Undifined local variable or method error

ruby-talk
1

Hi all,

Below is my code

h={}
  arr=[]
def gethash
  h[1]=0
  return h
end
arr[0]=gethash
puts arr[0].each {|k,v| puts "key #{k} value #{v}"}

For the above i get error saying "Undifined local variable or method 'h'
for main:Object(NameError)"

may i know reason for this error?

···

--
Posted via http://www.ruby-forum.com/.

2

to my dismay
def xxx... end
is *not* a closure
while
define_method :xxx is
IOW
h is just not visible in def while it would if you define gethas via
define_method

be careful though on the toplevel you cannot use define_method, do
something like
include( Module::new do
  h = {}
  define_method :xxx do h.tap{ |hh| h[1] = 0 } end
end )

puts xxx
xxx[:a] = 42
puts xxx

oh yes this code is ugly, but I wanted to demonstrate the semantics...
HTH
R.

···

On Sat, Apr 17, 2010 at 7:30 PM, Simbolla Simbolla <vinod236@gmail.com> wrote:

Hi all,

Below is my code

h={}
arr=
def gethash
h[1]=0
return h
end
arr[0]=gethash
puts arr[0].each {|k,v| puts "key #{k} value #{v}"}

--
The best way to predict the future is to invent it.
-- Alan Kay

3

Hi --

···

On Sun, 18 Apr 2010, Simbolla Simbolla wrote:

Hi all,

Below is my code

h={}
arr=
def gethash
h[1]=0
return h
end
arr[0]=gethash
puts arr[0].each {|k,v| puts "key #{k} value #{v}"}

For the above i get error saying "Undifined local variable or method 'h'
for main:Object(NameError)"

may i know reason for this error?

The def keyword starts a new local scope. The same happens with class:

   a = 1
   class C
     puts a # new local scope, so a is not defined
   end

David

--
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4

If you want h to be a global variable, accessible everywhere, prefix
it with a dollar sign:

$h={}
def foo
  $h[1]=0
  $h
end
foo
p $h
#=> {1=>0}

···

On Apr 17, 11:30 am, Simbolla Simbolla <vinod...@gmail.com> wrote:

h={}
arr=
def gethash
h[1]=0
return h
end
arr[0]=gethash
puts arr[0].each {|k,v| puts "key #{k} value #{v}"}

For the above i get error saying "Undifined local variable or method 'h'
for main:Object(NameError)"

5

Gavin Kistner wrote:

···

On Apr 17, 11:30�am, Simbolla Simbolla <vinod...@gmail.com> wrote:

for main:Object(NameError)"

If you want h to be a global variable, accessible everywhere, prefix
it with a dollar sign:

$h={}
def foo
  $h[1]=0
  $h
end
foo
p $h
#=> {1=>0}

But usually it would be better instead to:

(1) pass h as an argument to method foo; or
(2) define a class with instance variable @h

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