Altered behavior further to lean towards giving the developer more power over the end user

Specifically:
- PAGER environment variable is not used by default to set cmd2.Cmd.pager
    - This is done to ensure a consistent behavior of cmd2 applications across users by default

Developers are free to set pager and pager_chop in the __init__() for their class derived from cmd2.Cmd differently to ensure whatever behavior they desire.

Also:
- Updated the paged_output.py example to demonstrate using ppaged() with both wrapped and chopped/truncated text

Author: tleonhardt

CHANGELOG.md

@@ -4,8 +4,8 @@
 * Enhancements
     * Added ability to print a header above tab-completion suggestions using `completion_header` member
     * Added ``pager`` and ``pager_chop`` attributes to the ``cmd2.Cmd`` class
-        * ``pager`` looks for *PAGER* environment variable if present or uses sane defaults if not
-        * ``pager_chop`` appends a **-S** flag if ``pager`` starts with **less**
+        * ``pager`` defaults to **less -RXF** on POSIX and **more** on Windows
+        * ``pager_chop`` defaults to **less -SRXF** on POSIX and **more** on Windows
     * Added ``chop`` argument to ``cmd2.Cmd.ppaged()`` method for displaying output using a pager
         * If ``chop`` is ``False``, then ``self.pager`` is used as the pager
         * Otherwise ``self.pager_chop`` is used as the pager

cmd2/cmd2.py

@@ -535,22 +535,16 @@ def __init__(self, completekey: str='tab', stdin=None, stdout=None, persistent_h
         self.matches_delimited = False
 
         # Set the pager(s) for use with the ppaged() method for displaying output using a pager
-        self.pager = os.environ.get('PAGER')
-        if not self.pager:
-            if sys.platform.startswith('win'):
-                self.pager = self.pager_chop = 'more'
-            else:
-                # Here is the meaning of the various flags we are using with the less command:
-                # -S causes lines longer than the screen width to be chopped (truncated) rather than wrapped
-                # -R causes ANSI "color" escape sequences to be output in raw form (i.e. colors are displayed)
-                # -X disables sending the termcap initialization and deinitialization strings to the terminal
-                # -F causes less to automatically exit if the entire file can be displayed on the first screen
-                self.pager = 'less -RXF'
-                self.pager_chop = 'less -SRXF'
+        if sys.platform.startswith('win'):
+            self.pager = self.pager_chop = 'more'
         else:
-            self.pager_chop = self.pager
-            if self.pager_chop.startswith('less'):
-                self.pager_chop += ' -S'
+            # Here is the meaning of the various flags we are using with the less command:
+            # -S causes lines longer than the screen width to be chopped (truncated) rather than wrapped
+            # -R causes ANSI "color" escape sequences to be output in raw form (i.e. colors are displayed)
+            # -X disables sending the termcap initialization and deinitialization strings to the terminal
+            # -F causes less to automatically exit if the entire file can be displayed on the first screen
+            self.pager = 'less -RXF'
+            self.pager_chop = 'less -SRXF'
 
     # -----  Methods related to presenting output to the user -----
 

examples/paged_output.py

@@ -14,25 +14,43 @@ class PagedOutput(cmd2.Cmd):
     def __init__(self):
         super().__init__()
 
+    def page_file(self, file_path: str, chop: bool=False):
+        """Helper method to prevent having too much duplicated code."""
+        filename = os.path.expanduser(file_path)
+        try:
+            with open(filename, 'r') as f:
+                text = f.read()
+            self.ppaged(text, chop=chop)
+        except FileNotFoundError as ex:
+            self.perror('ERROR: file {!r} not found'.format(filename), traceback_war=False)
+
     @cmd2.with_argument_list
-    def do_page_file(self, args: List[str]):
-        """Read in a text file and display its output in a pager.
+    def do_page_wrap(self, args: List[str]):
+        """Read in a text file and display its output in a pager, wrapping long lines if they don't fit.
 
-        Usage: page_file <file_path>
+        Usage: page_wrap <file_path>
         """
         if not args:
-            self.perror('page_file requires a path to a file as an argument', traceback_war=False)
+            self.perror('page_wrap requires a path to a file as an argument', traceback_war=False)
             return
+        self.page_file(args[0], chop=False)
 
-        filename = os.path.expanduser(args[0])
-        try:
-            with open(filename, 'r') as f:
-                text = f.read()
-            self.ppaged(text)
-        except FileNotFoundError as ex:
-            self.perror('ERROR: file {!r} not found'.format(filename), traceback_war=False)
+    complete_page_wrap = cmd2.Cmd.path_complete
+
+    @cmd2.with_argument_list
+    def do_page_truncate(self, args: List[str]):
+        """Read in a text file and display its output in a pager, truncating long lines if they don't fit.
+
+        Truncated lines can still be accessed by scrolling to the right using the arrow keys.
+
+        Usage: page_chop <file_path>
+        """
+        if not args:
+            self.perror('page_truncate requires a path to a file as an argument', traceback_war=False)
+            return
+        self.page_file(args[0], chop=True)
 
-    complete_page_file = cmd2.Cmd.path_complete
+    complete_page_truncate = cmd2.Cmd.path_complete
 
 
 if __name__ == '__main__':