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Batch file include external file for variables
...tch scripts:
@echo off
rem Empty the variable to be ready for label config_all
set config_all_selected=
rem Go to the label with the parameter you selected
goto :config_%1
REM This next line is just to go to end of file
REM in case that the parameter %1 is not set
goto :end
REM next label is to...
std::shared_ptr thread safety explained
I'm reading http://gcc.gnu.org/onlinedocs/libstdc++/manual/shared_ptr.html and some thread safety issues are still not clear for me:
...
What is the recommended way to delete a large number of items from DynamoDB?
...
What I ideally want to do is call LogTable.DeleteItem(user_id) -
Without supplying the range, and have it delete everything for me.
An understandable request indeed; I can imagine advanced operations like these might get added over time by the AWS team (they have a history of st...
Why the switch statement cannot be applied on strings?
...er the string if you are using a predetermined set of strings:
enum string_code {
eFred,
eBarney,
eWilma,
eBetty,
...
};
string_code hashit (std::string const& inString) {
if (inString == "Fred") return eFred;
if (inString == "Barney") return eBarney;
...
}
voi...
Mean per group in a data.frame [duplicate]
... object. It’s easier to do what you’re after with dplyr: d %>% group_by(Name) %>% mutate(mean1=mean(Rate1), mean2=mean(Rate2))
– jbaums
May 29 '19 at 9:48
...
Comparing date part only without comparing time in JavaScript
...ne offset, or is already UTC, just keep the date part, reflecting the date _in that timezone_
if(typeof initDate === "string" && initDate.match(/((\+|-)\d{2}:\d{2}|Z)$/gm)){
utcMidnightDateObj = new Date( initDate.substring(0,10) + 'T00:00:00Z');
} else {
// if init date is no...
Bash set +x without it being printed
...ution to this just recently when I became annoyed with it:
shopt -s expand_aliases
_xtrace() {
case $1 in
on) set -x ;;
off) set +x ;;
esac
}
alias xtrace='{ _xtrace $(cat); } 2>/dev/null <<<'
This allows you to enable and disable xtrace as in the following, wh...
Argparse optional positional arguments?
...se nargs='?' (or nargs='*' if you will need more than one dir)
parser.add_argument('dir', nargs='?', default=os.getcwd())
extended example:
>>> import os, argparse
>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('-v', action='store_true')
_StoreTrueActi...
Split list into multiple lists with fixed number of elements
...st[List[X]] =
if (xs.size <= n) xs :: Nil
else (xs.splitAt(n)._1) :: split(n,xs.splitAt(n)._2)
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What is Weak Head Normal Form?
...es for an expression to be in WHNF:
A constructor: constructor expression_1 expression_2 ...
A built-in function with too few arguments, like (+) 2 or sqrt
A lambda-expression: \x -> expression
In other words, the head of the expression (i.e. the outermost function application) cannot be eval...