From: Robert Klemme <shortcutter@...>
Date: 2012-01-18T19:31:08+09:00
Subject: Re: global array

On Wed, Jan 18, 2012 at 10:46 AM, Emil Enemærke <eme@medical-insight.com> wrote:
> Hi,
>
> On 16 Jan, 2012, at 16:19 , Robert Klemme wrote:
>
>> On Mon, Jan 16, 2012 at 3:17 PM, Emil Enemærke <eme@medical-insight.com> wrote:
>>> Hi,
>>>
>>> Im trying to make an array a global array, but I cannot make it work.
>>
>> "server" references a Hash.
>>
>>> Here is what I have:
>>> ------------
>>> hostname=server1
>>> server = Hash.new { |hash, key| hash[key] = [] }
>>> service_name="service name"
>>> service=service1
>>>
>>> if server.key?(hostname)
>>
>> Will likely return false because the Hash is empty initially.
> That was the intention, if the hash is empty create it.

But this won't work as intended: you create the Hash stored in
"server" with a block which creates Arrays internally.  For that
mechanism to work you just access server[some_key] and work with what
you get.  If you ask whether the key exists you always get false:

irb(main):001:0> server = Hash.new { |hash, key| hash[key] = [] }
=> {}
irb(main):002:0> key = "foo"
=> "foo"
irb(main):003:0> server.key? key
=> false
irb(main):004:0> server
=> {}
irb(main):005:0> server[key]
=> []
irb(main):006:0> server
=> {"foo"=>[]}
irb(main):007:0> server.key? key
=> true

And if you ask for the key then you need to take action if it is NOT
there but your code assigns only to server[hostname] if server.key?
hostname returned true.  You need to at leas negate the condition.

>>>      server[hostname]=Hash.new { |hash, key| hash[key] = [] }
>>>      server[hostname]["service_name"]=Array.new
>>>      server[hostname]["service_name"]="service#{service_counter}"
>>>      server[hostname]["service_name"]=[x,x,x]
>>
>> The three lines above all overwrite the same entry.  That's almost
>> certainly not what you want.
>>
>>> end
>>> -----------------
>>>
>>> I have tried with
>>> $server[hostname]["service_name"]=[x,x,x]
>>> $server[hostname]["service_name"]=Array.new
>>>
>>> but that does not work... Any help is appreciated.
>>
>> I am not 100% sure what you intend but I think you might just want
>>
>> server = Hash.new { |hash, key| hash[key] = {} }
>> server[hostname]["service_name"] = ["service#{service_counter}", [x,x,x]]
>>
> That is a much more elegant solution than mine, thanks.
>
> But this does not solve my problem, I have the hash created within a loop but are not able to access to array from outside that loop, due the hash not being global. So how can I make the
> server[hostname]["service_name"] = ["service#{service_counter}", [x,x,x]]
> a global variable?

Prepend $.

Regards

robert


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