Standardize approach for passing string parameters in VTK and Qt classes

[jcfr]

Is your feature request related to a problem? Please describe.

The function parameters of type std::string and QString are not consistently passed, this leads to inconsistent API and related discussions¹

To both spare review cycles and also improve the developer experiences, we should develop guidelines suggestion which approach should be used.

This will also be helpful when refactoring existing one that has been using char* parameters.

In a nutshell:

void doSomething(std::string parameter);
void doSomething(QString parameter);

vs

void doSomething(const std::string& parameter);
void doSomething(const QString& parameter);

Describe the solution you'd like

Use of const references

Consistently using const std::string& parameter and const QString& parameter

In addition of avoiding unnecessary copy, it also indicates that the uidName parameter will not be modified within the function.

Use of pass by value with std::move

• https://clang.llvm.org/extra/clang-tidy/checks/modernize/pass-by-value.html
• https://stackoverflow.com/questions/10789740/passing-stdstring-by-value-or-reference

Describe alternatives you've considered

Additional context

Use of std::string vs const std::string&

As of 5e831bc, the use of std::string vs const std::string& is distributed ...

$ ack --headers "\(.+std::string \w+" --no-filename | wc -l
108

$ ack --headers "const std::string\& \w+" --no-filename | wc -l
199

Use of QString vs const QString&

As of 5e831bc, the use of const QString& is dominant:

$ ack --headers "\(.+QString \w+" --no-filename | wc -l
47

$ ack --headers "const QString\& \w+" --no-filename | wc -l
491

Footnotes

1. https://github.com/Slicer/Slicer/pull/7616#discussion_r1510816301 ↩