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bpo-30211: bdb: add docstrings (#1350)

This commit is contained in:
csabella 2017-05-16 18:28:02 -04:00 committed by terryjreedy
parent 4ae0149697
commit 0774e79b93
1 changed files with 212 additions and 18 deletions
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230
Lib/bdb.py
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@ -7,6 +7,7 @@ from inspect import CO_GENERATOR
__all__ = ["BdbQuit", "Bdb", "Breakpoint"]
class BdbQuit(Exception):
"""Exception to give up completely."""
@ -17,6 +18,12 @@ class Bdb:
This class takes care of details of the trace facility;
a derived class should implement user interaction.
The standard debugger class (pdb.Pdb) is an example.
The optional skip argument must be an iterable of glob-style
module name patterns. The debugger will not step into frames
that originate in a module that matches one of these patterns.
Whether a frame is considered to originate in a certain module
is determined by the __name__ in the frame globals.
"""
def __init__(self, skip=None):
@ -26,6 +33,13 @@ class Bdb:
self.frame_returning = None
def canonic(self, filename):
"""Return canonical form of filename.
For real filenames, the canonical form is a case-normalized (on
case insenstive filesystems) absolute path. 'Filenames' with
angle brackets, such as "<stdin>", generated in interactive
mode, are returned unchanged.
"""
if filename == "<" + filename[1:-1] + ">":
return filename
canonic = self.fncache.get(filename)
@ -36,12 +50,36 @@ class Bdb:
return canonic
def reset(self):
"""Set values of attributes as ready to start debugging."""
import linecache
linecache.checkcache()
self.botframe = None
self._set_stopinfo(None, None)
def trace_dispatch(self, frame, event, arg):
"""Dispatch a trace function for debugged frames based on the event.
This function is installed as the trace function for debugged
frames. Its return value is the new trace function, which is
usually itself. The default implementation decides how to
dispatch a frame, depending on the type of event (passed in as a
string) that is about to be executed.
The event can be one of the following:
line: A new line of code is going to be executed.
call: A function is about to be called or another code block
is entered.
return: A function or other code block is about to return.
exception: An exception has occurred.
c_call: A C function is about to be called.
c_return: A C functon has returned.
c_exception: A C function has raised an exception.
For the Python events, specialized functions (see the dispatch_*()
methods) are called. For the C events, no action is taken.
The arg parameter depends on the previous event.
"""
if self.quitting:
return # None
if event == 'line':
@ -62,12 +100,24 @@ class Bdb:
return self.trace_dispatch
def dispatch_line(self, frame):
"""Invoke user function and return trace function for line event.
If the debugger stops on the current line, invoke
self.user_line(). Raise BdbQuit if self.quitting is set.
Return self.trace_dispatch to continue tracing in this scope.
"""
if self.stop_here(frame) or self.break_here(frame):
self.user_line(frame)
if self.quitting: raise BdbQuit
return self.trace_dispatch
def dispatch_call(self, frame, arg):
"""Invoke user function and return trace function for call event.
If the debugger stops on this function call, invoke
self.user_call(). Raise BbdQuit if self.quitting is set.
Return self.trace_dispatch to continue tracing in this scope.
"""
# XXX 'arg' is no longer used
if self.botframe is None:
# First call of dispatch since reset()
@ -84,6 +134,12 @@ class Bdb:
return self.trace_dispatch
def dispatch_return(self, frame, arg):
"""Invoke user function and return trace function for return event.
If the debugger stops on this function return, invoke
self.user_return(). Raise BdbQuit if self.quitting is set.
Return self.trace_dispatch to continue tracing in this scope.
"""
if self.stop_here(frame) or frame == self.returnframe:
# Ignore return events in generator except when stepping.
if self.stopframe and frame.f_code.co_flags & CO_GENERATOR:
@ -100,6 +156,12 @@ class Bdb:
return self.trace_dispatch
def dispatch_exception(self, frame, arg):
"""Invoke user function and return trace function for exception event.
If the debugger stops on this exception, invoke
self.user_exception(). Raise BdbQuit if self.quitting is set.
Return self.trace_dispatch to continue tracing in this scope.
"""
if self.stop_here(frame):
# When stepping with next/until/return in a generator frame, skip
# the internal StopIteration exception (with no traceback)
@ -125,12 +187,14 @@ class Bdb:
# definition of stopping and breakpoints.
def is_skipped_module(self, module_name):
"Return True if module_name matches any skip pattern."
for pattern in self.skip:
if fnmatch.fnmatch(module_name, pattern):
return True
return False
def stop_here(self, frame):
"Return True if frame is below the starting frame in the stack."
# (CT) stopframe may now also be None, see dispatch_call.
# (CT) the former test for None is therefore removed from here.
if self.skip and \
@ -145,6 +209,11 @@ class Bdb:
return False
def break_here(self, frame):
"""Return True if there is an effective breakpoint for this line.
Check for line or function breakpoint and if in effect.
Delete temporary breakpoints if effective() says to.
"""
filename = self.canonic(frame.f_code.co_filename)
if filename not in self.breaks:
return False
@ -167,33 +236,43 @@ class Bdb:
return False
def do_clear(self, arg):
"""Remove temporary breakpoint.
Must implement in derived classes or get NotImplementedError.
"""
raise NotImplementedError("subclass of bdb must implement do_clear()")
def break_anywhere(self, frame):
"""Return True if there is any breakpoint for frame's filename.
"""
return self.canonic(frame.f_code.co_filename) in self.breaks
# Derived classes should override the user_* methods
# to gain control.
def user_call(self, frame, argument_list):
"""This method is called when there is the remote possibility
that we ever need to stop in this function."""
"""Called if we might stop in a function."""
pass
def user_line(self, frame):
"""This method is called when we stop or break at this line."""
"""Called when when we stop or break at a line."""
pass
def user_return(self, frame, return_value):
"""This method is called when a return trap is set here."""
"""Called when a return trap is set here."""
pass
def user_exception(self, frame, exc_info):
"""This method is called if an exception occurs,
but only if we are to stop at or just below this level."""
"""Called when we stop on an exception."""
pass
def _set_stopinfo(self, stopframe, returnframe, stoplineno=0):
"""Set the attributes for stopping.
If stoplineno is greater than or equal to 0, then stop at line
greater than or equal to the stopline. If stoplineno is -1, then
don't stop at all.
"""
self.stopframe = stopframe
self.returnframe = returnframe
self.quitting = False
@ -205,8 +284,8 @@ class Bdb:
# to affect the stepping state.
def set_until(self, frame, lineno=None):
"""Stop when the line with the line no greater than the current one is
reached or when returning from current frame"""
"""Stop when the line with the lineno greater than the current one is
reached or when returning from current frame."""
# the name "until" is borrowed from gdb
if lineno is None:
lineno = frame.f_lineno + 1
@ -236,7 +315,7 @@ class Bdb:
self._set_stopinfo(frame.f_back, frame)
def set_trace(self, frame=None):
"""Start debugging from `frame`.
"""Start debugging from frame.
If frame is not specified, debugging starts from caller's frame.
"""
@ -251,6 +330,10 @@ class Bdb:
sys.settrace(self.trace_dispatch)
def set_continue(self):
"""Stop only at breakpoints or when finished.
If there are no breakpoints, set the system trace function to None.
"""
# Don't stop except at breakpoints or when finished
self._set_stopinfo(self.botframe, None, -1)
if not self.breaks:
@ -262,6 +345,10 @@ class Bdb:
frame = frame.f_back
def set_quit(self):
"""Set quitting attribute to True.
Raises BdbQuit exception in the next call to a dispatch_*() method.
"""
self.stopframe = self.botframe
self.returnframe = None
self.quitting = True
@ -269,13 +356,18 @@ class Bdb:
# Derived classes and clients can call the following methods
# to manipulate breakpoints. These methods return an
# error message is something went wrong, None if all is well.
# error message if something went wrong, None if all is well.
# Set_break prints out the breakpoint line and file:lineno.
# Call self.get_*break*() to see the breakpoints or better
# for bp in Breakpoint.bpbynumber: if bp: bp.bpprint().
def set_break(self, filename, lineno, temporary=False, cond=None,
funcname=None):
"""Set a new breakpoint for filename:lineno.
If lineno doesn't exist for the filename, return an error message.
The filename should be in canonical form.
"""
filename = self.canonic(filename)
import linecache # Import as late as possible
line = linecache.getline(filename, lineno)
@ -285,14 +377,26 @@ class Bdb:
if lineno not in list:
list.append(lineno)
bp = Breakpoint(filename, lineno, temporary, cond, funcname)
return None
def _prune_breaks(self, filename, lineno):
"""Prune breakpoints for filname:lineno.
A list of breakpoints is maintained in the Bdb instance and in
the Breakpoint class. If a breakpoint in the Bdb instance no
longer exists in the Breakpoint class, then it's removed from the
Bdb instance.
"""
if (filename, lineno) not in Breakpoint.bplist:
self.breaks[filename].remove(lineno)
if not self.breaks[filename]:
del self.breaks[filename]
def clear_break(self, filename, lineno):
"""Delete breakpoints for filename:lineno.
If no breakpoints were set, return an error message.
"""
filename = self.canonic(filename)
if filename not in self.breaks:
return 'There are no breakpoints in %s' % filename
@ -303,16 +407,26 @@ class Bdb:
for bp in Breakpoint.bplist[filename, lineno][:]:
bp.deleteMe()
self._prune_breaks(filename, lineno)
return None
def clear_bpbynumber(self, arg):
"""Delete a breakpoint by its index in Breakpoint.bpbynumber.
If arg is invalid, return an error message.
"""
try:
bp = self.get_bpbynumber(arg)
except ValueError as err:
return str(err)
bp.deleteMe()
self._prune_breaks(bp.file, bp.line)
return None
def clear_all_file_breaks(self, filename):
"""Delete all breakpoints in filename.
If none were set, return an error message.
"""
filename = self.canonic(filename)
if filename not in self.breaks:
return 'There are no breakpoints in %s' % filename
@ -321,16 +435,27 @@ class Bdb:
for bp in blist:
bp.deleteMe()
del self.breaks[filename]
return None
def clear_all_breaks(self):
"""Delete all existing breakpoints.
If none were set, return an error message.
"""
if not self.breaks:
return 'There are no breakpoints'
for bp in Breakpoint.bpbynumber:
if bp:
bp.deleteMe()
self.breaks = {}
return None
def get_bpbynumber(self, arg):
"""Return a breakpoint by its index in Breakpoint.bybpnumber.
For invalid arg values or if the breakpoint doesn't exist,
raise a ValueError.
"""
if not arg:
raise ValueError('Breakpoint number expected')
try:
@ -346,17 +471,26 @@ class Bdb:
return bp
def get_break(self, filename, lineno):
"""Return True if there is a breakpoint for filename:lineno."""
filename = self.canonic(filename)
return filename in self.breaks and \
lineno in self.breaks[filename]
def get_breaks(self, filename, lineno):
"""Return all breakpoints for filename:lineno.
If no breakpoints are set, return an empty list.
"""
filename = self.canonic(filename)
return filename in self.breaks and \
lineno in self.breaks[filename] and \
Breakpoint.bplist[filename, lineno] or []
def get_file_breaks(self, filename):
"""Return all lines with breakpoints for filename.
If no breakpoints are set, return an empty list.
"""
filename = self.canonic(filename)
if filename in self.breaks:
return self.breaks[filename]
@ -364,12 +498,18 @@ class Bdb:
return []
def get_all_breaks(self):
"""Return all breakpoints that are set."""
return self.breaks
# Derived classes and clients can call the following method
# to get a data structure representing a stack trace.
def get_stack(self, f, t):
"""Return a list of (frame, lineno) in a stack trace and a size.
List starts with original calling frame, if there is one.
Size may be number of frames above or below f.
"""
stack = []
if t and t.tb_frame is f:
t = t.tb_next
@ -388,6 +528,14 @@ class Bdb:
return stack, i
def format_stack_entry(self, frame_lineno, lprefix=': '):
"""Return a string with information about a stack entry.
The stack entry frame_lineno is a (frame, lineno) tuple. The
return string contains the canonical filename, the function name
or '<lambda>', the input arguments, the return value, and the
line of code (if it exists).
"""
import linecache, reprlib
frame, lineno = frame_lineno
filename = self.canonic(frame.f_code.co_filename)
@ -418,6 +566,10 @@ class Bdb:
# Both can be given as a string, or a code object.
def run(self, cmd, globals=None, locals=None):
"""Debug a statement executed via the exec() function.
globals defaults to __main__.dict; locals defaults to globals.
"""
if globals is None:
import __main__
globals = __main__.__dict__
@ -436,6 +588,10 @@ class Bdb:
sys.settrace(None)
def runeval(self, expr, globals=None, locals=None):
"""Debug an expression executed via the eval() function.
globals defaults to __main__.dict; locals defaults to globals.
"""
if globals is None:
import __main__
globals = __main__.__dict__
@ -452,12 +608,17 @@ class Bdb:
sys.settrace(None)
def runctx(self, cmd, globals, locals):
"""For backwards-compatibility. Defers to run()."""
# B/W compatibility
self.run(cmd, globals, locals)
# This method is more useful to debug a single function call.
def runcall(self, func, *args, **kwds):
"""Debug a single function call.
Return the result of the function call.
"""
self.reset()
sys.settrace(self.trace_dispatch)
res = None
@ -472,6 +633,7 @@ class Bdb:
def set_trace():
"""Start debugging with a Bdb instance from the caller's frame."""
Bdb().set_trace()
@ -482,11 +644,15 @@ class Breakpoint:
(re)-enabling, and conditionals.
Breakpoints are indexed by number through bpbynumber and by
the file,line tuple using bplist. The former points to a
the (file, line) tuple using bplist. The former points to a
single instance of class Breakpoint. The latter points to a
list of such instances since there may be more than one
breakpoint per line.
When creating a breakpoint, its associated filename should be
in canonical form. If funcname is defined, a breakpoint hit will be
counted when the first line of that function is executed. A
conditional breakpoint always counts a hit.
"""
# XXX Keeping state in the class is a mistake -- this means
@ -519,6 +685,12 @@ class Breakpoint:
self.bplist[file, line] = [self]
def deleteMe(self):
"""Delete the breakpoint from the list associated to a file:line.
If it is the last breakpoint in that position, it also deletes
the entry for the file:line.
"""
index = (self.file, self.line)
self.bpbynumber[self.number] = None # No longer in list
self.bplist[index].remove(self)
@ -527,17 +699,31 @@ class Breakpoint:
del self.bplist[index]
def enable(self):
"""Mark the breakpoint as enabled."""
self.enabled = True
def disable(self):
"""Mark the breakpoint as disabled."""
self.enabled = False
def bpprint(self, out=None):
"""Print the output of bpformat().
The optional out argument directs where the output is sent
and defaults to standard output.
"""
if out is None:
out = sys.stdout
print(self.bpformat(), file=out)
def bpformat(self):
"""Return a string with information about the breakpoint.
The information includes the breakpoint number, temporary
status, file:line position, break condition, number of times to
ignore, and number of times hit.
"""
if self.temporary:
disp = 'del '
else:
@ -561,12 +747,20 @@ class Breakpoint:
return ret
def __str__(self):
"Return a condensed description of the breakpoint."
return 'breakpoint %s at %s:%s' % (self.number, self.file, self.line)
# -----------end of Breakpoint class----------
def checkfuncname(b, frame):
"""Check whether we should break here because of `b.funcname`."""
"""Return True if break should happen here.
Whether a break should happen depends on the way that b (the breakpoint)
was set. If it was set via line number, check if b.line is the same as
the one in the frame. If it was set via function name, check if this is
the right function and if it is on the first executable line.
"""
if not b.funcname:
# Breakpoint was set via line number.
if b.line != frame.f_lineno:
@ -576,7 +770,6 @@ def checkfuncname(b, frame):
return True
# Breakpoint set via function name.
if frame.f_code.co_name != b.funcname:
# It's not a function call, but rather execution of def statement.
return False
@ -586,20 +779,21 @@ def checkfuncname(b, frame):
# The function is entered for the 1st time.
b.func_first_executable_line = frame.f_lineno
if b.func_first_executable_line != frame.f_lineno:
if b.func_first_executable_line != frame.f_lineno:
# But we are not at the first line number: don't break.
return False
return True
# Determines if there is an effective (active) breakpoint at this
# line of code. Returns breakpoint number or 0 if none
def effective(file, line, frame):
"""Determine which breakpoint for this file:line is to be acted upon.
Called only if we know there is a bpt at this
location. Returns breakpoint that was triggered and a flag
that indicates if it is ok to delete a temporary bp.
Called only if we know there is a breakpoint at this location. Return
the breakpoint that was triggered and a boolean that indicates if it is
ok to delete a temporary breakpoint. Return (None, None) if there is no
matching breakpoint.
"""
possibles = Breakpoint.bplist[file, line]
for b in possibles: