Add const to params for non-mutating functions

[andreas-bok-sociomantic]

Adds const qualifier to POD params which are not mutated by the function.

Since it is (possibly) a breaking change for clients it is added to the milestone for the next major release

[bokchan]

const was added to all parameters which weren't mutated in the function. However as you note it might be redundant for the arguments passed by value.

[bokchan]

Seems there isn't a general agreement on whether to pass primitive types by const. It is recommended not to pass such as const ref, e.g. (const int &i).

• https://lefticus.gitbooks.io/cpp-best-practices/content/04-Considering_Safety.html
• https://stackoverflow.com/questions/117293/use-of-const-for-function-parameters

Thus using const in cases here doesn't make much difference wrt. efficiency but does provide the clarity in the API that the function won't mutate the argument.

[bokchan]

Updated based on comments from @daniel-zullo-sociomantic

[bokchan]

Documentation needs to be updated

[andreas-bok-sociomantic]

Updated rst documentation

[ben-palmer-sociomantic]

The Use relnotes folder to describe new features commit seems unrelated to this PR. It could easily be merged on its own.

[bokchan]

The Use relnotes folder to describe new features commit seems unrelated to this PR. It could easily be merged on its own.

Hmm true. v7.x.x is behind v6.x.x but somehow I managed to get the commit with the relnotes folder onto it 🤦‍♂️ . I will block this until v6.2.0 has been released and v6.x.x has been merged into v7.x.x

[codecov-io]

Codecov Report

Merging #326 into v7.x.x will not change coverage. The diff coverage is 44.92%.