>> It seems that this pattern has been quite popular for some time already.
>> It may be desirable for the list to try and agree on a great name for the
>> method. Anyone who implements it calls it differently: Object#then,
>> Object#with, Object#tap, Kernel#returning, Kernel#with, ...  Anyone with
>> arguments for or against certain names, or with a better name for the
>> method?
> 
> I suppose I'll cast my vote for either "with" or "suchthat" or even ":"
> (though IIRC, ":" can't be a method name).  They are all idiomatic in
> mathematical circles when introducing a new mathematical object in an
> argument.  

Yes, that's too why I like with.

>> It seems to me that it's impossible to invent a useful name for this
>> method with the term eigen in it, so a discussion should be possible
>> without too much battle.
> Interesting.  Why "eigen"?  

(NB: I wrote impossible, not possible.)  I intended to hint at the term
eigenclass, which is an example of a Ruby concept with more than one name. 
It naming sometimes enjoys heavy discussions.

> I don't know much German, but as far as I know, "eigen" means something along
> the lines of "characteristic of" or "particular to". 

It does. The inventors of the term eigenclass have supposingly thought of the
mathematical words eigenvector and eigenvalue. (You get them when solving
the characteristic equation of a matrix, assuming I got the English terms
right.) Characteristic and eigen mean the same here.

Kalman