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trace-out

Printf debugging done the right way

Features

  • Header-only.
  • No additional dependencies.
  • Output can be redirected.
  • Crossplatform.
  • Free for all (MIT license).

Quick example

Code:

#include "trace-out.hpp"

int main(int argc, const char *argv[])
{
    $f // pretty-print when function is called and returned
    $t("ah sh1t, here we go again.");

    int answer {42};
    std::string moto {"hellomoto!"};
    $t(answer, moto); // print "answer" and "moto" values

    $if (answer == 42) // print condition value
        $return answer; // print return value

    $return 0; // print return value
}

Output:

int main(int argc, const char *argv[])
{
    // ah sh1t, here we go again.
    answer = 42
    moto = "hellomoto!"
    if (answer == 42) => true
    {
        return 42
    }

} // int main(int argc, const char *argv[])

Get it

You can get it any way you want, as long as it's one of these

Download release

Here

Install system-wide

$ git clone --recurse-submodules https://github.com/shrpnsld/trace-out  # Download
$ cd trace-out; mkdir build; cd build; cmake .. # Generate build files
$ cmake --install . # Install

Generate single header manually

$ git clone --recurse-submodules https://github.com/shrpnsld/trace-out  # Download
$ cd trace-out; mkdir build; cd build; cmake .. # Generate build files
$ cmake --build . --target trace-out.hpp # Generate single header

Then, you can find single header at trace-out-amalgamated/include/trace-out/trace-out.hpp inside the build directory.

Pretty-printing

trace-out has several macros defined that pretty-print information about code.

Values

$t(<expression>) [C++98] – print value of a given expression. Can be used inside other expressions.

$t(<expression>, ...) [C++11 and later] – same as above, but it can accept multiple values. However, when it is passed multiple values, it can't be used inside other expressions.

$t("<C-string-literal>") – print some string.

$tbin(<expression>), $toct(<expression>), $thex(<expression>) – [C++98] – print binary, octal or hexadecimal representaions for a value of a given expression. Only numerical types are supported. When using floating point types with $tbin(...), it prints binary format representation, but $toct(...) and $thex print octal and hexadecimal values for each byte of the value. Can be used inside other expressions.

$tbin(<expression>, ...), $toct(<expression>, ...), $thex(<expression>, ...) – [C++11 and later] – same as above, but it can accept multiple values. However, when it is passed multiple values, it can't be used inside other expressions.

$tr(<begin>, <end>|<how_much>) – print values from a range defined by a pair of iterators or iterator and item count.

Memory

$m(<pointer>, <size>, [$<base>], [$grp(<count>)], [$be|$le], [$col(<count>)]) – print memory under <pointer>.

  • <pointer> – address of the memory to be printed
  • <size> – size of the memory in bytes
  • $<base> – numerical base; can be one of the following values:
    • $bin – binary
    • $hex – hexadecimal
    • $sdec – signed decimal
    • $udec – unsigned decimal
    • $flt – current float type
    • $dbl – current double type
    • $ldbl – current long double type
  • $grp(<count>) – how much bytes should be grouped together in a single column (1, 2, 4 or 8); this affects only $bin, $hex, $sdec, $udec bases
  • $be and $le – big-endian and little-endian byte orders, respectively; if not specified, the current byte order is used
  • $col(<count>) – print memory in specified column count; if printing exceeds output stream width, then more optimal value will be calculated

$<base>, $grp, $be, $le and $col are all optional and non-positional, but should always be listed after <pointer> and <size>.

The default memory representation is single-byte hexadecimals, with column count set to the maximum power of 2 that fits console width.

Statements

$if(<condition>) – pretty-print if statement.

$for(<statements>) – pretty-printfor loop.

$while(<condition>) – pretty-print while loop.

$f – print function call start and call end labels. Must be used inside a function.

$return <expression> – print expression value passed to the return statement.

$s(...) – trace statement execution.

Macros $f, $if, $for and $while shift output indentation inside their scope, while each thread keeps its own indentation.

Other

$thread(<name>) – set thread name that will be printed in the thread header.

$time(<name>, <any-code>) – measure code execution time in milliseconds.

$clocks(<name>, <any-code>) – measure code execution time in clocks.

$time_stats(<name>, <passes>, <any-code>) – gather code execution time measurements in milliseconds and print statistics (average, median, mode, range) each time number of passes has reached <passes> value.

$clock_stats(<name>, <passes>, <any-code>) – gather code execution time measurements in clocks and print statistics (average, median, mode, range) each time number of passes has reached <passes> value.

Supported types

  • all fundamental types, raw pointers, most of standard library types
  • types that define member functions .begin() and .end() which return iterators
  • sturctures and classes with data members or member functions x, y, z, w, width, height, origin, size, left, top, right, bottom, real, imag in both lowcase and Capital

Options

You can customize trace-out's behavior by defining the following macros.

Output

TRACE_OUT_MARKER <string> – add text marker before every trace-out line.

TRACE_OUT_SHOW_FILE_LINE – print file and line.

TRACE_OUT_STRIP_SCOPE <how-much> – show only <how-much> scope components when using $f macro.

TRACE_OUT_INDENTATION <string> – string that is used as an indentation. Default value is 4 spaces.

TRACE_OUT_SHOW_THREAD – show thread information.

Behavior

TRACE_OUT_OFF – turn trace-out off.

TRACE_OUT_SYNC_STREAM – enable output syncronization.

TRACE_OUT_STREAM_WIDTH <how-much> – width to which output is wrapped (actually, only memory output is wrapped).

Redirection

TRACE_OUT_STREAM_TO_ENDPOINT "<host>:<port>" – stream to a specified <host> and <port>.

TRACE_OUT_STREAM_TO_FILE "<file-path>" – stream to a specified file.

TRACE_OUT_STREAM_TO_WDO – stream to Windows debug output.

Custom redirection

If predefined redirections aren't enough, you can make your own (though with some involvement). To do this:

  1. Create a derived implementation of std::basic_streambuf<char> that outputs wherever you want.
  2. Create function std::ostream &stream() within some namespace. This function should return std::ostream instance, which uses your implementation of std::basic_streambuf<char>.
  3. Define macro TRACE_OUT_STREAM_TO with the namespace where you've created std::ostream &stream().

As an example, look at trace-out-to-endpoint.hpp or trace-out-to-wdo.hpp in src/trace-out/ directory.

Compatibility

TRACE_OUT_CPP_VERSION <number> – specify C++ standard version using same format as __cplusplus macro. Why? Visual Studio defines __cplusplus macro with the wrong value, and while it offers a fix with /Zc:__cplusplus, it can still cause issues in your project's code. So, to keep your project intact, you can use this macro, and it will only affect trace-out.