Getting a dictionary from an object

[Thanos Tsouanas]

Hello.

I would like to have a quick way to create dicts from object, so that a
call to foo['bar'] would return obj.bar.

The following works, but I would prefer to use a built-in way if one
exists. Is there one?

Thanks in advance.

class dictobj(dict):
"""
class dictobj(dict):
A dictionary d with an object attached to it,
which treats d['foo'] as d.obj.foo.
"""
def __init__(self, obj):
self.obj = obj
def __getitem__(sel f, key):
return self.obj.__geta ttribute__(key)

--
Thanos Tsouanas .: My Music: http://www.thanostsouanas.com/
http://thanos.sians.org/ .: Sians Music: http://www.sians.org/

[Bruno Desthuilliers]

Thanos Tsouanas a écrit :

Hello.

I would like to have a quick way to create dicts from object, so that a
call to foo['bar'] would return obj.bar.

The following works, but I would prefer to use a built-in way if one
exists. Is there one?

Thanks in advance.

class dictobj(dict):
"""
class dictobj(dict):
A dictionary d with an object attached to it,
which treats d['foo'] as d.obj.foo.
"""
def __init__(self, obj):
self.obj = obj
def __getitem__(sel f, key):
return self.obj.__geta ttribute__(key)

I'd replace this last line with:
return getattr(self.ob j, key)
Now given your specs, I don't see what's wrong with your solution.

[Thanos Tsouanas]

On Sat, Jul 23, 2005 at 11:30:19AM +0200, Bruno Desthuilliers wrote:

Thanos Tsouanas a écrit :

class dictobj(dict):
"""
class dictobj(dict):
A dictionary d with an object attached to it,
which treats d['foo'] as d.obj.foo.
"""
def __init__(self, obj):
self.obj = obj
def __getitem__(sel f, key):
return self.obj.__geta ttribute__(key)

I'd replace this last line with:
return getattr(self.ob j, key)

Now given your specs, I don't see what's wrong with your solution.

I just dont want to use my class, if one already exists in the
libraries (or any other way to achieve the same thing), that's all ;)

Thanks for the tip.

--
Thanos Tsouanas .: My Music: http://www.thanostsouanas.com/
http://thanos.sians.org/ .: Sians Music: http://www.sians.org/

[Steven D'Aprano]

On Sat, 23 Jul 2005 11:48:27 +0300, Thanos Tsouanas wrote:

Hello.

I would like to have a quick way to create dicts from object, so that a
call to foo['bar'] would return obj.bar.
That looks rather confusing to me. Why not just call obj.bar, since it
doesn't look like you are actually using the dictionary at all?
The following works, but I would prefer to use a built-in way if one
exists. Is there one?

Thanks in advance.

class dictobj(dict):
"""
class dictobj(dict):
A dictionary d with an object attached to it,
which treats d['foo'] as d.obj.foo.
"""
def __init__(self, obj):
self.obj = obj
def __getitem__(sel f, key):
return self.obj.__geta ttribute__(key)

I don't think this is particularly useful behaviour. How do you use it?

py> D = dictobj("hello world")
py> D
{}
py> D.obj
'hello world'
py> D["food"] = "spam"
py> D
{'food': 'spam'}
py> D["food"]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 5, in __getitem__
AttributeError: 'str' object has no attribute 'food'
--
Steven.

[Mike Meyer]

Steven D'Aprano <st***@REMOVETH IScyber.com.au> writes:

On Sat, 23 Jul 2005 11:48:27 +0300, Thanos Tsouanas wrote:

Hello.

I would like to have a quick way to create dicts from object, so that a
call to foo['bar'] would return obj.bar.

That looks rather confusing to me. Why not just call obj.bar, since it
doesn't look like you are actually using the dictionary at all?

Well, I needed exactly this functionality last week. I have a
collection of (rather messy) classes that have a slew of attributes as
values. I would have used a dictionary for this, but I didn't write
the code.

I have to be able to display these objects (in HTML, if it matters),
and have as a requirement that the format string live in a database.

My solution didn't look to different from dictobj. There's some extra
mechanism to fetch the format string from the database, and some
formatting of the attribute based on meta-information in the object,
but it's the same basic idea.

class dictobj(dict):
"""
class dictobj(dict):
A dictionary d with an object attached to it,
which treats d['foo'] as d.obj.foo.
"""
def __init__(self, obj):
self.obj = obj
def __getitem__(sel f, key):
return self.obj.__geta ttribute__(key)

I don't think this is particularly useful behaviour. How do you use it?

def __str__(self):
return self._format % self
<mike
--
Mike Meyer <mw*@mired.or g> http://www.mired.org/home/mwm/
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

[Thanos Tsouanas]

On Sat, Jul 23, 2005 at 11:22:21PM +1000, Steven D'Aprano wrote:

On Sat, 23 Jul 2005 11:48:27 +0300, Thanos Tsouanas wrote:

Hello.

I would like to have a quick way to create dicts from object, so that a
call to foo['bar'] would return obj.bar.

That looks rather confusing to me. Why not just call obj.bar, since it
doesn't look like you are actually using the dictionary at all?

[...]

I don't think this is particularly useful behaviour. How do you use it?

print foo %do

where do is a dictobj object...

--
Thanos Tsouanas .: My Music: http://www.thanostsouanas.com/
http://thanos.sians.org/ .: Sians Music: http://www.sians.org/

[Steven Bethard]

Thanos Tsouanas wrote:

I would like to have a quick way to create dicts from object, so that a
call to foo['bar'] would return obj.bar.

The following works, but I would prefer to use a built-in way if one
exists. Is there one?

Maybe I'm not understanding your problem, but have you looked at the
builtin "vars()"?

STeVe

[Steven D'Aprano]

On Sat, 23 Jul 2005 13:50:36 -0400, Mike Meyer wrote:

I don't think this is particularly useful behaviour. How do you use it?

def __str__(self):
return self._format % self

That doesn't work. It calls self.__str__ recursively until Python halts
the process.

class Thing(dict): .... _format = "Thing %s is good."
.... def __str__(self):
.... return self._format % self
.... X = Thing()
X # calls __repr__ so is safe {} str(X) # not safe

File "<stdin>", line 4, in __str__
File "<stdin>", line 4, in __str__
...
File "<stdin>", line 4, in __str__
File "<stdin>", line 4, in __str__
RuntimeError: maximum recursion depth exceeded
--
Steven.

[Steven D'Aprano]

On Sun, 24 Jul 2005 02:09:54 +0300, Thanos Tsouanas wrote:

On Sat, Jul 23, 2005 at 11:22:21PM +1000, Steven D'Aprano wrote:

On Sat, 23 Jul 2005 11:48:27 +0300, Thanos Tsouanas wrote:

> Hello.
>
> I would like to have a quick way to create dicts from object, so that a
> call to foo['bar'] would return obj.bar.

That looks rather confusing to me. Why not just call obj.bar, since it
doesn't look like you are actually using the dictionary at all?

> [...]

I don't think this is particularly useful behaviour. How do you use it?

print foo %do

where do is a dictobj object...

Are you telling me that the ONLY thing you use dictobj objects for is to
print them?

I don't think so. I do know how to print an object, amazingly.

Perhaps you would like to explain how you use the rest of the
functionality of the dictobj, instead of taking my words out of context
and giving an inane answer.

Why jump through all those hoops to get attributes when Python already
provides indexing and attribute grabbing machinery that work well? Why do
you bother to subclass dict, only to mangle the dict __getitem__ method so
that you can no longer retrieve items from the dict?
--
Steven.

[Thanos Tsouanas]

On Sun, Jul 24, 2005 at 01:43:43PM +1000, Steven D'Aprano wrote:

On Sun, 24 Jul 2005 02:09:54 +0300, Thanos Tsouanas wrote:

print foo %do

where do is a dictobj object...
Are you telling me that the ONLY thing you use dictobj objects for is to
print them?

I'm sorry to disappoint you, but yes. When you have a long text
template to fill-out, with lots of %(foo)s, and all those foos are
attributes of an object, it really helps to have dictobj.
I don't think so. I do know how to print an object, amazingly.
Please, tell me, how would you print it in my case?
Perhaps you would like to explain how you use the rest of the
functionality of the dictobj, instead of taking my words out of context
and giving an inane answer.
I dont see _ANY_ other functionality in the dictobj class. Do you?
Why jump through all those hoops to get attributes when Python already
provides indexing and attribute grabbing machinery that work well? Why do
you bother to subclass dict, only to mangle the dict __getitem__ method so
that you can no longer retrieve items from the dict?

Because *obviously* I don't know of these indexing and attribute
grabbing machineries you are talking about in my case. If you cared to
read my first post, all I asked was for the "normal", "built-in" way to
do it. Now, is there one, or not?

--
Thanos Tsouanas .: My Music: http://www.thanostsouanas.com/
http://thanos.sians.org/ .: Sians Music: http://www.sians.org/