From: Jim Freeze <jimfreeze@...>
Date: 2006-05-07T13:13:32+09:00
Subject: Re: A major ruby annoyance!

On May 6, 2006, at 6:00 PM, Talha Oktay wrote:

> I am a newbie in Ruby. I have read several books including pickaxe  
> and wrote
> several thousands lines of code. So far, as an ex perl user, I have  
> found
> the major annoyance with ruby is the lack of declaration of variables.
> Automatic creation,  in perl jargon autovification is the common  
> feature of
> many high level languages such as perl, paython, visual basic etc.  
> but most

You can customize autovivification in Ruby. Consider the Hash

h1 = Hash.new { |h,k| h[k] = 0 }
h1[:a]  #=> 0

h2 = Hash.new { |h,k| h[k] = 1 }
h2[:a]  #=> 1

h3 = Hash.new { |h,k| h[k] = [] }
h2[:a]  << "alpha"  #=> ["alpha"]

l = lambda { |h,k| h[k] = Hash.new &l }
h4 = Hash.new &l
h[:a][:b][:c] = 5   #=> { :a => { :b => { :c => {} }}}



> of the these languages have seen that this not necessarily a good  
> thing and
> created flags, commands to prohibit it if the developer wants to. I  
> really
> wish ruby had one.  Last  several hours  I spent debugging a  
> malfunctioning
> code just to see mistyped variable name was causing all the  
> problem. I had
> to put many log statements which polluted to the code.

You can try to up the warning level. It might also help to make  
smaller methods.
I you want, post your code and let some people take a look to give
you some pointers on how to prevent this type of thing.

> I guess in Pickaxe book, unit testing is presented as the cure for  
> this
> problem which I do not agree. I can not write a test code for every  
> peace of
> little functionality, besides I am eager to make the compiler or  
> interpreter
> to work for me. Why not tell the interpreter to check the code,  
> instead of
> writing very detailed test programs. I am not a very good typist  
> and I often
> mistype variable names, often I had to depend on vim's auto completion
> feature. But I do not want to depend to an editor or an IDE for this.

The compiler can't think for you. In Ruby, a little bit of code can  
do a lot,
in fact, a lot more than a compiler can guess at. Consider:

   [1,2,3].inject(0) { |prod,x| prod * x }
   [1,2,3].inject(1) { |prod,x| prod * x }

How is an interpretive language supposed to know (or take the time to  
know)
that the second case is what you want, not the first?

> I have also found the ruby's -w flag does not work as I perl -w  
> flag does.
> In perl warnings are really descriptive.  You can even use a module  
> called
> diagnostics which almost teaches to fix the problem that crashes  
> program or
> generates warning etc. I often do not use -w as because I receive  
> warnings
> from libraries that my code includes or warnings I do not  
> understand at all.
>
> May be I am the only one who is bothered with these. I do not know.

Some mental reprogramming takes time. We can't brain wash you  
overnight. ;)

Jim Freeze