you are pulling 'std::variant' into the global namespace (bad idea)

[Peter Ritter]

Hi

I have been struggling with some compiler errors involving 'variant'. I have my own 'variant' class in my library and it seemed to be clashing when I pulled in the tabulate header. I had a look and found this in tabulate.hpp:

#if __cplusplus >= 201703L
#include <string_view>
#include
using std::get_if;
using std::holds_alternative;
using std::string_view;
using std::variant;
using std::visit;

This is not a good practice to pull names from the standard library into the global namespace! Every library that uses tabulate will now have these names in the global namespace too.

I also found std::optional used this way.

I have manually gone and commented out all such using statements and added std:: prefix everywhere where they were used. It is not a lot of places - so it seems an easy fix!

Best Regards, P.

[Pranav]

Hi,

Thanks for the report. Would you be open to creating a PR? I agree with your comments here.

Regards,
Pranav

[Peter Ritter]

Hi,
I fixed it for myself in the 'single_include/tabulate.hpp' which is what I am using. I don't know what it looks like in the rest of the library. There may be other places that need fixing too in the non-amalgamated files. I also don't know what the interaction is with the 'nonstd' namespace - if that would create issues with that? I really just uncommented these and equivalent lines:

#if __cplusplus >= 201703L
#include <string_view>
#include
//using std::get_if;
//using std::holds_alternative;
//using std::string_view;
//using std::variant;
//using std::visit;
#else
// #include <tabulate/string_view_lite.hpp>
// #include <tabulate/variant_lite.hpp>
using nonstd::get_if;
using nonstd::holds_alternative;
using nonstd::string_view;
using nonstd::variant;
using nonstd::visit;
#endif

...and then added the 'std::' prefix where required.
Regards, Peter

PS: In practice, I realized that when populating large tables, it is not really practical to then iterate over the table again to set formating. It's really at the time of appending a cell to a row, that I would like to define the formating of the cell, as it is at that point that I know what the value type is. I tried quite hard to try to figure out how to format the cells in a row before appending a table. But i didn't quite manage to figure out how. If you ever get around to it that would be a good way to enhance the library.