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Unable to install gem - Failed to build gem native extension - cannot load such file — mkmf (LoadErr
...mitry S.Dmitry S.
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How to add column if not exists on PostgreSQL?
...statement:
DO $$
BEGIN
BEGIN
ALTER TABLE <table_name> ADD COLUMN <column_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
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Generate a random double in a range
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This is generally correct, but beware of its limits. If you do double rangeMax= Double.MAX_VALUE; and double rangeMin= -rangeMax; you will always get an infinite value in return. You might want to check for Double.valueOf(rangeMax-range...
How can I initialize base class member variables in derived class constructor?
...ince it would destroy encapsulation. Instead, create a constructor in A to allow B (or any subclass of A) to initialize them:
class A
{
protected:
A(int a, int b) : a(a), b(b) {} // Accessible to derived classes
// Change "protected" to "public" to allow others to instantiate A.
private:
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Max or Default?
...wiggering the spacklerorke, and riding the flying unicorn to Neverland are all meaningless, impossible, undefined.
Now, what is it that you actually want to do?
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Mixin vs inheritance
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A mixin is typically used with multiple inheritance. So, in that sense, there's "no difference".
The detail is that a mixin is rarely useful as a standalone object.
For example, say you have a mixin named "ColorAndDimension", which adds a co...
Amazon S3 - HTTPS/SSL - Is it possible? [closed]
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answered Jun 16 '10 at 21:32
Kerry JonesKerry Jones
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How to have the cp command create any necessary folders for copying a file to a destination [duplica
... the mkdir/cp command above. It just creates a single level of folder. Actually I'm not sure when it can be useful.
– Penghe Geng
Apr 13 '15 at 14:30
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Formatting code snippets for blogging on Blogger [closed]
... I spent a couple hours on it and I can't get this to work at all.
– thepaulpage
Mar 21 '13 at 15:43
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Matching a space in regex
...X is the physical tab character (and each is preceded by a single space in all those examples).
These will work in every* regex engine I've ever seen (some of which don't even have the one-or-more "+" character, ugh).
If you know you'll be using one of the more modern regex engines, "\s" and its v...