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[Andrew425]

Thanks guys for the help. I couldn't figure out your way but I managed to make mine work.

[fergus]

Python trouble again D:
(please forgive my non-existent knowledge about how to call everything )

I have 'game' which is an (also the only) instance of the Game class, and contains all default variables and other thins like the current year.
I also have a Person class, and a bunch of instances of that (people). All of these instances also contain a reference to 'game'.

Now when I do this (in an instance of a Person class):

Code: [Select]

self.age = self.game.personAge # personAge is the default age of a newly created personself.age just refers to the value in the game class. It is not 'independent', and thus when anyone ages, they all age Dx, including the default starting age itself. Any idea how to fix this?

It sounds like your changing a mutable object.
Is game.personAge an integer? How are you increasing self.age?

[Dutchling]

Why are you setting age first in your game class rather than in your person class?

Because I thought it'd be good to have all the default variables in one place, so I wouldn't lose track of them.

It sounds like your changing a mutable object.
Is game.personAge an integer? How are you increasing self.age?

It is a list of two integers. And I increase the second integer once for every person every month.

Considering nobody seems to know how to fix this (and 'fixing' it obviously isn't the best thing to do here), I'll just do what everybody seems to want me to do and move the default values of Person to Person.py

[alexandertnt]

It is a list of two integers. And I increase the second integer once for every person every month.

Considering nobody seems to know how to fix this (and 'fixing' it obviously isn't the best thing to do here), I'll just do what everybody seems to want me to do and move the default values of Person to Person.py

Ah, a list.
Try:

Code: [Select]

self.age = list(self.game.personAge) # personAge is a copy of the default age of a newly created person

to copy the list

[Dutchling]

Thanks. I actually did it as everybody suggested (I got it working now) but I was curious how to use variables defined in classes.

[fergus]

Why are you setting age first in your game class rather than in your person class?

Because I thought it'd be good to have all the default variables in one place, so I wouldn't lose track of them.

It sounds like your changing a mutable object.
Is game.personAge an integer? How are you increasing self.age?

It is a list of two integers. And I increase the second integer once for every person every month.

Considering nobody seems to know how to fix this (and 'fixing' it obviously isn't the best thing to do here), I'll just do what everybody seems to want me to do and move the default values of Person to Person.py

When you do

Code: [Select]

self.age = self.game.personAge # personAge is the default age of a newly created personyour taking a copy of a reference to a list, not a copy of the list itself, so when you increment the second value, everyone is looking at the same list and getting the incremented version. Instead you should either make self.game.personAge a tuple, which can't be changed in-place, or do:

Code: [Select]

self.age = copy.copy(self.game.personAge)which will make a separate copy of the list.

[olemars]

People like to complain that pointers and references in C++ are somehow complicated, but at least you can know they're there and what to expect from them.

[SethCreiyd]

It is a list of two integers. And I increase the second integer once for every person every month.

Considering nobody seems to know how to fix this (and 'fixing' it obviously isn't the best thing to do here), I'll just do what everybody seems to want me to do and move the default values of Person to Person.py

When you do

Code: [Select]

self.age = self.game.personAge # personAge is the default age of a newly created personyour taking a copy of a reference to a list, not a copy of the list itself, so when you increment the second value, everyone is looking at the same list and getting the incremented version. Instead you should either make self.game.personAge a tuple, which can't be changed in-place, or do:

Code: [Select]

self.age = copy.copy(self.game.personAge)which will make a separate copy of the list.

You could also use index slicing, the list built-in, or a comprehension (which would be a bit overkill for this):

Code: [Select]

self.age = self.game.personAge[:]
self.age = list(self.game.personAge)
self.age = [n for n in self.game.personAge]

You might prefer using two separate attributes here, rather than storing a list of two integers, unless there's a good reason to keep those values in a sequence.  You could still use multiple assignment with a sequence in the initialization:

Code: [Select]

age_values = [100,1]
self.maxAge, self.currentAge = age_values


[Dutchling]

Thanks. Didn't know the comprehension thing. Might prove useful later on.

The list is actually [<year>, <month>]. Don't really see a point in making those two values, unless you have some good reason for it

[Skyrunner]

People like to complain that pointers and references in C++ are somehow complicated, but at least you can know they're there and what to expect from them.

It's nice to know that if something goes wrong, it's always my fault , not how the high-level feature implements my commands xD

[alexandertnt]

People like to complain that pointers and references in C++ are somehow complicated, but at least you can know they're there and what to expect from them.

You know what to expect from them - they just work somewhat differently to C/C++'s pointers. Plus no seg-faults

The list is actually [<year>, <month>]. Don't really see a point in making those two values, unless you have some good reason for it

I would suggest making a sepeate date class alltogether. It would allow for easy expansion in the future if you wanted to make the date system more complicated (adding day, minutes etc to improve accuracy would have you modifying the date class, rather than a person class with lots of other unrelated-to-date stuff) and it would allow you to give other non-person items a date without having to copy and paste anything if you needed to.

Its totally fine to make seemingly-trivial several-line-long classes, as long as it makes sense.

[Dutchling]

I'm not sure why replacing a variable with a class containing a variable would be useful.

Might as well assume there is a good reason for it and do it anyway

[Siquo]

I'm not sure why replacing a variable with a class containing a variable would be useful.

I can think of many uses...
Making your own casting, operator behavior, caching, event listeners, polymorphism, the possibilities are ENDLESS!

[Twiggie]

Basically its gonna make things a hell of a lot easier when you want to change your code. Instead of combing though your code looking for every instance of these integers, you'll be able to update the whole functionality from one file (assuming your interface doesn't need to change)

[Dutchling]

I have no idea what you (Siquo) are talking about

Anyway, how do you create new classes inside of a class? I tried to do it like I do it in a function (which works) but I get this:

Code: [Select]

File "C:\<~~>\person.py", line 13, in __init__
    self.age = time.Time(1, 20)
AttributeError: 'module' object has no attribute 'Time'I can move this to the function which creates the person class, but I'd prefer to do it in __init__.