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How do I declare class-level properties in Objective-C?

...mething that's equivalent to a static variable? E.g. only one instance for all types of Foo? To declare class functions in Objective-C you use the + prefix instead of - so your implementation would look something like: // Foo.h @interface Foo { } + (NSDictionary *)dictionary; // Foo.m + (NSDicti...
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How to do parallel programming in Python?

For C++, we can use OpenMP to do parallel programming; however, OpenMP will not work for Python. What should I do if I want to parallel some parts of my python program? ...
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Using OR in SQLAlchemy

... From the tutorial: from sqlalchemy import or_ filter(or_(User.name == 'ed', User.name == 'wendy')) share | improve this answer | follow ...
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phpcms v9类别调用方法 - 更多技术 - 清泛网 - 专注C/C++及内核技术

...前面加一句把类别缓存加载进来: <?php $TYPE = getcache('type_content','commons');?> 然后在循环里写: <a href="index.php?m=content&c=type&catid={$catid}&typeid={$r[typeid]}">{$TYPE[$r[typeid]][name]}</a> 这样就可以调用出来类别了,不过链接暂时无效,因...
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Using the rJava package on Win7 64 bit with R

I'm trying to install rJava on a computer with Win 7 64 bit. When I run 12 Answers 1...
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How to read a large file - line by line?

... The for line in f treats the file object f as an iterable, which automatically uses buffered I/O and memory management so you don't have to worry about large files. There should be one -- and preferably only one -- obvious way to do it. ...
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Impossible to Install PG gem on my mac with Mavericks

I'm trying to install the pg gem in order to work again with my rails projects. But I get this error: 26 Answers ...
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xtree(1796): warning C4800: “int”: 将值强制为布尔值“true”或“false...

...e\xtree(1775): 参见对正在编译的函数 模板 实例化“std::pair<_Ty1,_Ty2> std::_Tree<_Traits>::_Insert_nohint<std::pair<const _Kty,_Ty>&,_Nodety>(bool,_Valty,_Nodety)”的引用 1> with 1> [ 1> _Ty1=std::_Tree_iterator<std::_Tree_val<std::_Tree_simple_t...
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Understanding Apache's access log

...the client IP) %l is the identity of the user determined by identd (not usually used since not reliable) %u is the user name determined by HTTP authentication %t is the time the request was received. %r is the request line from the client. ("GET / HTTP/1.0") %&gt;s is the status code sent from the s...
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MySQL: What's the difference between float and double?

...00002 | 1.6900000000 | This is using MySQL 6.7 Query: SELECT float_1 + float_2 as 'float add', double_1 + double_2 as 'double add', decimal_1 + decimal_2 as 'decimal add', float_1 * float_2 as 'float multiply', double_1 * double_2 as 'double multiply', decimal_1 * decim...