fix: Catch case where current_changes_description is None

Author: jhewers-pf

openevolve/prompt/sampler.py

@@ -110,11 +110,17 @@ def build_prompt(
 
         if self.config.programs_as_changes_description:
             if self.config.system_message_changes_description:
-                system_message_changes_description = self.config.system_message_changes_description.strip()
+                system_message_changes_description = (
+                    self.config.system_message_changes_description.strip()
+                )
             else:
-                system_message_changes_description = self.template_manager.get_template("system_message_changes_description")
+                system_message_changes_description = self.template_manager.get_template(
+                    "system_message_changes_description"
+                )
 
-            system_message = self.template_manager.get_template("system_message_with_changes_description").format(
+            system_message = self.template_manager.get_template(
+                "system_message_with_changes_description"
+            ).format(
                 system_message=system_message,
                 system_message_changes_description=system_message_changes_description,
             )
@@ -160,8 +166,10 @@ def build_prompt(
             **kwargs,
         )
 
-        if self.config.programs_as_changes_description:
-            user_message = self.template_manager.get_template("user_message_with_changes_description").format(
+        if self.config.programs_as_changes_description and current_changes_description is not None:
+            user_message = self.template_manager.get_template(
+                "user_message_with_changes_description"
+            ).format(
                 user_message=user_message,
                 changes_description=current_changes_description.rstrip(),
             )
@@ -265,11 +273,8 @@ def _format_evolution_history(
 
         for i, program in enumerate(reversed(selected_previous)):
             attempt_number = len(previous_programs) - i
-            changes = (
-                program.get("changes_description")
-                or program.get("metadata", {}).get(
-                    "changes", self.template_manager.get_fragment("attempt_unknown_changes")
-                )
+            changes = program.get("changes_description") or program.get("metadata", {}).get(
+                "changes", self.template_manager.get_fragment("attempt_unknown_changes")
             )
 
             # Format performance metrics using safe formatting
@@ -334,9 +339,7 @@ def _format_evolution_history(
         for i, program in enumerate(selected_top):
             use_changes = self.config.programs_as_changes_description
             program_code = (
-                program.get("changes_description", "")
-                if use_changes
-                else program.get("code", "")
+                program.get("changes_description", "") if use_changes else program.get("code", "")
             )
             if not program_code:
                 program_code = "<missing changes_description>" if use_changes else ""
@@ -351,11 +354,20 @@ def _format_evolution_history(
                 for name, value in program.get("metrics", {}).items():
                     if isinstance(value, (int, float)):
                         try:
-                            key_features.append(self.template_manager.get_fragment("top_program_metrics_prefix") + f" {name} ({value:.4f})")
+                            key_features.append(
+                                self.template_manager.get_fragment("top_program_metrics_prefix")
+                                + f" {name} ({value:.4f})"
+                            )
                         except (ValueError, TypeError):
-                            key_features.append(self.template_manager.get_fragment("top_program_metrics_prefix") + f" {name} ({value})")
+                            key_features.append(
+                                self.template_manager.get_fragment("top_program_metrics_prefix")
+                                + f" {name} ({value})"
+                            )
                     else:
-                        key_features.append(self.template_manager.get_fragment("top_program_metrics_prefix") + f" {name} ({value})")
+                        key_features.append(
+                            self.template_manager.get_fragment("top_program_metrics_prefix")
+                            + f" {name} ({value})"
+                        )
 
             key_features_str = ", ".join(key_features)
 
@@ -385,7 +397,11 @@ def _format_evolution_history(
                 # Use random sampling to get diverse programs
                 diverse_programs = random.sample(remaining_programs, num_diverse)
 
-                diverse_programs_str += "\n\n## " + self.template_manager.get_fragment("diverse_programs_title") + "\n\n"
+                diverse_programs_str += (
+                    "\n\n## "
+                    + self.template_manager.get_fragment("diverse_programs_title")
+                    + "\n\n"
+                )
 
                 for i, program in enumerate(diverse_programs):
                     use_changes = self.config.programs_as_changes_description
@@ -404,7 +420,8 @@ def _format_evolution_history(
                     key_features = program.get("key_features", [])
                     if not key_features:
                         key_features = [
-                            self.template_manager.get_fragment("diverse_program_metrics_prefix") + f" {name}"
+                            self.template_manager.get_fragment("diverse_program_metrics_prefix")
+                            + f" {name}"
                             for name in list(program.get("metrics", {}).keys())[
                                 :2
                             ]  # Just first 2 metrics
@@ -416,7 +433,9 @@ def _format_evolution_history(
                         top_program_template.format(
                             program_number=f"D{i + 1}",
                             score=f"{score:.4f}",
-                            language=("text" if self.config.programs_as_changes_description else language),
+                            language=(
+                                "text" if self.config.programs_as_changes_description else language
+                            ),
                             program_snippet=program_code,
                             key_features=key_features_str,
                         )
@@ -466,9 +485,7 @@ def _format_inspirations_section(
         for i, program in enumerate(inspirations):
             use_changes = self.config.programs_as_changes_description
             program_code = (
-                program.get("changes_description", "")
-                if use_changes
-                else program.get("code", "")
+                program.get("changes_description", "") if use_changes else program.get("code", "")
             )
             if not program_code:
                 program_code = "<missing changes_description>" if use_changes else ""
@@ -551,16 +568,24 @@ def _extract_unique_features(self, program: Dict[str, Any]) -> str:
                 and self.config.include_changes_under_chars
                 and len(changes) < self.config.include_changes_under_chars
             ):
-                features.append(self.template_manager.get_fragment("inspiration_changes_prefix").format(changes=changes))
+                features.append(
+                    self.template_manager.get_fragment("inspiration_changes_prefix").format(
+                        changes=changes
+                    )
+                )
 
         # Analyze metrics for standout characteristics
         metrics = program.get("metrics", {})
         for metric_name, value in metrics.items():
             if isinstance(value, (int, float)):
                 if value >= 0.9:
-                    features.append(f"{self.template_manager.get_fragment('inspiration_metrics_excellent').format(metric_name=metric_name, value=value)}")
+                    features.append(
+                        f"{self.template_manager.get_fragment('inspiration_metrics_excellent').format(metric_name=metric_name, value=value)}"
+                    )
                 elif value <= 0.3:
-                    features.append(f"{self.template_manager.get_fragment('inspiration_metrics_alternative').format(metric_name=metric_name)}")
+                    features.append(
+                        f"{self.template_manager.get_fragment('inspiration_metrics_alternative').format(metric_name=metric_name)}"
+                    )
 
         # Code-based features (simple heuristics)
         code = program.get("code", "")
@@ -571,22 +596,32 @@ def _extract_unique_features(self, program: Dict[str, Any]) -> str:
             if "numpy" in code_lower or "np." in code_lower:
                 features.append(self.template_manager.get_fragment("inspiration_code_with_numpy"))
             if "for" in code_lower and "while" in code_lower:
-                features.append(self.template_manager.get_fragment("inspiration_code_with_mixed_iteration"))
+                features.append(
+                    self.template_manager.get_fragment("inspiration_code_with_mixed_iteration")
+                )
             if (
                 self.config.concise_implementation_max_lines
                 and len(code.split("\n")) <= self.config.concise_implementation_max_lines
             ):
-                features.append(self.template_manager.get_fragment("inspiration_code_with_concise_line"))
+                features.append(
+                    self.template_manager.get_fragment("inspiration_code_with_concise_line")
+                )
             elif (
                 self.config.comprehensive_implementation_min_lines
                 and len(code.split("\n")) >= self.config.comprehensive_implementation_min_lines
             ):
-                features.append(self.template_manager.get_fragment("inspiration_code_with_comprehensive_line"))
+                features.append(
+                    self.template_manager.get_fragment("inspiration_code_with_comprehensive_line")
+                )
 
         # Default if no specific features found
         if not features:
             program_type = self._determine_program_type(program)
-            features.append(self.template_manager.get_fragment("inspiration_no_features_postfix").format(program_type=program_type))
+            features.append(
+                self.template_manager.get_fragment("inspiration_no_features_postfix").format(
+                    program_type=program_type
+                )
+            )
 
         # Use num_top_programs as limit for features (similar to how we limit programs)
         feature_limit = self.config.num_top_programs
@@ -629,7 +664,12 @@ def _render_artifacts(self, artifacts: Dict[str, Union[str, bytes]]) -> str:
             sections.append(f"### {key}\n```\n{content}\n```")
 
         if sections:
-            return "## " + self.template_manager.get_fragment("artifact_title") + "\n\n" + "\n\n".join(sections)
+            return (
+                "## "
+                + self.template_manager.get_fragment("artifact_title")
+                + "\n\n"
+                + "\n\n".join(sections)
+            )
         else:
             return ""