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I have a function getTotal:
int getTotal( const HitMap& hitMap, bool( *accept)(int chan) )
where the second argument is a bool function specifying which members of the container hitMap should be added to the total.
I'm trying to call it with a lambda. This works:
auto boxresult =
getTotal(piHits, [](int pmt)->bool
{ return (pmt/100) == 1;} );
but this doesn't:
int sector = 100;
auto boxresult =
getTotal(piHits, [sector](int pmt)->bool
{ return (pmt/sector) == 1;} );
I get the error
cannot convert ‘main(int, char**)::<lambda(int)>’ to ‘bool (*)(int)’
for argument ‘2’ to ‘int getTotal(const HitMap&, bool (*)(int))’
from my compiler (GCC 4.6.3). I tried [§or] and [=sector] but it didn't make any difference.
What am I doing wrong?
356
When editing a lambda function, you can go Actions > Export Function > Download deployment package. This downloads a . zip file of the function. This duplicates the code and npm modules etc...
A lambda is a syntax for creating a class. Capturing a variable means that variable is passed to the constructor for that class. A lambda can specify whether it's passed by reference or by value.
If you want to stop future invocations a simple way to do this is by removing the related permission from the IAM role associated with your Lambda. You can find a link to the IAM role in the permissions tab of the Lambda.
But a lambda cannot be recursive, it has no way to invoke itself. A lambda has no name and using this within the body of a lambda refers to a captured this (assuming the lambda is created in the body of a member function, otherwise it is an error).
When a lambda has a capture clause it can no longer be treated as a function pointer. To correct, use std::function<bool(int)> as the argument type for getTotal():
int getTotal( const HitMap& hitMap, std::function<bool(int)> accept)
The lambda function with capturing is not what you expect, you can use these ways:
template <typename F>
int getTotal( const HitMap& hitMap, F accept )
{
}
or
int getTotal( const HitMap& hitMap, std::function<bool(int)> accept )
{
}
The template based getTotal has better performance. Read more.
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