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Bash Templating: How to build configuration files from templates with Bash?
...:
#!/bin/bash
while read -r line ; do
while [[ "$line" =~ (\$\{[a-zA-Z_][a-zA-Z_0-9]*\}) ]] ; do
LHS=${BASH_REMATCH[1]}
RHS="$(eval echo "\"$LHS\"")"
line=${line//$LHS/$RHS}
done
echo "$line"
done
. Solution that does not hang if RHS references some variable th...
Is there a MySQL option/feature to track history of changes to records?
...
For example, if you have a table like this:
CUSTOMER
---------
CUSTOMER_ID PK
CUSTOMER_NAME
CUSTOMER_ADDRESS
and you wanted to keep track over time, you would amend it as follows:
CUSTOMER
------------
CUSTOMER_ID PK
CUSTOMER_VALID_FROM PK
CUSTOMER_VALID_UNTIL PK
CUSTOMER_STAT...
What is the easiest way to parse an INI file in Java?
...port java.util.regex.Pattern;
public class IniFile {
private Pattern _section = Pattern.compile( "\\s*\\[([^]]*)\\]\\s*" );
private Pattern _keyValue = Pattern.compile( "\\s*([^=]*)=(.*)" );
private Map< String,
Map< String,
String >> _entries = new HashMap...
How to get these two divs side-by-side?
...
#parent_div_1, #parent_div_2, #parent_div_3 {
width: 100px;
height: 100px;
border: 1px solid red;
margin-right: 10px;
float: left;
}
.child_div_1 {
float: left;
margin-right: 5px;
}
Check working example at http://js...
Getting the object's property name
...DN
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/keys
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How to use the PI constant in C++
...ially older) platforms (see the comments below) you might need to
#define _USE_MATH_DEFINES
and then include the necessary header file:
#include <math.h>
and the value of pi can be accessed via:
M_PI
In my math.h (2014) it is defined as:
# define M_PI 3.1415926535897932384...
Is it true that one should not use NSLog() on production code?
... line number to make it easier to track down log statements.
#define DEBUG_MODE
#ifdef DEBUG_MODE
#define DebugLog( s, ... ) NSLog( @"<%p %@:(%d)> %@", self, [[NSString stringWithUTF8String:__FILE__] lastPathComponent], __LINE__, [NSString stringWithFormat:(s), ##__VA_ARGS__] )
#else
...
Why is printing to stdout so slow? Can it be sped up?
... I experimented earlier with huge (up to 10MB with fp = os.fdopen(sys.__stdout__.fileno(), 'w', 10000000)) python-side buffers. Impact was nil. ie: still long tty delays. This made me think/realize that you just postpone the slow tty problem... when python's buffer finally flushes the tty st...
List comprehension: Returning two (or more) items for each item
...bda x: x + 2
>>> g = lambda x: x ** 2
>>> list(chain.from_iterable((f(x), g(x)) for x in range(3)))
[2, 0, 3, 1, 4, 4]
Timings:
from timeit import timeit
f = lambda x: x + 2
g = lambda x: x ** 2
def fg(x):
yield f(x)
yield g(x)
print timeit(stmt='list(chain.from_itera...
Finding quaternion representing the rotation from one vector to another
...ion is produced -- check and see for yourself).
// N.B. the arguments are _not_ axis and angle, but rather the
// raw scalar-vector components.
Quaternion(float w, Vector3 xyz);
Quaternion get_rotation_between(Vector3 u, Vector3 v)
{
// It is important that the inputs are of equal length when
...