add back factory

docs/Toy/toy/dialects/toy.py

@@ -191,11 +191,9 @@ def __init__(
 
     @staticmethod
     def implicit_builder(name: str, ftype: FunctionType, /, private: bool = False):
-        Builder.assert_implicit()
-        block = Block(arg_types=ftype.inputs)
-        region = Region(block)
-        _op = FuncOp(name, ftype, region, private=private)
-        return Builder(block).implicit()
+        return Builder.op(
+            lambda body: FuncOp(name, ftype, body, private=private), ftype.inputs
+        )
 
     @staticmethod
     def from_callable(

xdsl/builder.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 from types import TracebackType
 
-from typing import Callable, ClassVar, Sequence, TypeAlias, overload
+from typing import Callable, ClassVar, Iterable, Sequence, TypeAlias, overload
 import threading
 import contextlib
 
@@ -207,6 +207,22 @@ def assert_implicit():
                 "op_builder must be called within an implicit builder block"
             )
 
+    @staticmethod
+    def op(
+        func: Callable[[Region], Operation],
+        arg_types: Iterable[Attribute] = (),
+    ) -> _ImplicitBuilder:
+        """
+        Will construct an op with a region, and populate child region.
+        Must be called within an implicit builder context.
+        """
+        Builder.assert_implicit()
+        b = Block(arg_types=arg_types)
+        r = Region(b)
+        # will be added to parent implicit builder
+        _op = func(r)
+        return Builder(b).implicit()
+
 
 # Implicit builders
 

xdsl/dialects/func.py

@@ -102,11 +102,10 @@ def implicit_builder(
         input_types: Sequence[Attribute],
         return_types: Sequence[Attribute],
     ):
-        Builder.assert_implicit()
-        block = Block(arg_types=input_types)
-        region = Region(block)
-        _op = FuncOp.from_region(name, input_types, return_types, region)
-        return Builder(block).implicit()
+        return Builder.op(
+            lambda body: FuncOp.from_region(name, input_types, return_types, body),
+            input_types,
+        )
 
     def replace_argument_type(self, arg: int | BlockArgument, new_type: Attribute):
         """

xdsl/dialects/pdl.py

@@ -495,11 +495,7 @@ def implicit_builder(
         benefit: int | IntegerAttr[IntegerType],
         sym_name: str | StringAttr | None,
     ):
-        Builder.assert_implicit()
-        block = Block()
-        body = Region(block)
-        PatternOp(benefit, sym_name, body)
-        return Builder(block).implicit()
+        return Builder.op(lambda body: PatternOp(benefit, sym_name, body))
 
     @classmethod
     def parse(cls, parser: Parser) -> PatternOp:
@@ -824,11 +820,7 @@ def implicit_builder(
         name: str | StringAttr | None = None,
         external_args: Sequence[SSAValue] = (),
     ):
-        Builder.assert_implicit()
-        block = Block()
-        body = Region(block)
-        RewriteOp(root, body, name, external_args)
-        return Builder(block).implicit()
+        return Builder.op(lambda body: RewriteOp(root, body, name, external_args))
 
 
 @irdl_op_definition