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ThorsLogging API

Leveled logging macros for C++ with optional exception throwing. Wraps loguru in full builds or falls back to std::cerr in header-only mode.

Namespace: ThorsAnvil::Logging

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Header

#include "ThorsLogging/ThorsLogging.h"

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Log-Only Macros

Log a message at a specified verbosity level. These do not throw exceptions.

ThorsLogFatal(Scope, Function, ...)
ThorsLogError(Scope, Function, ...)
ThorsLogWarning(Scope, Function, ...)
ThorsLogInfo(Scope, Function, ...)
ThorsLogDebug(Scope, Function, ...)

Parameters:

Parameter	Description
Scope	Class or module name (string literal)
Function	Function name (string literal)
...	One or more streamable values, concatenated into the message

Example:

void MyClass::doWork(int id)
{
    ThorsLogInfo("MyClass", "doWork", "Processing item: ", id);
    ThorsLogDebug("MyClass", "doWork", "Finished processing item: ", id);
}

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Log-and-Throw Macros

Log a message and throw an exception of the specified type:

ThorsLogAndThrowFatal(ExceptionType, Scope, Function, ...)
ThorsLogAndThrowError(ExceptionType, Scope, Function, ...)
ThorsLogAndThrowWarning(ExceptionType, Scope, Function, ...)
ThorsLogAndThrowInfo(ExceptionType, Scope, Function, ...)

Example:

void MyClass::open(std::string const& path)
{
    if (!fileExists(path)) {
        ThorsLogAndThrowError(std::runtime_error, "MyClass", "open",
                              "File not found: ", path);
    }
}

The exception is constructed from the formatted message string. Any exception type constructible from std::string works.

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Verbosity Levels

Level	Numeric	Description
FATAL	-3	Unrecoverable error; application terminates
ERROR	-2	Serious error requiring attention
WARNING	-1	Potential problem
INFO	0	Normal operational messages
(debug)	3	Detailed diagnostics

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Verbosity Control

// Set verbosity level
ThorsLogLevel(WARNING);           // Only FATAL, ERROR, WARNING will print

// Save and restore
int prev = ThorsLogLevelGet();
ThorsLogLevelSet(9);              // Enable all messages
// ... verbose section ...
ThorsLogLevelSet(prev);           // Restore

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Temporary Verbosity (RAII)

ThorsLogTemp temporarily changes the verbosity for the duration of a scope:

void diagnose()
{
    ThorsLogTemp verbose(9);  // max verbosity
    ThorsLogAll("Diagnostics", "diagnose", "Starting full diagnostic...");
    // ... detailed logging throughout ...
}   // previous verbosity restored here

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Catch/Rethrow Helpers

try {
    riskyOperation();
}
catch (std::exception const& e) {
    ThorsCatchMessage("MyClass", "run", e.what());
    // handle...
}

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Build Modes

Mode	Define	Backend
Linked	THORS_LOGGING_HEADER_ONLY=0 (default)	loguru (full features)
Header-only	THORS_LOGGING_HEADER_ONLY=1	std::cerr (no link dependency)

In header-only mode, THOR_LOGGING_DEFAULT_LOG_LEVEL (default: 3) controls the compile-time verbosity ceiling.

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Complete Example

Makefile

CXXFLAGS    = -std=c++20

LDLIBS      = -lThorsLogging

all:        ThorsLogApp

ThorsLogApp.cpp

#include "ThorsLogging/ThorsLogging.h"
#include <stdexcept>

class NetworkClient
{
    // Example fail
    bool doConnect(std::string const& host, int port) {
        return false;
    }
public:
    void connect(std::string const& host, int port)
    {
        ThorsLogInfo("NetworkClient", "connect",
                     "Connecting to ", host, ":", port);

        if (!doConnect(host, port)) {
            ThorsLogAndThrowError(std::runtime_error,
                                  "NetworkClient", "connect",
                                  "Failed to connect to ", host, ":", port);
        }

        ThorsLogDebug("NetworkClient", "connect", "Connection established");
    }
};

int main()
{
    ThorsLogLevel(INFO);  // show INFO and above

    NetworkClient client;
    try {
        client.connect("example.com", 8080);
    }
    catch (std::exception const& e) {
        ThorsCatchMessage("main", "main", e.what());
    }
}

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