From: lalawawa <usenet@...>
Date: 2010-06-10T07:35:09+09:00
Subject: Re: newbie question

Hi Robert,

I assume that if I use the value of an unassigned variable ruby will
catch me.  What I am worried about is if I misspell a variable name
while assigning to it.

myLongName = 'woof'
if haveACat
  myLoongName += ' and meow'
end
puts myLongName

I misspelled 'myLongName' the second time, so it's like the assinment
didn't happen.  If I had been in perl and said 'my myLongName' and 'use
strict', it would have caught the first time I ran it, even if I didn't
test the case where 'haveACat' is true.

Robert Klemme wrote:
> 2010/6/9 lalawawa <usenet@ccjj.info>:
>> In perl, one is able to sort of 'declare' variables by mentioning them
>> in 'my' statements.  Then, if you say 'use strict;', no variables that
>> weren't previously thus 'declared' are allowed.  This is useful in that
>> it catches typos that might be difficult to detect in testing.
>>
>> Does ruby have an equivalent mechanism?
> 
> Better: you do not need an additional declaration, rather Ruby will
> catch situations for you where you forgot to initialize (aka assign) a
> local variable:
> 
> $ ruby19 -e 'puts foo'
> -e:1:in `<main>': undefined local variable or method `foo' for
> main:Object (NameError)
> 
> The grain of salt is this
> 
> - this does not work for instance variables, these spring into
> existence whenever you use them,
> 
> - because there is the method local variable ambiguity you might still
> run into erroneous situations when forgetting to initialize a local
> variable which shares name with a method.
> 
> Kind regards
> 
> robert
>