Remove std::bind from examples #8891
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/rebuild |
examples/step-13/step-13.cc
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| AssemblyCopyData & copy_data) { | ||
| this->local_assemble_matrix(cell, scratch_data, copy_data); | ||
| }, | ||
| [this, &linear_system](const AssemblyCopyData ©_data) { |
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Since this is in a tutorial program where simplicity is a concern, what would you think about omitting the explicit captures here?
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I don't feel that listing the captures is a big issue, but I find it a lot more readable if you move the definition of the lambda above the function call and give it a descriptive name.
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My reasoning for the explicit capture list would be that we make it as clear as possible what the lambda is really doing (and which variables it is using).
I don't have a strong opinion here, though. If someone strongly prefers one variant I am happy to change all of them in the examples.
I think that we should discuss both variants here in any way.
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Also see http://open-std.org/JTC1/SC22/WG21/docs/papers/2018/p0806r2.html and https://en.cppreference.com/w/cpp/language/lambda:
The implicit capture of *this when the capture default is = is deprecated. (since C++20).
examples/step-14/step-14.cc
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| AssemblyCopyData & copy_data) { | ||
| this->local_assemble_matrix(cell, scratch_data, copy_data); | ||
| }, | ||
| [this, &linear_system](const AssemblyCopyData ©_data) { |
examples/step-14/step-14.cc
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| std::ref(face_integrals)), | ||
| [this, | ||
| &error_indicators, | ||
| &face_integrals](const active_cell_iterator & cell, |
| Assembly::CopyData::StokesPreconditioner<dim> & data) { | ||
| this->local_assemble_stokes_preconditioner(cell, scratch, data); | ||
| }, | ||
| [this](const Assembly::CopyData::StokesPreconditioner<dim> &data) { |
examples/step-32/step-32.cc
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| &BoussinesqFlowProblem<dim>::copy_local_to_global_temperature_rhs, | ||
| this, | ||
| std::placeholders::_1), | ||
| [this, global_T_range, maximal_velocity, global_entropy_variation]( |
Co-Authored-By: Wolfgang Bangerth <bangerth@colostate.edu>
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Please make the minor changes and merge yourself.
I think my question about how explicit we want to be with the capture comes from the feeling that most of our users will only ever have seen lambdas that start with [] and simply capture everything. I suspect that a capture list isn't in their vocabulary, and it's not like the syntax of lambda functions isn't already complicated enough...
examples/step-51/step-51.cc
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| unsigned int & data) { | ||
| this->postprocess_one_cell(cell, scratch, data); | ||
| }, | ||
| [](const unsigned int &) {}, |
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On second thought, this is a severe degradation here. WorkStream::run checks whether the copied is an empty function object std::function<void(const unsigned int &)>() and uses a far more efficient algorithm in that case. An empty lambda function is not the same as the empty function argument.
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Same issue here as before: you really do want the do_nothing_copier here.
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Hmm... yes, we need to document this (internal) peculiarity.
Co-Authored-By: Wolfgang Bangerth <bangerth@colostate.edu>
Co-Authored-By: Wolfgang Bangerth <bangerth@colostate.edu>
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@bangerth Would you mind approving this "officially" since you already gave your consent in the comments? Pull request authors can't approve their own pull requests. |
This pull request removes all the uses of
std::bindfrom the examples. I am happy for suggestions for improving the documentation. Currently, I am removing all occurences ofstd::bindalso in the documentation for the examples but would also be fine to mention it as long as we encourage using lambdas.