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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?
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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
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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"
# ...
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 ...
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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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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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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Remove duplicate values from JS array [duplicate]
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Quick and dirty using jQuery:
var names = ["Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"];
var uniqueNames = [];
$.each(names, function(i, el){
if($.inArray(el, uniqueNames) === -1) uniqueNames.push(el);
});
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How to delete duplicate lines in a file without sorting it in Unix?
...ay then seen[$0] will evaluate to false. The ! is the logical NOT operator and will invert the false to true. Awk will print the lines where the expression evaluates to true. The ++ increments seen so that seen[$0] == 1 after the first time a line is found and then seen[$0] == 2, and so on.
Awk eval...
Hidden features of Python [closed]
...ue
In case you're thinking it's doing 1 < x, which comes out as True, and then comparing True < 10, which is also True, then no, that's really not what happens (see the last example.) It's really translating into 1 < x and x < 10, and x < 10 and 10 < x * 10 and x*10 < 100, but...