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What's wrong with foreign keys?
... a foreign key (if I remember correctly). However, to me they seem pretty vital to avoid duplication and subsequent data integrity problems throughout your database.
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How can I pretty-print JSON in a shell script?
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With Python 2.6+ you can just do:
echo '{"foo": "lorem", "bar": "ipsum"}' | python -m json.tool
or, if the JSON is in a file, you can do:
python -m json.tool my_json.json
if the JSON is from an internet source such as ...
Placement of the asterisk in pointer declarations
...ng I do not really understand about pointers or more precisely, their definition.
12 Answers
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Pure virtual function with implementation
...he base type can still define an implementation. A derived class can explicitly call the base class implementation (if access permissions allow it) by using a fully-scoped name (by calling A::f() in your example - if A::f() were public or protected). Something like:
class B : public A {
virtu...
UTF-8 all the way through
...and retrieve values encoded natively in UTF-8. Note that MySQL will implicitly use utf8mb4 encoding if a utf8mb4_* collation is specified (without any explicit character set).
In older versions of MySQL (< 5.5.3), you'll unfortunately be forced to use simply utf8, which only supports a subset o...
Why shouldn't all functions be async by default?
The async-await pattern of .net 4.5 is paradigm changing. It's almost too good to be true.
4 Answers
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What is a covariant return type?
... to be a subtype of the overridden method's return type.
To clarify this with an example, a common case is Object.clone() - which is declared to return a type of Object. You could override this in your own class as follows:
public class MyFoo
{
...
// Note covariant return here, method do...
How to use a variable to specify column name in ggplot
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If for whatever reason you'd rather not use aes_string, you could change it to (the somewhat more cumbersome):
ggplot( rates.by.groups, aes(x=name, y=rate, colour= get(column),
group=get(column) ) )
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How do I disable a Pylint warning?
..."more than one statement on a single line" -- I often put if statements with short single-line results on the same line), in Pylint 0.21.1 (if it matters: astng 0.20.1, common 0.50.3, Python 2.6.6 (r266:84292, Sep 15 2010, 16:22:56)).
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How to list the files inside a JAR file?
...e == null)
break;
String name = e.getName();
if (name.startsWith("path/to/your/dir/")) {
/* Do something with this entry. */
...
}
}
}
else {
/* Fail... */
}
Note that in Java 7, you can create a FileSystem from the JAR (zip) file, and then use NIO's directory wa...