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Python None comparison: should I use “is” or ==?
... when you want to check against an object's identity (e.g. checking to see if var is None). Use == when you want to check equality (e.g. Is var equal to 3?).
Explanation:
You can have custom classes where my_var == None will return True
e.g:
class Negator(object):
def __eq__(self,other):
...
Remove local git tags that are no longer on the remote repository
... This must be my favourite git answer on StackOverflow. It combines knowledge, simplicity and trickery an explains everything. Great
– tymtam
Nov 30 '11 at 8:12
26
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Hidden features of Ruby
Continuing the "Hidden features of ..." meme, let's share the lesser-known but useful features of Ruby programming language.
...
How can Perl's print add a newline by default?
...
The real danger comes from the fact that all code will now add newlines, even code in other people's modules that weren't expecting it. Imagine networking code that would have sent the message "helo\r\n" that now sends "helo\r\n\n".
– Chas. Owens
...
How do you round a floating point number in Perl?
... can have serious implications, and
the rounding method used should be specified precisely. In these
cases, it probably pays not to trust whichever system rounding is being
used by Perl, but to instead implement the rounding function you need
yourself.
To see why, notice how you'll still have an i...
No internet on Android emulator - why and how to fix? [closed]
...ator command line solved the issue for me. Android had no internet before, now it has. Running on Win10. I'm puzzled why that command line argument was necessary though?
– mipnw
Apr 1 '18 at 3:18
...
✔ Checkmark selected row in UITableViewCell
...
What if I want only the checkmark and want to deselect the row after a selection?
– gyozo kudor
Jan 8 '15 at 8:59
...
Remove a string from the beginning of a string
... form, without regex:
$prefix = 'bla_';
$str = 'bla_string_bla_bla_bla';
if (substr($str, 0, strlen($prefix)) == $prefix) {
$str = substr($str, strlen($prefix));
}
Takes: 0.0369 ms (0.000,036,954 seconds)
And with:
$prefix = 'bla_';
$str = 'bla_string_bla_bla_bla';
$str = preg_replace('/^...
不同品牌的防火墙组成高可靠性集群 - 更多技术 - 清泛网 - 专注C/C++及内核技术
... 100
icmp-echo 172.16.110.80
ip sla schedule 100 life forever start-time now
ip sla 110
icmp-echo 172.16.100.50
ip sla schedule 110 life forever start-time now
track 100 rtr 100 reachability
track 110 rtr 110 reachability
route add 172.16.100.0 255.255.255.0 172.16.110.253 10 track ...
How to get a cross-origin resource sharing (CORS) post request working
...llow the response to continue. You need to ensure the response header specifically includes the required headers. ie:
Access-Control-Allow-Headers: x-requested-with
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