New variable?

[tmallen]

What's the proper way to instantiate a new variable? x = ""?

 

[Chris]

What's the proper way to instantiate a new variable? x = ""?

You don't need to pre-declare your variables. Just assign them as you
need them and they will take the correct type.

 

[tmallen]

You don't need to pre-declare your variables. Just assign them as you
need them and they will take the correct type.

unless I'm using the += or a similar operator, right? That doesn't
seem to instantiate a variable.

 

[Dan Upton]

unless I'm using the += or a similar operator, right? That doesn't
seem to instantiate a variable.

Right... because you don't have anything to increment or append to. I
guess this also comes up in the case of something like lists or
dictionaries you want to uniformly create in a loop. I guess you
could call it instantiating, but really it's more like going ahead and
assigning to them as Chris mentioned and you're just starting them
with a default value. Assuming you're working with strings, x=""
should work just fine in that case. Lists, x=[], dictionaries, x={},
integers, probably x=1 or x=0...

 

[Reedick, Andrew]

-----Original Message-----

From: [email protected] [mailtoython-
[email protected]] On Behalf Of tmallen
Sent: Tuesday, June 03, 2008 2:41 PM
To: (e-mail address removed)
Subject: New variable?

What's the proper way to instantiate a new variable? x = ""?

I've always used
X = None
in those cases where I need to pre-declare a variable to set scope.


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[Chris]

unless I'm using the += or a similar operator, right? That doesn't
seem to instantiate a variable.

Right... because you don't have anything to increment or append to.  I
guess this also comes up in the case of something like lists or
dictionaries you want to uniformly create in a loop.  I guess you
could call it instantiating, but really it's more like going ahead and
assigning to them as Chris mentioned and you're just starting them
with a default value.  Assuming you're working with strings, x=""
should work just fine in that case.  Lists, x=[], dictionaries, x={},
integers, probably x=1 or x=0...

You can always use the conversion functions if you want to be explicit
str(), int(), list(), dict(), set() etc

 

[Lie]

What's the proper way to instantiate a new variable? x = ""?

You don't need to. The reason why you need to "declare" variable when
doing something like a += 1 is because this is actually a shorthand
for a = a + 1 (unless you override __radd__), the a on the right-hand
side is not yet assigned to any objects (remember that python use the
"name tag" model instead of "variable" model).