Moved clipboard/pastebuffer functionality to new file clipboard.py

Also:
- Converted global can_clip variable to an instance attribute of cmd2.Cmd class

Author: tleonhardt

cmd2/clipboard.py

@@ -0,0 +1,49 @@
+# coding=utf-8
+"""
+This module provides basic ability to copy from and paste to the clipboard/pastebuffer.
+"""
+import sys
+
+import pyperclip
+
+# Newer versions of pyperclip are released as a single file, but older versions had a more complicated structure
+try:
+    from pyperclip.exceptions import PyperclipException
+except ImportError:  # pragma: no cover
+    # noinspection PyUnresolvedReferences
+    from pyperclip import PyperclipException
+
+# Can we access the clipboard?  Should always be true on Windows and Mac, but only sometimes on Linux
+# noinspection PyUnresolvedReferences
+try:
+    # Get the version of the pyperclip module as a float
+    pyperclip_ver = float('.'.join(pyperclip.__version__.split('.')[:2]))
+
+    # The extraneous output bug in pyperclip on Linux using xclip was fixed in more recent versions of pyperclip
+    if sys.platform.startswith('linux') and pyperclip_ver < 1.6:
+        # Avoid extraneous output to stderr from xclip when clipboard is empty at cost of overwriting clipboard contents
+        pyperclip.copy('')
+    else:
+        # Try getting the contents of the clipboard
+        _ = pyperclip.paste()
+except PyperclipException:
+    can_clip = False
+else:
+    can_clip = True
+
+
+def get_paste_buffer() -> str:
+    """Get the contents of the clipboard / paste buffer.
+
+    :return: contents of the clipboard
+    """
+    pb_str = pyperclip.paste()
+    return pb_str
+
+
+def write_to_paste_buffer(txt: str) -> None:
+    """Copy text to the clipboard / paste buffer.
+
+    :param txt: text to copy to the clipboard
+    """
+    pyperclip.copy(txt)

cmd2/cmd2.py

@@ -41,16 +41,15 @@
 import sys
 from typing import Any, Callable, Dict, List, Mapping, Optional, Tuple, Union
 
-import pyperclip
-
 from . import constants
 from . import utils
-
-from cmd2.parsing import StatementParser, Statement
+from .argparse_completer import AutoCompleter, ACArgumentParser
+from .clipboard import can_clip, get_paste_buffer, write_to_paste_buffer
+from .parsing import StatementParser, Statement
 
 # Set up readline
 from .rl_utils import rl_type, RlType
-if rl_type == RlType.NONE: # pragma: no cover
+if rl_type == RlType.NONE:  # pragma: no cover
     rl_warning = "Readline features including tab completion have been disabled since no \n" \
                  "supported version of readline was found. To resolve this, install \n" \
                  "pyreadline on Windows or gnureadline on Mac.\n\n"
@@ -79,15 +78,6 @@
         rl_basic_quote_characters = ctypes.c_char_p.in_dll(readline_lib, "rl_basic_quote_characters")
         orig_rl_basic_quotes = ctypes.cast(rl_basic_quote_characters, ctypes.c_void_p).value
 
-from .argparse_completer import AutoCompleter, ACArgumentParser
-
-# Newer versions of pyperclip are released as a single file, but older versions had a more complicated structure
-try:
-    from pyperclip.exceptions import PyperclipException
-except ImportError: # pragma: no cover
-    # noinspection PyUnresolvedReferences
-    from pyperclip import PyperclipException
-
 # Collection is a container that is sizable and iterable
 # It was introduced in Python 3.6. We will try to import it, otherwise use our implementation
 try:
@@ -121,7 +111,7 @@ def __subclasshook__(cls, C):
 try:
     # noinspection PyUnresolvedReferences,PyPackageRequirements
     from IPython import embed
-except ImportError: # pragma: no cover
+except ImportError:  # pragma: no cover
     ipython_available = False
 
 __version__ = '0.9.2a'
@@ -271,48 +261,6 @@ def cmd_wrapper(instance, cmdline):
     return arg_decorator
 
 
-# Can we access the clipboard?  Should always be true on Windows and Mac, but only sometimes on Linux
-# noinspection PyUnresolvedReferences
-try:
-    # Get the version of the pyperclip module as a float
-    pyperclip_ver = float('.'.join(pyperclip.__version__.split('.')[:2]))
-
-    # The extraneous output bug in pyperclip on Linux using xclip was fixed in more recent versions of pyperclip
-    if sys.platform.startswith('linux') and pyperclip_ver < 1.6:
-        # Avoid extraneous output to stderr from xclip when clipboard is empty at cost of overwriting clipboard contents
-        pyperclip.copy('')
-    else:
-        # Try getting the contents of the clipboard
-        _ = pyperclip.paste()
-except PyperclipException:
-    can_clip = False
-else:
-    can_clip = True
-
-
-def disable_clip() -> None:
-    """ Allows user of cmd2 to manually disable clipboard cut-and-paste functionality."""
-    global can_clip
-    can_clip = False
-
-
-def get_paste_buffer() -> str:
-    """Get the contents of the clipboard / paste buffer.
-
-    :return: contents of the clipboard
-    """
-    pb_str = pyperclip.paste()
-    return pb_str
-
-
-def write_to_paste_buffer(txt: str) -> None:
-    """Copy text to the clipboard / paste buffer.
-
-    :param txt: text to copy to the clipboard
-    """
-    pyperclip.copy(txt)
-
-
 class EmbeddedConsoleExit(SystemExit):
     """Custom exception class for use with the py command."""
     pass
@@ -546,6 +494,9 @@ def __init__(self, completekey: str='tab', stdin=None, stdout=None, persistent_h
             self.pager = 'less -RXF'
             self.pager_chop = 'less -SRXF'
 
+        # This boolean flag determines whether or not the cmd2 application can interact with the clipboard
+        self.can_clip = can_clip
+
     # -----  Methods related to presenting output to the user -----
 
     @property
@@ -1881,7 +1832,7 @@ def _redirect_output(self, statement: Statement) -> None:
                 raise ex
         elif statement.output:
             import tempfile
-            if (not statement.output_to) and (not can_clip):
+            if (not statement.output_to) and (not self.can_clip):
                 raise EnvironmentError("Cannot redirect to paste buffer; install 'pyperclip' and re-run to enable")
             self.kept_state = Statekeeper(self, ('stdout',))
             self.kept_sys = Statekeeper(sys, ('stdout',))

tests/test_cmd2.py

@@ -22,6 +22,7 @@
     from unittest import mock
 
 import cmd2
+from cmd2 import clipboard
 from cmd2 import utils
 from .conftest import run_cmd, normalize, BASE_HELP, BASE_HELP_VERBOSE, \
     HELP_HISTORY, SHORTCUTS_TXT, SHOW_TXT, SHOW_LONG, StdOut
@@ -735,7 +736,7 @@ def test_pipe_to_shell_error(base_app, capsys):
     assert err.startswith("EXCEPTION of type '{}' occurred with message:".format(expected_error))
 
 
-@pytest.mark.skipif(not cmd2.cmd2.can_clip,
+@pytest.mark.skipif(not clipboard.can_clip,
                     reason="Pyperclip could not find a copy/paste mechanism for your system")
 def test_send_to_paste_buffer(base_app):
     # Test writing to the PasteBuffer/Clipboard
@@ -1454,13 +1455,12 @@ def test_multiline_complete_statement_without_terminator(multiline_app):
     assert statement.command == command
 
 
-def test_clipboard_failure(capsys):
+def test_clipboard_failure(base_app, capsys):
     # Force cmd2 clipboard to be disabled
-    cmd2.cmd2.disable_clip()
-    app = cmd2.Cmd()
+    base_app.can_clip = False
 
     # Redirect command output to the clipboard when a clipboard isn't present
-    app.onecmd_plus_hooks('help > ')
+    base_app.onecmd_plus_hooks('help > ')
 
     # Make sure we got the error output
     out, err = capsys.readouterr()