Logging
-
only if the condition is
false (or 0, or NULL) something will be logged
-
there are no log levels
-
the macro will throw an
std::exception if the condition was not met
-
this normally terminates the running program
2
@Add(includes)
#include <iostream>
#include <exception>
@End(includes)
-
std::cerr from <iostream> is used to write log messages
-
a standard exception from
<exception> is used to indicate failed conditions
3
@Def(frag prereqs)
#define ASSERT(COND) \
if (! (COND)) { \
@mul(log preamble) \
@mul(log newline) \
@mul(throw) \
}
@End(frag prereqs)
-
the plain
ASSERT macro does nothing if the condition evaluates to true
-
otherwise the position of the line with the assertion will be written
-
and a small message
-
no details are given and the line is terminated with a newline
-
then an exception is raised
4
@Add(frag prereqs)
#define ASSERT_MSG(COND, MSG) \
if (! (COND)) { \
@mul(log preamble) \
std::cerr << ": " << MSG; \
@mul(log newline) \
@mul(throw) \
}
@End(frag prereqs)
-
the macro
ASSERT_MSG has an additional argument that the macro writes after the preamble
-
MSG can be multiple parameters concatenated by <<
5
@Add(frag prereqs)
#define WARN_MSG(MSG) \
std::cerr << __FILE__ << ':' << \
__LINE__ << ' '; \
std::cerr << MSG; \
@mul(log newline)
@end(frag prereqs)
-
a warning writes the same message, as an assertion
-
but it will not terminate the program
6
@def(log preamble) \
std::cerr << \
__FILE__ << ':' << __LINE__ << \
' ' << #COND << " FAILED"; \
@end(log preamble)
-
the preamble starts with the position in the format
filename:line
-
this is recognized by a number of editors
-
afterwards a short error message is written
7
@def(log newline) \
std::cerr << '\n'; \
@end(log newline)
-
a simple newline terminates an error message
8
@def(throw) \
throw std::exception(); \
@end(throw)
-
the assert macros throw a generic
std::exception if the condition was not met