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What is the meaning of “… …” token? i.e. double ellipsis operator on parameter pack

...s paired with a case of a regular single ellipsis. template<typename _Res, typename... _ArgTypes> struct _Weak_result_type_impl<_Res(_ArgTypes...)> { typedef _Res result_type; }; template<typename _Res, typename... _ArgTypes> struct _Weak_result_type_impl<_Res(...
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what is the right way to treat Python argparse.Namespace() as a dictionary?

...store me' >>> args.baz 'store me' Yes, it is okay to access the __dict__ attribute. It is a well-defined, tested, and guaranteed behavior. share | improve this answer | ...
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sqlalchemy unique across multiple columns

... declares those in the table definition, or if using declarative as in the __table_args__: # version1: table definition mytable = Table('mytable', meta, # ... Column('customer_id', Integer, ForeignKey('customers.customer_id')), Column('location_code', Unicode(10)), UniqueConstraint...
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How to get the original value of an attribute in Rails

... Before rails 5.1 Appending _was to your attribute will give you the previous value. For rails 5.1+ Copied from Lucas Andrade's answer below: https://stackoverflow.com/a/50973808/9359123 Appending _was is deprecated in rails 5.1, now you should ap...
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how do you filter pandas dataframes by multiple columns

...r function using query in pandas. Here you have filtering of df results by all the kwargs parameters. Dont' forgot to add some validators(kwargs filtering) to get filter function for your own df. def filter(df, **kwargs): query_list = [] for key in kwargs.keys(): query_list.append(f...
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What's the need of array with zero elements?

... This is a way to have variable sizes of data, without having to call malloc (kmalloc in this case) twice. You would use it like this: struct bts_action *var = kmalloc(sizeof(*var) + extra, GFP_KERNEL); This used to be not standard and was considered a hack (as Aniket said), but it was s...
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Routes with Dash `-` Instead of Underscore `_` in Ruby on Rails

... there has to be a better and faster way to convert all routes that has undersore to hyphens – carbonr Mar 31 '13 at 17:59 ...
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How could I use requests in asyncio?

I want to do parallel http request tasks in asyncio , but I find that python-requests would block the event loop of asyncio . I've found aiohttp but it couldn't provide the service of http request using a http proxy. ...
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Bash empty array expansion with `set -u`

...ad. Other patterns, such as ${arr[@]-} or ${arr[@]:0}, are not safe across all major versions of Bash. As the table below shows, the only expansion that is reliable across all modern-ish Bash versions is ${arr[@]+"${arr[@]}"} (column +"). Of note, several other expansions fail in Bash 4.2, includin...
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how to bypass Access-Control-Allow-Origin?

I'm doing a ajax call to my own server on a platform which they set prevent these ajax calls (but I need it to fetch the data from my server to display retrieved data from my server's database). My ajax script is working , it can send the data over to my server's php script to allow it to process. H...