set_pattern() for different loggers with the same sink

[amirych]

I'm a little confused with this:

#include <spdlog/sinks/basic_file_sink.h>

int main() {
    auto sharedFileSink = std::make_shared<spdlog::sinks::basic_file_sink_mt>("fileName.txt");

    auto firstLogger = std::make_shared<spdlog::logger>("firstLoggerName", sharedFileSink);
    auto secondLogger = std::make_unique<spdlog::logger>("secondLoggerName", sharedFileSink);

    firstLogger->set_pattern("[1] %v");
    secondLogger->set_pattern("[2] %v");


    firstLogger->info("msg1");
    secondLogger->info("msg2");

    return 0;
}

fileName.txt content is:

[2] msg1
[2] msg2

I supposed format pattern setting in one logger should not change one in other, even if loggers share the same sink.
Am I mistaken?

[tt4g]

The formatter is an attribute of the sink, not the logger.

spdlog::logger::set_pattern is a short hand to set the formatter for each sink in the logger.

spdlog/include/spdlog/logger-inl.h

Lines 82 to 105 in 100f300

	// set formatting for the sinks in this logger.
	// each sink will get a separate instance of the formatter object.
	SPDLOG_INLINE void logger::set_formatter(std::unique_ptr<formatter> f)
	{
	for (auto it = sinks_.begin(); it != sinks_.end(); ++it)
	{
	if (std::next(it) == sinks_.end())
	{
	// last element - we can be move it.
	(*it)->set_formatter(std::move(f));
	break; // to prevent clang-tidy warning
	}
	else
	{
	(*it)->set_formatter(f->clone());
	}
	}
	}
	SPDLOG_INLINE void logger::set_pattern(std::string pattern, pattern_time_type time_type)
	{
	auto new_formatter = details::make_unique<pattern_formatter>(std::move(pattern), time_type);
	set_formatter(std::move(new_formatter));
	}

[amirych]

Ok, now I see