void
addedPrefixFunc(
const fcf::NTest::Loger::PrefixFunctionType& a_prefix)
Class: fcf::NTest::Logger
Package: fcfTest
File: test.hpp
Available from version: 1.0.1
Adds a dynamic functional prefix to all subsequent log messages, allowing for real-time data injection such as timestamps or thread IDs
The addedPrefixFunc method allows you to attach a callback function that generates a prefix for every log entry. Unlike static strings, this functional prefix is evaluated at the moment the log message is written, making it ideal for dynamic metadata.
The callback receives a reference to the fcf::NTest::Logger instance and the current fcf::NTest::ELogLevel, allowing the prefix to change based on the severity of the message.
Arguments
const fcf::NTest::Loger::PrefixFunctionType& a_prefix
- A std::function with the signature std::string(fcf::NTest::Logger&, fcf::NTest::ELogLevel)
Example: Adding dynamic timestamps
The most common use case is prefixing logs with a human-readable timestamp
#include <ctime>
#include <iomanip>
#include <sstream>
#define FCF_TEST_IMPLEMENTATION
#include <fcfTest/test.hpp>
int main(int a_argc, char* a_argv[]) {
fcf::NTest::logger().addedPrefixFunc([](fcf::NTest::Logger& a_logger, fcf::NTest::ELogLevel a_level) {
auto time = std::time(nullptr);
return (std::stringstream()
<< "[" << std::put_time(std::localtime(&time), "%H:%M:%S") << "] "
<< "[" << a_logger.toLevelStr(a_level) << "] "
).str();
});
fcf::NTest::log() << "System started." << std::endl;
return 0;
}
Output:
[14:30:05] [inf] System started.
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