build.Cmd: Add module

Cmd is meant as a base class for classes representing commands
currently still implemented as methods of the Project class.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/build/Cmd.py

@@ -0,0 +1,58 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import annotations
+from typing import Type, Union, TypeVar
+import inspect, abc, argparse
+from argparse import ArgumentParser
+
+class Cmd(abc.ABC): # export
+
+    def __init__(self, name: str, help: str) -> None:
+        from .App import App
+        self.name = name
+        self.help = help
+        self.parent = None
+        self.children: list[Cmd] = []
+        self.child_classes: list[Type[Cmd]] = []
+        self.app: App|None = None
+
+    @abc.abstractmethod
+    def _run(self, args):
+        pass
+
+    def run(self, args):
+        return self._run(args)
+
+    def add_parser(self, parsers) -> ArgumentParser:
+        r = parsers.add_parser(self.name, help=self.help,
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+        r.set_defaults(func=self.run)
+        return r
+
+    def add_subcommands(self, cmd: Union[str, Type[Cmd], list[Type[Cmd]]]) -> None:
+        if isinstance(cmd, str):
+            import sys, re
+            sc = []
+            for name, obj in inspect.getmembers(sys.modules[self.__class__.__module__]):
+                if inspect.isclass(obj):
+                    if re.search(cmd, str(obj)):
+                        sc.append(obj)
+                        log.slog(log.DEBUG, f"Found subcommand {obj}")
+            self.add_subcommands(sc)
+            return
+        if isinstance(cmd, list):
+            for c in cmd:
+                self.add_subcommands(c)
+            return
+        self.child_classes.append(cmd)
+
+    # To be overridden by derived class in case the command does take arguments.
+    # Will be called from App base class constructor and set up the parser hierarchy
+    def add_arguments(self, parser: ArgumentParser) -> None:
+        pass
+
+    def conf_value(self, path, default=None):
+        ret = None if self.app is None else self.app.conf_value(path, default)
+        if ret is None and default is not None:
+            return default
+        return ret