Remove deprecated functions (#642)

* Remove deprecated frontend methods

* Removed deprecated legacy model builder class

* fix

* Fix serializer test

Author: hcho3

docs/treelite-api.rst

@@ -28,19 +28,13 @@ Model builder
     :members:
     :member-order: bysource
 
-Model builder (Legacy)
-----------------------
-
-.. autoclass:: treelite.ModelBuilder
-    :members:
-    :member-order: bysource
-
 Model class
 -----------
 
 .. autoclass:: treelite.Model
    :members:
    :member-order: bysource
+   :exclude-members: load, from_xgboost, from_xgboost_json, from_lightgbm
 
 
 .. _field_accessors:

ops/test-serializer-compatibility.sh

@@ -3,7 +3,7 @@
 set -euo pipefail
 
 echo "##[section]Building Treelite..."
-mkdir build
+mkdir -p build
 cd build
 cmake .. -GNinja
 ninja
@@ -19,6 +19,14 @@ PYTHONPATH=./python/ python tests/serializer/compatibility_tester.py --task load
   --checkpoint-path checkpoint.bin --model-pickle-path model.pkl \
   --expected-treelite-version ${CURRENT_VERSION}
 
+echo "##[section]Testing serialization: 4.3.0 -> ${CURRENT_VERSION}"
+pip install --force-reinstall treelite==4.3.0
+python tests/serializer/compatibility_tester.py --task save --checkpoint-path checkpoint.bin \
+  --model-pickle-path model.pkl --expected-treelite-version 4.3.0
+PYTHONPATH=./python/ python tests/serializer/compatibility_tester.py --task load \
+  --checkpoint-path checkpoint.bin --model-pickle-path model.pkl \
+  --expected-treelite-version ${CURRENT_VERSION}
+
 echo "##[section]Testing serialization: ${CURRENT_VERSION} -> ${CURRENT_VERSION}"
 PYTHONPATH=./python/ python tests/serializer/compatibility_tester.py --task save \
   --checkpoint-path checkpoint.bin --model-pickle-path model.pkl \

python/treelite/__init__.py

@@ -5,7 +5,6 @@
 from . import frontend, gtil, model_builder, sklearn
 from .core import TreeliteError
 from .model import Model
-from .model_builder_legacy import ModelBuilder
 
 VERSION_FILE = pathlib.Path(__file__).parent / "VERSION"
 with open(VERSION_FILE, "r", encoding="UTF-8") as _f:
@@ -18,6 +17,5 @@
     "sklearn",
     "model_builder",
     "TreeliteError",
-    "ModelBuilder",
     "__version__",
 ]