Merge pull request #4542 from ivanov/history-clear

new `ipython history clear` subcommand

This new subcommand is equivalent to ipython history trim --HistoryTrim.keep=0, which is now supported (and also has a more convenient --keep alias)

This command comes with a fix to bash completion of flags for ipython history subcmd

also included is a tiny fix for nbconvert completion that was pointed out by @jakobgager in  #4528

also included is a change to our utils.io.ask_yes_no function that allows for specifying the behavior of a KeyboardInterrupt.

docs/source/whatsnew/pr/bash-completion.rst

@@ -0,0 +1,1 b''
+* bash completion updated with support for all ipython subcommands and flags, including nbconvert

docs/source/whatsnew/pr/history-clear.rst

@@ -0,0 +1,4 b''
+* ``ipython history trim``: added ``--keep=<N>`` as an alias for the more verbose
+  ``--HistoryTrim.keep=<N>``
+* new ``ipython history clear`` subcommand, which is the same as the newly supported
+  ``ipython history trim --keep=0``

IPython/core/historyapp.py

@@ -12,13 +12,25 b' import sqlite3'
 from IPython.config.application import Application
 from IPython.core.application import BaseIPythonApplication
 from IPython.utils.traitlets import Bool, Int, Dict
+from IPython.utils.io import ask_yes_no
 
 trim_hist_help = """Trim the IPython history database to the last 1000 entries.
 
 This actually copies the last 1000 entries to a new database, and then replaces
-the old file with the new.
+the old file with the new. Use the `--keep=` argument to specify a number
+other than 1000.
 """
 
+clear_hist_help = """Clear the IPython history database, deleting all entries.
+
+Because this is a destructive operation, IPython will prompt the user if they
+really want to do this. Passing a `-f` flag will force clearing without a
+prompt.
+
+This is an handy alias to `ipython history trim --keep=0`
+"""
+
+
 class HistoryTrim(BaseIPythonApplication):
     description = trim_hist_help
     
@@ -30,10 +42,14 b' class HistoryTrim(BaseIPythonApplication):'
     
     flags = Dict(dict(
         backup = ({'HistoryTrim' : {'backup' : True}},
-            "Set Application.log_level to 0, maximizing log output."
+            backup.get_metadata('help')
         )
     ))
     
+    aliases=Dict(dict(
+        keep = 'HistoryTrim.keep'
+    ))
+    
     def start(self):
         profile_dir = self.profile_dir.location
         hist_file = os.path.join(profile_dir, 'history.sqlite')
@@ -44,13 +60,14 b' class HistoryTrim(BaseIPythonApplication):'
                                 'history ORDER BY session DESC, line DESC LIMIT ?', (self.keep+1,)))
         if len(inputs) <= self.keep:
             print("There are already at most %d entries in the history database." % self.keep)
-            print("Not doing anything.")
+            print("Not doing anything. Use --keep= argument to keep fewer entries")
             return
         
         print("Trimming history to the most recent %d entries." % self.keep)
         
         inputs.pop() # Remove the extra element we got to check the length.
         inputs.reverse()
+        if inputs:
         first_session = inputs[0][0]
         outputs = list(con.execute('SELECT session, line, output FROM '
                                    'output_history WHERE session >= ?', (first_session,)))
@@ -78,6 +95,7 b' class HistoryTrim(BaseIPythonApplication):'
         new_db.commit()
 
 
+        if inputs:
         with new_db:
             # Add the recent history into the new database.
             new_db.executemany('insert into sessions values (?,?,?,?,?)', sessions)
@@ -98,6 +116,27 b' class HistoryTrim(BaseIPythonApplication):'
         
         os.rename(new_hist_file, hist_file)
 
+class HistoryClear(HistoryTrim):
+    description = clear_hist_help
+    keep = Int(0, config=False,
+        help="Number of recent lines to keep in the database.")
+    
+    force = Bool(False, config=True,
+        help="Don't prompt user for confirmation")
+    
+    flags = Dict(dict(
+        force = ({'HistoryClear' : {'force' : True}},
+            force.get_metadata('help')),
+        f = ({'HistoryTrim' : {'force' : True}},
+            force.get_metadata('help')
+        )
+    ))
+    aliases = Dict()
+
+    def start(self):
+        if self.force or ask_yes_no("Really delete all ipython history? ",
+                default="no", interrupt="no"):
+            HistoryTrim.start(self)
 
 class HistoryApp(Application):
     name = u'ipython-history'
@@ -105,6 +144,7 b' class HistoryApp(Application):'
 
     subcommands = Dict(dict(
         trim = (HistoryTrim, HistoryTrim.description.splitlines()[0]),
+        clear = (HistoryClear, HistoryClear.description.splitlines()[0]),
     ))
 
     def start(self):

IPython/utils/io.py

@@ -155,11 +155,13 b' class Tee(object):'
             self.close()
 
 
-def ask_yes_no(prompt,default=None):
+def ask_yes_no(prompt, default=None, interrupt=None):
     """Asks a question and returns a boolean (y/n) answer.
 
     If default is given (one of 'y','n'), it is used if the user input is
-    empty. Otherwise the question is repeated until an answer is given.
+    empty. If interrupt is given (one of 'y','n'), it is used if the user
+    presses Ctrl-C. Otherwise the question is repeated until an answer is
+    given.
 
     An EOF is treated as the default answer.  If there is no default, an
     exception is raised to prevent infinite loops.
@@ -174,7 +176,8 b' def ask_yes_no(prompt,default=None):'
             if not ans:  # response was an empty string
                 ans = default
         except KeyboardInterrupt:
-            pass
+            if interrupt:
+                ans = interrupt
         except EOFError:
             if default in answers.keys():
                 ans = default

examples/core/ipython-completion.bash

@@ -46,12 +46,21 b' _ipython()'
 
     if [[ ${cur} == -* ]]; then
         case $mode in
-            "notebook" | "qtconsole" | "console" | "kernel")
+            "notebook" | "qtconsole" | "console" | "kernel" | "nbconvert")
                 _ipython_get_flags $mode
                 opts=$"${opts} ${baseopts}"
                 ;;
-            "locate" | "history" | "profile")
+            "locate" | "profile")
                 _ipython_get_flags $mode
+                ;;
+            "history")
+                if [[ $COMP_CWORD -ge 3 ]]; then
+                    # 'history trim' and 'history clear' covered by next line
+                    _ipython_get_flags history\ "${COMP_WORDS[2]}"
+                else
+                    _ipython_get_flags $mode
+
+                fi
                 opts=$"${opts}"
                 ;;
             *)
@@ -63,9 +72,16 b' _ipython()'
         return 0
     elif [[ $mode == "profile" ]]; then
         opts="list create locate"
+        local IFS=$'\t\n'
         COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
     elif [[ $mode == "history" ]]; then
-        opts="trim"
+        if [[ $COMP_CWORD -ge 3 ]]; then
+            # drop into flags
+            opts="--"
+        else
+            opts="trim 	clear "
+        fi
+        local IFS=$'\t\n'
         COMPREPLY=( $(compgen -W "${opts}" -- ${cur}) )
     elif [[ $mode == "locate" ]]; then
         opts="profile"