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comp.lang.ruby

Re: scope questions

botp

9/18/2007 4:00:00 PM

On 9/18/07, Mister Rohit <pigdog@gmail.com> wrote:
> which yields a different output than the PERL code. Is this type of thing
> possible in Ruby without creating a class?

is def method good enough for you?

irb(main):001:0> def m
irb(main):002:1> var = 2
irb(main):003:1> puts "inner var = #{var}"
irb(main):004:1> end
=> nil
irb(main):005:0> var = 1
=> 1
irb(main):006:0> m
inner var = 2
=> nil
irb(main):007:0> puts "outer var = #{var}"
outer var = 1
=> nil

you can nest methods too

irb(main):008:0> def m2
irb(main):009:1> var = 1
irb(main):010:1> def m3
irb(main):011:2> var = 2
irb(main):012:2> puts "inner var = #{var}"
irb(main):013:2> end
irb(main):014:1> puts "outer var = #{var}"
irb(main):015:1> end
=> nil
irb(main):016:0> m2
outer var = 1
=> nil
irb(main):017:0> m2.m3
outer var = 1
inner var = 2
=> nil
irb(main):018:0> m3
inner var = 2
=> nil

kind regards -botp
2 Answers

Paul Brannan

9/20/2007 1:42:00 PM

0

On Wed, Sep 19, 2007 at 12:59:58AM +0900, botp wrote:
> irb(main):008:0> def m2
> irb(main):009:1> var = 1
> irb(main):010:1> def m3
> irb(main):011:2> var = 2
> irb(main):012:2> puts "inner var = #{var}"
> irb(main):013:2> end
> irb(main):014:1> puts "outer var = #{var}"
> irb(main):015:1> end
> => nil
> irb(main):016:0> m2
> outer var = 1
> => nil
> irb(main):017:0> m2.m3
> outer var = 1
> inner var = 2
> => nil
> irb(main):018:0> m3
> inner var = 2
> => nil

This might not be doing what you think it is:

irb(main):020:0> $VERBOSE = true
=> true
irb(main):023:0> m2.m3
(irb):9: warning: method redefined; discarding old m3
outer var = 1
inner var = 2
=> nil
irb(main):024:0> m2
(irb):9: warning: method redefined; discarding old m3
outer var = 1
=> nil
irb(main):025:0> nil.m3
inner var = 2
=> nil

(your example made it look like m3 is inside m2, which it isn't. m2 is
returning nil, and since you made m3 a public method, m2.m3 is the same as
m2(); nil.m3())

Paul

Peña, Botp

9/21/2007 4:19:00 AM

0

From: Paul Brannan [mailto:pbrannan@atdesk.com]
# On Wed, Sep 19, 2007 at 12:59:58AM +0900, botp wrote:
# > irb(main):008:0> def m2
# > irb(main):009:1> var = 1
# > irb(main):010:1> def m3
# > irb(main):011:2> var = 2
# > irb(main):012:2> puts "inner var = #{var}"
# > irb(main):013:2> end
# > irb(main):014:1> puts "outer var = #{var}"
# > irb(main):015:1> end
# > => nil
# > irb(main):016:0> m2
# > outer var = 1
# > => nil
# > irb(main):017:0> m2.m3
# > outer var = 1
# > inner var = 2
# > => nil
# > irb(main):018:0> m3
# > inner var = 2
# > => nil
#
# This might not be doing what you think it is:
#
# irb(main):020:0> $VERBOSE = true
# => true
# irb(main):023:0> m2.m3
# (irb):9: warning: method redefined; discarding old m3
# outer var = 1
# inner var = 2
# => nil
# irb(main):024:0> m2
# (irb):9: warning: method redefined; discarding old m3
# outer var = 1
# => nil
# irb(main):025:0> nil.m3
# inner var = 2
# => nil

my bad. sorry for the confusion.

i simply meant that you can define m3 inside m2, and that its var will not clash with that of m2, and that you can only invoke m3 if you've invoked m2 already.

in other words, you cannot do m3 right away. you'll have to do m2 first, or if you wish to run m3 immediately, you may follow it thru after m2, or m2.m3. i guess it would be clearer if i nest it further like m1.m2.m3.m4. i could go that route to reach m4 immediately, or just wait and just do m1; then later, m2, then later m3... from then on m4 will be defined and i could then just invoke it plainly as m4. (of course by this behaviour, one can also redefine methods by inserting them within methods)

pls correct me if i'm wrong, i usually make stupid assumptions based on my limited experience. pardon a nuby pls :(

kind regards -botp