Austin Bingham wrote:
To put it in code, I want this:
s = set(hash_func = lambda obj: hash(obj.name), eq_func = ...)
...
x.name = 'foo'
y.name = 'foo'
s.add(x)
s.add(y) # no-op because of uniqueness criteria
assert len(s) == 1
The part of this that seems
Austin Bingham wrote:
On Thu, Oct 15, 2009 at 7:49 PM, Ethan Furman et...@stoneleaf.us wrote:
Austin Bingham wrote:
I'm feeling really dense about now... What am I missing?
What you're missing is the entire discussion up to this point. I was
looking for a way to use an alternative
Austin Bingham wrote:
On Thu, Oct 15, 2009 at 7:49 PM, Ethan Furman et...@stoneleaf.us wrote:
Austin Bingham wrote:
I'm feeling really dense about now... What am I missing?
What you're missing is the entire discussion up to this point. I was
looking for a way to use an alternative
On Oct 16, 12:24 pm, Ethan Furman et...@stoneleaf.us wrote:
[snip]
As for what you want: No, it's not currently possible. If it's so big
a deal that the various methods presented don't meet with your approval,
break out the C and write your own. Then you could give that back to
the
On Oct 15, 9:31 pm, Austin Bingham austin.bing...@gmail.com wrote:
Yes, what you've got there provides the interface of what I want. And
no doubt we could concoct countless ways to implement some version of
this. However, if set itself accepted an alternate hash function, then
I could do it
On Thu, Oct 15, 2009 at 4:24 AM, Austin Bingham
austin.bing...@gmail.com wrote:
If I understand things correctly, the set class uses hash()
universally to calculate hash values for its elements. Is there a
standard way to have set use a different function? Say I've got a
collection of objects
Austin Bingham austin.bing...@gmail.com wrote:
If I understand things correctly, the set class uses hash()
universally to calculate hash values for its elements. Is there a
standard way to have set use a different function? Say I've got a
collection of objects with names. I'd like to create a
That's definitely a workable solution, but it still rubs me the wrong
way. The uniqueness criteria of a set seems, to me, like a property of
the set, whereas the python model forces it onto each set element.
Another issue I have with the HashWrapper approach is its space
requirements. Logically,
I guess we see things differently. I think it's quite natural to want
a set of unique objects where unique is defined as an operation on
some subset/conflation/etc. of the attributes of the elements. That's
all that the regular set class is, except that it always uses the
hash() function to
Austin Bingham wrote:
If I understand things correctly, the set class uses hash()
universally to calculate hash values for its elements. Is there a
standard way to have set use a different function? Say I've got a
collection of objects with names. I'd like to create a set of these
objects
Chris Rebert wrote:
On Thu, Oct 15, 2009 at 4:24 AM, Austin Bingham
austin.bing...@gmail.com wrote:
If I understand things correctly, the set class uses hash()
universally to calculate hash values for its elements. Is there a
standard way to have set use a different function? Say I've got a
Austin Bingham wrote:
That's definitely a workable solution, but it still rubs me the wrong
way. The uniqueness criteria of a set seems, to me, like a property of
the set, whereas the python model forces it onto each set element.
This is a POV, but to to me, the set just deals with a very
Austin Bingham wrote:
On Thu, Oct 15, 2009 at 2:23 PM, Diez B. Roggisch de...@nospam.web.de
wrote:
Austin Bingham wrote:
This is a POV, but to to me, the set just deals with a very minimal
protocol - hash-value equality. Whatever you feed it, it has to cope
with that. It strikes *me* as
On Thu, Oct 15, 2009 at 3:02 PM, Diez B. Roggisch de...@nospam.web.de wrote:
Austin Bingham wrote:
You do. Hashes can collide, and then you need equality. Sets are *based* on
equality actually, the hash is just one optimization. ...
Right, thanks for clearing that up. Not reading closely
And if there were something that would decide on context which of several
implementations to use, you'd have less to worry. As things are, there
isn't such thing (I don't even have the slightest idea what could work),
you are as well off with defining two functions.
But this context decider
Austin Bingham schrieb:
I guess we see things differently. I think it's quite natural to want
a set of unique objects where unique is defined as an operation on
some subset/conflation/etc. of the attributes of the elements.
What you seem to imply is that the hash function imposes some kind of
On Thu, Oct 15, 2009 at 3:43 PM, Diez B. Roggisch de...@nospam.web.de wrote:
The context-decider isn't the same thing because it isn't designed yet :)
And most probably won't ever be. It's just the abstract idea that
hashing/equality change for one object depending on the circumstances they
On Oct 15, 7:24 am, Austin Bingham austin.bing...@gmail.com wrote:
[snip] I'd like to create a set of these
objects where the hashing is done on these names. [snip]
Why not use a dict? The key would be the object name. Pretty much
the same behavior as a set (via the key), and you can still
On Thu, Oct 15, 2009 at 3:50 PM, Mick Krippendorf mad.m...@gmx.de wrote:
Austin Bingham schrieb:
What you seem to imply is that the hash function imposes some kind of
uniqueness constraint on the set which uses it. That's just not the
case, the uniqueness constraint is always the (in-)equality
On Thu, Oct 15, 2009 at 4:06 PM, Anthony Tolle anthony.to...@gmail.com wrote:
Why not use a dict? The key would be the object name. Pretty much
the same behavior as a set (via the key), and you can still easily
iterate over the objects.
To reiterate, dict only gets me part of what I want.
On Oct 15, 10:42 am, Austin Bingham austin.bing...@gmail.com wrote:
On Thu, Oct 15, 2009 at 4:06 PM, Anthony Tolle To reiterate, dict only gets
me part of what I want. Whereas a set
with uniqueness defined over 'obj.name' would guarantee no name
collisions, dict only sorta helps me keep
On Thu, Oct 15, 2009 at 5:22 AM, Diez B. Roggisch de...@nospam.web.de wrote:
Chris Rebert wrote:
On Thu, Oct 15, 2009 at 4:24 AM, Austin Bingham
austin.bing...@gmail.com wrote:
If I understand things correctly, the set class uses hash()
universally to calculate hash values for its elements.
En Thu, 15 Oct 2009 11:42:20 -0300, Austin Bingham
austin.bing...@gmail.com escribió:
On Thu, Oct 15, 2009 at 4:06 PM, Anthony Tolle anthony.to...@gmail.com
wrote:
Why not use a dict? The key would be the object name. Pretty much
the same behavior as a set (via the key), and you can still
On Thu, Oct 15, 2009 at 5:15 PM, Gabriel Genellina
gagsl-...@yahoo.com.ar wrote:
En Thu, 15 Oct 2009 11:42:20 -0300, Austin Bingham
austin.bing...@gmail.com escribió:
I think you didn't understand correctly Anthony Tolle's suggestion:
py class Foo:
... def __init__(self, name): self.name =
On Thu, 15 Oct 2009 09:11:00 -0700, Austin Bingham
austin.bing...@gmail.com wrote:
On Thu, Oct 15, 2009 at 5:15 PM, Gabriel Genellina
gagsl-...@yahoo.com.ar wrote:
En Thu, 15 Oct 2009 11:42:20 -0300, Austin Bingham
austin.bing...@gmail.com escribió:
I think you didn't understand correctly
On Oct 15, 12:11 pm, Austin Bingham austin.bing...@gmail.com wrote:
To put it in code, I want this:
s = set(hash_func = lambda obj: hash(obj.name), eq_func = ...)
...
x.name = 'foo'
y.name = 'foo'
s.add(x)
s.add(y) # no-op because of uniqueness criteria
assert len(s) == 1
I
En Thu, 15 Oct 2009 13:24:18 -0300, Rami Chowdhury
rami.chowdh...@gmail.com escribió:
On Thu, 15 Oct 2009 09:11:00 -0700, Austin Bingham
austin.bing...@gmail.com wrote:
On Thu, Oct 15, 2009 at 5:15 PM, Gabriel Genellina
gagsl-...@yahoo.com.ar wrote:
En Thu, 15 Oct 2009 11:42:20 -0300,
Austin Bingham wrote:
Yes, I can construct a dict as you
specify, where all of the keys map to values with name attributes
equal to the key. My point is that dict doesn't really help me enforce
that beyond simply letting me set it up; it doesn't care about the
values at all, just the keys. All
On Oct 15, 1:49 pm, Ethan Furman et...@stoneleaf.us wrote:
I'm still not sure I understand your concern about the values in a set,
though. Sets keep the first object of a given key, dicts keep the last
object of a given key; in both cases, all other objects with the same
key are lost.
So is
On Thu, Oct 15, 2009 at 7:05 PM, Anthony Tolle anthony.to...@gmail.com wrote:
I wrote a quick subclass of set that does something similar, but uses
just one function for the object uniqueness:
class MySet(set):
def __init__(self, iterable = (), idfunc = lambda x: x):
self.idfunc =
On Thu, Oct 15, 2009 at 7:49 PM, Ethan Furman et...@stoneleaf.us wrote:
Austin Bingham wrote:
I'm feeling really dense about now... What am I missing?
What you're missing is the entire discussion up to this point. I was
looking for a way to use an alternative uniqueness criteria in a set
On Thu, Oct 15, 2009 at 8:10 PM, Anthony Tolle anthony.to...@gmail.com wrote:
I think that without a practical example of what this would be used
for, we're all going to be a little lost on this one.
So far, we've not seen the original problem, only the author's
preferred method for solving
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