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Using the Swift if let with logical AND operator &&
...
As of Swift 1.2, this is now possible. The Swift 1.2 and Xcode 6.3 beta release notes state:
More powerful optional unwrapping with if let — The if let construct
can now unwrap multiple optionals at once, as well as include
intervening boolean conditions. This lets you express co...
Extract traceback info from an exception object
...to this question depends on the version of Python you're using.
In Python 3
It's simple: exceptions come equipped with a __traceback__ attribute that contains the traceback. This attribute is also writable, and can be conveniently set using the with_traceback method of exceptions:
raise Exceptio...
How to get random value out of an array?
I have an array called $ran = array(1,2,3,4);
20 Answers
20
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What is a “callable”?
...
314
A callable is anything that can be called.
The built-in callable (PyCallable_Check in object...
How many bytes does one Unicode character take?
...ion. Those are the various unicode encodings, such as utf-8, utf-16le, utf-32 etc. They are distinguished largely by the size of of their codeunits. UTF-32 is the simplest encoding, it has a codeunit that is 32bits, which means an individual codepoint fits comfortably into a codeunit. The other enco...
Passing an integer by reference in Python
...he integer in a container which can be mutated:
def change(x):
x[0] = 3
x = [1]
change(x)
print x
This is ugly/clumsy at best, but you're not going to do any better in Python. The reason is because in Python, assignment (=) takes whatever object is the result of the right hand side and binds...
Tri-state Check box in HTML?
...ution:
HTML5 defines a property for checkboxes called indeterminate
See w3c reference guide. To make checkbox appear visually indeterminate set it to true:
element.indeterminate = true;
Here is Janus Troelsen's fiddle. Note, however, that:
The indeterminate state cannot be set in the HTML mar...
How to convert JSON to XML or XML to JSON?
...
13 Answers
13
Active
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What are the differences between “=” and “
...ithout further ado:
x
# Error: object 'x' not found
sum((x = 1), 2)
# [1] 3
x
# [1] 1
Clearly we’ve performed an assignment, using =, outside of contexts (a) and (b). So, why has the documentation of a core R language feature been wrong for decades?
It’s because in R’s syntax the symbol = ...
What is the preferred/idiomatic way to insert into a map?
...|
edited Nov 26 '10 at 18:37
user229044♦
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