Replace shell/Perl-style variables in install schemes with format-style.

2 files changed, 60 insertions, 47 deletions

diff --git a/distutils/command/install.py b/distutils/command/install.py
index 1267a51e..0f4ff70c 100644
--- a/distutils/command/install.py
+++ b/distutils/command/install.py
@@ -21,62 +21,62 @@ from site import USER_SITE
 HAS_USER_SITE = True
 
 WINDOWS_SCHEME = {
-    'purelib': '$base/Lib/site-packages',
-    'platlib': '$base/Lib/site-packages',
-    'include': '$base/Include/$dist_name',
-    'scripts': '$base/Scripts',
-    'data'   : '$base',
+    'purelib': '{base}/Lib/site-packages',
+    'platlib': '{base}/Lib/site-packages',
+    'include': '{base}/Include/{dist_name}',
+    'scripts': '{base}/Scripts',
+    'data'   : '{base}',
 }
 
 INSTALL_SCHEMES = {
     'unix_prefix': {
-        'purelib': '$base/lib/python$py_version_short/site-packages',
-        'platlib': '$platbase/$platlibdir/python$py_version_short/site-packages',
-        'include': '$base/include/python$py_version_short$abiflags/$dist_name',
-        'scripts': '$base/bin',
-        'data'   : '$base',
+        'purelib': '{base}/lib/python{py_version_short}/site-packages',
+        'platlib': '{platbase}/{platlibdir}/python{py_version_short}/site-packages',
+        'include': '{base}/include/python{py_version_short}{abiflags}/{dist_name}',
+        'scripts': '{base}/bin',
+        'data'   : '{base}',
         },
     'unix_home': {
-        'purelib': '$base/lib/python',
-        'platlib': '$base/$platlibdir/python',
-        'include': '$base/include/python/$dist_name',
-        'scripts': '$base/bin',
-        'data'   : '$base',
+        'purelib': '{base}/lib/python',
+        'platlib': '{base}/{platlibdir}/python',
+        'include': '{base}/include/python/{dist_name}',
+        'scripts': '{base}/bin',
+        'data'   : '{base}',
         },
     'nt': WINDOWS_SCHEME,
     'pypy': {
-        'purelib': '$base/site-packages',
-        'platlib': '$base/site-packages',
-        'include': '$base/include/$dist_name',
-        'scripts': '$base/bin',
-        'data'   : '$base',
+        'purelib': '{base}/site-packages',
+        'platlib': '{base}/site-packages',
+        'include': '{base}/include/{dist_name}',
+        'scripts': '{base}/bin',
+        'data'   : '{base}',
         },
     'pypy_nt': {
-        'purelib': '$base/site-packages',
-        'platlib': '$base/site-packages',
-        'include': '$base/include/$dist_name',
-        'scripts': '$base/Scripts',
-        'data'   : '$base',
+        'purelib': '{base}/site-packages',
+        'platlib': '{base}/site-packages',
+        'include': '{base}/include/{dist_name}',
+        'scripts': '{base}/Scripts',
+        'data'   : '{base}',
         },
     }
 
 # user site schemes
 if HAS_USER_SITE:
     INSTALL_SCHEMES['nt_user'] = {
-        'purelib': '$usersite',
-        'platlib': '$usersite',
-        'include': '$userbase/Python$py_version_nodot/Include/$dist_name',
-        'scripts': '$userbase/Python$py_version_nodot/Scripts',
-        'data'   : '$userbase',
+        'purelib': '{usersite}',
+        'platlib': '{usersite}',
+        'include': '{userbase}/Python{py_version_nodot}/Include/{dist_name}',
+        'scripts': '{userbase}/Python{py_version_nodot}/Scripts',
+        'data'   : '{userbase}',
         }
 
     INSTALL_SCHEMES['unix_user'] = {
-        'purelib': '$usersite',
-        'platlib': '$usersite',
+        'purelib': '{usersite}',
+        'platlib': '{usersite}',
         'include':
-            '$userbase/include/python$py_version_short$abiflags/$dist_name',
-        'scripts': '$userbase/bin',
-        'data'   : '$userbase',
+            '{userbase}/include/python{py_version_short}{abiflags}/{dist_name}',
+        'scripts': '{userbase}/bin',
+        'data'   : '{userbase}',
         }
 
 # The keys to an installation scheme; if any new types of files are to be
diff --git a/distutils/util.py b/distutils/util.py
index f5aca794..81d6869f 100644
--- a/distutils/util.py
+++ b/distutils/util.py
@@ -187,30 +187,43 @@ def check_environ ():
 
 
 def subst_vars (s, local_vars):
-    """Perform shell/Perl-style variable substitution on 'string'.  Every
-    occurrence of '$' followed by a name is considered a variable, and
-    variable is substituted by the value found in the 'local_vars'
-    dictionary, or in 'os.environ' if it's not in 'local_vars'.
+    """
+    Perform variable substitution on 'string'.
+    Variables are indicated by format-style braces ("{var}").
+    Variable is substituted by the value found in the 'local_vars'
+    dictionary or in 'os.environ' if it's not in 'local_vars'.
     'os.environ' is first checked/augmented to guarantee that it contains
     certain values: see 'check_environ()'.  Raise ValueError for any
     variables not found in either 'local_vars' or 'os.environ'.
     """
     check_environ()
-    def _subst (match, local_vars=local_vars):
-        var_name = match.group(1)
-        if var_name in local_vars:
-            return str(local_vars[var_name])
-        else:
-            return os.environ[var_name]
-
+    lookup = dict(os.environ)
+    lookup.update((name, str(value)) for name, value in local_vars.items())
     try:
-        return re.sub(r'\$([a-zA-Z_][a-zA-Z_0-9]*)', _subst, s)
+        return _subst_compat(s).format_map(lookup)
     except KeyError as var:
         raise ValueError("invalid variable '$%s'" % var)
 
 # subst_vars ()
 
 
+def _subst_compat(s):
+    """
+    Replace shell/Perl-style variable substitution with
+    format-style. For compatibility.
+    """
+    def _subst(match):
+        return f'{{{match.group(1)}}}'
+    repl = re.sub(r'\$([a-zA-Z_][a-zA-Z_0-9]*)', _subst, s)
+    if repl != s:
+        import warnings
+        warnings.warn(
+            "shell/Perl-style substitions are deprecated",
+            DeprecationWarning,
+        )
+    return repl
+
+
 def grok_environment_error (exc, prefix="error: "):
     # Function kept for backward compatibility.
     # Used to try clever things with EnvironmentErrors,