Rewrite file clone implementation

This method avoids calling `__init__` on the clones, and instead clones each
member. It also improves how we track "parent" objects and how shallow clones
work.

Author: jimporter

bfg9000/builtins/copy_file.py

@@ -34,9 +34,9 @@ def convert_args(context, name, file, kwargs):
             directory = buildpath(context, directory, strict=True)
         file = context['auto_file'](file)
 
-        def pathfn(file):
+        def pathfn(p, obj):
             if name is None:
-                path = file.path.reroot()
+                path = p.reroot()
                 if directory:
                     return within_directory(path, directory)
                 return path
@@ -62,8 +62,8 @@ def __init__(self, context, output, file, *, extra_deps=None,
     def convert_args(context, file, kwargs):
         file = context['auto_file'](file)
 
-        def pathfn(file):
-            return file.path.reroot().addext('.gz')
+        def pathfn(p, obj):
+            return p.reroot().addext('.gz')
 
         output = file.clone(pathfn)
         return output, file, kwargs

bfg9000/builtins/install.py

@@ -49,28 +49,28 @@ def __iter__(self):
 
 
 def installify(file, *, directory=None, cross=None):
-    def pathfn(f):
-        if f is not file and f.private:
+    def pathfn(p, obj):
+        if obj is not file and obj.private:
             # Private subfiles won't (and in some cases can't) be installed.
-            return f.path
-        if f.path.root not in (path.Root.srcdir, path.Root.builddir):
+            return p
+        if p.root not in (path.Root.srcdir, path.Root.builddir):
             raise ValueError('external files are not installable')
 
         # Get the install root.
         if isinstance(directory, path.Path):
             install_root = directory
             if not isinstance(install_root.root, path.InstallRoot):
                 raise ValueError('not an install directory')
-        elif f.install_root is None:
+        elif obj.install_root is None:
             raise TypeError(('{!r} is not installable; specify an absolute ' +
-                             'install directory?').format(type(f).__name__))
+                             'install directory?').format(type(obj).__name__))
         elif directory:
-            install_root = path.Path(directory, f.install_root)
+            install_root = path.Path(directory, obj.install_root)
         else:
-            install_root = f.install_root
+            install_root = obj.install_root
 
-        cls = cross.target_platform.Path if cross else type(f.path)
-        return cls(f.install_suffix, install_root, destdir=not cross)
+        cls = cross.target_platform.Path if cross else type(p)
+        return cls(obj.install_suffix, install_root, destdir=not cross)
 
     if not isinstance(file, BaseFile):
         raise TypeError('expected a file or directory')