Merge pull request #441 from python-cmd2/ppaged_pager_env

Added pager and pager_chop attributes to Cmd class

1 files changed, 25 insertions, 14 deletions

diff --git a/cmd2/cmd2.py b/cmd2/cmd2.py
index 75946764..f143d7b3 100644
--- a/cmd2/cmd2.py
+++ b/cmd2/cmd2.py
@@ -534,6 +534,18 @@ class Cmd(cmd.Cmd):
         # quote matches that are completed in a delimited fashion
         self.matches_delimited = False
 
+        # Set the pager(s) for use with the ppaged() method for displaying output using a 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'
+
     # -----  Methods related to presenting output to the user -----
 
     @property
@@ -608,14 +620,20 @@ class Cmd(cmd.Cmd):
             else:
                 sys.stderr.write("{}\n".format(msg))
 
-    def ppaged(self, msg: str, end: str='\n') -> None:
+    def ppaged(self, msg: str, end: str='\n', chop: bool=False) -> None:
         """Print output using a pager if it would go off screen and stdout isn't currently being redirected.
 
         Never uses a pager inside of a script (Python or text) or when output is being redirected or piped or when
         stdout or stdin are not a fully functional terminal.
 
-        :param msg: str - message to print to current stdout - anything convertible to a str with '{}'.format() is OK
-        :param end: str - string appended after the end of the message if not already present, default a newline
+        :param msg: message to print to current stdout - anything convertible to a str with '{}'.format() is OK
+        :param end: string appended after the end of the message if not already present, default a newline
+        :param chop: True  -> causes lines longer than the screen width to be chopped (truncated) rather than wrapped
+                              - truncated text is still accessible by scrolling with the right & left arrow keys
+                              - chopping is ideal for displaying wide tabular data as is done in utilities like pgcli
+                     False -> causes lines longer than the screen width to wrap to the next line
+                              - wrapping is ideal when you want to avoid users having to use horizontal scrolling
+                     WARNING: On Windows, the text always wraps regardless of what the chop argument is set to
         """
         import subprocess
         if msg is not None and msg != '':
@@ -635,17 +653,10 @@ class Cmd(cmd.Cmd):
                 # Don't attempt to use a pager that can block if redirecting or running a script (either text or Python)
                 # Also only attempt to use a pager if actually running in a real fully functional terminal
                 if functional_terminal and not self.redirecting and not self._in_py and not self._script_dir:
-
-                    if sys.platform.startswith('win'):
-                        pager_cmd = '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
-                        pager_cmd = 'less -SRXF'
-                    self.pipe_proc = subprocess.Popen(pager_cmd, shell=True, stdin=subprocess.PIPE)
+                    pager = self.pager
+                    if chop:
+                        pager = self.pager_chop
+                    self.pipe_proc = subprocess.Popen(pager, shell=True, stdin=subprocess.PIPE)
                     try:
                         self.pipe_proc.stdin.write(msg_str.encode('utf-8', 'replace'))
                         self.pipe_proc.stdin.close()