pyobjectdict 1.0.4

Package provides a js-like dictionary object with a more convenient support of dot syntax plus a few additional methods

PyObjectDict

Python dictionaries for more convenient use

Overview

The problem

When it comes to the Python dict syntax, what makes it clanky and annoying is the need to always pass keys as strings and use square brackets when accessing a dict's value:

x = {'a': 1, 'b': 2}
value = x['b'] # we have to write square brackets and use strings inside them

It is made quite concise in JavaScript language where all you need is access your value through the dot syntax like the following:

x = {'a': 1, 'b': 2}
value = x.b // no need to use square brackets or strings!

The solution This simple package introduces a new Python dict object which has some similarities to the JavaScript object in terms of dot syntax. The object is called PyObjectDict.

How to use

import the package and try to initialize your PyObjectDict in a preferred way:

from object_dict import PyObjectDict

a = PyObjectDict({'a': 2, 'b': 3, 'c': 10, 'd': 8})
b = PyObjectDict.form(**{'a': 2, 'b': 3, 'c': 4, 'g': 8})

Note: PyObjectDict constructor works with types: dict, OrderedDict, and PyObjectDict (to create a copy)

you may add new attributes to the object by simply using the dot syntax:

a.e = 1
a.f = 1
a.g = 1
a.h = 1
a.i = 1

you may then easily access any attribute by using:

print(a.a) # will print 2
print(a.e) # will print 1

The PyObjectDict also exposes a lot of additional convenience methods as well as standard dict methods. They are listed in the table above and an example of their usage can be seen below it.

Methods of PyObjectDict

Name	Parameters	Return value	Description
length	-	int	returns the lenght of the dictionary
keys	-	list	returns the list of keys of the dictionary
items	-	list of tuples	returns the list of tuples containing key, value pairs of each item in the dicrionary
iteritems	-	iterator	iterator for items method
values	-	list	returns the list of values of the dictionary
update	other (PyObjectDict)	None	updates one PyObjectDict with the other (merges them) in place. Returns nothing
get	key (str), default (None)	type of key or type of default parameter	returns value of the key if key exists or default parameter (which isNone by default)
add	other (PyObjectDict)	PyObjectDict	merges two PyObjectDicts and returns a merged copy
add_each_value	other (PyObjectDict)	PyObjectDict	merges the keys of two PyObjectDicts and adds the corresponding key values together. returns a merged copy
sub	other (PyObjectDict)	PyObjectDict	subtracts one PyObjectDict from another and returns a copy containing not intersecting keys of the first PyObjectDict with their values
sub_each_value	other (PyObjectDict)	PyObjectDict	subtracts the values of the corresponding keys of the first PyObjectDict from the second one. Returns a copy
sub_by_value	other (PyObjectDict)	PyObjectDict	the same as sub but subtraction happens by the unique key: value pairs not just the unique keys

Operators of PyObjectDict

Name	Parameters	Return value	Description
+	other (PyObjectDict)	PyObjectDict	the same as add method
+=	other (PyObjectDict)	PyObjectDict	the same as add method but assigns the result to the PyObjectDict to the left side of the operator
|	other (PyObjectDict)	PyObjectDict	the same as add method
|=	other (PyObjectDict)	PyObjectDict	the same as += operator
-	other (PyObjectDict)	PyObjectDict	the same as sub method
-=	other (PyObjectDict)	PyObjectDict	the same as sub method but assigns the result to the PyObjectDict to the left side of the operator

Dunder methods of PyObjectDict

Name	Parameters	Return value	Description
len	-	int	returns the lenght of the dictionary
str	-	str	returns the string representation of the dicrionary

Constructors of PyObjectDict

Name	Parameters	Return value	Description
PyObjectDict	-	PyObjectDict	creates an PyObjectDict from dict, OrderedDict, or PyObjectDict (copy)
PyObjectDict.from	-	PyObjectDict	creates an PyObjectDict from the key value pairs that are successively passed to the constructor

An Example of Usage

from pyobjectdict import PyObjectDict

a = PyObjectDict({'a': 2, 'b': 3, 'c': 10, 'd': 8})
b = PyObjectDict.form(**{'a': 2, 'b': 3, 'c': 4, 'g': 8})

print('a:', a)
print('b:', b)

c = a.sub_by_value(b)
print('c:', c)

print('c.length():', c.length())
print('c.keys():', c.keys())
print('c.items():', c.items())
print('c.iteritems():', list(c.iteritems()))
print('c.values():', c.values())
print('c.update(PyObjectDict({"a": 1, "b": 2, "c": 3})):', c.update(PyObjectDict({'a': 1, 'b': 2, 'c': 3})))
print('c.update(PyObjectDict({"a": 1, "b": 2, "c": 3})):', c.update(PyObjectDict({'a': 1, 'b': 2, 'c': 3})))

print('iteratibng over c:')
for k in c:
    print('key: ', k)


print('a + b:', a + b)
print('a | b:', a | b)
print('a.add(b):', a.add(b))
print('a.add_each_value(b):', a.add_each_value(b))
a.update(b)
print('a after a.update(b):', a)

a.cc = 12
b.cc = 12
print('a after adding "cc": 12:', a)
print('b after adding "cc": 12:', b)

print('a - b:', a - b)
print('a.sub(b):', a.sub(b))
print('a.sub_by_value(b):', a.sub_by_value(b))
print('a.sub_each_value(b):', a.sub_each_value(b))

a += b
print('a after a += b:', a)
a -= b
print('a after a -= b:', a)
a |= b
print('a after a |= b', a)

The result of the code above will be:

a: PyObjectDict({'a': 2, 'b': 3, 'c': 10, 'd': 8})
b: PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'g': 8})
c: PyObjectDict({'c': 10, 'd': 8})
c.length(): 2
c.keys(): ['c', 'd']
c.items(): [('c', 10), ('d', 8)]
list(c.iteritems()): [('c', 10), ('d', 8)]
c.values(): [10, 8]
c.update(PyObjectDict({"a": 1, "b": 2, "c": 3})): None
c.update(PyObjectDict({"a": 1, "b": 2, "c": 3})): None
iteratibng over c:
key:  c
key:  d
key:  a
key:  b
a + b: PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'd': 8, 'g': 8})
a | b: PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'd': 8, 'g': 8})
a.add(b): PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'd': 8, 'g': 8})
a.add_each_value(b): PyObjectDict({'a': 4, 'b': 6, 'c': 14, 'd': 8})
a after a.update(b): PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'd': 8, 'g': 8})
a after adding "cc": 12: PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'd': 8, 'g': 8, 'cc': 12})
b after adding "cc": 12: PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'g': 8, 'cc': 12})
a - b: PyObjectDict({'d': 8})
a.sub(b): PyObjectDict({'d': 8})
a.sub_by_value(b): PyObjectDict({'d': 8})
a.sub_each_value(b): PyObjectDict({'a': 0, 'b': 0, 'c': 0, 'd': 8, 'g': 0, 'cc': 0})
a after a += b: PyObjectDict({'a': 2, 'b': 3, 'c': 4, 'd': 8, 'g': 8, 'cc': 12})
a after a -= b: PyObjectDict({'d': 8})
a after a |= b PyObjectDict({'d': 8, 'a': 2, 'b': 3, 'c': 4, 'g': 8, 'cc': 12})

Notes

Remember that in JavaScripts objects it is possible to access a non-existing attribute and receve an undefined value. However, since Python has no concept of undefined and checking for None could be missleading (+ the limitations of Python objects), you cannot access an unexisting attribute of PyObjectDict without triggering an AttributeError exception. Alternatively you can use get method as in standard Python dicts to check if the attribute exists before accessing it.