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Determine if a function exists in bash
...function, external command, or just not defined. Example:
$ LC_ALL=C type foo
bash: type: foo: not found
$ LC_ALL=C type ls
ls is aliased to `ls --color=auto'
$ which type
$ LC_ALL=C type type
type is a shell builtin
$ LC_ALL=C type -t rvm
function
$ if [ -n "$(LC_ALL=C type -t rvm)" ] &&a...
Why does X[Y] join of data.tables not allow a full outer join, or a left join?
... in data.table does all that in one step for
you. When you write X[Y,sum(foo*bar)], data.table automatically inspects the j expression to see which columns it uses. It will only subset those columns only; the others are ignored. Memory is only created for the columns the j uses, and Y columns enjo...
Stored procedure slow when called from web, fast from Management Studio
...null)
begin
select @dateTo = GETUTCDATE()
end
select foo
from dbo.table
where createdDate < @dateTo
end
After I changed it to
create procedure dbo.procedure
@dateTo datetime = null
begin
declare @to datetime = coalesce(@dateTo, getutcdate())
select fo...
Why is there an injected class name?
...class name can be used without a template argument list, e.g. using simply Foo instead of the full template-id Foo<blah, blah, blah>, so it's easy to refer to the current instantiation. See DR 176 for a change between C++98 and C++03 that clarified that.
The idea of the injected class name wa...
Big O, how do you calculate/approximate it?
... < 2*n; i += 2) { // 1
for (j=n; j > i; j--) { // 2
foo(); // 3
}
}
The first thing you needed to be asked is the order of execution of foo(). While the usual is to be O(1), you need to ask your professors about it. O(1) means (almost, mostly) constant C...
Allowed characters in Linux environment variable names
... by ConfigMap
test.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: foo-config
data:
"xx.ff-bar": "1234"
---
apiVersion: v1
kind: Pod
metadata:
name: foobar
spec:
containers:
- name: test-container
image: k8s.gcr.io/busybox
command: [ "/bin/sh", "-c", "env" ]
envF...
Boolean vs boolean in Java
...-definable classes using another keyword class)
or in other words
boolean foo = true;
vs.
Boolean foo = true;
The first "thing" (type) can not be extended (subclassed) and not without a reason. Effectively Java terminology of primitive and wrapping classes can be simply translated into inline...
How to normalize a path in PowerShell?
...nContext.SessionState.Path.GetUnresolvedProviderPathFromPSPath(".\nonexist\foo.txt") Works with non-existant paths too. "x0n" deserves the credit for this btw. As he notes, it resolves to PSPaths, not flilesystem paths, but if you're using the paths in PowerShell, who cares? stackoverflow.com/que...
What special characters must be escaped in regular expressions?
...k in the left hand side of a substitution string in sed, namely
sed -e 's/foo\(bar/something_else/'
I tend to just use a simple character class definition instead, so the above expression becomes
sed -e 's/foo[(]bar/something_else/'
which I find works for most regexp implementations.
BTW Char...
How to redirect all HTTP requests to HTTPS
...7), but this has issues for me on certain URLs. For example, http://server/foo?email=someone%40example.com redirects to https://server/foo?email=someone%2540example.com i.e. the "@" sign gets URL-quoted twice. Using the method in @ssc's answer does not have this issue.
– psmear...