factory: LazyFunction to just call a function in the simplest case

No need to wrap it in a lambda to strip the object argument from LazyAttribute or the sequence argument from Sequence.

2 files changed, 18 insertions, 0 deletions

diff --git a/factory/__init__.py b/factory/__init__.py
index c8bc396..1fa581b 100644
--- a/factory/__init__.py
+++ b/factory/__init__.py
@@ -43,6 +43,7 @@ from .base import (
 from .faker import Faker
 
 from .declarations import (
+    LazyFunction,
     LazyAttribute,
     Iterator,
     Sequence,
diff --git a/factory/declarations.py b/factory/declarations.py
index f0dbfe5..9ab7462 100644
--- a/factory/declarations.py
+++ b/factory/declarations.py
@@ -57,6 +57,23 @@ class OrderedDeclaration(object):
         raise NotImplementedError('This is an abstract method')
 
 
+class LazyFunction(OrderedDeclaration):
+    """Simplest OrderedDeclaration computed by calling the given function.
+
+    Attributes:
+        function (function): a function without arguments and
+            returning the computed value.
+    """
+
+    def __init__(self, function, *args, **kwargs):
+        super(LazyFunction, self).__init__(*args, **kwargs)
+        self.function = function
+
+    def evaluate(self, sequence, obj, create, extra=None, containers=()):
+        logger.debug("LazyFunction: Evaluating %r on %r", self.function, obj)
+        return self.function()
+
+
 class LazyAttribute(OrderedDeclaration):
     """Specific OrderedDeclaration computed using a lambda.