Good evening all together!

I didn't find discussions about that in clr or ruby-core, so I hope it isn't 
already discussed long ago.

The methods listed in the header return "nil" when nothing was done. This may be 
usefull and used in several situations.

Unfortunately there is possible usage of these methods, when this return value 
is a very bad thing: In a method-chain like...

"I am a 20MB string".downcase.split(/\s+/).reject{|s|s.length>20}

In this case the initial string, the result of "downcase", and of "split" will 
only be used once - they are single threaded. If, as the example text will name, 
the original String object is about 20MB, "downcase" will produce a copy, which 
will be thrown away. The same is true for "reject". It would be much better to 
use...

"I am a 20MB string".downcase!.split(/\s+/).reject!{|s|s.length>20}

...but this is not possible, because "downcase!" and "reject!" will return "nil" 
if they have nothing to do.

It is very easy to build a workaround - e.g. for "reject"...

class Array
   def reject_ch(&b)
     self.reject!(&b)
     self
   end
end

...which guarantees that the changed Array will always be returned.

My proposal IS NOT to change the existing "!" methods, because they may have 
substancial usage, but to add methods to Array, String, and possibly other 
classes, that change the objects in place and do always return them.

I have no ideas about naming (I also have no ambitions in giving names), but I 
think the functionality will be useful in these standard Ruby classes.

Wolfgang Nádasi-Donner