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Why does Python use 'magic methods'?
I've been playing around with Python recently, and one thing I'm finding a bit odd is the extensive use of 'magic methods', e.g. to make its length available, an object implements a method, def __len__(self) , and then it is called when you write len(obj) .
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Understand convertRect:toView:, convertRect:FromView:, convertPoint:toView: and convertPoint:fromVie
I'm trying to understand the functionalities of these methods. Could you provide me a simple usecase to understand theirs semantics?
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How to check if field is null or empty in MySQL?
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end as field1
from tablename
If you only want to check for null and not for empty strings then you can also use ifnull() or coalesce(field1, 'empty'). But that is not suitable for empty strings.
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How do I use grep to search the current directory for all files having the a string “hello” yet disp
How do I use grep to search the current directory for any and all files containing the string "hello" and display only .h and .cc files?
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CREATE TABLE IF NOT EXISTS equivalent in SQL Server [duplicate]
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if not exists (select * from sysobjects where name='cars' and xtype='U')
create table cars (
Name varchar(64) not null
)
go
The above will create a table called cars if the table does not already exist.
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Double negation (!!) in javascript - what is the purpose? [duplicate]
...good case for it after I posted that. When doing a return from a function and needing a boolean type to be returned and not the object itself, such as: return !!guess; I can see why the earlier usage is not totally necessary. (guess = !!option.guess)
– JoePC
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c++获取windows程序的版本号 - C/C++ - 清泛网 - 专注C/C++及内核技术
... // Get the version information size for allocate the buffer
DWORD dwHandle;
DWORD dwDataSize = ::GetFileVersionInfoSize((LPTSTR)lpszModuleName, &dwHandle);
if ( dwDataSize == 0 )
return FALSE;
// Allocate buffer and retrieve version information
LPBYTE lpVersion...
How to delete a workspace in Perforce (using p4v)?
I'm new to Perforce and have created a few workspaces as exercises for getting familiar with it. Now I would like to delete some of the workspaces. I just want to get rid of the workspaces so that they do not appear on the drop-down in the workspaces view ( do not want to do anything with actual de...
Java 8 NullPointerException in Collectors.toMap
...ws a NullPointerException if one of the values is 'null'. I don't understand this behaviour, maps can contain null pointers as value without any problems. Is there a good reason why values cannot be null for Collectors.toMap ?
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How to map atan2() to degrees 0-360
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For those not comfortable with this notation, and without the conversion to degrees built in: if(x>0) {radians = x;} else {radians = 2*PI + x;} so we are just adding 2PI to the result if it is less than 0.
– David Doria
Sep 25 '1...