To handle fatal errors and establish how problem sigils work.

• §1. Sudden exits
• §3. Configuration
• §6. Sigils

§1. Sudden exits. In my beginning is my end: this lowest level of the error-handling system deals with systemic collapses, and it begins with the exit itself. Note that the exit code depends on whether the parent tool, perversely perhaps, actually wants to have issued a given problem — this is used when testing Inform.

By convention our exit codes are 0 for success, 1 for failure, and 2 for a filing-system-related failure.

text_stream *sigil_of_required_problem = NULL;

int sigil_of_required_problem_found = FALSE;
int echo_problem_message_sigils = FALSE;
int crash_on_all_problems = FALSE;

void ProblemSigils::exit?Usage of ProblemSigils::exit:
§2
Problems, Level 2 - §15
Problems, Level 3 - §3, §11(int code) {
    if ((sigil_of_required_problem) && (sigil_of_required_problem_found == FALSE))
        exit(0);  so that the problem test case will fail in intest
    exit(code);
}

§2. The following function has had an amusing evolution over the years. It does something nobody is ever supposed to do: deliberately crashes the process. At one time it executed int x = 1/0;, but compilers got wise to that, or else would detect that such an expression had no side effects and was not used. What we now do is to dereference a null pointer, while apparently trying to make use of the result.

void ProblemSigils::force_crash?Usage of ProblemSigils::force_crash:
Problems, Level 2 - §10, §15
Problems, Level 3 - §3(void) {
    STREAM_FLUSH(STDOUT);
    STREAM_FLUSH(DL);
    WRITE_TO(STDERR,
        "*** Intentionally crashing to force stack backtrace to console logs ***\n");
    STREAM_FLUSH(STDERR);
    parse_node *PN = NULL; LOG("$T", PN->next);
    ProblemSigils::exit(1);  should never in fact be reached
}

§3. Configuration. Inform calls this in response to its -require-problem command line switch:

void ProblemSigils::require(text_stream *sigil) {
    sigil_of_required_problem = Str::duplicate(sigil);
}

§4. And this in response to -sigils, which causes the sigil of any problem to be echoed to standard output (i.e., printed). Again, this is useful in testing.

void ProblemSigils::echo_sigils(int state) {
    echo_problem_message_sigils = state;
}

§5. And this in response to -crash-all, an ugly expedient for working with Inform in the debugger.

void ProblemSigils::crash_on_problems(int state) {
    crash_on_all_problems = state;
}

§6. Sigils. Every problem message in Inform is identified by a sigil, a short alphanumeric symbol. The _p_ notation is used to write these; this expands to the name in double quotes followed by the source section and line number at which it is generated.

define _p_(sigil) #sigil, __FILE__, __LINE__

§7. That means that when a _p_ argument is given to a function, it is actually a list of three arguments, matching the SIGIL_ARGUMENTS prototype. SIGIL_ARGUMENTS appears as a pseudo-argument in the function prototypes of the many of the functions in this module as a result.

Each such function should either ACT_ON_SIGIL itself or else pass over to another problem function, using PASS_SIGIL as the pseudo-argument.

define SIGIL_ARGUMENTS char *sigil, char *file, int line
define PASS_SIGIL sigil, file, line

§8. We will maintain the following variables. The distinction is that the "unlinked" one holds the sigil of a message which is next up to be hyperlinked to documentation; sigil_of_latest_unlinked_problem is then emptied when this is done, whereas sigil_of_latest_problem keeps its value until the next problem is issued.

text_stream *sigil_of_latest_problem = NULL;
text_stream *sigil_of_latest_unlinked_problem = NULL;

§9. So, then, the following long macro is how a function "acts" on a sigil:

define ACT_ON_SIGIL
    LOG("Problem %s issued from %s, line %d\n", sigil, file, line);
    if (sigil_of_latest_unlinked_problem == NULL)
        sigil_of_latest_unlinked_problem = Str::new();
    else
        Str::clear(sigil_of_latest_unlinked_problem);
    WRITE_TO(sigil_of_latest_unlinked_problem, "%s", sigil);
    if (sigil_of_latest_problem == NULL)
        sigil_of_latest_problem = Str::new();
    else
        Str::clear(sigil_of_latest_problem);
    WRITE_TO(sigil_of_latest_problem, "%s", sigil);
    if (Str::eq(sigil_of_required_problem, sigil_of_latest_problem))
        sigil_of_required_problem_found = TRUE;
    if (echo_problem_message_sigils)
        WRITE_TO(STDERR, "Problem__ %S\n", sigil_of_latest_problem);