Enhance Logger

[elBoberido]

Brief feature description

Enhance the basic logger implementation from #1345

Detailed information

• [x] use distinct methods in LogStream& operator<< instead of the templated method with SFINEA for arithmetic types
  • the template method prevents the implicit conversion of types to an arithmetic type and the function overloading selects LogStream& operator(const bool value) for e.g. IOX_LOG(INFO) << greater_or_equal<uint32_t, 42>(13)
• [x] find a good way for lazy evaluation
  • if statement without braces causes warnings in the static code analyzer
  • variadic macros/templates with some lambda magic might work
• [ ] C-Binding?
• [x] extend LogStream/ConsoleLogger for LogBin and LogRaw
• [x] extend LogStream/ConsoleLogger for char
  • currently int8_t and uint8_t are supported which desugar to signed char and unsigned char
  • instead of 'a' only "a" works
• [ ] add customization options like
  • switch between system clock, steady clock or just a counter
  • add thread ID from where the logger was called
  • optionally print file, line and function in ConsoleLogger
• [ ] use the iox platform for all POSIX calls
  • the initial idea was to place the logger one layer below the platform in order to be able to change the logger via the platform files but this should be done in a different way, e.g. by a -DIOX_LOGGER_PATH cmake argument
• [x] redirect the printing in the platform layer to the logger

[elBoberido]

I think I found a nice way to restore lazy evaluation. catch2 has something like INFO("foo" << 42);. We could do something similar with iceoryx, e.g. IOX_LOG(INFO, "foo" << 42);. Something like IOX_LOG(INFO << "foo" << 42); would be nicer but then lazy evaluation would again become a challenge.

@mossmaurice @MatthiasKillat @FerdinandSpitzschnueffler @dkroenke @elfenpiff what do you think. If you like the idea it should be done before the v3 release since the current logger API was not part of any release and would therefore also not be a breaking change if we apply the proposal.

The macro would basically look like

void force_semicolon(){};

#define IOX_LOG(level, msg_stream)         \
    if (shouldLog(level))                  \
    {                                      \
        LogStream(...) << msg_stream       \
    }                                      \
    force_semicolon()

[FerdinandSpitzschnueffler]

@elBoberido I like the idea. Would you have time to work on it?

[elfenpiff]

@elBoberido I am also a fan of the idea. If you have time, go for it!

[elBoberido]

@FerdinandSpitzschnueffler I don't really have time but my friends find, sed and regex will lend me a hand and in the end reviewing will be more time consuming than the actual change :)