This way goto source doesn't end up in a generated file for those parts and they can be edited directly.
I have way too often accidentally edited the generated file.
With it when using multiple Machine in one process only the first would store the pre-allocated error.
Instead Heap.resource_err_loc is now Option<NonZero<usize>> instead of usize using None for uninitialized.
The cell at index 0 should alredy be used by a runtime reserved interstitial cell that is allocated prior. So requiring the offset to be non zero should be fine.
- reserve the complete required length at the beginning to reduce reallocations
- use u8 instead of char so that we can re-use the allocation for the string
The -t flag is not limited to arity 0 predicates - it accepts any
goal including goals with arguments (e.g., -t 'halt(1)'). Updated
the help text to remove the incorrect "(arity 0 predicate)" constraint.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
Per maintainer feedback, switches must come before files to follow
the convention: switches before files are Scryer-specific, switches
after files are application-specific.
The custom_toplevel.pl unit tests were trivial and didn't actually test
the functionality. All real testing is done via comprehensive CLI tests
in tests/scryer/cli/src_tests/custom_toplevel.md
- Add dynamic directive in toplevel.pl with other module-level directives
- Update test files to reference it as '':g_caused_exception/2
- Remove redundant dynamic directives from test files
- All tests passing
Following TESTING_GUIDE.md, added tests at layers 2 and 3:
Layer 2 - Prolog Integration Tests (src/tests/custom_toplevel.pl):
- Test that g_caused_exception/2 is not asserted when no exception occurs
- Test that g_caused_exception/2 can be checked from custom toplevel
- Added check_for_exception/0 helper predicate for testing
Layer 3 - CLI Tests (tests/scryer/cli/src_tests/custom_toplevel.md):
- Test g_caused_exception/2 with exception thrown
- Test g_caused_exception/2 with no exception
- Test g_caused_exception/2 with error/2 terms
- Added test helper predicates in fixtures/toplevel_test_helper.pl
All tests pass successfully.
Co-Authored-By: J.J.'s Robot <jjtolton@gmail.com>
When a goal throws an exception during initialization (-g flag), the
system now asserts g_caused_exception(Goal, Exception) in the user
module. This allows custom toplevels (-t flag) to check if an error
occurred and handle it appropriately.
Example usage:
scryer-prolog -g "throw(error)" -t check_error
Where check_error can be:
:- dynamic(g_caused_exception/2).
check_error :-
( g_caused_exception(_, E) ->
write('Error: '), write(E), nl, halt(1)
; halt(0)
).
This enables scripts to use custom toplevels for sophisticated error
handling and exit code logic.
Addresses: https://github.com/mthom/scryer-prolog/pull/3147#issuecomment-3503875719
Co-Authored-By: J.J.'s Robot <jjtolton@gmail.com>
