From: John Joyce <dangerwillrobinsondanger@...>
Date: 2007-03-22T08:10:47+09:00
Subject: Re: does Ruby not support multiple "initialize" methods for a class???

Why do people want to do this? Other than just to do it. What was it  
about C letting you shoot yourself in the foot, and C++ letting you  
blow your whole leg off...
On Mar 22, 2007, at 6:28 AM, ara.t.howard@noaa.gov wrote:

> On Thu, 22 Mar 2007, Florian Frank wrote:
>
>> I don't consider this to be a pattern, I consider overloading  
>> constructors
>> an anti-pattern.
>>
>> One of the few good Java books (among all the mediocre or even  
>> worse ones)
>> is "Effective Java" by Joshua Bloch:
>>
>> http://java.sun.com/docs/books/effective/toc.html
>>
>> In the first chapter (actually chapter 2) in the first item Bloch  
>> advises
>> Java programmers to consider using static factory methods instead  
>> of public
>> and/or overloaded constructors. He lists the following advantages:
>>
>> : One advantage of static factory methods is that, unlike  
>> constructors, they have names.
>> : If the parameters to a constructor do not, in and of themselves,  
>> describe the object being
>> : returned, a static factory with a well-chosen name can make a  
>> class easier to use and the
>> : resulting client code easier to read.
>> : [...]
>>
>> The same is true in Ruby, if you use class methods (methods of a  
>> class's
>> eigenclass). The workarounds in the initialize method even *look*  
>> code
>> smelly. In Java overloading a constructor once or twice doesn't  
>> seem to be
>> such a bad idea. But other programmers tend to just copy and paste  
>> another
>> constructor below the others. Once you have a class that comes  
>> into the two
>> digit range of constructors, it gets quite difficult to remember  
>> all the
>> different possible permutations of types. (Yes, I had to maintain  
>> code like
>> that.)
>>
>> And I think, overloading in general isn't such a good idea either.  
>> It can
>> lead to really funny semantic errors, if it teams up with Java's  
>> numeric
>> type promotion for example. (Yeah, this happened to me, too.)
>
> and this doesn't even take into account the confusion that can be  
> heaped upon
> the programmer when default parameters are thrown into the mix.  if  
> parameter
> overloading were allowed in ruby we could have this:
>
>   def m int
>     p int
>     p 42.0
>   end
>
>   def m int, float = 42.0
>     p int
>     p float
>   end
>
>   m 42
>
> now, which one is called?  in order to understand this kind of  
> stuff in c++
> you have to become the compiler.
>
> it's even worse when you can do
>
>   m *args  # yikes, which one is called?
>
> no thanks!
>
> cheers.
>
> -a
> -- 
> be kind whenever possible... it is always possible.
> - the dalai lama
>