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How does @synchronized lock/unlock in Objective-C?
Does @synchronized not use "lock" and "unlock" to achieve mutual exclusion? How does it do lock/unlock then?
5 Answers
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What is the preferred syntax for initializing a dict: curly brace literals {} or the dict() function
...on't work:
a = dict(import='trade', 1=7.8)
>> SyntaxError: invalid syntax ^
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Array.sort() doesn't sort numbers correctly [duplicate]
In Chrome 14, and Firefox 5 (haven't tested other browsers), the following code doesn't sort the numbers correctly:
5 Answe...
Delete the first three rows of a dataframe in pandas
...o this in a groupby()? This works but returns duplicate columns in the index df=pd.DataFrame({'v':np.arange(10).tolist()*2,'g':['a']*10+['b']*10});df.groupby('g').apply(lambda x: x.iloc[3:])
– citynorman
Aug 6 '17 at 22:24
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How to sum all the values in a dictionary?
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As you'd expect:
sum(d.values())
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Most efficient way to check for DBNull and then assign to a variable?
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I must be missing something. Isn't checking for DBNull exactly what the DataRow.IsNull method does?
I've been using the following two extension methods:
public static T? GetValue<T>(this DataRow row, string columnName) where T : struct
{
if (row.IsNull(columnName))
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Is there any difference between “!=” and “” in Oracle Sql?
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!= is easier to store in an XML file!
– Mark McLaren
Jul 19 '17 at 7:02
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Difference between core and processor
...y the basic computation unit of the CPU - it can run a single program context (or multiple ones if it supports hardware threads such as hyperthreading on Intel CPUs), maintaining the correct program state, registers, and correct execution order, and performing the operations through ALUs. For optimi...
How do I download a tarball from GitHub using cURL?
...ects:
curl -L https://github.com/pinard/Pymacs/tarball/v0.24-beta2 | tar zx
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Jinja2 template variable if None Object set a default value
...do:
{{ p|default('', true) }}
Cause None casts to False in boolean context.
Update: As lindes mentioned, it works only for simple data types.
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