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ruby on rails f.select options with custom attributes
...=>c.currency_code}] },
selected_key = f.object.country_id) %>
If you need grouped options, you can use the grouped_options_for_select helper, like this (if @continents is an array of continent objects, each having a countries method):
<%= f.select :country_id, grouped_options_for_se...
Pick a random element from an array
...
Swift 4.2 and above
The new recommended approach is a built-in method on the Collection protocol: randomElement(). It returns an optional to avoid the empty case I assumed against previously.
let array = ["Frodo", "Sam", "Wis...
CFLAGS vs CPPFLAGS
...ou use to define include paths is a matter of personal taste. For instance if foo.c is a file in the current directory
make foo.o CPPFLAGS="-I/usr/include"
make foo.o CFLAGS="-I/usr/include"
will both call your compiler in exactly the same way, namely
gcc -I/usr/include -c -o foo.o foo.c
The d...
What does $1 [QSA,L] mean in my .htaccess file?
... in short;
RewriteCond basically means "execute the next RewriteRule only if this is true". The !-l path is the condition that the request is not for a link (! means not, -l means link)
The RewriteRule basically means that if the request is done that matches ^(.+)$ (matches any URL except the serv...
How can I check if a Perl array contains a particular value?
... turn the array into a hash:
my %params = map { $_ => 1 } @badparams;
if(exists($params{$someparam})) { ... }
You can also add more (unique) params to the list:
$params{$newparam} = 1;
And later get a list of (unique) params back:
@badparams = keys %params;
...
Select rows of a matrix that meet a condition
...
This is easier to do if you convert your matrix to a data frame using as.data.frame(). In that case the previous answers (using subset or m$three) will work, otherwise they will not.
To perform the operation on a matrix, you can define a column...
How can I repeat a character in Bash?
...
If you functionalise this it's best to rearrange it from $s%.0s to %.0s$s otherwise dashes cause a printf error.
– KomodoDave
Jul 30 '14 at 7:35
...
Using Default Arguments in a Function
...you can do what you want:
function foo($blah, $x = null, $y = null) {
if (null === $x) {
$x = "some value";
}
if (null === $y) {
$y = "some other value";
}
code here!
}
This way, you can make a call like foo('blah', null, 'non-default y value'); and have it ...
How do I add PHP code/file to HTML(.html) files?
... this? Moreover, he should update server config rather than use .htaccess if that's an option.
– Explosion Pills
Jul 3 '12 at 13:51
11
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A non-blocking read on a subprocess.PIPE in Python
...standard output. Is there a way to make .readline non-blocking or to check if there is data on the stream before I invoke .readline ? I'd like this to be portable or at least work under Windows and Linux.
...