requires dependencies

alto/images/docker_image.py

@@ -31,6 +31,7 @@
     _check_optional_key_in_conf
 )
 from alto.output import OutputManager
+from alto.utils import requires_dependencies
 
 
 ##########
@@ -53,6 +54,10 @@ class Docker(BaseImage, ConfigMixin):
     CLIENT: Any
     image_version: Optional[str] = None
 
+    @requires_dependencies(
+        "docker",
+        "docker",
+    )
     def __init__(self,
         alto_wkdir: Path,
         image_name: str,

alto/utils.py

@@ -4,8 +4,10 @@
 
 # Imports
 from dataclasses import dataclass
-from typing import Any, Dict, Optional, List, Union
+from functools import wraps
+import importlib
 from pathlib import Path
+from typing import Any, Dict, Callable, Optional, List, Union
 
 
 # Functions / Utils
@@ -167,3 +169,52 @@ def paths_flattener(list_of_paths: List[Union[str, Path]]) -> List[Path]:
         flattened_paths.append(Path("/".join(spath)))
 
     return flattened_paths
+
+
+def requires_dependencies(
+    dependencies: Union[str, List[str]],
+    extras: Optional[str] = None,
+):
+    """
+    Wrapper used to prompt the user to `pip install` a package and/or Prism extracts in
+    order to run a function. Borrowed heavily from the `unstructured` library:
+        https://github.com/Unstructured-IO/unstructured/blob/main/unstructured/utils.py
+
+    args:
+        dependencies: required dependencies
+        extracts: list of Prism extras that the user can `pip install`
+    """
+    if isinstance(dependencies, str):
+        dependencies = [dependencies]
+
+    def decorator(func: Callable[..., Any]) -> Callable[..., Any]:
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            missing_deps: List[str] = []
+            for dep in dependencies:
+                if not dependency_exists(dep):
+                    missing_deps.append(dep)
+            if len(missing_deps) > 0:
+                raise ImportError(
+                    f"""Following dependencies are missing: {', '.join(["`" + dep + "`" for dep in missing_deps])}. """  # noqa
+                    + (  # noqa
+                        f"""Please install them using `pip install "alto-dev[{extras}]"`."""  # noqa
+                        if extras
+                        else f"Please install them using `pip install {' '.join(missing_deps)}`."  # noqa
+                    ),
+                )
+            return func(*args, **kwargs)
+
+        return wrapper
+    return decorator
+
+
+def dependency_exists(dependency: str):
+    try:
+        importlib.import_module(dependency)
+    except ImportError as e:
+        # Check to make sure this isn't some unrelated import error.
+        pkg = dependency.split(".")[0]
+        if pkg in repr(e):
+            return False
+    return True