enh: use function decorator

Co-authored-by: Chris Markiewicz <[email protected]>

Author: oesteban

templateflow/api.py

@@ -4,9 +4,10 @@
 import re
 import sys
 
-from .conf import TF_LAYOUT, TF_S3_ROOT, TF_USE_DATALAD
+from .conf import TF_LAYOUT, TF_S3_ROOT, TF_USE_DATALAD, requires_layout
 
 
+@requires_layout
 def get(template, raise_empty=False, **kwargs):
     """
     Fetch one file from one particular template.
@@ -61,10 +62,6 @@ def get(template, raise_empty=False, **kwargs):
     ...
 
     """
-    if TF_LAYOUT is None:
-        from bids import __version__
-        raise RuntimeError(f"A layout with PyBIDS <{__version__}> could not be initiated")
-
     out_file = [
         Path(p) for p in TF_LAYOUT.get(template=template, return_type="file", **kwargs)
     ]
@@ -115,9 +112,10 @@ def get(template, raise_empty=False, **kwargs):
     return out_file
 
 
+@requires_layout
 def templates(**kwargs):
     """
-    Returns a list of available templates.
+    Return a list of available templates.
 
     Keyword Arguments
     -----------------
@@ -141,13 +139,10 @@ def templates(**kwargs):
     ['MNI152Lin', 'MNI152NLin2009cAsym', 'MNI152NLin2009cSym', 'MNIInfant', 'MNIPediatricAsym']
 
     """
-    if TF_LAYOUT is None:
-        from bids import __version__
-        raise RuntimeError(f"A layout with PyBIDS <{__version__}> could not be initiated")
-
     return sorted(TF_LAYOUT.get_templates(**kwargs))
 
 
+@requires_layout
 def get_metadata(template):
     """
     Fetch one file from one template.
@@ -163,10 +158,6 @@ def get_metadata(template):
     'Linear ICBM Average Brain (ICBM152) Stereotaxic Registration Model'
 
     """
-    if TF_LAYOUT is None:
-        from bids import __version__
-        raise RuntimeError(f"A layout with PyBIDS <{__version__}> could not be initiated")
-
     tf_home = Path(TF_LAYOUT.root)
     filepath = tf_home / ("tpl-%s" % template) / "template_description.json"
 

templateflow/conf/__init__.py

@@ -3,6 +3,7 @@
 from warnings import warn
 from pathlib import Path
 from contextlib import suppress
+from functools import wraps
 
 TF_DEFAULT_HOME = Path.home() / ".cache" / "templateflow"
 TF_HOME = Path(getenv("TEMPLATEFLOW_HOME", str(TF_DEFAULT_HOME)))
@@ -17,6 +18,20 @@
 )
 TF_CACHED = True
 
+
+def requires_layout(func):
+    """Decorate function to ensure ``TF_LAYOUT`` is correctly initiated."""
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        from templateflow.conf import TF_LAYOUT
+
+        if TF_LAYOUT is None:
+            from bids import __version__
+            raise RuntimeError(f"A layout with PyBIDS <{__version__}> could not be initiated")
+        return func(*args, **kwargs)
+    return wrapper
+
+
 if not TF_HOME.exists() or not list(TF_HOME.iterdir()):
     TF_CACHED = False
     warn(