From: Hal Fulton <hal9000@...>
Date: 2005-05-04T08:24:15+09:00
Subject: Re: Typo-checking instead of static typing

Nick Woolley wrote:
> 
> Also, conceivably, couldn't (optional) implicit run-time checks be added 
> which match the declared 'type' of an assignee variable to the current 
> type of the assigned object?  No type inference, just a little extra 
> runtime overhead (which could be switched off).  And/or similar optional 
> preconditions on method arguments?
> 
> e.g.
> 
>   Fruit var1 = Banana.new  # ok
>   Flesh var2 = Sausage.new # ok
>   Object var3 = Hamster.new # no checks on this var
>   var3 = var2 # so, Sausages are okay here
>   var3 = var1 # so are Bananas
>   var1 = var2 # but not here, cos Sausages aren't Fruit - bang!
>   var4 = 0 # var4 isn't predeclared - bang!
> 
> Um, this seems so obvious I am expecting someone to reveal my 
> cluelessness imminently.
> 

It's not a question of cluelessness, but I would state it
this way: Absence of explicit typing and variable declarations
are two of Ruby's best features, and they are foundational in
its design.


Hal