fix(defaults): Lazy Loading fetchers to lower memory usage on importing

scrapling/defaults.py

@@ -1,10 +1,19 @@
-from .fetchers import AsyncFetcher as _AsyncFetcher
-from .fetchers import Fetcher as _Fetcher
-from .fetchers import PlayWrightFetcher as _PlayWrightFetcher
-from .fetchers import StealthyFetcher as _StealthyFetcher
-
 # If you are going to use Fetchers with the default settings, import them from this file instead for a cleaner looking code
-Fetcher = _Fetcher()
-AsyncFetcher = _AsyncFetcher()
-StealthyFetcher = _StealthyFetcher()
-PlayWrightFetcher = _PlayWrightFetcher()
+
+# A lightweight approach to create lazy loader for each import for backward compatibility
+# This will reduces initial memory footprint significantly (only loads what's used)
+def __getattr__(name):
+    if name == 'Fetcher':
+        from scrapling.fetchers import Fetcher as cls
+        return cls()
+    elif name == 'AsyncFetcher':
+        from scrapling.fetchers import AsyncFetcher as cls
+        return cls()
+    elif name == 'StealthyFetcher':
+        from scrapling.fetchers import StealthyFetcher as cls
+        return cls()
+    elif name == 'PlayWrightFetcher':
+        from scrapling.fetchers import PlayWrightFetcher as cls
+        return cls()
+    else:
+        raise AttributeError(f"module 'scrapling' has no attribute '{name}'")