Initialize attributes object class and makes it const
0
I want to create read only attribute.
The example below works well, and it is inspired and simplified from https://howto.lintel.in/how-to-create-read-only-attributes-and-restrict-setting-attribute-values-on-object-in-python/
class Attr1(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class Attr2(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
A = Class()
A.attr1 = 1
A.attr2 = 2
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class()
B.attr1 = 3
B.attr2 = 3
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
And outputs this:
Class A attr1 = 1
Class A attr2 = 2
Class A attrFormula = 0.5
Class B attr1 = 3
Class B attr2 = 3
Class B attrFormula = 1
But now, i want to change
A = Class()
A.attr1 = 1
A.attr2 = 2
by
A = Class(1,2)
because i want to disable all setter attributes and make the attributes unmodifiable. Something desired like that :
class Attr1(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr1")
class Attr2(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr2")
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
def __init__(self, attr1, attr2):
self.attr1 = attr1 # ERROR because it calls __set__
self.attr2 = attr2
A = Class(1,2)
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class(5,7)
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
B.attr1 = 10 # Forbidden, desired error
How to init attr1 and attr2 in Class ?
python python-3.x
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
add a comment |
0
I want to create read only attribute.
The example below works well, and it is inspired and simplified from https://howto.lintel.in/how-to-create-read-only-attributes-and-restrict-setting-attribute-values-on-object-in-python/
class Attr1(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class Attr2(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
A = Class()
A.attr1 = 1
A.attr2 = 2
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class()
B.attr1 = 3
B.attr2 = 3
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
And outputs this:
Class A attr1 = 1
Class A attr2 = 2
Class A attrFormula = 0.5
Class B attr1 = 3
Class B attr2 = 3
Class B attrFormula = 1
But now, i want to change
A = Class()
A.attr1 = 1
A.attr2 = 2
by
A = Class(1,2)
because i want to disable all setter attributes and make the attributes unmodifiable. Something desired like that :
class Attr1(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr1")
class Attr2(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr2")
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
def __init__(self, attr1, attr2):
self.attr1 = attr1 # ERROR because it calls __set__
self.attr2 = attr2
A = Class(1,2)
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class(5,7)
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
B.attr1 = 10 # Forbidden, desired error
How to init attr1 and attr2 in Class ?
python python-3.x
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
You want read-only attributes, so you've used a code snippet that... doesn't actually create read-only attributes? (Also you're storing data on the descriptor object instead of the instance, which is going to lead to all instances sharing the same attribute values.)
– user2357112
Nov 13 '18 at 23:28
I guessattrFormulais read-only, but it's still a really verbose and buggy way to implement whatpropertywould do much easier.
– user2357112
Nov 13 '18 at 23:30
1
Why not useattrsordataclasses?
– user2357112
Nov 13 '18 at 23:31
add a comment |
0
0
0
I want to create read only attribute.
The example below works well, and it is inspired and simplified from https://howto.lintel.in/how-to-create-read-only-attributes-and-restrict-setting-attribute-values-on-object-in-python/
class Attr1(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class Attr2(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
A = Class()
A.attr1 = 1
A.attr2 = 2
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class()
B.attr1 = 3
B.attr2 = 3
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
And outputs this:
Class A attr1 = 1
Class A attr2 = 2
Class A attrFormula = 0.5
Class B attr1 = 3
Class B attr2 = 3
Class B attrFormula = 1
But now, i want to change
A = Class()
A.attr1 = 1
A.attr2 = 2
by
A = Class(1,2)
because i want to disable all setter attributes and make the attributes unmodifiable. Something desired like that :
class Attr1(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr1")
class Attr2(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr2")
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
def __init__(self, attr1, attr2):
self.attr1 = attr1 # ERROR because it calls __set__
self.attr2 = attr2
A = Class(1,2)
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class(5,7)
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
B.attr1 = 10 # Forbidden, desired error
How to init attr1 and attr2 in Class ?
python python-3.x
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
I want to create read only attribute.
The example below works well, and it is inspired and simplified from https://howto.lintel.in/how-to-create-read-only-attributes-and-restrict-setting-attribute-values-on-object-in-python/
class Attr1(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class Attr2(object):
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
self.value = int(value)
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
A = Class()
A.attr1 = 1
A.attr2 = 2
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class()
B.attr1 = 3
B.attr2 = 3
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
And outputs this:
Class A attr1 = 1
Class A attr2 = 2
Class A attrFormula = 0.5
Class B attr1 = 3
Class B attr2 = 3
Class B attrFormula = 1
But now, i want to change
A = Class()
A.attr1 = 1
A.attr2 = 2
by
A = Class(1,2)
because i want to disable all setter attributes and make the attributes unmodifiable. Something desired like that :
class Attr1(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr1")
class Attr2(object):
def __init__(self, value=None):
self.value = value
def __get__(self, instance, owner):
return self.value
def __set__(self, instance, value):
raise AttributeError("You can't change attr2")
class AttrFormula(object):
def __get__(self, instance, owner):
return instance.attr1 / instance.attr2
class Class(object):
attr1 = Attr1()
attr2 = Attr2()
attrFormula = AttrFormula()
def __init__(self, attr1, attr2):
self.attr1 = attr1 # ERROR because it calls __set__
self.attr2 = attr2
A = Class(1,2)
print("Class A attr1 =", A.attr1)
print("Class A attr2 =", A.attr2)
print("Class A attrFormula =", A.attrFormula)
B = Class(5,7)
print("Class B attr1 =", B.attr1)
print("Class B attr2 =", B.attr2)
print("Class B attrFormula =", B.attrFormula)
B.attr1 = 10 # Forbidden, desired error
How to init attr1 and attr2 in Class ?
python python-3.x
python python-3.x
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
edited Nov 13 '18 at 23:39
martineau
67.2k1089181
67.2k1089181
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
asked Nov 13 '18 at 23:24
RodrigueRodrigue
1229
1229
You want read-only attributes, so you've used a code snippet that... doesn't actually create read-only attributes? (Also you're storing data on the descriptor object instead of the instance, which is going to lead to all instances sharing the same attribute values.)
– user2357112
Nov 13 '18 at 23:28
I guessattrFormulais read-only, but it's still a really verbose and buggy way to implement whatpropertywould do much easier.
– user2357112
Nov 13 '18 at 23:30
1
Why not useattrsordataclasses?
– user2357112
Nov 13 '18 at 23:31
add a comment |
You want read-only attributes, so you've used a code snippet that... doesn't actually create read-only attributes? (Also you're storing data on the descriptor object instead of the instance, which is going to lead to all instances sharing the same attribute values.)
– user2357112
Nov 13 '18 at 23:28
I guessattrFormulais read-only, but it's still a really verbose and buggy way to implement whatpropertywould do much easier.
– user2357112
Nov 13 '18 at 23:30
1
Why not useattrsordataclasses?
– user2357112
Nov 13 '18 at 23:31
You want read-only attributes, so you've used a code snippet that... doesn't actually create read-only attributes? (Also you're storing data on the descriptor object instead of the instance, which is going to lead to all instances sharing the same attribute values.)
– user2357112
Nov 13 '18 at 23:28
You want read-only attributes, so you've used a code snippet that... doesn't actually create read-only attributes? (Also you're storing data on the descriptor object instead of the instance, which is going to lead to all instances sharing the same attribute values.)
– user2357112
Nov 13 '18 at 23:28
I guess
attrFormula is read-only, but it's still a really verbose and buggy way to implement what property would do much easier.– user2357112
Nov 13 '18 at 23:30
I guess
attrFormula is read-only, but it's still a really verbose and buggy way to implement what property would do much easier.– user2357112
Nov 13 '18 at 23:30
1
1
Why not use
attrs or dataclasses?– user2357112
Nov 13 '18 at 23:31
Why not use
attrs or dataclasses?– user2357112
Nov 13 '18 at 23:31
add a comment |
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You want read-only attributes, so you've used a code snippet that... doesn't actually create read-only attributes? (Also you're storing data on the descriptor object instead of the instance, which is going to lead to all instances sharing the same attribute values.)
– user2357112
Nov 13 '18 at 23:28
I guess
attrFormulais read-only, but it's still a really verbose and buggy way to implement whatpropertywould do much easier.– user2357112
Nov 13 '18 at 23:30
1
Why not use
attrsordataclasses?– user2357112
Nov 13 '18 at 23:31