a synonym if you will.
Defined as the receiver object of the current method.

4

On Apr 16, 4:57 am, Chad P. [email protected] wrote:

method of object Object.

Is that correct? I would have thought main was an instance of Object,
and thus was an object itself, not a method of class Object. Using
Object.methods within irb doesn’t list a main method, so I’m skeptical.

–
CCD CopyWrite Chad P. [http://ccd.apotheon.org]
Brian K. Reid: “In computer science, we stand on each other’s feet.”

Hi Chad,

I stand corrected.

That was the impression I was carrying when I started learning Ruby
(and coming from a long Java background). I realized my folly a long
time back and corrected my statement here -
http://sitekreator.com/satishtalim/first_program.html

but forgot to correct the same at the url you mention. Thanks for
pointing it out - it’s now corrected.

Satish

5

On Mon, Apr 16, 2007 at 10:14:49AM +0900, John J. wrote:

indeed, main is a method of class Thread
check it with ri
ri main
gives you
Thread.main
which returns the main thread for the process.

self is the current object, a synonym if you will.
Defined as the receiver object of the current method.

Roseanne’s evidence seems to corroborate my impression – that main (in
the context of the main scope of a Ruby program) is an object of type
Object, not a method. I believe the Thread.main method is a method that
just happens to have the same name as the main instance of Object.

6

On Mon, Apr 16, 2007 at 11:15:10AM +0900, smtalim wrote:

main. Therefore while running this program you are executing the main
Hi Chad,

I stand corrected.

That was the impression I was carrying when I started learning Ruby
(and coming from a long Java background). I realized my folly a long
time back and corrected my statement here -
- Log In

but forgot to correct the same at the url you mention. Thanks for
pointing it out - it’s now corrected.

I’m glad I could be of help, then. Thanks for the tutorial, by the way.
I find that, even when I’m experienced with a given language beyond the
target audience of a given tutorial, every halfway decent programming
tutorial has something to teach me – and yours has helped.

7

Chad P. wrote:

I was surprised, while reading Satish T.'s ruby tutorial, to discover

E:\ex>ruby -e "puts self.kind_of?(Class)"
false

E:\ex>ruby -e "puts self.kind_of?(Module)"
false

E:\ex>ruby -e "puts self.kind_of?(Object)"
true

E:\ex>ruby -e "puts self"
main

E:\ex>ruby -e "puts self.class"
Object