+"""
+This module provides a useful debugging framework that supports
+showing nesting of function calls and allows a program to contain
+lots of debugging print statements that can easily be turned on
+or off to debug the code. It also supports the ability to
+have each function indent the debugging statements contained
+within it, including those of any other function called within
+its scope, thus allowing you to see in what order functions are
+being called, and from where.
+
+This capability is particularly useful in wxPython applications,
+where exactly events occur that cause functions to be called is
+not entirely clear, and because wxPython programs can't be run
+from inside other debugging environments that have their own
+message loops.
+
+This module defines a Logger class, responsible for managing
+debugging output. Each Logger instance can be given a name
+at construction; if this is done, '<name>:' will precede each
+logging output made by that Logger instance.
+
+The log() function this class provides takes a set of positional
+arguments that are printed in order if debugging is enabled
+(just like print does), followed by a set of keyword arguments
+that control the behavior of the log() function itself on subsequent
+calls. The current keyword arguments are:
+
+indent
+ When set to a value of 1, this increments the current
+ indentation level, causing all subsequent dbg() outputs to be
+ indented by 3 more spaces. When set to a value of 0,
+ this process is reversed, causing the indent to decrease by
+ 3 spaces. The default indentation level is 0.
+
+enable
+ When set to a value of 1, this turns on dbg() output for
+ for program importing this module, until told to do otherwise.
+ When set to a value of 0, dbg output is turned off. (dbg
+ output is off by default.)
+
+suspend
+ When set to a value of 1, this increments the current
+ "suspension" level. This makes it possible for a function
+ to temporarily suspend its and any of its dependents'
+ potential outputs that use the same Logger instance.
+ When set to a value of 0, the suspension level is
+ decremented. When the value goes back to 0, potential
+ logging is resumed (actual output depends on the
+ "enable" status of the Logger instance in question.)
+
+wxlog
+ When set to a value of 1, the output will be sent to the
+ active wxLog target.
+
+stream
+ When set to a non-None value, the current output stream
+ (default of sys.stdout) is pushed onto a stack of streams,
+ and is replaced in the dbg system with the specified stream.
+ When called with a value of None, the previous stream will
+ be restored (if stacked.) If set to None without previously
+ changing it will result in no action being taken.
+
+You can also call the log function implicitly on the Logger
+instance, ie. you can type:
+ from wxPython.tools.dbg import Logger
+ dbg = Logger()
+ dbg('something to print')
+
+Using this fairly simple mechanism, it is possible to get fairly
+useful debugging output in a program. Consider the following
+code example:
+
+>>> d = {1:'a', 2:'dictionary', 3:'of', 4:'words'}
+>>> dbg = dbg.Logger('module')
+>>> dbg(enable=1)
+module: dbg enabled
+>>> def foo(d):
+... dbg('foo', indent=1)
+... bar(d)
+... dbg('end of foo', indent=0)
+...
+>>> def bar(d):
+... dbg('bar', indent=1)
+... dbg('contents of d:', indent=1)
+... l = d.items()
+... l.sort()
+... for key, value in l:
+... dbg('%d =' % key, value)
+... dbg(indent=0)
+... dbg('end of bar', indent=0)
+...
+>>> foo(d)
+module: foo
+ module: bar
+ module: contents of d:
+ module: 1 = a
+ module: 2 = dictionary
+ module: 3 = of
+ module: 4 = words
+ module: end of bar
+ module: end of foo
+>>>
+
+"""
+
+
+class Logger:
+ def __init__(self, name=None):
+ import sys
+ self.name = name
+ self._indent = 0 # current number of indentations
+ self._dbg = 0 # enable/disable flag
+ self._suspend = 0 # allows code to "suspend/resume" potential dbg output
+ self._wxLog = 0 # use wxLogMessage for debug output
+ self._outstream = sys.stdout # default output stream
+ self._outstream_stack = [] # for restoration of streams as necessary
+
+
+ def IsEnabled():
+ return self._dbg
+
+ def IsSuspended():
+ return _suspend
+
+
+ def log(self, *args, **kwargs):
+ """
+ This function provides a useful framework for generating
+ optional debugging output that can be displayed at an
+ arbitrary level of indentation.
+ """
+ if not self._dbg and not 'enable' in kwargs.keys():
+ return
+
+ if self._dbg and len(args) and not self._suspend:
+ # (emulate print functionality; handle unicode as best as possible:)
+ strs = []
+ for arg in args:
+ try:
+ strs.append(str(arg))
+ except:
+ strs.append(repr(arg))
+
+ output = ' '.join(strs)
+ if self.name: output = self.name+': ' + output
+ output = ' ' * 3 * self._indent + output
+
+ if self._wxLog:
+ from wxPython.wx import wxLogMessage # (if not already imported)
+ wxLogMessage(output)
+ else:
+ self._outstream.write(output + '\n')
+ self._outstream.flush()
+ # else do nothing
+
+ # post process args:
+ for kwarg, value in kwargs.items():
+ if kwarg == 'indent':
+ self.SetIndent(value)
+ elif kwarg == 'enable':
+ self.SetEnabled(value)
+ elif kwarg == 'suspend':
+ self.SetSuspend(value)
+ elif kwarg == 'wxlog':
+ self.SetWxLog(value)
+ elif kwarg == 'stream':
+ self.SetStream(value)
+
+ # aliases for the log function
+ dbg = log # backwards compatible
+ msg = log #
+ __call__ = log # this one lets you 'call' the instance directly
+
+
+ def SetEnabled(self, value):
+ if value:
+ old_dbg = self._dbg
+ self._dbg = 1
+ if not old_dbg:
+ self.dbg('dbg enabled')
+ else:
+ if self._dbg:
+ self.dbg('dbg disabled')
+ self._dbg = 0
+
+
+ def SetSuspend(self, value):
+ if value:
+ self._suspend += 1
+ elif self._suspend > 0:
+ self._suspend -= 1
+
+
+ def SetIndent(self, value):
+ if value:
+ self._indent += 1
+ elif self._indent > 0:
+ self._indent -= 1
+
+
+ def SetWxLog(self, value):
+ self._wxLog = value
+
+
+ def SetStream(self, value):
+ if value:
+ self._outstream_stack.append( self._outstream )
+ self._outstream = value
+ elif value is None and len(self._outstream_stack) > 0:
+ self._outstream = self._outstream_stack.pop(-1)
+
+
+#------------------------------------------------------------
+
+if __name__ == "__main__":
+ import sys
+ import wx
+
+ wx.Log_SetActiveTarget( wx.LogStderr() )
+ logger = Logger('module')
+ dbg = logger.dbg
+ dbg(enable=1)
+ logger('test __call__ interface')
+ dbg('testing wxLog output to stderr:', wxlog=1, indent=1)
+ dbg('1,2,3...')
+ dbg('testing wx.LogNull:')
+ devnull = wx.LogNull()
+ dbg('4,5,6...') # shouldn't print, according to doc...
+ del devnull
+ dbg('(resuming to wx.LogStdErr)', '7,8,9...', indent=0)
+ dbg('disabling wx.Log output, switching to stderr:')
+ dbg(wxlog=0, stream=sys.stderr)
+ dbg(logger._outstream, 'switching back to stdout:')
+ dbg(stream=None)
+ dbg(logger._outstream )
+ def foo(str):
+ dbg('foo:', indent=1)
+ dbg(str, indent=0)
+ foo('testing dbg inside function')
+ class bar(Logger):
+ def __init__(self, name):
+ Logger.__init__(self, name)
+ def enable(self, value):
+ self.dbg(enable=value)
+ def foo(self, str):
+ self.dbg('foo:', indent=1)
+ self.dbg(str, indent=0)
+ f = bar('class mixin')
+ f.foo("shouldn't print")
+ f.enable(1)
+ f.foo("should print")
+ dbg('test completed.', enable=0)
+ dbg('(double-checking ;-)')
projects / wxWidgets.git / blobdiff