Merge pull request #191 from mahmoud/pipe-spec

pipe spec

glom/__init__.py

@@ -21,6 +21,7 @@
                        Let,  # backwards compat 2020-07
                        Coalesce,
                        Inspect,
+                       Pipe,
                        GlomError,
                        BadSpec,
                        PathAccessError,

glom/core.py

@@ -1779,6 +1779,26 @@ def _handle_tuple(target, spec, scope):
     return res
 
 
+class Pipe(object):
+    """Evaluate specs one after the other, passing the result of
+    the previous evaluation in as the target of the next spec:
+
+      >>> glom({'a': {'b': -5}}, Pipe('a', 'b', abs))
+      5
+
+    Same behavior as ``Auto(tuple(steps))``, but useful for explicit
+    usage in other modes.
+    """
+    def __init__(self, *steps):
+        self.steps = steps
+
+    def glomit(self, target, scope):
+        return _handle_tuple(target, self.steps, scope)
+
+    def __repr__(self):
+        return self.__class__.__name__ + bbrepr(self.steps)
+
+
 class TargetRegistry(object):
     '''
     responsible for registration of target types for iteration

glom/test/test_basic.py

@@ -5,7 +5,7 @@
 import pytest
 
 from glom import glom, SKIP, STOP, Path, Inspect, Coalesce, CoalesceError, Val, Call, T, S, Invoke, Spec, Ref
-from glom import Auto, Fill, Iter, A, Vars, Val, Literal, GlomError
+from glom import Auto, Fill, Iter, A, Vars, Val, Literal, GlomError, Pipe
 
 import glom.core as glom_core
 from glom.core import UP, ROOT, bbformat, bbrepr
@@ -424,6 +424,11 @@ def test_ref():
     glom(etree, etree2tuples)
 
 
+def test_pipe():
+    assert glom(1, Pipe("__class__", "__name__", str.upper)) == 'INT'
+    assert repr(Pipe(1, Pipe([2], dict))) == 'Pipe(1, Pipe([2], dict))'
+
+
 _IS_PYPY = '__pypy__' in sys.builtin_module_names
 @pytest.mark.skipif(_IS_PYPY, reason='pypy othertype.__repr__ is never object.__repr__')
 def test_api_repr():