C++ - lambda expression, capture clause and class members
c++, lambda, parallel-processing, ppl
Solution
You need to capture `this` to access the member variables (remember that `formulaCommand` is equivalent to `this->formulaCommand`).
[&functionEvaluation, varModel_, this](int i) { ... }
(BTW, you should probably use a smart pointer (`unique_ptr<MLEquationCommand>`) instead of manually `delete`-ing the raw pointer `command_`.)
Problem
I am using PPL and parallel_for syntax to have a for loop. In the capture clause, I have 3 variables, one of them is a class member. There is a compilation error due to the presence of a class member among variables in the capture clause. However, if I have this class member in lambda body, it does not compile either, and error stated is that variable in enclosing scope should be in capture clause. How to proceed? Should I copy the variable member to a local variable beforehand, and have it passed in the capture clause? Here is the code, with formulaCommand the class member. ``` parallel_for (m_rowStart,m_rowEnd+1,[&functionEvaluation,varModel_,formulaCommand](int i) { MLEquationVariableModel model_(varModel_); model_.addVariable("i", i); model_.addVariable("j", 1); MLEquationCommand* command_ = formulaCommand->duplicate(&model_); double d = command_->execute().toDouble(); if(d==NO_VALUE) { functionEvaluation.local() = NO_VALUE; } else { functionEvaluation.local() += d; } delete command_; }); ``` Thanks!