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Double negation (!!) in javascript - what is the purpose? [duplicate]
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It casts to boolean. The first ! negates it once, converting values like so:
undefined to true
null to true
+0 to true
-0 to true
'' to true
NaN to true
false to true
All other expressions to false
Then the other ! negates i...
os.path.dirname(__file__) returns empty
...irname(filename) + os.path.basename(filename) == filename
Both dirname() and basename() only split the passed filename into components without taking into account the current directory. If you want to also consider the current directory, you have to do so explicitly.
To get the dirname of the ab...
Change default primary key in Eloquent
...d to make sure you set public $incrementing = false otherwise laravel will cast the field to an Integer, giving 0
class User extends Model {
protected $primaryKey = 'my_string_key';
public $incrementing = false;
}
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How to get Linux console window width in Python
...mns = os.popen('stty size', 'r').read().split()
uses the 'stty size' command which according to a thread on the python mailing list is reasonably universal on linux. It opens the 'stty size' command as a file, 'reads' from it, and uses a simple string split to separate the coordinates.
Unlike the...
How do I change the working directory in Python?
cd is the shell command to change the working directory.
14 Answers
14
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Correct way to write line to file?
...rifies my intent. Feel free to edit my answers if they are "rather useless and misleading".
– Johnsyweb
Dec 3 '14 at 9:57
1
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How to write log to file
...The safer permissions are 0644 or even 0664 to allow user read/write, user and group read/write, and in both cases disallow everyone write.
– Jonathan
Jun 10 '16 at 16:22
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How do you do a simple “chmod +x” from within python?
...e os.stat() to get the current permissions, use | to or the bits together, and use os.chmod() to set the updated permissions.
Example:
import os
import stat
st = os.stat('somefile')
os.chmod('somefile', st.st_mode | stat.S_IEXEC)
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How to know user has clicked “X” or the “Close” button?
...er X or your CloseButton, you may get it through the sender object. Try to cast sender as a Button control, and verify perhaps for its name "CloseButton", for instance.
private void Form1_FormClosing(object sender, FormClosingEventArgs e) {
if (string.Equals((sender as Button).Name, @"CloseButt...
How to set enum to null
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@equiman no need to cast since the type is specified on the left, you are basically duplicating the first part of my answer that is already accepted.
– Rodney S. Foley
Jul 8 '15 at 22:50
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