Sound null safety

Author: DevNico

.github/workflows/dart.yml

@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
 
     container:
-      image:  google/dart:latest
+      image: google/dart:2.12-beta
 
     steps:
     - uses: actions/checkout@v2

lib/src/ansi_color.dart

@@ -6,8 +6,8 @@ class AnsiColor {
   /// Reset all colors and options for current SGRs to terminal defaults.
   static const ansiDefault = '${ansiEsc}0m';
 
-  final int fg;
-  final int bg;
+  final int? fg;
+  final int? bg;
   final bool color;
 
   AnsiColor.none()

lib/src/filters/development_filter.dart

@@ -10,7 +10,7 @@ class DevelopmentFilter extends LogFilter {
   bool shouldLog(LogEvent event) {
     var shouldLog = false;
     assert(() {
-      if (event.level.index >= level.index) {
+      if (event.level.index >= level!.index) {
         shouldLog = true;
       }
       return true;

lib/src/filters/production_filter.dart

@@ -5,6 +5,6 @@ import 'package:logger/src/log_filter.dart';
 class ProductionFilter extends LogFilter {
   @override
   bool shouldLog(LogEvent event) {
-    return event.level.index >= level.index;
+    return event.level.index >= level!.index;
   }
 }

lib/src/log_filter.dart

@@ -5,7 +5,7 @@ import 'package:logger/src/logger.dart';
 /// You can implement your own `LogFilter` or use [DevelopmentFilter].
 /// Every implementation should consider [Logger.level].
 abstract class LogFilter {
-  Level level;
+  Level? level;
   void init() {}
 
   /// Is called every time a new log message is sent and decides if

lib/src/logger.dart

@@ -21,7 +21,7 @@ class LogEvent {
   final Level level;
   final dynamic message;
   final dynamic error;
-  final StackTrace stackTrace;
+  final StackTrace? stackTrace;
 
   LogEvent(this.level, this.message, this.error, this.stackTrace);
 }
@@ -57,10 +57,10 @@ class Logger {
   /// defaults: [PrettyPrinter], [DevelopmentFilter] and [ConsoleOutput] will be
   /// used.
   Logger({
-    LogFilter filter,
-    LogPrinter printer,
-    LogOutput output,
-    Level level,
+    LogFilter? filter,
+    LogPrinter? printer,
+    LogOutput? output,
+    Level? level,
   })  : _filter = filter ?? DevelopmentFilter(),
         _printer = printer ?? PrettyPrinter(),
         _output = output ?? ConsoleOutput() {
@@ -71,38 +71,38 @@ class Logger {
   }
 
   /// Log a message at level [Level.verbose].
-  void v(dynamic message, [dynamic error, StackTrace stackTrace]) {
+  void v(dynamic message, [dynamic error, StackTrace? stackTrace]) {
     log(Level.verbose, message, error, stackTrace);
   }
 
   /// Log a message at level [Level.debug].
-  void d(dynamic message, [dynamic error, StackTrace stackTrace]) {
+  void d(dynamic message, [dynamic error, StackTrace? stackTrace]) {
     log(Level.debug, message, error, stackTrace);
   }
 
   /// Log a message at level [Level.info].
-  void i(dynamic message, [dynamic error, StackTrace stackTrace]) {
+  void i(dynamic message, [dynamic error, StackTrace? stackTrace]) {
     log(Level.info, message, error, stackTrace);
   }
 
   /// Log a message at level [Level.warning].
-  void w(dynamic message, [dynamic error, StackTrace stackTrace]) {
+  void w(dynamic message, [dynamic error, StackTrace? stackTrace]) {
     log(Level.warning, message, error, stackTrace);
   }
 
   /// Log a message at level [Level.error].
-  void e(dynamic message, [dynamic error, StackTrace stackTrace]) {
+  void e(dynamic message, [dynamic error, StackTrace? stackTrace]) {
     log(Level.error, message, error, stackTrace);
   }
 
   /// Log a message at level [Level.wtf].
-  void wtf(dynamic message, [dynamic error, StackTrace stackTrace]) {
+  void wtf(dynamic message, [dynamic error, StackTrace? stackTrace]) {
     log(Level.wtf, message, error, stackTrace);
   }
 
   /// Log a message with [level].
   void log(Level level, dynamic message,
-      [dynamic error, StackTrace stackTrace]) {
+      [dynamic error, StackTrace? stackTrace]) {
     if (!_active) {
       throw ArgumentError('Logger has already been closed.');
     } else if (error != null && error is StackTrace) {

lib/src/outputs/file_output.dart

@@ -9,10 +9,10 @@ class FileOutput extends LogOutput {
   final File file;
   final bool overrideExisting;
   final Encoding encoding;
-  IOSink _sink;
+  IOSink? _sink;
 
   FileOutput({
-    this.file,
+    required this.file,
     this.overrideExisting = false,
     this.encoding = utf8,
   });
@@ -27,12 +27,12 @@ class FileOutput extends LogOutput {
 
   @override
   void output(OutputEvent event) {
-    _sink.writeAll(event.lines, '\n');
+    _sink?.writeAll(event.lines, '\n');
   }
 
   @override
   void destroy() async {
-    await _sink.flush();
-    await _sink.close();
+    await _sink?.flush();
+    await _sink?.close();
   }
 }

lib/src/outputs/memory_output.dart

@@ -9,7 +9,7 @@ class MemoryOutput extends LogOutput {
   final int bufferSize;
 
   /// A secondary [LogOutput] to also received events.
-  final LogOutput secondOutput;
+  final LogOutput? secondOutput;
 
   /// The buffer of events.
   final ListQueue<OutputEvent> buffer;
@@ -25,8 +25,6 @@ class MemoryOutput extends LogOutput {
 
     buffer.add(event);
 
-    if (secondOutput != null) {
-      secondOutput.output(event);
-    }
+    secondOutput?.output(event);
   }
 }

lib/src/outputs/multi_output.dart

@@ -3,18 +3,23 @@ import 'package:logger/src/logger.dart';
 
 /// Logs simultaneously to multiple [LogOutput] outputs.
 class MultiOutput extends LogOutput {
-  List<LogOutput> _outputs;
+  late List<LogOutput> _outputs;
 
-  MultiOutput(List<LogOutput> outputs) {
+  MultiOutput(List<LogOutput?>? outputs) {
     _outputs = _normalizeOutputs(outputs);
   }
-
-  List<LogOutput> _normalizeOutputs(List<LogOutput> outputs) {
-    if (outputs == null) return [];
-
-    outputs.removeWhere((o) => o == null);
-
-    return outputs;
+  List<LogOutput> _normalizeOutputs(List<LogOutput?>? outputs) {
+    final normalizedOutputs = <LogOutput>[];
+
+    if (outputs != null) {
+      for (final output in outputs) {
+        if (output != null) {
+          normalizedOutputs.add(output);
+        }
+      }
+    }
+
+    return normalizedOutputs;
   }
 
   @override

lib/src/outputs/stream_output.dart

@@ -4,7 +4,7 @@ import 'package:logger/src/logger.dart';
 import 'package:logger/src/log_output.dart';
 
 class StreamOutput extends LogOutput {
-  StreamController<List<String>> _controller;
+  late StreamController<List<String>> _controller;
   bool _shouldForward = false;
 
   StreamOutput() {