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Difference between std::result_of and decltype
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result_of was introduced in Boost, and then included in TR1, and finally in C++0x. Therefore result_of has an advantage that is backward-compatible (with a suitable library).
decltype is an entirely new thing in C++0x, does not restrict only to return type of a function, and is a language fe...
When is “i += x” different from “i = i + x” in Python?
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This depends entirely on the object i.
+= calls the __iadd__ method (if it exists -- falling back on __add__ if it doesn't exist) whereas + calls the __add__ method1 or the __radd__ method in a few cases2.
From an API perspective, __iadd__ is supposed to be used fo...
Are there any free Xml Diff/Merge tools available? [closed]
...e line returns in convenient locations.
See also my feature comparison table.
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What does it mean to “program to an interface”?
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Using interfaces is a key factor in making your code easily testable in addition to removing unnecessary couplings between your classes. By creating an interface that defines the operations on your class, you allow classes that want to use that functionality the ability to use it withou...
How to run code when a class is subclassed? [duplicate]
...- Watcher subclasses type, not object. 2 - SuperClass has no superclass at all, not object. I'm just so used to writing down object as a superclass for every class I defined that I somehow missed it that this code was using something else. Although there doesn't seem to be any harm in making SuperCl...
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...
What's the common practice for enums in Python? [duplicate]
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@Joan You could do _unused, Shaded, Shiny, Transparent, Matte = range(5)
– zekel
Dec 9 '10 at 2:12
81
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Oracle TNS names not showing when adding new connection to SQL Developer
...cognized, use the following procedure:
Define an environmental variable called TNS_ADMIN to point to the folder that contains your tnsnames.ora file.
In Windows, this is done by navigating to Control Panel > System > Advanced system settings > Environment Variables...
In Linux, define...
How can I get the current network interface throughput statistics on Linux/UNIX? [closed]
...$dev/statistics";
my %stats = do {
opendir +(my $dh), $dir;
local @_ = readdir $dh;
closedir $dh;
map +($_, []), grep !/^\.\.?$/, @_;
};
if (-t STDOUT) {
while (1) {
print "\033[H\033[J", run();
my ($time, $us) = gettimeofday();
my ($sec, $min, $hour) = l...
Select between two dates with Django
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Use the __range operator:
...filter(current_issue__isnull=True, created_at__range=(start_date, end_date))
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