Create child class of Python dict with modified values

[dmitrey]

hi all,
suppose I have defined a child class of Python dict, currently it
constructor looks like that:
def __init__(self, *args, **kwargs):
dict.__init__(self, *args, **kwargs)
#(+some more insufficient code)

Constructor should be capable of calling with either any way Python
dict is constructed or with a Python dict instance to be derived from;
calculations speed is important.

So it works well for now, but I want __init__ to set modified values,
like this:
values_of_the_dict = [some_func(elem) for elem in self.values()]

How this could be done?

Thank you in advance,
Dmitrey.

 

[Peter Otten]

hi all,
suppose I have defined a child class of Python dict, currently it
constructor looks like that:
def __init__(self, *args, **kwargs):
dict.__init__(self, *args, **kwargs)
#(+some more insufficient code)

Constructor should be capable of calling with either any way Python
dict is constructed or with a Python dict instance to be derived from;
calculations speed is important.

So it works well for now, but I want __init__ to set modified values,
like this:
values_of_the_dict = [some_func(elem) for elem in self.values()]

How this could be done?

.... def __init__(self, *args, **kw):
.... if args:
.... args = ((k, v.upper()) for k, v in args[0]),
.... if kw:
.... for k in kw: kw[k] = 10*kw[k]
.... dict.__init__(self, *args, **kw)
....

D(["ab", "cd"], e="f")

{'a': 'B', 'c': 'D', 'e': 'ffffffffff'}

Replace v.upper() and 10*kw[k] with the appropriate some_func() calls.
Personally I would apply the function before passing the data to the dict
subclass.

Peter

 

[dmitrey]

hi all,
suppose I have defined a child class of Python dict, currently it
constructor looks like that:
    def __init__(self, *args, **kwargs):
        dict.__init__(self, *args, **kwargs)
        #(+some more insufficient code)

Constructor should be capable of calling with either any way Python
dict is constructed or with a Python dict instance to be derived from;
calculations speed is important.

So it works well for now, but I want __init__ to set modified values,
like this:
values_of_the_dict = [some_func(elem) for elem in self.values()]

How this could be done?

...     def __init__(self, *args, **kw):
...             if args:
...                     args = ((k, v.upper()) for k, v in args[0]),
...             if kw:
...                     for k in kw: kw[k] = 10*kw[k]
...             dict.__init__(self, *args, **kw)
...>>> D(["ab", "cd"], e="f")

{'a': 'B', 'c': 'D', 'e': 'ffffffffff'}

Replace v.upper() and 10*kw[k] with the appropriate some_func() calls.

OK, thank you.

Personally I would apply the function before passing the data to the dict
subclass.

It's impossible for the situation in hand.

D.