[TransWarp] Addition and Recipe Order? (was Re: Components Stable?)

Steve Alexander steve at cat-box.net
Sat Jul 7 07:47:28 EDT 2001

Phillip J. Eby wrote:

> Thing is, TransWarp actually works with the sequence A,B to put B on top of
> A, because builders *do* in fact build up on top of one another.  So if I
> decide to use Python ordering, I'll have to internally *reverse* the
> contents of recipes in order to use them.  This is probably very minor as a
> performance issue, but it just seems "wrong" to me because it hides the
> sequencing of component build operations - which is something you *may need
> to know about* when composing complex specification objects whose behavior
> depends on what you overlay them on.  Ty's counter-argument is that this is
> a logical sequence, not a physical one, and that left-to-right or
> right-to-left ordering is separate from the *meaning* of the sequence.  In
> other words, Python base classes overlay in the opposite order, and this is
> perfectly understandable.  :)

I wonder what GvR meant in PEP-0253 when he wrote (about metatypes in 

     I'll argue that left-to-right depth-first is not the best
     solution when you want to get the most use from multiple

Unfortunately, this looks like a note to self to write about that later. 
There is no further discussion of that issue in the PEP.

See http://python.sourceforge.net/peps/pep-0253.html

Steve Alexander

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