Modularization fixes for fast_callable interpreters

src/sage/ext/fast_callable.pyx

@@ -465,41 +465,72 @@ def fast_callable(x, domain=None, vars=None,
         etb = ExpressionTreeBuilder(vars=vars, domain=domain)
         et = x._fast_callable_(etb)
 
-    if isinstance(domain, sage.rings.abc.RealField):
-        from sage.ext.interpreters.wrapper_rr import Wrapper_rr as builder
-        str = InstructionStream(sage.ext.interpreters.wrapper_rr.metadata,
-                                len(vars),
-                                domain)
-
-    elif isinstance(domain, sage.rings.abc.ComplexField):
-        from sage.ext.interpreters.wrapper_cc import Wrapper_cc as builder
-        str = InstructionStream(sage.ext.interpreters.wrapper_cc.metadata,
-                                len(vars),
-                                domain)
-
-    elif isinstance(domain, sage.rings.abc.RealDoubleField) or domain is float:
-        from sage.ext.interpreters.wrapper_rdf import Wrapper_rdf as builder
-        str = InstructionStream(sage.ext.interpreters.wrapper_rdf.metadata,
-                                len(vars),
-                                domain)
-    elif isinstance(domain, sage.rings.abc.ComplexDoubleField):
-        from sage.ext.interpreters.wrapper_cdf import Wrapper_cdf as builder
-        str = InstructionStream(sage.ext.interpreters.wrapper_cdf.metadata,
-                                len(vars),
-                                domain)
-    elif domain is None:
-        from sage.ext.interpreters.wrapper_py import Wrapper_py as builder
-        str = InstructionStream(sage.ext.interpreters.wrapper_py.metadata,
-                                len(vars))
-    else:
-        from sage.ext.interpreters.wrapper_el import Wrapper_el as builder
-        str = InstructionStream(sage.ext.interpreters.wrapper_el.metadata,
-                                len(vars),
-                                domain)
+    builder, str = _builder_and_stream(vars=vars, domain=domain)
+
     generate_code(et, str)
     str.instr('return')
     return builder(str.get_current())
 
+
+def _builder_and_stream(vars, domain):
+    r"""
+    Return a builder and a stream.
+
+    INPUT:
+
+    - ``vars`` -- a sequence of variable names
+
+    - ``domain`` -- a Sage parent or Python type or ``None``; if non-``None``,
+      all arithmetic is done in that domain
+
+    OUTPUT: A :class:`Wrapper`, an class:`InstructionStream`
+
+    EXAMPLES:
+
+        sage: from sage.ext.fast_callable import _builder_and_stream
+        sage: _builder_and_stream(ZZ, ["x", "y"])
+
+    """
+    if isinstance(domain, sage.rings.abc.RealField):
+        try:
+            from sage.ext.interpreters.wrapper_rr import metadata, Wrapper_rr as builder
+        except ImportError:
+            pass
+        else:
+            return builder, InstructionStream(metadata, len(vars), domain)
+
+    if isinstance(domain, sage.rings.abc.ComplexField):
+        try:
+            from sage.ext.interpreters.wrapper_cc import metadata, Wrapper_cc as builder
+        except ImportError:
+            pass
+        else:
+            return builder, InstructionStream(metadata, len(vars), domain)
+
+    if isinstance(domain, sage.rings.abc.RealDoubleField) or domain is float:
+        try:
+            from sage.ext.interpreters.wrapper_rdf import metadata, Wrapper_rdf as builder
+        except ImportError:
+            pass
+        else:
+            return builder, InstructionStream(metadata, len(vars), domain)
+
+    if isinstance(domain, sage.rings.abc.ComplexDoubleField):
+        try:
+            from sage.ext.interpreters.wrapper_cdf import metadata, Wrapper_cdf as builder
+        except ImportError:
+            pass
+        else:
+            return builder, InstructionStream(metadata, len(vars), domain)
+
+    if domain is None:
+        from sage.ext.interpreters.wrapper_py import metadata, Wrapper_py as builder
+        return builder, InstructionStream(metadata, len(vars))
+
+    from sage.ext.interpreters.wrapper_el import metadata, Wrapper_el as builder
+    return builder, InstructionStream(metadata, len(vars), domain)
+
+
 def function_name(fn):
     r"""
     Given a function, return a string giving a name for the function.

src/sage_setup/autogen/interpreters/__init__.py

@@ -119,25 +119,10 @@
 from .instructions import *
 from .memory import *
 from .specs.base import *
-from .specs.cdf import *
-from .specs.element import *
-from .specs.python import *
-from .specs.rdf import *
-from .specs.rr import *
-from .specs.cc import *
 from .storage import *
 from .utils import *
 
 
-# Gather up a list of all interpreter classes imported into this module
-# A better way might be to recursively iterate InterpreterSpec.__subclasses__
-# or to use a registry, but this is fine for now.
-_INTERPRETERS = sorted(filter(lambda c: (isinstance(c, type) and
-                                         issubclass(c, InterpreterSpec) and
-                                         c.name),
-                              globals().values()),
-                       key=lambda c: c.name)
-
 # Tuple of (filename_root, extension, method) where filename_root is the
 # root of the filename to be joined with "_<interpreter_name>".ext and
 # method is the name of a get_ method on InterpreterGenerator that returns
@@ -174,7 +159,7 @@ def build_interp(interp_spec, dir):
         write_if_changed(path, method())
 
 
-def rebuild(dirname, force=False):
+def rebuild(dirname, force=False, interpreters=None, distribution=None):
     r"""
     Check whether the interpreter and wrapper sources have been written
     since the last time this module was changed.  If not, write them.
@@ -194,6 +179,20 @@ def rebuild(dirname, force=False):
     # you run it).
     print("Building interpreters for fast_callable")
 
+    if interpreters is None:
+        interpreters = ['CDF', 'Element', 'Python', 'RDF', 'RR', 'CC']
+
+    from importlib import import_module
+
+    _INTERPRETERS = [getattr(import_module('sage_setup.autogen.interpreters.specs.' + interpreter.lower()),
+                             interpreter + 'Interpreter')
+                     for interpreter in interpreters]
+
+    if distribution is None:
+        all_py = 'all.py'
+    else:
+        all_py = f'all__{distribution.replace("-", "_")}.py'
+
     try:
         os.makedirs(dirname)
     except OSError:
@@ -213,7 +212,7 @@ class NeedToRebuild(Exception):
     try:
         if force:
             raise NeedToRebuild("-> Force rebuilding interpreters")
-        gen_file = os.path.join(dirname, 'all.py')
+        gen_file = os.path.join(dirname, all_py)
         if not os.path.isfile(gen_file):
             raise NeedToRebuild("-> First build of interpreters")
 
@@ -235,5 +234,5 @@ class NeedToRebuild(Exception):
     for interp in _INTERPRETERS:
         build_interp(interp(), dirname)
 
-    with open(os.path.join(dirname, 'all.py'), 'w') as f:
+    with open(os.path.join(dirname, all_py), 'w') as f:
         f.write("# " + AUTOGEN_WARN)