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If table exists drop table then create it, if it does not exist just create it

...e and swap it with an old one (table contents are lost): CREATE TABLE `bla__new` (id int); /* if not ok: terminate, report error */ RENAME TABLE `bla__new` to `bla`; /* if ok: terminate, report success */ RENAME TABLE `bla` to `bla__old`, `bla__new` to `bla`; DROP TABLE IF EXISTS `bla__old`; You...
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Hash Map in Python

...anged easily. Rehashing is out of scope of this code. class Node: def __init__(self, key, value): self.key = key self.value = value self.next = None class HashMap: def __init__(self): self.store = [None for _ in range(16)] def get(self, key): ind...
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Why does GCC generate 15-20% faster code if I optimize for size instead of speed?

...ssembly from gcc-4.6.4 -Os (executes in 0.709 secs): 00000000004004d2 <_ZL3addRKiS0_.isra.0>: 4004d2: 8d 04 37 lea eax,[rdi+rsi*1] 4004d5: c3 ret 00000000004004d6 <_ZL4workii>: 4004d6: 41 55 push r13 4...
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Should import statements always be at the top of a module?

...ent libraries, don't break if an optional library is not installed. In the __init__.py of a plugin, which might be imported but not actually used. Examples are Bazaar plugins, which use bzrlib's lazy-loading framework. shar...
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Use of #pragma in C

... == 7 Here's how you'd do the same thing in GCC: struct PackedStructure __attribute__((__packed__)) { char a; int b; short c; }; // sizeof(PackedStructure == 7) The GCC code is more portable, because if you want to compile that with a non-GCC compiler, all you have to do is #define __att...
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Which is more preferable to use: lambda functions or nested functions ('def')?

...orted(['a1', 'b0'], key= lambda x: int(x[1])) – Chris_Rands Apr 9 '18 at 12:09 add a comment  |  ...
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【解决】scrapyd启动job时报错:exceptions.TypeError: __init__() got an ...

【解决】scrapyd启动job时报错:exceptions.TypeError: __init__() got an unexpected keyword argument '_job'进入项目spiders目录, 修改 spider py 文件(你自己的spider的主文件):def __init__(self):改为:def __init__(self, *args, **kwargs):最后不要忘了重新部署一...
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Is inject the same thing as reduce in ruby?

... If you want to create your own aliases, you may be interested in alias_method. – Nick McCurdy Oct 25 '13 at 2:16 ...
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Get $_POST from multiple checkboxes

... Set the name in the form to check_list[] and you will be able to access all the checkboxes as an array($_POST['check_list'][]). Here's a little sample as requested: <form action="test.php" method="post"> <input type="checkbox" name="check_list...
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Method Resolution Order (MRO) in new-style classes?

...gt; D.x 'c' >>> here, new-style, the order is: >>> D.__mro__ (<class '__main__.D'>, <class '__main__.B'>, <class '__main__.C'>, <class '__main__.A'>, <type 'object'>) with A forced to come in resolution order only once and after all of its s...