added utility decorator for better function signatures

slic/utils/__init__.py

@@ -1,5 +1,6 @@
 
 from .utils import *
+from .argfwd import forwards_to
 from .channels import Channels
 from .config import Config
 from .elog import Elog

slic/utils/argfwd.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python
+
+import inspect
+
+
+def forwards_to(func_inner, nfilled=0):
+    """
+    Decorator inserting an explicit signature for functions that forward their arguments to other function via *args/**kwargs
+
+    The decorated function forwards its arguments to func_inner
+    This decorator replaces *args and **kwargs in the signature of the decorated function with explicit arguments from the signature of func_inner
+    nfilled positional arguments of func_inner are filled by the decorated function and thus ignored during the replacement
+    """
+    pos_inner, kw_inner = get_args(func_inner)
+    pos_inner = pos_inner[nfilled:]
+
+    def deco(func_outer):
+        pos_outer, kw_outer = get_args(func_outer)
+
+        pos_comb = merge_lists_unique(pos_outer, pos_inner)
+        kw_comb  = merge_dicts_unique(kw_outer, kw_inner)
+
+        func_outer.__signature__ = make_signature(pos_comb, kw_comb)
+        return func_outer
+
+    return deco
+
+
+
+def get_args(func):
+    spec = inspect.getfullargspec(func) #TODO replace by inspect.signature?
+    all_args = spec.args
+
+    defaults = spec.defaults or []
+    isplit = -len(defaults) or None
+
+    pos, kw = split_at(all_args, isplit)
+    kw = dict(zip(kw, defaults))
+
+    #TODO treat these separately (also positional only)
+    kwonly = spec.kwonlydefaults
+    if kwonly:
+        kw.update(kwonly)
+
+    return pos, kw
+
+
+def split_at(lst, index):
+    return lst[:index], lst[index:]
+
+def merge_lists_unique(a, b):
+    only_in_b = [i for i in b if i not in a]
+    return a + only_in_b
+
+def merge_dicts_unique(a, b):
+    only_in_b = {k:v for k, v in b.items() if k not in a}
+    return dict(**a, **only_in_b)
+
+def make_signature(pos, kw):
+    params = make_params_pos(pos) + make_params_kw(kw)
+    return inspect.Signature(parameters=params)
+
+def make_params_pos(pos, kind=inspect.Parameter.POSITIONAL_OR_KEYWORD):
+    return [inspect.Parameter(n, kind) for n in pos]
+
+def make_params_kw(kw, kind=inspect.Parameter.POSITIONAL_OR_KEYWORD):
+    return [inspect.Parameter(n, kind, default=v) for n, v in kw.items()]
+
+
+
+
+
+if __name__ == "__main__":
+
+    def old(xold, yold, a, b, c=10, d=11):
+        print(a, b, c, d)
+
+    @forwards_to(old, nfilled=2)
+    def new(x, y, z, a, *args, d=12, **kwargs):
+        print(x, y, z, a, d)
+        return old(1, 2, a, *args, d=d, **kwargs)
+
+
+    class Scanner:
+
+        def make_scan(self, adjustables, positions, n_pulses, filename, detectors=None, channels=None, pvs=None, acquisitions=(), start_immediately=True, step_info=None, return_to_initial_values=None, repeat=1):
+            pass
+
+        @forwards_to(make_scan, nfilled=3)
+        def scan1D(self, adjustable, start_pos, end_pos, step_size, *args, relative=False, **kwargs):
+            pass
+
+
+