Trac #24286: py3: minor fixes to sage.repl.load and sage.repl.attach

This will be one of many tickets I will be opening for miscellaneous
minor fixes to specific modules.

In some cases I'll keep these more "thematic" in which case they might
span multiple modules, but in other cases it is simpler to submit one
module at a time for minor fixes.

See the commit messages for more details about individual fixes.

URL: https://trac.sagemath.org/24286
Reported by: embray
Ticket author(s): Erik Bray
Reviewer(s): Jeroen Demeyer

src/sage/repl/attach.py

@@ -39,7 +39,7 @@
     ....:     traceback.print_exc()
     Traceback (most recent call last):
     ...
-        exec(preparse_file(open(fpath).read()) + "\n", globals)
+        exec(preparse_file(f.read()) + "\n", globals)
       File "<string>", line 3, in <module>
     ValueError: third
     sage: detach(src)

src/sage/repl/load.py

@@ -16,6 +16,8 @@
 import os
 import base64
 
+from sage.cpython.string import str_to_bytes, bytes_to_str, FS_ENCODING
+
 def is_loadable_filename(filename):
     """
     Returns whether a file can be loaded into Sage.  This checks only
@@ -96,33 +98,36 @@ def load(filename, globals, attach=False):
     Note that ``.py`` files are *not* preparsed::
 
         sage: t = tmp_filename(ext='.py')
-        sage: _ = open(t,'w').write("print 'hi', 2/3; z = -2/7")
+        sage: with open(t, 'w') as f:
+        ....:     _ = f.write("print(('hi', 2^3)); z = -2^7")
         sage: z = 1
-        sage: sage.repl.load.load(t, globals())  # py2
-        hi 0
-        sage: z  # py2
-        -1
+        sage: sage.repl.load.load(t, globals())
+        ('hi', 1)
+        sage: z
+        -7
 
     A ``.sage`` file *is* preparsed::
 
         sage: t = tmp_filename(ext='.sage')
-        sage: _ = open(t,'w').write("print 'hi', 2/3; z = -2/7")
+        sage: with open(t, 'w') as f:
+        ....:     _ = f.write("print(('hi', 2^3)); z = -2^7")
         sage: z = 1
         sage: sage.repl.load.load(t, globals())
-        hi 2/3
+        ('hi', 8)
         sage: z
-        -2/7
+        -128
 
     Cython files are *not* preparsed::
 
         sage: t = tmp_filename(ext='.pyx')
-        sage: _ = open(t,'w').write("print 'hi', 2/3; z = -2/7")
+        sage: with open(t, 'w') as f:
+        ....:     _ = f.write("print(('hi', 2^3)); z = -2^7")
         sage: z = 1
         sage: sage.repl.load.load(t, globals())
         Compiling ...
-        hi 0
+        ('hi', 1)
         sage: z
-        -1
+        -7
 
     If the file isn't a Cython, Python, or a Sage file, a ValueError
     is raised::
@@ -145,7 +150,8 @@ def load(filename, globals, attach=False):
     We attach a file::
 
         sage: t = tmp_filename(ext='.py')
-        sage: _ = open(t,'w').write("print 'hello world'")
+        sage: with open(t, 'w') as f:
+        ....:     _ = f.write("print('hello world')")
         sage: sage.repl.load.load(t, globals(), attach=True)
         hello world
         sage: t in attached_files()
@@ -166,10 +172,12 @@ def load(filename, globals, attach=False):
         sage: load_attach_path()
         ['.']
         sage: t_dir = tmp_dir()
-        sage: fullpath = os.path.join(t_dir, 'test.py')
-        sage: _ = open(fullpath, 'w').write("print 37 * 3")
+        sage: fname = 'test.py'
+        sage: fullpath = os.path.join(t_dir, fname)
+        sage: with open(fullpath, 'w') as f:
+        ....:     _ = f.write("print(37 * 3)")
         sage: load_attach_path(t_dir)
-        sage: attach('test.py')
+        sage: attach(fname)
         111
         sage: sage.repl.attach.reset(); reset_load_attach_path() # clean up
 
@@ -185,7 +193,9 @@ def load(filename, globals, attach=False):
 
     Make sure that load handles filenames with spaces in the name or path::
 
-        sage: t = tmp_filename(ext=' b.sage'); _ = open(t,'w').write("print 2")
+        sage: t = tmp_filename(ext=' b.sage')
+        sage: with open(t, 'w') as f:
+        ....:     _ = f.write("print(2)")
         sage: sage.repl.load.load(t, globals())
         2
 
@@ -244,7 +254,8 @@ def load(filename, globals, attach=False):
             # Preparse in memory only for speed.
             if attach:
                 add_attached_file(fpath)
-            exec(preparse_file(open(fpath).read()) + "\n", globals)
+            with open(fpath) as f:
+                exec(preparse_file(f.read()) + "\n", globals)
     elif ext == '.spyx' or ext == '.pyx':
         if attach:
             add_attached_file(fpath)
@@ -286,8 +297,14 @@ def load_wrap(filename, attach=False):
         'sage.repl.load.load(sage.repl.load.base64.b64decode("Zm9vLnB5"),globals(),True)'
         sage: sage.repl.load.load_wrap('foo.sage')
         'sage.repl.load.load(sage.repl.load.base64.b64decode("Zm9vLnNhZ2U="),globals(),False)'
-        sage: sage.repl.load.base64.b64decode("Zm9vLnNhZ2U=")
-        'foo.sage'
+        sage: m = sage.repl.load.base64.b64decode("Zm9vLnNhZ2U=")
+        sage: m == b'foo.sage'
+        True
     """
+
+    # Note: On Python 3 b64encode only accepts bytes, and returns bytes (yet
+    # b64decode does accept str, but always returns bytes)
+    b64 = base64.b64encode(str_to_bytes(filename, FS_ENCODING,
+                                        "surrogateescape"))
     return 'sage.repl.load.load(sage.repl.load.base64.b64decode("{}"),globals(),{})'.format(
-        base64.b64encode(filename), attach)
+            bytes_to_str(b64, 'ascii'), attach)