Patch run() placeholder substitutions to honor configuration defaults

This is the companion of datalad/datalad#7509

Closes #478

datalad_next/patches/enabled.py

@@ -12,4 +12,5 @@
     test_keyring,
     customremotes_main,
     create_sibling_gitlab,
+    run,
 )

datalad_next/patches/run.py

@@ -0,0 +1,84 @@
+"""Enhance ``run()`` placeholder substitutions to honor configuration defaults
+
+Previously, ``run()`` would not recognize configuration defaults for
+placeholder substitution. This means that any placeholders globally declared in
+``datalad.interface.common_cfg``, or via ``register_config()`` in DataLad
+extensions would not be effective.
+
+This patch makes run's ``format_command()`` helper include such defaults
+explicitly, and thereby enable the global declaration of substitution defaults.
+
+Moreoever a ``{python}`` placeholder is now defined via this mechanism, and
+points to the value of ``sys.executable`` by default. This particular
+placeholder was found to be valueable for improving the portability of
+run-recording across (specific) Python versions, or across different (virtual)
+environments. See https://github.com/datalad/datalad-container/issues/224 for
+an example use case.
+
+https://github.com/datalad/datalad/pull/7509
+"""
+
+import sys
+
+from datalad.core.local.run import (
+    GlobbedPaths,
+    SequenceFormatter,
+    normalize_command,
+    quote_cmdlinearg,
+)
+from datalad.interface.common_cfg import definitions as cfg_defs
+from datalad.support.constraints import EnsureStr
+from datalad.support.extensions import register_config
+
+from . import apply_patch
+
+
+# This function is taken from datalad-core@a96c51c0b2794b2a2b4432ec7bd51f260cb91a37
+# datalad/core/local/run.py
+# The change has been proposed in https://github.com/datalad/datalad/pull/7509
+def format_command(dset, command, **kwds):
+    """Plug in placeholders in `command`.
+
+    Parameters
+    ----------
+    dset : Dataset
+    command : str or list
+
+    `kwds` is passed to the `format` call. `inputs` and `outputs` are converted
+    to GlobbedPaths if necessary.
+
+    Returns
+    -------
+    formatted command (str)
+    """
+    command = normalize_command(command)
+    sfmt = SequenceFormatter()
+
+    for k in set(cfg_defs.keys()).union(dset.config.keys()):
+        v = dset.config.get(
+            k,
+            # pull a default from the config definitions
+            # if we have no value, but a key
+            cfg_defs.get(k, {}).get('default', None))
+        sub_key = k.replace("datalad.run.substitutions.", "")
+        if sub_key not in kwds:
+            kwds[sub_key] = v
+
+    for name in ["inputs", "outputs"]:
+        io_val = kwds.pop(name, None)
+        if not isinstance(io_val, GlobbedPaths):
+            io_val = GlobbedPaths(io_val, pwd=kwds.get("pwd"))
+        kwds[name] = list(map(quote_cmdlinearg, io_val.expand(dot=False)))
+    return sfmt.format(command, **kwds)
+
+
+apply_patch(
+    'datalad.core.local.run', None, 'format_command', format_command)
+register_config(
+    'datalad.run.substitutions.python',
+    'Substitution for {python} placeholder',
+    description='Path to a Python interpreter executable',
+    type=EnsureStr(),
+    default=sys.executable,
+    dialog='question',
+)

datalad_next/patches/tests/test_run.py

@@ -0,0 +1,25 @@
+import pytest
+
+from datalad_next.exceptions import IncompleteResultsError
+from datalad_next.tests.utils import (
+    SkipTest,
+    assert_result_count,
+)
+
+
+def test_substitution_config_default(existing_dataset):
+    ds = existing_dataset
+
+    if ds.config.get('datalad.run.substitutions.python') is not None:
+        # we want to test default handling when no config is set
+        raise SkipTest(
+            'Test assumptions conflict with effective configuration')
+
+    # the {python} placeholder is not explicitly defined, but it has
+    # a default, which run() should discover and use
+    res = ds.run('{python} -c "True"', result_renderer='disabled')
+    assert_result_count(res, 1, action='run', status='ok')
+
+    # make sure we could actually detect breakage with the check above
+    with pytest.raises(IncompleteResultsError):
+        ds.run('{python} -c "breakage"', result_renderer='disabled')

docs/source/patches.rst

@@ -16,3 +16,4 @@ DataLad patches
    push_to_export_remote
    test_keyring
    siblings
+   run