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Why can templates only be implemented in the header file?
...f;
When reading this line, the compiler will create a new class (let's call it FooInt), which is equivalent to the following:
struct FooInt
{
int bar;
void doSomething(int param) {/* do stuff using int */}
}
Consequently, the compiler needs to have access to the implementation of the m...
Changing a specific column name in pandas DataFrame
...
A one liner does exist:
In [27]: df=df.rename(columns = {'two':'new_name'})
In [28]: df
Out[28]:
one three new_name
0 1 a 9
1 2 b 8
2 3 c 7
3 4 d 6
4 5 e 5
Following is the docstring for the rename method.
De...
How do I get the information from a meta tag with JavaScript?
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What you really want is 'let' to keep them locally defined ;)
– tommed
Mar 23 '15 at 21:54
26
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I need to generate uuid for my rails application. What are the options(gems) I have? [duplicate]
...to be in Ruby 1.8.7. Looks like it was added in 1.9.3: apidock.com/ruby/v1_9_3_392/SecureRandom/uuid/class
– existentialmutt
Aug 25 '14 at 17:31
2
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What are C++ functors and their uses?
...42); // create an instance of the functor class
int i = add42(8); // and "call" it
assert(i == 50); // and it added 42 to its argument
std::vector<int> in; // assume this contains a bunch of values)
std::vector<int> out(in.size());
// Pass a functor to std::transform, which calls the fu...
Ruby: How to turn a hash into HTTP parameters?
...uery
# => "a=a&b[c]=c&b[d]"
The gem is 'addressable'
gem install addressable
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Python set to list
...k that you didn't overwrite list by accident:
>>> assert list == __builtins__.list
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How to get the concrete class name as a string? [duplicate]
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instance.__class__.__name__
example:
>>> class A():
pass
>>> a = A()
>>> a.__class__.__name__
'A'
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Determine if Android app is being used for the first time
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Beware for Android 6.0 (API 23 - Marshmallow) or above auto backup (developer.android.com/guide/topics/data/autobackup.html)is enabled by default. If the users uninstalls and then reinstalls the app the shared preferences will be recovered. So on reinstalls you ca...
How do I execute a command and get the output of the command within C++ using POSIX?
...use the C stdio API, I prefer the iostreams API. popen requires you to manually clean up the FILE handle, pstreams do that automatically. popen only accepts a const char* for the argument, which requires care to avoid shell injection attacks, pstreams allows you to pass a vector of strings similar t...