Scope is an enclosing context where values and expressions are associated. Use this tag for questions about different types of scope as well for questions where scope may be unclear.
Questions tagged [scope]
17524 questions
381
votes
10 answers
What underlies this JavaScript idiom: var self = this?
I saw the following in the source for WebKit HTML 5 SQL Storage Notes Demo:
function Note() {
var self = this;
var note = document.createElement('div');
note.className = 'note';
note.addEventListener('mousedown', function(e) { return…
Thomas L Holaday
- 13,614
- 6
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370
votes
5 answers
Python 3: UnboundLocalError: local variable referenced before assignment
The following code gives the error UnboundLocalError: local variable 'Var1' referenced before assignment:
Var1 = 1
Var2 = 0
def function():
if Var2 == 0 and Var1 > 0:
print("Result 1")
elif Var2 == 1 and Var1 > 0:
…
Eden Crow
- 14,684
- 11
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- 24
316
votes
8 answers
Is it possible to declare two variables of different types in a for loop?
Is it possible to declare two variables of different types in the initialization body of a for loop in C++?
For example:
for(int i=0,j=0 ...
defines two integers. Can I define an int and a char in the initialization body? How would this be done?
Nathan Osman
- 71,149
- 71
- 256
- 361
312
votes
12 answers
Why use a public method in an internal class?
There is a lot of code in one of our projects that looks like this:
internal static class Extensions
{
public static string AddFoo(this string s)
{
if (s == null)
{
return "Foo";
}
return…
bopapa_1979
- 8,949
- 10
- 51
- 76
289
votes
6 answers
Is the underscore prefix for property and method names merely a convention?
Is the underscore prefix in JavaScript only a convention, like for example in Python private class methods are?
From the 2.7 Python documentation:
“Private” instance variables that
cannot be accessed except from inside
an object don’t exist in…
Kenny Meyer
- 7,849
- 6
- 45
- 66
289
votes
5 answers
How to create module-wide variables in Python?
Is there a way to set up a global variable inside of a module? When I tried to do it the most obvious way as appears below, the Python interpreter said the variable __DBNAME__ did not exist.
...
__DBNAME__ = None
def initDB(name):
if not…
daveslab
- 10,000
- 21
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- 86
288
votes
14 answers
UnboundLocalError trying to use a variable (supposed to be global) that is (re)assigned (even after first use)
When I try this code:
a, b, c = (1, 2, 3)
def test():
print(a)
print(b)
print(c)
c += 1
test()
I get an error from the print(c) line that says:
UnboundLocalError: local variable 'c' referenced before assignment
in newer versions…
tba
- 6,229
- 8
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- 63
275
votes
8 answers
A variable modified inside a while loop is not remembered
In the following program, if I set the variable $foo to the value 1 inside the first if statement, it works in the sense that its value is remembered after the if statement. However, when I set the same variable to the value 2 inside an if which is…
Eric Lilja
- 3,323
- 4
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- 15
258
votes
8 answers
Can I access variables from another file?
Is it possible to use a variable in a file called first.js inside another file called second.js?
first.js contains a variable called colorcodes.
SAK
- 3,780
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257
votes
8 answers
Scoping in Python 'for' loops
I'm not asking about Python's scoping rules; I understand generally how scoping works in Python for loops. My question is why the design decisions were made in this way. For example (no pun intended):
for foo in xrange(10):
bar = 2
print(foo,…
chimeracoder
- 20,648
- 21
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- 60
254
votes
5 answers
How do I pass the this context to a function?
I thought this would be something I could easily google, but maybe I'm not asking the right question...
How do I set whatever "this" refers to in a given javascript function?
for example, like with most of jQuery's functions such as: …
user126715
- 3,648
- 3
- 23
- 25
242
votes
10 answers
Accessing class variables from a list comprehension in the class definition
How do you access other class variables from a list comprehension within the class definition? The following works in Python 2 but fails in Python 3:
class Foo:
x = 5
y = [x for i in range(1)]
Python 3.2 gives the error:
NameError: global…
Mark Lodato
- 50,015
- 5
- 41
- 32
226
votes
9 answers
Is it possible to define more than one function per file in MATLAB, and access them from outside that file?
When I was studying for my undergraduate degree in EE, MATLAB required each function to be defined in its own file, even if it was a one-liner.
I'm studying for a graduate degree now, and I have to write a project in MATLAB. Is this still a…
Nathan Fellman
- 122,701
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225
votes
4 answers
Access a variable outside the scope of a Handlebars.js each loop
I have a handlebars.js template, just like this:
{{externalValue}}
And this is the generated…
lucke84
- 4,516
- 3
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- 58
216
votes
8 answers
Why does this UnboundLocalError occur (closure)?
What am I doing wrong here?
counter = 0
def increment():
counter += 1
increment()
The above code throws an UnboundLocalError.
Randomblue
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