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List changes unexpectedly after assignment. How do I clone or copy it to prevent this?
...-needing method, but sometimes unavoidable.
Example:
import copy
class Foo(object):
def __init__(self, val):
self.val = val
def __repr__(self):
return 'Foo({!r})'.format(self.val)
foo = Foo(1)
a = ['foo', foo]
b = a.copy()
c = a[:]
d = list(a)
e = copy.copy(a)
f = cop...
How do I find all of the symlinks in a directory tree?
...
find already looks recursively by default:
[15:21:53 ~]$ mkdir foo
[15:22:28 ~]$ cd foo
[15:22:31 ~/foo]$ mkdir bar
[15:22:35 ~/foo]$ cd bar
[15:22:36 ~/foo/bar]$ ln -s ../foo abc
[15:22:40 ~/foo/bar]$ cd ..
[15:22:47 ~/foo]$ ln -s foo abc
[15:22:52 ~/foo]$ find ./ -type l
.//abc
.//bar/...
How to get “wc -l” to print just the number of lines without file name?
...unt; for line count you'd do wc -l. echo -n omits the trailing line break.
FOO="bar"
echo -n "$FOO" | wc -c # " 3" (x)
echo -n "$FOO" | wc -c | bc # "3" (√)
echo -n "$FOO" | wc -c | tr -d ' ' # "3" (√)
echo -n...
How to sort git tags by version string order of form rc-X.Y.Z.W?
...
Prepend "-" to reverse sort order.
So, if you have:
git tag foo1.3 &&
git tag foo1.6 &&
git tag foo1.10
Here is what you would get:
# lexical sort
git tag -l --sort=refname "foo*"
foo1.10
foo1.3
foo1.6
# version sort
git tag -l --sort=version:refname "foo*"
foo1.3
...
Inserting a string into a list without getting split into characters
...
To add to the end of the list:
list.append('foo')
To insert at the beginning:
list.insert(0, 'foo')
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How do I find files that do not contain a given string pattern?
... out the files in the current directory which do not contain the word foo (using grep )?
16 Answers
...
How does RewriteBase work in .htaccess
...ative paths in the rule's target. So say you have this rule:
RewriteRule ^foo$ bar.php [L]
The bar.php is a relative path, as opposed to:
RewriteRule ^foo$ /bar.php [L]
where the /bar.php is an absolute path. The absolute path will always be the "root" (in the directory structure above). That ...
What's the difference between using “let” and “var”?
...sing block denoted by { } (hence the block scope).
function run() {
var foo = "Foo";
let bar = "Bar";
console.log(foo, bar);
{
let baz = "Bazz";
console.log(baz);
}
console.log(baz); // ReferenceError
}
run();
The reason why let keyword was introduced to the language was f...
Concatenating two lists - difference between '+=' and extend()
... for function and also not global)
def main():
l = [1, 2, 3]
def foo():
l.extend([4])
def boo():
l += [5]
foo()
print l
boo() # this will fail
main()
It's because for extend case compiler will load the variable l using LOAD_DEREF instruction, but for +...
Match multiple cases classes in scala
...String parameters, and want to treat B and C the same, so:
def matcher(l: Foo): String = {
l match {
case A() => "A"
case B(_) | C(_) => "B"
case _ => "default"
}
}
If you must, must, must extract the parameter and treat them in the same code block, you could:
def matche...