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What's wrong with nullable columns in composite primary keys?
...s version the "ext" part of the tuple is NOT NULL but defaults to an empty string -- which is semantically (and practically) different from a NULL. A NULL is an unknown, whereas an empty string is a deliberate record of "something not being present". In other words, "empty" and "null" are different ...
Regex, every non-alphanumeric character except white space or colon
... - matches all the letters
^ - negates them all - so you get - non numeric chars, non spaces and non colons
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Use of alloc init instead of new
...selected ones are:
new doesn't support custom initializers (like initWithString)
alloc-init is more explicit than new
General opinion seems to be that you should use whatever you're comfortable with.
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Check if a value is an object in JavaScript
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@Tresdin The best way is to run Object.prototype.toString.call(yourVar), being yourVar what you need to inspect. In case of arrays, Object.prototype.toString.call([1,2]) returns [object Array]
– Jose Rui Santos
Feb 25 '16 at 9:48
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Why should I avoid using Properties in C#?
...ly-typed system, to avoid what Fowler calls Syntactic Noise. We don't want extra parentheses, extra get/set warts, or extra method signatures - not if we can avoid them without any loss of clarity.
Say whatever you like, but foo.Bar.Baz = quux.Answers[42] is always going to be a lot easier to read ...
Difference between HashMap, LinkedHashMap and TreeMap
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private TreeMap<String ,Integer> mySection2 = new TreeMap<>(); mySection2.put("abc1", 2); mySection2.put("abc2",5); mySection2.put("abc3",3); ...
Disabling swap files creation in vim
...ing which is a large part of vim use for a lot of people, it seems like an extra bookeeping job better left out. I personally prefer for all jobs to just have no swaps or other auto-backups. If I really need to develop something, I'd rather have a more high level framework to protect me, preferably ...
Using union and order by clause in mysql
...organize.
But this way has the advantage of being fast, not introducing extra variables, and making it easy to separate out each query including the sort. The ability to add a limit is simply an extra bonus.
And of course feel free to turn the union all into a union and add a sort for the whole...
How to drop rows of Pandas DataFrame whose value in a certain column is NaN
...ilippSchwarz This error occurs if the column (EPS in the example) contains strings or other types that cannot be digested by np.isfinite(). I recommend to use pandas.notnull() that will handle this more generously.
– normanius
Apr 5 '18 at 10:02
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Bash script to receive and repass quoted parameters
...# $4= "ddd ddd"
"$*" - quoted-dollar-star smashes the args into a single string (~1% of the time you actually want this behavior, eg in a conditional: if [[ -z "$*" ]]; then ...):
./quoted-dollar-star.sh aaa '' "'cc cc'" '"ddd ddd"'
# $1= aaa 'cc cc' "ddd ddd"
# $2=
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