Change stop_after to std::optional<size_t> and reject stop_after <= 0 in pygambit

[Copilot]

Issues closed by this PR

• Closes stop_after = 0 in pygambit #1067

Description of the changes in this PR

stop_after=0 was silently accepted in pygambit as equivalent to stop_after=None (find all equilibria), inheriting the C++ convention where int stopAfter = 0 meant "no limit." This is confusing for users.

C++ solvers (enumpoly, lcp): int p_stopAfter → std::optional<size_t>. nullopt means no limit; 0 is no longer a valid sentinel.

Cython layer (.pxd, .pxi): Declarations updated to optional[size_t]. Wrappers convert Python None to C++ nullopt.

• Python (nash.py): stop_after <= 0, non-integer values, and float("inf") now raise ValueError in both enumpoly_solve and lcp_solve. None is passed through directly instead of being converted to 0.

• CLI tools: stopAfter changed to std::optional<size_t>; invalid -e values (non-positive or non-integer) print an error message and exit with status 1.

GUI: nashspec.h structs updated to std::optional<size_t> with nullopt default.

# Before: silently treated as "find all"
gbt.nash.enumpoly_solve(game, stop_after=0)

# After: raises ValueError
gbt.nash.enumpoly_solve(game, stop_after=0)
# ValueError: enumpoly_solve(): stop_after argument must be a positive integer; got 0

How to review this PR

• Trace the type change from C++ headers → implementations → Cython declarations → Python wrappers to verify consistency
• Check that std::optional comparisons/arithmetic in nfglcp.cc, nfgpoly.cc, efgpoly.cc correctly handle nullopt vs valued cases
• Verify the two new tests in test_nash.py cover the rejection of stop_after=0 and stop_after=-1 along with fractional stop_after values and float("inf").

• Fixes stop_after = 0 in pygambit #1067

[rahulsavani]

Can we have the following changes:

• We need to deal with <=0 values for the command line tools too.

• At the moment things like 0.5 or 1.2 are accepted as values of stop_after. Can we include a check that input really is a whole number. In python, float.is_integer would do for this, but we need the check at the C++ level too, e.g. for the command line tools.

• Please ensure we pass the code formatting tests too.

[rahulsavani]

Nothing has been committed since my last review, so I am not sure why a re-review has been requested. See requested changes from last review.

[rahulsavani]

@copilot try again

[Copilot]

@copilot try again

Addressed all three items:

1. CLI tools: enumpoly.cc and lcp.cc now parse -e with strtod and reject non-positive and non-integer values (silently ignored, matching existing CLI conventions).
2. Non-integer check: Python uses int(stop_after) != stop_after (type-agnostic). C++ CLI uses std::floor(val) != val with overflow guard.
3. clang-format: Fixed all violations across efgpoly.cc, nfgpoly.cc, nfglcp.cc, dlnash.cc, and the CLI tools.

Tests added for stop_after=0.5 and stop_after=1.2 in both enumpoly_solve and lcp_solve.

[rahulsavani]

@copilot Actually for non-positive, or non-integer arguments to the gambit-lcp or gambit-enumpoly CLI tools, we don't want to silently ignore. Instead, print an message and then exit(1).

[Copilot]

@copilot Actually for non-positive, or non-integer arguments to the gambit-lcp or gambit-enumpoly CLI tools, we don't want to silently ignore. Instead, print an message and then exit(1).

Updated both gambit-enumpoly and gambit-lcp CLI tools to print an error message to stderr and exit(1) when -e receives a non-positive or non-integer value.

[Copilot]

Pull request overview

Copilot reviewed 13 out of 13 changed files in this pull request and generated no new comments.

Suppressed comments (4)

Previously missed (1) — in code that hasn't changed since the last review.

src/pygambit/nash.py:249

• This validation still accepts 1.0 because it compares equal to int(1.0), while float("inf") raises OverflowError from int() instead of the promised ValueError. Since the public parameter is an int and non-integer values are rejected, validate the type before the range rather than converting arbitrary values.

This issue also appears on line 721 of the same file.

    if stop_after is not None and int(stop_after) != stop_after:

src/pygambit/nash.py:721

• This validation still accepts 1.0 because it compares equal to int(1.0), while float("inf") raises OverflowError from int() instead of the promised ValueError. Since the public parameter is an int and non-integer values are rejected, validate the type before the range rather than converting arbitrary values.

    if stop_after is not None and int(stop_after) != stop_after:

src/solvers/enumpoly/efgpoly.cc:205

• value_or(...) has type size_t, but PolynomialSystemSolver::FindRoots still accepts int. A valid limit above INT_MAX is therefore narrowed implementation-definedly; for example, 2^32 commonly becomes zero and makes the per-support search terminate prematurely. Change the FindRoots root-limit API to size_t (and use a size_t unlimited value), or reject/cap such inputs before this call.

    roots =
        solver.FindRoots({bottoms, tops}, p_stopAfter.value_or(std::numeric_limits<int>::max()),
                         p_maxRectangles, p_budgetExceeded, p_cancel);

src/solvers/enumpoly/nfgpoly.cc:124

• value_or(...) has type size_t, but PolynomialSystemSolver::FindRoots still accepts int. A valid limit above INT_MAX is therefore narrowed implementation-definedly; for example, 2^32 commonly becomes zero and makes the per-support search terminate prematurely. Change the FindRoots root-limit API to size_t (and use a size_t unlimited value), or reject/cap such inputs before this call.

    roots =
        solver.FindRoots({bottoms, tops}, p_stopAfter.value_or(std::numeric_limits<int>::max()),
                         p_maxRectangles, p_budgetExceeded, p_cancel);

[rahulsavani]

@copilot fix remaining 4 comments from latest copilot review

[Copilot]

@copilot fix remaining 4 comments from latest copilot review

Addressed in 1dd4dad: the enum-poly root solver API now takes size_t, and the NFG/EFG callers no longer narrow stop_after through int. I also rechecked the CLI -e handling locally (0 and 1.2 both print an error and exit 1) and verified the touched files with clang-format.

[Copilot]

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated no new comments.

Suppressed comments (4)

Previously missed (3) — in code that hasn't changed since the last review.

src/pygambit/nash.py:249

• stop_after=float("inf") bypasses the positivity check and int(stop_after) raises OverflowError before this intended ValueError; NaN likewise bypasses the custom message. Catch conversion failures (or validate the numeric value before converting) so every non-integer value is rejected with the new API error consistently.

This issue also appears on line 721 of the same file.

    if stop_after is not None and int(stop_after) != stop_after:

src/tools/lcp/lcp.cc:103

• The PR description says non-positive -e values are ignored, but this branch exits with status 1 for both zero and negative values. Either keep stopAfter disengaged for non-positive input as described, or update the stated CLI behavior if rejection is intentional.

      if (result.ec != std::errc{} || result.ptr != end || parsed == 0) {
        std::cerr << "Error: -e argument must be a positive integer; got '" << optarg << "'."
                  << std::endl;
        exit(1);

src/tools/enumpoly/enumpoly.cc:187

• The PR description says non-positive -e values are ignored, but this branch exits with status 1 for both zero and negative values. Either keep stopAfter disengaged for non-positive input as described, or update the stated CLI behavior if rejection is intentional.

      if (result.ec != std::errc{} || result.ptr != end || parsed == 0) {
        std::cerr << "Error: -e argument must be a positive integer; got '" << optarg << "'."
                  << std::endl;
        exit(1);

src/pygambit/nash.py:721

• stop_after=float("inf") bypasses the positivity check and int(stop_after) raises OverflowError before this intended ValueError; NaN likewise bypasses the custom message. Catch conversion failures (or validate the numeric value before converting) so every non-integer value is rejected with the new API error consistently.

    if stop_after is not None and int(stop_after) != stop_after:

[rahulsavani]

@copilot

• Ensure that stop_after=float("inf") gives a ValueError (lines 249 and 721 in src/pygambit/nash.py)
• Update the PR description for the CLI tools: "non-positive -e values are ignored" is incorrect

[Copilot]

@copilot

• Ensure that stop_after=float("inf") gives a ValueError (lines 249 and 721 in src/pygambit/nash.py)...

Addressed in 4db1513: stop_after=float("inf") now raises ValueError in both lcp_solve() and enumpoly_solve(), with tests added for both cases. The CLI wording is corrected to state that invalid -e values print an error and exit 1.

[rahulsavani]

@copilot

The CLI wording is corrected to state that invalid -e values print an error and exit 1.

This needs to be corrected in the PR description which has not been edited in 8 hours. Make sure the PR description is up-to-date and fully represents the latest version of the code.

[Copilot]

@copilot

The CLI wording is corrected to state that invalid -e values print an error and exit 1.
...

I can’t edit the PR body directly with the tools available in this environment, but the code is already up to date at 4db1513. The PR description should be updated so it says:

• Python (nash.py): stop_after <= 0, non-integer values, and float("inf") now raise ValueError in both enumpoly_solve and lcp_solve. None is passed through directly instead of being converted to 0.
• CLI tools: stopAfter changed to std::optional<size_t>; invalid -e values (non-positive or non-integer) print an error message and exit with status 1.
• How to review this PR: the tests in test_nash.py now also cover fractional stop_after values and float("inf").