#include <_Log_.h>

#include <_Log_.h>

void Example() {
    _Log_("A great number is: {}", 42);
}

What?

A simple logging interface for C++ libraries.

Installation

xmake

xmake.lua

add_repositories("MrowrLib https://github.com/MrowrLib/Packages.git")
add_requires("_Log_")

-- And if you want to use spdlog for log output
add_requires("spdlog")

target("Example")
    add_packages("_Log_")
    add_packages("spdlog") -- if using 'spdlog'

vcpkg

CMakeLists.txt

add_executable(Example main.cpp)

# Find _Log_ and link it to your target
find_package(_Log_ CONFIG REQUIRED)
target_link_libraries(Example PRIVATE _Log_::_Log_)

# Also find and link spdlog, if you plan on using it
find_package(spdlog CONFIG REQUIRED)
target_link_libraries(Example PRIVATE spdlog::spdlog)

vcpkg.json

{
    "dependencies": ["mrowr-log"]
}

And if you want to use spdlog:

{
    "dependencies": ["mrowr-log", "spdlog"]
}

vcpkg-configuration.json

{
    "default-registry": {
        "kind": "git",
        "repository": "https://github.com/microsoft/vcpkg.git",
        "baseline": "95252eadd63118201b0d0df0b4360fa613f0de84"
    },
    "registries": [
        {
            "kind": "git",
            "repository": "https://github.com/MrowrLib/Packages.git",
            "baseline": "eab80da25303df9f93918b1d1cf65d25a1119718",
            "packages": ["mrowr-log"]
        }
    ]
}

Update the default-registry baseline to the latest commit from https://github.com/microsoft/vcpkg
Update the MrowrLib/Packages baseline to the latest commit from https://github.com/MrowrLib/Packages

Why?

I want my libraries to all support logging.

But I want folks to be able to BYOL: Bring Your Own Logger.

Want to use spdlog? Great!

This will automatically detect spdlog and use it.

By default, however, it will do nothing.

Naming?

Searching across GitHub, there are many libraries which...

• #include <_Log_.h> or #include <Log.h>
• Have a Logging or Log class or namespace
• Have a Log or LOG or _log_ or _LOG_ function or macro

Because almost all of my libraries use this library, I wanted to make sure that this library's names were very, very unlikely to conflict with other libraries.

Hence #include <_Log_.h> and _Log_ / _LogToFile_.

I couldn't find anyone using _Log_ (camel case) across GitHub.

You can safely use this in your own libraries.

I also don't like to "sign" my own work, so I didn't want something like <Mrowr/Logging.h>

Log Levels?

Meh.

Use your own logger if you want log levels.

I really wanted one simple _Log_ macro that would work for all libraries.

Update: I eventually added log levels 😹

If you #include <_Log_/_Log_.h> then you only get _Log_ (defaults to info)

If you #include <_Log_/_Debug_.h> then you get _Debug_ (and so on...)

If you #include <_Log_.h> then you get all of the log levels.

To change the default log level for _Log_:

#include <_Log_/LogLevels/warn.h> // Must be BEFORE the Log includes

// Then...
#include <_Log_.h>

// Or...
#include <_Log_/_Fatal_.h> // etc...

How?

I simplified it all down to a simple macros:

#include <_Log_.h>

// Log a message
_Log_("A great number is: {}", 42);

// Set a target filename for the log
_LogToFile_("my.log"); // (Optional)

// Change the log level
_SetLogLevel_(warn);

// Or use any of the other macros of different log levels:
_Error_("Oh noes!");

Recommendation: never use _LogToFile_ in libraries. It's global. Let users configure this.
(You can always provide your own interface for users to configure it)

This makes it super easy for folks to use their own logging libraries.

No Logging

By default, _Log_ is defined as a macro that does nothing.

So libraries can safely _Log_ and it won't do anything.

The same is true of ALL macros. They do NOTHING by default.

spdlog

If spdlog headers are detected when <_Log_.h> is included, then _Log_ is defined as a macro that uses spdlog.

If no target filename is set via _LogToFile_, then spdlog will log to stderr.

Bring Your Own Logger

Easy.

Just define _Log_ before including any library headers.

If a _Log_ macro is defined, then this library will use it.

Optionally also define _LogToFile_ (defaults to an empty macro)
and whichever log levels you want to implement (etc)

License

Use however, no attribution required.

BSD Zero Clause License (SPDX: 0BSD)

Permission to use, copy, modify, and/or distribute this software for any purpose
with or without fee is hereby granted.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.