django - How can I write my own OrderedDict class in Python? -

basically want understand how thing works under hood. tried create list of tuples [(), (), ...] , each tuple have 2 values, qst wuld key , second value. not actual dictionary , there performance issue (i mean read/write/delete operations.

so how should write class myordereddict (probably) extending default dict class.

any hint or resource appreciated.

ps: similar functional have in django. sorteddict

from django.utils.datastructures import sorteddict

are both same or follow same approach in implementation?

help on class sorteddict in module django.utils.datastructures:  class sorteddict(__builtin__.dict)  |  dictionary keeps keys in order in they're inserted.  |    |  method resolution order:  |      sorteddict  |      __builtin__.dict  |      __builtin__.object  |    |  methods defined here: 

the class manage dictionary , list. behind scenes, every standard dict operation use both:

dvalues = {"foo":"x","bar":"y","baz":"z"} lorder = ["bar","baz","foo"] 

to value key, standard dictionary:

return dvalues[key] 

to value order m entered:

return dvalues[lorder[m]] 

add key,value:

dvalues[key] = value lorder.append(key) 

etc.