🌐 Mailman 3 March 2000 - Python-list - python.org

Debugging?
by chris davis April 2, 2000

April 2, 2000

Ok, I just need to know the best way to debug my python scripts? If this is a stupid question, I apologize, but I currently use IDLE and it's completely useless when it comes to debugging. It locks up on both my window and Linux machines and doesn't set break points! Is there another way? another IDE? anything? If there isn't that's fines, I can wait until IDLE is fully developed, but I just don't want to waste my time searching.

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Python or OS forking/threading problem?
by nsiam＠yahoo.com April 2, 2000

April 2, 2000

Running the Python program below results in either: i) Python segfaults (that is the parent process, see below) ii) One or more processes hogging all the CPU I have tried this on different setups: a) Uni-processor Linux RH6.0 running kernel 2.2.9 b) Dual-processor Linux RH6.0 running kernel 2.2.5-15smp Both running Python 1.5.2 When running on setup a) it runs for some time then it fails. Setup b) fails almost immediately. I know there are some issues with forking in a thread (I assume pthreads are used in the implementation) but as far as I can see it should only affect the child process (deadlocks, etc if child process inherits locks from parent). The parent process should not be affected by this. I would appreciate any suggestions what is wrong here and what I can to fix this. I have a fairly large multi-threaded application that calls some backend scripts. My Zope server crashes once-in-a-while because of this problem. Since I really don't need to continue running in Python in the child process (only want to do exec) I am going to implement my own fork/exec function in C. What I'm hoping to achieve with that is to avoid the Python VM locks. I suspect they have something to do with this because when my parent process segfaults it happens in PyThread_aquireLock (I don't remember the exact name of the function). Thanks --- THE EVIL PROGRAM --- import threading import os class MyThread(threading.Thread): def run(self): for i in range(100): self.once() def once(self): pid = os.fork() if pid == 0: print " hello mom" os._exit(0) pid2, sts = os.waitpid(pid,0) print "bye baby" threads = [] for i in range(10): threads.append(MyThread()) map(lambda x: x.start(), threads) import time time.sleep(1000) print "DONE" Sent via Deja.com http://www.deja.com/ Before you buy.

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regular expressions questions
by Newhard, Nick April 2, 2000

April 2, 2000

I have started working with regular expressions (using the re.py module) for parsing text input and have a few questions. 1. Single quote detection myrule = re.compile(r"^/('|say)(?:[\t ]*$|[\t ]+(.*))") s1 = "/say Hello!" s2 = "/' Hello!" String s1 matches and returns a group ('say', 'Hello!') but string s2 does not match. Any ideas? I tried variations with the single quote (\', etc.) without success. The command list I use in my rule ('|say) is a lot larger. Any comments on a better way to set up this rule? 2. Groups and patterns s2 = "aabbabaaabbb" If I have a large string containing a random collection of patterns, in this case a's and b's, how would I for a rule to return groups of them? For this case, I would want ('aa', 'bb', 'a', 'b', 'aaa', 'bbb') 2a. What if I want to collect whitespace with the a's in the groups too? s2 = "aa bb a b aaa bbb" For this case, I would want ('aa ', 'bb', ' a ', 'b', ' aaa ', 'bbb') Thanks for your help!! (P.S. I have "Mastering Regular Expressions" on order but it will be days before I receive it. *sigh*)

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Tkinter dying a Flailing Death?
by anders schneiderman April 1, 2000

April 1, 2000

I've been working for a while on a Tkinter program, and almost every time I quit it, it twice complains that "This program has performed an illegal operation and will be shut down." Since I'm new to Python, I figured it must be something I was doing. So, I tried running a demo from the Tkinter library, Dialog.py. Surprise! It also dies twice, bitterly complaining about illegal operations. The code below is the Tkinter demo. Any idea why it's so unhappy when it quits? Thanks, Anders Schneiderman National Journal Daily Briefings Group P.S. I've got 8.0.5 Tcl and Python 1.5.2 and I'm running Win95. ---------------------------------------------------------------- # Dialog.py -- Tkinter interface to the tk_dialog script. from Tkinter import * from Tkinter import _cnfmerge if TkVersion <= 3.6: DIALOG_ICON = 'warning' else: DIALOG_ICON = 'questhead' class Dialog(Widget): def __init__(self, master=None, cnf={}, **kw): cnf = _cnfmerge((cnf, kw)) self.widgetName = '__dialog__' Widget._setup(self, master, cnf) self.num = self.tk.getint( apply(self.tk.call, ('tk_dialog', self._w, cnf['title'], cnf['text'], cnf['bitmap'], cnf['default']) + cnf['strings'])) try: Widget.destroy(self) except TclError: pass def destroy(self): pass def _test(): d = Dialog(None, {'title': 'File Modified', 'text': 'File "Python.h" has been modified' ' since the last time it was saved.' ' Do you want to save it before' ' exiting the application.', 'bitmap': DIALOG_ICON, 'default': 0, 'strings': ('Save File', 'Discard Changes', 'Return to Editor')}) print d.num if __name__ == '__main__': t = Button(None, {'text': 'Test', 'command': _test, Pack: {}}) q = Button(None, {'text': 'Quit', 'command': t.quit, Pack: {}}) t.mainloop()

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Single-line functions
by Randall Hopper April 1, 2000

April 1, 2000

I'll probably hate myself when you tell me why this doesn't work: def f(): if a == b: doit() This yields: File "<stdin>", line 1 def f(): if a == b: doit() ^ SyntaxError: invalid syntax Why is it invalid? This works: if a == b: doit() and this works: def f(): a = b Which syntax rule did I break? Thanks, Randall -- Randall Hopper aa8vb(a)yahoo.com

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pdb will not continue
by Tim Egbert April 1, 2000

April 1, 2000

I'm new to the pbd module, but think I've got most of it working. The problem I'm having, however, is that even though I can set break points, I can't get pdb to 'continue' ('cont' or 'c') to the break point. All it will do is advance one line. What am I doing wrong? Tim P.S. Here's my interactive session: Python 1.5.2 (#1, Sep 17 1999, 20:15:36) [GCC egcs-2.91.66 19990314/Linux (egcs- on linux-i386 Copyright 1991-1995 Stichting Mathematisch Centrum, Amsterdam >>> import mymodule >>> import pdb >>> mmod=mymodule.mymodule() >>> pdb.runcall(mmod.mymethod,arg) > mymodule.py(156)mymethod() -> def mymethod(self,arg): (Pdb) b 166 Breakpoint 1 at mymodule.py:166 (Pdb) l 163,167 163 ix=0 164 while 1: 165 if ix>=len(arr): break 166 B val=arr[ix] 167 nlen=ix+1 (Pdb) continue > mymodule.py(158)mymethod() -> words=string.split(textsegment) (Pdb) l 156,158 156 def mymethod(self,arg): 157 # --- initialization 158 -> words=string.split(arg) (Pdb)

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Qutting the interpreter
by Michael Ackerman April 1, 2000

April 1, 2000

Hi, I am trying to find a way of quitting the interpreter. On p.3 of the tutorial it says this can be done by 'import sys; sys.exit()', but this produces an error message when I try it. I used to be able to quit by 'raise SystemExit', but that no longer works either. So how is this done? I am using version 1.5.2c.1 of Python on a Mac. Thanks, Michael

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Format of HTML Source Output
by Joseph C. Kopec April 1, 2000

April 1, 2000

I have been sucessfully using Python cgi scripts to generate HTML pages. When I use a text editor to pull up the HTML source, however, all the source is on one or a few lines, making it difficult to review. Are there any techniques people typically use with Python cgi scripts to produce HTML output that not only is good HTML when viewed through a browser, but produces nicely formatted HTML source? Would outputting \n and other escaped characters work without disrupting the browser-viewed HTML document? Thanks in advance.

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Python Threading and sys.exit() codes
by dickenson＠serviceware.com April 1, 2000

April 1, 2000

I'm working my first multithreaded Python program. This program compares the contents of an ftp site with a local copy. (It is not a pure mirror site, but there is a 1-1 correspondence of files.) It then ftp's only files which are newer on the source site than the target site. There are often many files, so the ftp is set up to use multiple threads, each of which repeatedly locks a global semaphore, pops a task off a stack, releases the semaphore, and executes the task (a file to ftp) ad nauseam. My problem is this: I want to run this program as a scheduled task under a job scheduler (currently testing cronDsys from #ifdef). The single-threaded version of the program posts an appropriate code to the environment via sys.exit(). The job scheduler traps this and takes conditional action. So far, so good. In the multi-threaded version of the program, the exit codes are not getting posted and the main process is not terminating cleanly, at least from the perspective of the job scheduler -- it appears to run until manually terminated from the scheduler control console although the NT command window disappears from the target desktop as expected. The code fragments below are the ftp thread class and the __main__ section. Can anybody help me with this ?? class FTPThread(Threading.Thread): # def __init__(self,group,target,name,args,kwargs): # print "in Init" def run(self): print self._Thread__name print self._Thread__args try: ftp=ftplib.FTP('ftp.microsoft.com') ftp.login('anonymous','dickenson(a)serviceware.com') ftp.cwd('misc/kb') except: sys.exit(3) subdir=self._Thread__args[0] # print self,self._Thread__args b=stacklen(self._Thread__args[1]) print "b at start=",b while (b > 0): # print "thread ",self._Thread__name," attempting to get semaphore" a=stacksem.acquire() # print "thread ",self._Thread__name," got semaphore" msfilepath=getstack(self._Thread__args[1]) newtime=getstack(self._Thread__args[2]) # print "thread ",self._Thread__name," attempting to release semaphore" a=stacksem.release() # print "thread ",self._Thread__name," released semaphore" #print "msfilepath",msfilepath local0=string.replace(msfilepath,".","",1) local1=string.replace(local0,"\\","") localdrive=Target_Root+"updates\\\\"+subdir+"\\\\" local=[localdrive,local1] local2=string.join(local) localfilepath=string.replace(local2," ","") file=open(localfilepath,"w") cmdstrings=["retr ",msfilepath] cmd=string.join(cmdstrings) try: ftp.retrbinary(cmd,file.write) print b," - file", msfilepath, "retrieved successfully by thread ",self._Thread__name if subdir=="revised": revisecount=revisecount+1 if subdir=="new": newcount=newcount+1 #print "success by thread ",self._Thread__name #filecount=filecount+1 #print "filecount=",filecount except NameError: pass else: print sys.exc_info() print "file ", msfilepath, " was not retrieved" #print "failure by thread ",self._Thread__name file.close() os.system("erase "+localfilepath) sys.exit(1) file.close() # print "newtime",newtime os.utime(localfilepath,(newtime,newtime)) b=stacklen(self._Thread__args[1]) # print "b at exit=",b ftp.quit sys.exit(0) def notify(target,newcount,revisecount): host="SNERT" fromstring="Python Auto-FTP" # tostring=["dickenson(a)serviceware.com"] tostring= ["dickenson(a)serviceware.com","hlewis(a)serviceware.com","gkindel@servicewa re.com","mciaramitaro(a)serviceware.com"] msg="Subject: AutoFTP results\n\nUpdated files: " + str(revisecount) +"\nNew files: "+str(newcount)+"\nlocated in subdirs off "+target + "\\\\updates" s=smtplib.SMTP(host) s.sendmail(fromstring,tostring,msg) if __name__=='__main__': Threadpool=12 stacksem=Threading.Semaphore(1) Month_Num_Dict= {'Jan':1,'Feb':2,'Mar':3,'Apr':4,'May':5, 'Jun':6,'Jul':7,'Aug':8,'Sep': 9,'Oct':10,'Nov':11,'Dec':12} Target_Dict={} Source_Dict={} Fix_These=Stack(500) Fix_Time=Stack(500) New_These=Stack(500) New_Time=Stack(500) newcount=0 revisecount=0 Target_Root="S:\\\\Microsoft\\\\" #Target_Root="M:\\\\msftp\\\\" print "read source" a=DateTime.now() print a.hour, a.minute, a.second read_source() print "read target" a=DateTime.now() print a.hour, a.minute, a.second read_target() print "lookup source" a=DateTime.now() print a.hour, a.minute, a.second newcount,revisecount=lookup_source() print "start ftp..." a=DateTime.now() print a.hour, a.minute,a.second threads=[] for i in range(Threadpool): my_thread=FTPThread(group=None,target=None,name=None,args= ("revised","Fix_These","Fix_Time"),kwargs={}) #my_thread.__init__(group=None,target=None,name="Revised 1",args=("revised","Fix_These","Fix_Time"),kwargs={}) my_thread.start() threads.append(my_thread) # for i in range(6): my_thread=FTPThread(group=None,target=None,name=None,args= ("new","New_These","New_Time"),kwargs={}) # my_thread.__init__(group=None,target=None,name="New 1",args= ("new","New_These","New_Time"),kwargs={}) my_thread.start() threads.append(my_thread) for thread in threads: thread.join() print "all threads finished" try: notify(Target_Root,newcount,revisecount) print "notify done" finally: sys.exit(0) Sent via Deja.com http://www.deja.com/ Before you buy.

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Re: Python x ibook (Mac)
by Matheus Rodrigues April 1, 2000

April 1, 2000

>At 6:48 PM +0000 30-03-2000, Matheus Rodrigues wrote: > >Is there anyone here that could tell me what are the Python features that >I > >will not have in a ibook (notebook from apple) ? > >What are my limits once I try to run Python on this machine ? Just van Rossum wrote: >The same as on any other Mac I presume... Mainly: no threading (yet), no >forking. Does it mean that IDLE and the Tkinter extensions work fine too ? You said "no threading (yet)". Is there anyone working on that ? Matheus ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

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