change: Implement override solution for pipeline variables

src/sagemaker/estimator.py

@@ -74,9 +74,7 @@
     get_config_value,
     name_from_base,
 )
-from sagemaker.workflow.entities import Expression
-from sagemaker.workflow.parameters import Parameter
-from sagemaker.workflow.properties import Properties
+from sagemaker.workflow.entities import PipelineVariable
 
 logger = logging.getLogger(__name__)
 
@@ -602,7 +600,7 @@ def _json_encode_hyperparameters(hyperparameters: Dict[str, Any]) -> Dict[str, A
         current_hyperparameters = hyperparameters
         if current_hyperparameters is not None:
             hyperparameters = {
-                str(k): (v if isinstance(v, (Parameter, Expression, Properties)) else json.dumps(v))
+                str(k): (v.to_string() if isinstance(v, PipelineVariable) else json.dumps(v))
                 for (k, v) in current_hyperparameters.items()
             }
         return hyperparameters
@@ -1813,7 +1811,7 @@ def _get_train_args(cls, estimator, inputs, experiment_config):
         current_hyperparameters = estimator.hyperparameters()
         if current_hyperparameters is not None:
             hyperparameters = {
-                str(k): (v if isinstance(v, (Parameter, Expression, Properties)) else str(v))
+                str(k): (v.to_string() if isinstance(v, PipelineVariable) else str(v))
                 for (k, v) in current_hyperparameters.items()
             }
 

src/sagemaker/parameter.py

@@ -14,9 +14,8 @@
 from __future__ import absolute_import
 
 import json
-from sagemaker.workflow.parameters import Parameter as PipelineParameter
-from sagemaker.workflow.functions import JsonGet as PipelineJsonGet
-from sagemaker.workflow.functions import Join as PipelineJoin
+
+from sagemaker.workflow.entities import PipelineVariable
 
 
 class ParameterRange(object):
@@ -73,11 +72,11 @@ def as_tuning_range(self, name):
         return {
             "Name": name,
             "MinValue": str(self.min_value)
-            if not isinstance(self.min_value, (PipelineParameter, PipelineJsonGet, PipelineJoin))
-            else self.min_value,
+            if not isinstance(self.min_value, PipelineVariable)
+            else self.min_value.to_string(),
             "MaxValue": str(self.max_value)
-            if not isinstance(self.max_value, (PipelineParameter, PipelineJsonGet, PipelineJoin))
-            else self.max_value,
+            if not isinstance(self.max_value, PipelineVariable)
+            else self.max_value.to_string(),
             "ScalingType": self.scaling_type,
         }
 
@@ -112,8 +111,7 @@ def __init__(self, values):  # pylint: disable=super-init-not-called
         """
         values = values if isinstance(values, list) else [values]
         self.values = [
-            str(v) if not isinstance(v, (PipelineParameter, PipelineJsonGet, PipelineJoin)) else v
-            for v in values
+            str(v) if not isinstance(v, PipelineVariable) else v.to_string() for v in values
         ]
 
     def as_tuning_range(self, name):

src/sagemaker/tuner.py

@@ -38,6 +38,7 @@
     IntegerParameter,
     ParameterRange,
 )
+from sagemaker.workflow.entities import PipelineVariable
 from sagemaker.workflow.parameters import Parameter as PipelineParameter
 from sagemaker.workflow.functions import JsonGet as PipelineJsonGet
 from sagemaker.workflow.functions import Join as PipelineJoin
@@ -376,9 +377,7 @@ def _prepare_static_hyperparameters(
         """Prepare static hyperparameters for one estimator before tuning."""
         # Remove any hyperparameter that will be tuned
         static_hyperparameters = {
-            str(k): str(v)
-            if not isinstance(v, (PipelineParameter, PipelineJsonGet, PipelineJoin))
-            else v
+            str(k): str(v) if not isinstance(v, PipelineVariable) else v.to_string()
             for (k, v) in estimator.hyperparameters().items()
         }
         for hyperparameter_name in hyperparameter_ranges.keys():

src/sagemaker/workflow/entities.py

@@ -16,7 +16,7 @@
 import abc
 
 from enum import EnumMeta
-from typing import Any, Dict, List, Union
+from typing import Any, Dict, List, Union, Optional
 
 PrimitiveType = Union[str, int, bool, float, None]
 RequestType = Union[Dict[str, Any], List[Dict[str, Any]]]
@@ -57,3 +57,80 @@ class Expression(abc.ABC):
     @abc.abstractmethod
     def expr(self) -> RequestType:
         """Get the expression structure for workflow service calls."""
+
+
+class PipelineVariable(Expression):
+    """Base object for pipeline variables
+
+    PipelineVariables must implement the expr property.
+    """
+
+    def __add__(self, other: Union[Expression, PrimitiveType]):
+        """Add function for PipelineVariable
+
+        Args:
+            other (Union[Expression, PrimitiveType]): The other object to be concatenated.
+
+        Always raise an error since pipeline variables do not support concatenation
+        """
+
+        raise TypeError("Pipeline variables do not support concatenation.")
+
+    def __str__(self):
+        """Override built-in String function for PipelineVariable"""
+        raise TypeError("Pipeline variables do not support __str__ operation.")
+
+    def __int__(self):
+        """Override built-in Integer function for PipelineVariable"""
+        raise TypeError("Pipeline variables do not support __int__ operation.")
+
+    def __float__(self):
+        """Override built-in Float function for PipelineVariable"""
+        raise TypeError("Pipeline variables do not support __float__ operation.")
+
+    def to_string(self):
+        """Prompt the pipeline to convert the pipeline variable to String in runtime"""
+        from sagemaker.workflow.functions import Join
+
+        return Join(on="", values=[self])
+
+    @property
+    @abc.abstractmethod
+    def expr(self) -> RequestType:
+        """Get the expression structure for workflow service calls."""
+
+    def startswith(
+        self,
+        prefix: Union[str, tuple],  # pylint: disable=unused-argument
+        start: Optional[int] = None,  # pylint: disable=unused-argument
+        end: Optional[int] = None,  # pylint: disable=unused-argument
+    ) -> bool:
+        """Simulate the Python string's built-in method: startswith
+
+        Args:
+            prefix (str, tuple): The (tuple of) string to be checked.
+            start (int): To set the start index of the matching boundary (default: None).
+            end (int): To set the end index of the matching boundary (default: None).
+
+        Return:
+            bool: Always return False as Pipeline variables are parsed during execution runtime
+        """
+        return False
+
+    def endswith(
+        self,
+        suffix: Union[str, tuple],  # pylint: disable=unused-argument
+        start: Optional[int] = None,  # pylint: disable=unused-argument
+        end: Optional[int] = None,  # pylint: disable=unused-argument
+    ) -> bool:
+        """Simulate the Python string's built-in method: endswith
+
+        Args:
+            suffix (str, tuple): The (tuple of) string to be checked.
+            start (int): To set the start index of the matching boundary (default: None).
+            end (int): To set the end index of the matching boundary (default: None).
+
+        Return:
+            bool: Always return False as Pipeline variables are parsed during execution runtime
+        """
+        return False

src/sagemaker/workflow/execution_variables.py

@@ -14,12 +14,12 @@
 from __future__ import absolute_import
 
 from sagemaker.workflow.entities import (
-    Expression,
     RequestType,
+    PipelineVariable,
 )
 
 
-class ExecutionVariable(Expression):
+class ExecutionVariable(PipelineVariable):
     """Pipeline execution variables for workflow."""
 
     def __init__(self, name: str):
@@ -30,6 +30,13 @@ def __init__(self, name: str):
         """
         self.name = name
 
+    def to_string(self) -> PipelineVariable:
+        """Prompt the pipeline to convert the pipeline variable to String in runtime
+
+        As ExecutionVariable is treated as String in runtime, no extra actions are needed.
+        """
+        return self
+
     @property
     def expr(self) -> RequestType:
         """The 'Get' expression dict for an `ExecutionVariable`."""

src/sagemaker/workflow/functions.py

@@ -17,12 +17,12 @@
 
 import attr
 
-from sagemaker.workflow.entities import Expression
+from sagemaker.workflow.entities import PipelineVariable
 from sagemaker.workflow.properties import PropertyFile
 
 
 @attr.s
-class Join(Expression):
+class Join(PipelineVariable):
     """Join together properties.
 
     Examples:
@@ -38,15 +38,23 @@ class Join(Expression):
     Attributes:
         values (List[Union[PrimitiveType, Parameter, Expression]]):
             The primitive type values, parameters, step properties, expressions to join.
-        on_str (str): The string to join the values on (Defaults to "").
+        on (str): The string to join the values on (Defaults to "").
     """
 
     on: str = attr.ib(factory=str)
     values: List = attr.ib(factory=list)
 
+    def to_string(self) -> PipelineVariable:
+        """Prompt the pipeline to convert the pipeline variable to String in runtime
+
+        As Join is treated as String in runtime, no extra actions are needed.
+        """
+        return self
+
     @property
     def expr(self):
         """The expression dict for a `Join` function."""
+
         return {
             "Std:Join": {
                 "On": self.on,
@@ -58,7 +66,7 @@ def expr(self):
 
 
 @attr.s
-class JsonGet(Expression):
+class JsonGet(PipelineVariable):
     """Get JSON properties from PropertyFiles.
 
     Attributes:

src/sagemaker/workflow/parameters.py

@@ -24,6 +24,7 @@
     Entity,
     PrimitiveType,
     RequestType,
+    PipelineVariable,
 )
 
 
@@ -48,7 +49,7 @@ def python_type(self) -> Type:
 
 
 @attr.s
-class Parameter(Entity):
+class Parameter(PipelineVariable, Entity):
     """Pipeline parameter for workflow.
 
     Attributes:
@@ -170,6 +171,13 @@ def __hash__(self):
         """Hash function for parameter types"""
         return hash(tuple(self.to_request()))
 
+    def to_string(self) -> PipelineVariable:
+        """Prompt the pipeline to convert the pipeline variable to String in runtime
+
+        As ParameterString is treated as String in runtime, no extra actions are needed.
+        """
+        return self
+
     def to_request(self) -> RequestType:
         """Get the request structure for workflow service calls."""
         request_dict = super(ParameterString, self).to_request()

src/sagemaker/workflow/properties.py

@@ -13,16 +13,17 @@
 """The properties definitions for workflow."""
 from __future__ import absolute_import
 
+from abc import ABCMeta
 from typing import Dict, Union, List
 
 import attr
 
 import botocore.loaders
 
-from sagemaker.workflow.entities import Expression
+from sagemaker.workflow.entities import Expression, PipelineVariable
 
 
-class PropertiesMeta(type):
+class PropertiesMeta(ABCMeta):
     """Load an internal shapes attribute from the botocore service model
 
     for sagemaker and emr service.
@@ -44,7 +45,7 @@ def __new__(mcs, *args, **kwargs):
         return super().__new__(mcs, *args, **kwargs)
 
 
-class Properties(metaclass=PropertiesMeta):
+class Properties(PipelineVariable, metaclass=PropertiesMeta):
     """Properties for use in workflow expressions."""
 
     def __init__(