dict.updated

[Rick Morrison]

Would there be any way to add a method to all dict objects that operated
like the .update() method, but also returned a reference to the updated
dict?

..update() is clumsy to use inside of list comprehensions and the like. Or am
I missing something?

Thanks,
Rick

[Steven Bethard]

Re: dict.updated

Rick Morrison wrote:[color=blue]
> Would there be any way to add a method to all dict objects that operated
> like the .update() method, but also returned a reference to the updated
> dict?[/color]

Are you looking for updated() to parallel sorted(), where sorted()
returns a *new* list? I doubt you'll be able to rally much support for
a method that changes an object and returns a reference to it -- check
the archives to see these kind of things getting rejected over and over.

Could you do something like:

py> import itertools
py> d1 = dict(a=1, b=2)
py> d2 = dict(c=3, d=4)
py> d3 = dict(itertools. chain(d1.iterit ems(), d2.iteritems()) )
py> d3
{'a': 1, 'c': 3, 'b': 2, 'd': 4}

Steve

[Rick Morrison]

Re: dict.updated

I could live with creating a new dict, sure (although it seems wasteful). I
realize that something like this probably doesn't stand a chance of ever
making it into the std library for what might be called "philosophi cal"
reasons. I just want it for me (my personal philosophy runs more to the
pragmatic -- well at least for coding).

I suppose the in-place version would be more along the lines of:
[color=blue][color=green][color=darkred]
>>> def updated(d, updates):[/color][/color][/color]
.... d.update(update s)
.... return d
....[color=blue][color=green][color=darkred]
>>> [updated(d, {'c':3}) for d in [{'a':1, 'b':2}, {'x':10, 'y':'11'}]][/color][/color][/color]
[{'a': 1, 'c': 3, 'b': 2}, {'y': '11', 'x': 10, 'c': 3}]

But I'd like to put the "updated" method on the "dict" object, which is what
I can't seem to figure out.
Yeah I know that's "bad", but to my mind so is polluting the global
namespace with the "updated" function.

-- Or maybe I'm just lazy and picked up too many bad habits from
Javascript.

Rick


"Steven Bethard" <steven.bethard @gmail.com> wrote in message
news:dvKdnWal2s VXAXjcRVn-2g@comcast.com. ..[color=blue]
> Rick Morrison wrote:[color=green]
> > Would there be any way to add a method to all dict objects that operated
> > like the .update() method, but also returned a reference to the updated
> > dict?[/color]
>
> Are you looking for updated() to parallel sorted(), where sorted()
> returns a *new* list? I doubt you'll be able to rally much support for
> a method that changes an object and returns a reference to it -- check
> the archives to see these kind of things getting rejected over and over.
>
> Could you do something like:
>
> py> import itertools
> py> d1 = dict(a=1, b=2)
> py> d2 = dict(c=3, d=4)
> py> d3 = dict(itertools. chain(d1.iterit ems(), d2.iteritems()) )
> py> d3
> {'a': 1, 'c': 3, 'b': 2, 'd': 4}
>
> Steve[/color]

[Stephen Thorne]

Re: dict.updated

On Wed, 12 Jan 2005 23:47:13 GMT, Rick Morrison
<ram@forefron t-tech.no.lunch.m eat.com> wrote:[color=blue]
> I could live with creating a new dict, sure (although it seems wasteful). I
> realize that something like this probably doesn't stand a chance of ever
> making it into the std library for what might be called "philosophi cal"
> reasons. I just want it for me (my personal philosophy runs more to the
> pragmatic -- well at least for coding).
>
> I suppose the in-place version would be more along the lines of:
>[color=green][color=darkred]
> >>> def updated(d, updates):[/color][/color]
> ... d.update(update s)
> ... return d
> ...[color=green][color=darkred]
> >>> [updated(d, {'c':3}) for d in [{'a':1, 'b':2}, {'x':10, 'y':'11'}]][/color][/color]
> [{'a': 1, 'c': 3, 'b': 2}, {'y': '11', 'x': 10, 'c': 3}]
>
> But I'd like to put the "updated" method on the "dict" object, which is what
> I can't seem to figure out.
> Yeah I know that's "bad", but to my mind so is polluting the global
> namespace with the "updated" function.[/color]

[dict(d.items() + {'c':3}.items() ) for d in [{'a':1, 'b':2}, {'x':10,
'y':'11'}]]
seems logical enough to me....
[color=blue]
> -- Or maybe I'm just lazy and picked up too many bad habits from
> Javascript.[/color]

probably.

Stephen.

[Steven Bethard]

Re: dict.updated

Rick Morrison wrote:[color=blue]
> I could live with creating a new dict, sure (although it seems wasteful). I
> realize that something like this probably doesn't stand a chance of ever
> making it into the std library for what might be called "philosophi cal"
> reasons. I just want it for me (my personal philosophy runs more to the
> pragmatic -- well at least for coding).
>
> I suppose the in-place version would be more along the lines of:
>
>[color=green][color=darkred]
>>>>def updated(d, updates):[/color][/color]
>
> ... d.update(update s)
> ... return d
> ...
>[color=green][color=darkred]
>>>>[updated(d, {'c':3}) for d in [{'a':1, 'b':2}, {'x':10, 'y':'11'}]][/color][/color]
>
> [{'a': 1, 'c': 3, 'b': 2}, {'y': '11', 'x': 10, 'c': 3}]
>
> But I'd like to put the "updated" method on the "dict" object, which is what
> I can't seem to figure out.
> Yeah I know that's "bad", but to my mind so is polluting the global
> namespace with the "updated" function.[/color]

You could do something like:

py> class dict(dict):
.... def updated(self, *args, **kwds):
.... self.update(*ar gs, **kwds)
.... return self
....
py> [d.updated(c=3) for d in [dict(a=1, b=2), dict(x=10, y=11)]]
[{'a': 1, 'c': 3, 'b': 2}, {'y': 11, 'x': 10, 'c': 3}]

It'd mean you'd have to create all your dicts with the dict constructor
instead of {} though.

Steve

[hanz]

Re: dict.updated


Rick Morrison wrote:[color=blue][color=green][color=darkred]
> >>> [updated(d, {'c':3}) for d in [{'a':1, 'b':2}, {'x':10,[/color][/color][/color]
'y':'11'}]][color=blue]
> [{'a': 1, 'c': 3, 'b': 2}, {'y': '11', 'x': 10, 'c': 3}][/color]

I don't really understand the use of this. Can you give a less toy
example? I'd probably just do

dicts = [{'a':1, 'b':2}, {'x':10, 'y':'11'}]
for d in dicts: d.update({'c':3 })

This isn't really more typing or any clumsier IMO, so I can't see why
you'd want to use list comprehensions in this case.

[Bengt Richter]

Re: dict.updated

On Wed, 12 Jan 2005 23:47:13 GMT, "Rick Morrison" <ram@forefron t-tech.No.Lunch.m eat.com> wrote:
[color=blue]
>I could live with creating a new dict, sure (although it seems wasteful). I
>realize that something like this probably doesn't stand a chance of ever
>making it into the std library for what might be called "philosophi cal"
>reasons. I just want it for me (my personal philosophy runs more to the
>pragmatic -- well at least for coding).
>
>I suppose the in-place version would be more along the lines of:
>[color=green][color=darkred]
>>>> def updated(d, updates):[/color][/color]
>... d.update(update s)
>... return d
>...[color=green][color=darkred]
>>>> [updated(d, {'c':3}) for d in [{'a':1, 'b':2}, {'x':10, 'y':'11'}]][/color][/color]
>[{'a': 1, 'c': 3, 'b': 2}, {'y': '11', 'x': 10, 'c': 3}]
>[/color]
It's kind of a strange list comp, but I guess you're just illustrating something.
But for this case you could just write
[color=blue][color=green][color=darkred]
>>> [d.update({'c':3 }) or d for d in [{'a':1, 'b':2}, {'x':10, 'y':'11'}]][/color][/color][/color]
[{'a': 1, 'c': 3, 'b': 2}, {'y': '11', 'x': 10, 'c': 3}]

taking advantage of normal d.update() returning None and so forcing the 'or' term.


Regards,
Bengt Richter