Plain macro zero-dependency single-file library to get rid of complex logging libraries and boilerplate logging code while keeping logs pretty.
Default output looks like this (screen from VSCode terminal):
Though the library is highly customizable.
// foo.c
// ...other includes...
#include <milo.h>
void foo() {
trace("won't show because of default logging level");
info("example info");
for (int i = 0; i < 3; i++)
warn("example warn #%i", i);
error("example %s", "error");
fatal("%10s", "say hello! the rest is ignored");
}Default logging level is set to info, but you can modify it by redefining MILO_DEFAULT_LVL at the build level. More on this below.
It is possible to use different logging levels for different files, for example:
// bar.c
// ...other includes...
#include "foo.c" // example from above
// this should be blow all other incldes
#define MILO_LVL MILO_LVL_ERROR
#include <milo.h>
void bar() {
info("won't do anything");
error("example error"); // will print an error
foo(); // will print all messages as expected
}Available MILO_LVLs:
MILO_LVL_TRACE(aliasedMILO_LVL_ALL)MILO_LVL_INFOMILO_LVL_WARNMILO_LVL_ERRORMILO_LVL_FATALMILO_LVL_NONE(aliasedMILO_LVL_SILENT)
Because milo "functions" are actually function-like macros, they will always shadow variables and functions with the same name. MiLo provides a MILO_USE_SHORTCUTS definition to adress that situation. It is enabled by default, but can be changed when necessary:
#define MILO_USE_SHORTCUTS (0)
#define MILO_LVL MILO_LVL_WARN
#include <milo.h>
int check_unwanted_condition() {
int error = 0;
if (unwanted_condition) {
// now milo functions from are called like this
milo_error("unexpected unwanted condition!");
error = 1;
}
// ...
return error;
}It is separate for each inclusion of the library, exactly like MILO_LVL.
There are a bunch of options to customize:
| definition | default value | description |
|---|---|---|
milo_printf(fmt, ...) |
fprintf(stdout, fmt, ...), fflush(stdout) |
Used in trace, info and warn |
milo_eprintf(fmt, ...) |
fprintf(stderr, fmt, ...), fflush(stderr) |
Used in error and fatal |
MILO_DEFAULT_LVL |
MILO_LVL_INFO |
Used if MILO_LVL is not defined |
MILO_NO_TA |
Disables text attributes | |
MILO_TA_TRACE |
clear all, blue | Text attribute for trace |
MILO_TA_INFO |
clear all, green | Text attribute for info |
MILO_TA_WARN |
clear all, bright yellow | Text attribute for warn |
MILO_TA_ERROR |
clear all, red | Text attribute for error |
MILO_TA_FATAL |
clear all, bold, red | Text attribute for fatal |
MILO_TA_FILE |
clear all, faded | Text attribute for filename |
MILO_TA_CLEAR |
clear all | Text attribute for everything else |
MILO_LVL_NAME_TRACE |
"trc" |
Log level name for trace |
MILO_LVL_NAME_INFO |
"inf" |
Log level name for info |
MILO_LVL_NAME_WARN |
"wrn" |
Log level name for warn |
MILO_LVL_NAME_ERROR |
"err" |
Log level name for error |
MILO_LVL_NAME_FATAL |
"ftl" |
Log level name for fatal |
MILO_PREFIX_FORMAT |
"[{attr}{lvl} {file}:{line}] " |
Default format for the log prefix |
MILO_PREFIX_ARGS(attr, lvl) |
attr, lvl, MILO_FILE, MILO_LINE |
Arguments for the log prefix |
MILO_SUFFIX_FORMAT |
"\n" |
Default format for the log suffix |
MILO_TA_FILE,MILO_TA_CLEAR,MILO_PREFIX_FORMATandMILO_PREFIX_ARGSmust not include parentheses since they rely on string concatenation and other macro tricks.
MILO_TA_TRACE,MILO_TA_INFO,MILO_TA_WARN,MILO_TA_ERROR,MILO_TA_FATAL,MILO_TA_FILEandMILO_TA_CLEARare redefined together. If this group is defined,MILO_NO_TAhas no effect.
MILO_LVL_NAME_TRACE,MILO_LVL_NAME_INFO,MILO_LVL_NAME_WARN,MILO_LVL_NAME_ERROR,MILO_LVL_NAME_FATALare only redefined together.
If
milo_printfis defined, butmilo_eprintfis not, it will be the same asmilo_printf.
All definitions must be globally defined to ensure proper functionality. Otherwise, inconsistencies may arise.
# because this is bash, "FOO" becomes FOO in C, so we need additional quotes
gcc -o main main.c foo.c bar.c \
-D 'MILO_LVL_NAME_TRACE="TRACE"' \
-D 'MILO_LVL_NAME_INFO="INFO"' \
-D 'MILO_LVL_NAME_WARN="WARN"' \
-D 'MILO_LVL_NAME_ERROR="ERROR"' \
-D 'MILO_LVL_NAME_FATAL="FATAL"'Writing a lot of definitions in build scripts is not very efficent, so MiLo provides another way of doing this: MILO_CONFIG macro. You only need to define it, all other settings go there.
// milo_config.h
#define MILO_TA_TRACE ("\033[0;2;36m") // made slightly faded
#define MILO_TA_INFO ("\033[0;32m") // default
#define MILO_TA_WARN ("\033[0;95m") // yellow changed to purple
#define MILO_TA_ERROR ("\033[0;31m") // default
#define MILO_TA_FATAL ("\033[0;1;41m") // color background instead of text
#define MILO_TA_FILE "\033[0;3;2m" // made italic
#define MILO_TA_CLEAR "\033[0;3m" // all text except level names and filenames made italicgcc -o main main.c foo.c bar.c -D 'MILO_CONFIG="milo_config.h"'In both cases, this will look similar to this:
This part is not so obvious, so here is an example:
#ifndef MILO_CONFIG_H
#define MILO_CONFIG_H
#include <time.h>
static char buf[32] = {0};
static inline char const *milo_timestamp(char const *const fmt) {
time_t const t = time(NULL);
strftime(buf, sizeof(buf), fmt, localtime(&t));
return buf;
}
#define MILO_TA_TRACE ("\033[0;30m")
#define MILO_TA_INFO ("\033[0;37m")
#define MILO_TA_WARN ("\033[0;93m")
#define MILO_TA_ERROR ("\033[0;31m")
#define MILO_TA_FATAL ("\033[0;41;30m")
#define MILO_TA_FILE "\033[0;2m"
#define MILO_TA_CLEAR "\033[0m"
// be careful not to include parentheses in these two, as they rely heavily on
// string concatenation
#define MILO_PREFIX_FORMAT \
MILO_TA_CLEAR \
"%s" /* {attr} */ \
"%s" /* {timestamp} */ \
" %s %s: " /* {file}:{line} {func} */
#define MILO_PREFIX_ARGS(attr, lvl) \
(attr), milo_timestamp("%b %d %H:%M:%S"), MILO_FILE, MILO_FUNC
#endifThis is trying to immitate a format similar to journalctl output, and does this quite well.