Help with sets

[Steve Howell]

In message


No idea. It’s just that the example being discussed in this thread seemed to
come under the old term “orthogonality”, so I wondered why a different term
was being used.

So far no-one has come up with a good excuse for using a different term.

Ask the authors of PEP 234 why they use the term symmetry:

http://www.python.org/dev/peps/pep-0234/

That was the original context of my comment. The term "symmetry" gets
used a couple times in that PEP, and I think we're in violent
agreement that the concept of "symmetry" is wishy-washy at best.

Here is just one example from the PEP:

The symmetry between "if x in y" and "for x in y"
suggests that it should iterate over keys. This symmetry has
been
observed by many independently and has even been used to
"explain"
one using the other.

I think I'm just making the same observation as you coming from a
different angle. Why talk about "symmetry" when it's such a tricky
balance?

 

[Gregory Ewing]

That was the original context of my comment. The term "symmetry" gets
used a couple times in that PEP, and I think we're in violent
agreement that the concept of "symmetry" is wishy-washy at best.

Here is just one example from the PEP:

The symmetry between "if x in y" and "for x in y"
suggests that it should iterate over keys.

Maybe "analogy" or "similarity" would be a better word here.

 

[Steve Howell]

Maybe "analogy" or "similarity" would be a better word here.

Agreed. "Analogy" seems particularly appropriate.

 

[Lawrence D'Oliveiro]

In message

Agreed. "Analogy" seems particularly appropriate.

Except that, while analogies can be handy for illustrating things, they are
useless for actually supporting arguments.

 

[Steve Howell]

In message



Except that, while analogies can be handy for illustrating things, they are
useless for actually supporting arguments.

And only a fool would try to support his argument by actually
illustrating a point, right?