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Understanding dict.copy() - shallow or deep?
... 3, 4, 5]}, {1: [1, 2, 3, 4]})
So:
b = a: Reference assignment, Make a and b points to the same object.
b = a.copy(): Shallow copying, a and b will become two isolated objects, but their contents still share the same reference
b = copy.deepcopy(a): Deep copying, a and b's structure and conte...
Difference between a Seq and a List in Scala
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In Java terms, Scala's Seq would be Java's List, and Scala's List would be Java's LinkedList.
Note that Seq is a trait, which is equivalent to Java's interface, but with the equivalent of up-and-coming defender methods. Scala's List is an abstract class that is extended by...
Does Java 8 provide a good way to repeat a value or function?
...- 1)
.forEach(System.out::println);
Or build a custom iteration and limit the size of the iteration:
IntStream.iterate(1, i -> i + 2)
.limit(8)
.forEach(System.out::println);
share
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Best practices for in-app database migration for Sqlite
I am using sqlite for my iphone and I anticipate the database schema might change over time. What are the gotchas, naming conventions and things to watch out for to do a successful migration each time?
...
Set cURL to use local virtual hosts
... applies, but simply pretends the DNS lookup returned the data in your command-line option. It works just like /etc/hosts should.
Note --resolve takes a port number, so for HTTPS you would use
curl --resolve 'yada.com:443:127.0.0.1' https://yada.com/something
...
How to concatenate twice with the C preprocessor and expand a macro as in “arg ## _ ## MACRO”?
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Standard C Preprocessor
$ cat xx.c
#define VARIABLE 3
#define PASTER(x,y) x ## _ ## y
#define EVALUATOR(x,y) PASTER(x,y)
#define NAME(fun) EVALUATOR(fun, VARIABLE)
extern void NAME(mine)(char *x);
$ gcc -E xx.c
# 1 "xx.c"
# ...
Cartesian product of x and y array points into single array of 2D points
I have two numpy arrays that define the x and y axes of a grid. For example:
13 Answers
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Difference between dispatch_async and dispatch_sync on serial queue?
...k is finished whereas dispatch_async return after it is added to the queue and may not finished.
for this code
dispatch_async(_serialQueue, ^{ printf("1"); });
printf("2");
dispatch_async(_serialQueue, ^{ printf("3"); });
printf("4");
It may print 2413 or 2143 or 1234 but 1 always before 3
for ...
Difference between Pragma and Cache-Control headers?
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Pragma is the HTTP/1.0 implementation and cache-control is the HTTP/1.1 implementation of the same concept. They both are meant to prevent the client from caching the response. Older clients may not support HTTP/1.1 which is why that header is still in use.
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Regex lookahead, lookbehind and atomic groups
...hat I can use them for.
Does somebody have examples so I can try to understand how they work?
3 Answers
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