Mailman 3 February 2002 - Python-Dev

syntactic sugar idea for {static,class}methods
by Gareth McCaughan Feb. 15, 2002

Feb. 15, 2002

Michael Hudson wrote (replying to Barry Warsaw): > > Very interesting! Why the square brackets though? Is that just for > > visual offset or is there a grammar constraint that requires them? > > Um, no big reason; they were what Gareth suggested, so I implemented > that. He may have got the idea from the slides from one of Guido's > presentations -- it was reading them that reminded me I'd done this > and wanted to mention it here. Four reasons for the brackets. 1. Easier for the parser, I think. 2. Visually distinctive. 3. For me, it "reads" better than it would without the brackets. 4. Generalizes to a sequence of transformations. #4 is much the most important of these in my mind. One drawback of allowing an arbitrary list of transformations is that it might not be completely clear what order they're done in. I conjecture that most people will have the same intuition as I do about this, namely that the first-listed transformation is applied first. (It would be less obvious if the list came before the name of the definiendum instead of after.) Oh, and for the record: My suggestion was made long before I ever saw Guido's slides. :-) -- Gareth McCaughan

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Is Barry receiving email at barry@zope.com? PEP number please.
by Trent Mick Feb. 15, 2002

Feb. 15, 2002

Barry, Could I have a PEP number for my logging system proposal please? Here is what I have put together so far. Others, Feel free to send me comments on this if you like. I will official post a request for comment when I get a PEP number for it. Trent ------------------------------------------------------------------------------ PEP: XXX Title: A Logging System Version: $Revision$ Last-Modified: $Date$ Author: trentm(a)activestate.com (Trent Mick) Python-Version: 2.3 Status: Draft Type: Standards Track Created: 4-Feb-2002 Post-History: Abstract This PEP describes a proposed logging package for Python's standard library. Basically the system involves the user creating one or more logging objects on which methods are called to log debugging notes/general information/warnings/errors/etc. Different logging 'levels' can be used to distinguish important messages from trivial ones. A registry of named singleton logger objects is maintained so that (1) different logical logging streams (or 'channels') exist (say, one for 'zope.zodb' stuff and another for 'mywebsite'-specific stuff); and (2) one does not have to pass logger object references around. The system is configurable at runtime. This configuration mechanism allows one to tune the level and type of logging done while not touching the application itself. Motivation If a single logging mechanism is enshrined in the standard library, 1) logging is more likely to be done 'well', and 2) multiple libraries will be able to be integrated into larger applications which can be logged reasonably coherently. Influences This proposal was put together after having somewhat studied the following logging packages: o java.util.logging in JDK 1.4 (a.k.a. JSR047) [1] o log4j [2] These two systems are *very* similar. o the Syslog package from the Protomatter project [3] o MAL's mx.Log package [4] This proposal will basically look like java.util.logging with a smattering of log4j. Simple Example This shows a very simple example of how the logging package can be used to generate simple logging output on stdout. --------- mymodule.py ------------------------------- import logging log = logging.getLogger("MyModule") def doit(): log.debug("doin' stuff") # do stuff ... ----------------------------------------------------- --------- myapp.py ---------------------------------- import mymodule, logging log = logging.getLogger("MyApp") log.info("start my app") try: mymodule.doit() except Exception, e: log.error("There was a problem doin' stuff.") log.info("end my app") ----------------------------------------------------- > python myapp.py 0 [myapp.py:4] INFO MyApp - start my app 36 [mymodule.py:5] DEBUG MyModule - doin' stuff 51 [myapp.py:9] INFO MyApp - end my app ^^ ^^^^^^^^^^^^ ^^^^ ^^^^^ ^^^^^^^^^^ | | | | `-- message | | | `-- logging name/channel | | `-- level | `-- location `-- time NOTE: Not sure exactly what the default format will look like yet. Control Flow [Note: excerpts from Java Logging Overview. [5]] Applications make logging calls on *Logger* objects. Loggers are organized in a hierarchical namespace and child Loggers may inherit some logging properties from their parents in the namespace. Notes on namespace: Logger names fit into a "dotted name" namespace, with dots (periods) indicating subnamespaces. The namespace of logger objects therefore corresponds to a single tree data structure. "" is the root of the namespace "Zope" would be a child node of the root "Zope.ZODB" would be a child node of "Zope" These Logger objects allocate *LogRecord* objects which are passed to *Handler* objects for publication. Both Loggers and Handlers may use logging *levels* and (optionally) *Filters* to decide if they are interested in a particular LogRecord. When it is necessary to publish a LogRecord externally, a Handler can (optionally) use a *Formatter* to localize and format the message before publishing it to an I/O stream. Each Logger keeps track of a set of output Handlers. By default all Loggers also send their output to their parent Logger. But Loggers may also be configured to ignore Handlers higher up the tree. The APIs are structured so that calls on the Logger APIs can be cheap when logging is disabled. If logging is disabled for a given log level, then the Logger can make a cheap comparison test and return. If logging is enabled for a given log level, the Logger is still careful to minimize costs before passing the LogRecord into the Handlers. In particular, localization and formatting (which are relatively expensive) are deferred until the Handler requests them. Levels The logging levels, in increasing order of importance, are: DEBUG INFO WARN ERROR FATAL ALL This is consistent with log4j and Protomatter's Syslog and not with JSR047 which has a few more levels and some different names. Implementation-wise: these are just integer constants, to allow simple comparsion of importance. See "What Logging Levels?" below for a debate on what standard levels should be defined. Loggers Each Logger object keeps track of a log level (or threshold) that it is interested in, and discards log requests below that level. The *LogManager* maintains a hierarchical namespace of named Logger objects. Generations are denoted with dot-separated names: Logger "foo" is the parent of Loggers "foo.bar" and "foo.baz". The main logging method is: class Logger: def log(self, level, msg, *args): """Log 'msg % args' at logging level 'level'.""" ... however convenience functions are defined for each logging level: def debug(self, msg, *args): ... def info(self, msg, *args): ... def warn(self, msg, *args): ... def error(self, msg, *args): ... def fatal(self, msg, *args): ... XXX How to defined a nice convenience function for logging an exception? mx.Log has something like this, doesn't it? XXX What about a .raising() convenience function? How about: def raising(self, exception, level=ERROR): ... It would create a log message describing an exception that is about to be raised. I don't like that 'level' is not first when it *is* first for .log(). Handlers Handlers are responsible for doing something useful with a given LogRecord. The following core Handlers will be implemented: - StreamHandler: A handler for writing to a file-like object. - FileHandler: A handler for writing to a single file or set of rotating files. More standard Handlers may be implemented if deemed desireable and feasible. Other interesting candidates: - SocketHandler: A handler for writing to remote TCP ports. - CreosoteHandler: A handler for writing to UDP packets, for low-cost logging. Jeff Bauer already had such a system [5]. - MemoryHandler: A handler that buffers log records in memory (JSR047). - SMTPHandler: Akin to log4j's SMTPAppender. - SyslogHandler: Akin to log4j's SyslogAppender. - NTEventLogHandler: Akin to log4j's NTEventLogAppender. - SMTPHandler: Akin to log4j's SMTPAppender. Formatters A Formatter is responsible for converting a LogRecord to a string representation. A Handler may call its Formatter before writing a record. The following core Formatters will be implemented: - Formatter: Provide printf-like formatting, perhaps akin to log4j's PatternAppender. Other possible candidates for implementation: - XMLFormatter: Serialize a LogRecord according to a specific schema. Could copy the schema from JSR047's XMLFormatter or log4j's XMLAppender. - HTMLFormatter: Provide a simple HTML output of log information. (See log4j's HTMLAppender.) Filters A Filter can be called by a Logger or Handler to decide if a LogRecord should be logged. JSR047 and log4j have slightly different filtering interfaces. The former is simpler: class Filter: def isLoggable(self): """Return a boolean.""" The latter is modeled after Linux's ipchains (where Filter's can be chained with each filter either 'DENY'ing, 'ACCEPT'ing, or being 'NEUTRAL' on each check). I would probably favor to former because it is simpler and I don't immediate see the need for the latter. No filter implementations are currently proposed (other that the do nothing base class) because I don't have enough experience to know what kinds of filters would be common. Users can always subclass Filter for their own purposes. Log4j includes a few filters that might be interesting. Configuration Note: Configuration for the proposed logging system is currently under-specified. The main benefit of a logging system like this is that one can control how much and what logging output one gets from an application without changing that application's source code. Log4j and Syslog provide for configuration via an external XML file. Log4j and JSR047 provide for configuration via Java properties (similar to -D #define's to a C/C++ compiler). All three provide for configuration via API calls. Configuration includes the following: - What logging level a logger should be interested in. - What handlers should be attached to which loggers. - What filters should be attached to which handlers and loggers. - Specifying attributes specific to certain Handlers and Filters. - Defining the default configuration. - XXX Add others. In general each application will have its own requirements for how a user may configure logging output. One application (e.g. distutils) may want to control logging levels via '-q,--quiet,-v,--verbose' options to setup.py. Zope may want to configure logging via certain environment variables (e.g. 'STUPID_LOG_FILE' :). Komodo may want to configure logging via its preferences system. This PEP proposes to clearly document the API for configuring each of the above listed configurable elements and to define a reasonable default configuration. This PEP does not propose to define a general XML or .ini file configuration schema and the backend to parse it. It might, however, be worthwhile to define an abstraction of the configuration API to allow the expressiveness of Syslog configuration. Greg Wilson made this argument: In Protomatter [Syslog], you configure by saying "give me everything that matches these channel+level combinations", such as "server.error" and "database.*". The log4j "configure by inheritance" model, on the other hand, is very clever, but hard for non-programmers to manage without a GUI that essentially reduces it to Protomatter's. Case Scenarios This section presents a few usage scenarios which will be used to help decide how best to specify the logging API. (1) A short simple script. This script does not have many lines. It does not heavily use an third party modules (i.e. the only code doing any logging would be the main script). Only one logging channel is really needed and thus, the channel name is unnecessary. The user doesn't want to bother with logging system configuration much. (2) Medium sized app with C extension module. Includes a few Python modules and a main script. Employs, perhaps, a few logging channels. Includes a C extension module which might want to make logging calls as well. (3) Distutils. A large number of Python packages/modules. Perhaps (but not necessarily) a number of logging channels are used. Specifically needs to facilitate the controlling verbosity levels via simple command line options to 'setup.py'. (4) Large, possibly multi-language, app. E.g. Zope or (my experience) Komodo. (I don't expect this logging system to deal with any cross-language issues but it is something to think about.) Many channels are used. Many developers involved. People providing user support are possibly not the same people who developed the application. Users should be able to generate log files (i.e. configure logging) while reproducing a bug to send back to developers. Implementation XXX Details to follow consensus that this proposal is a good idea. What Logging Levels? The following are the logging levels defined by the systems I looked at: - log4j: DEBUG, INFO, WARN, ERROR, FATAL - syslog: DEBUG, INFO, WARNING, ERROR, FATAL - JSR047: FINEST, FINER, FINE, CONFIG, INFO, WARNING, SEVERE - zLOG (used by Zope): TRACE=-300 -- Trace messages DEBUG=-200 -- Debugging messages BLATHER=-100 -- Somebody shut this app up. INFO=0 -- For things like startup and shutdown. PROBLEM=100 -- This isn't causing any immediate problems, but deserves attention. WARNING=100 -- A wishy-washy alias for PROBLEM. ERROR=200 -- This is going to have adverse effects. PANIC=300 -- We're dead! - mx.Log: SYSTEM_DEBUG SYSTEM_INFO SYSTEM_UNIMPORTANT SYSTEM_MESSAGE SYSTEM_WARNING SYSTEM_IMPORTANT SYSTEM_CANCEL SYSTEM_ERROR SYSTEM_PANIC SYSTEM_FATAL The current proposal is to copy log4j. XXX I suppose I could see adding zLOG's "TRACE" level, but I am not sure of the usefulness of others. Static Logging Methods (as per Syslog)? Both zLOG and Syslog provide module-level logging functions rather (or in addition to) logging methods on a created Logger object. XXX Is this something that is deemed worth including? Pros: - It would make the simplest case shorter: import logging logging.error("Something is wrong") instead of import logging log = logging.getLogger("") log.error("Something is wrong") Cons: - It provides more than one way to do it. - It encourages logging without a channel name, because this mechanism would likely be implemented by implicitly logging on the root (and nameless) logger of the hierarchy. References [1] java.util.logging http://java.sun.com/j2se/1.4/docs/guide/util/logging/ [2] log4j: a Java logging package http://jakarta.apache.org/log4j/docs/index.html [3] Protomatter's Syslog http://protomatter.sourceforge.net/1.1.6/index.html http://protomatter.sourceforge.net/1.1.6/javadoc/com/protomatter/syslog/sys… [4] MAL mentions his mx.Log logging module: http://mail.python.org/pipermail/python-dev/2002-February/019767.html [5] Jeff Bauer's Mr. Creosote http://starship.python.net/crew/jbauer/creosote/ Copyright This document has been placed in the public domain. Local Variables: mode: indented-text indent-tabs-mode: nil fill-column: 70 End: -- Trent Mick TrentM(a)ActiveState.com

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The Python of Pythagoras?
by M.-A. Lemburg Feb. 14, 2002

Feb. 14, 2002

Pythaguidoras ?! http://greatserpentmound.org/articles/python.html -- Marc-Andre Lemburg CEO eGenix.com Software GmbH ______________________________________________________________________ Company & Consulting: http://www.egenix.com/ Python Software: http://www.egenix.com/files/python/

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student projects
by Greg Wilson Feb. 14, 2002

Feb. 14, 2002

I'm going to be supervising one-term programming projects for several (3-4) senior Computer Science majors starting in September. They'll have 5-6 hours a week for 13 weeks to (a) learn their way around whatever technology is thrown at them, (b) build something worth building, and (c) write it up. So: any little itches anyone on this list would like to see scratched? Any little add-ons or uses for Jabber, SOAP, etc. that would only take you a weekend or two, but you've never quite gotten around to building? Thanks, Greg p.s. please reply to me directly; if there's enough interest, I'll put together a summary and re-post. ----------------------------------------------------------------------------------------------------------------- The information contained in this message is confidential and is intended for the addressee(s) only. If you have received this message in error or there are any problems please notify the originator immediately. The unauthorized use, disclosure, copying or alteration of this message is strictly forbidden. Baltimore Technologies plc will not be liable for direct, special, indirect or consequential damages arising from alteration of the contents of this message by a third party or as a result of any virus being passed on. This footnote confirms that this email message has been swept by Baltimore MIMEsweeper for Content Security threats, including computer viruses.

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Re: [Python-Dev] SSL support in _socket
by Anthony Baxter Feb. 14, 2002

Feb. 14, 2002

The whole subject of socket and SSL support came up at a lunchtime chat on developers day (and my jetlagged brain has totally failed to supply me the names of who I was talking to at the time...). Wouldn't it be better to rip the SSL support out entirely, and provide a way to hook the transport layer stuff on top of the standard socket object? Anthony -- Anthony Baxter <anthony(a)interlink.com.au> It's never to late to have a happy childhood.

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Partnership Proposal
by MR MICHEAL ADAM Feb. 14, 2002

Feb. 14, 2002

ATTN: THE PRESIDENT/CEO Dear Sir / Madam, I am Dr. Mrs. Marian Abacha, wife to the late Nigerian Head of state, General Sani Abacha who died on the 8th of June 1998 while still on active service for our Country. I am contacting you with the hope that you will be of great assistance to me, I currently have within my reach the sum of 76MILLION U.S dollars cash which l intend to use for investment purposes outside Nigeria. This money came as a result of a payback contract deal between my husband and a Russian firm in our country's multi-billion dollar Ajaokuta steel plant. The Russian partners returned my husband's share being the above sum after his death. Presently, the new civilian Government has intensified their probe into my husband's financial resources, which has led to the freezing of all our accounts, local and foreign, the revoking of all our business licenses and the arrest of my First son. In view of this I acted very fast to withdraw this money from one of our finance houses before it was closed down. I have deposited the money in a security vault for safe keeping with the help of very loyal officials of my late husband. No record is known about this fund by the government because there is no documentation showing that we received such funds. Due to the current situation in the country and government attitude to my financial affairs, I cannot make use of this money within. Bearing in mind that you may assist me, 20% of the total amount will be paid to you for your assistance, while 5% will be set aside for expenses incurred by the parties involved and this will be paid before sharing. Half of my75% will be paid in to my account on your instruction once the money hits your account, while the other half will be invested by your humble self in any viable business venture you deem fit, with you as manager of the invested funds. Remunerations, during the investment period will be on a 50/50 basis. Your URGENT response is needed. All correspondence must be through my lawyer,fax:234-1-4709814. Attentioned to my attorney (HAMZA IBU). Please do not forget to include your direct tel/fax line for easy reach. I hope I can trust you with my family's last financial hope.Regards Dr. Mrs. Marian Sani Abacha. C/o HAMZA IBU (counsel) URGENT AND CONFIDENTIAL MR. MICHEAL ADAM FAX: 234-1-7590900 Attn: The Chief Executive Officer REQUEST FOR URGENT AND CONFIDENTIAL BUSINESS RELATIONSHIP Please permit me to introduce myself to you, my names are Mr. MICHEAL ADAM a Petroleum Engineer with the Nigerian National Petroleum Corporation and a member of the contract award committee of the above corporation, which is under, The Federal Ministry of Petroleum and Natural Resources. CONFIDENTIAL THE SOURCE OF THE FUND IS AS FOLLOWS: With the assistance of some senior officials of the Federal Ministry of Finance and Office of the Accountant General of the Federation, we want to quietly transfer the sum of Nineteen Million US Dollars only ($19m US Dollars only) out of my country Nigeria. This US$19 M US Dollar was quietly over-estimated on the contract for Turn around Maintenance (TAM) of Port Harcourt petrochemical refinery in Nigeria (SOUTHERN NIGERIA) and the Rehabilitation of Petroleum Pipelines, Depot and Jetties. The actual contract value of this said project was US$171M US Dollars, but my colleagues and I deliberately increased the contract to our own benefit to the tune of $190M US Dollars, of which the over-estimated value of US$19M US Dollars belongs to us and this amount is what we want to secretly transfer into your personal or company account for safe keeping and sharing. The Federal Government and the Federal Ministry of Petroleum and Natural Resources have approved the total sum of US$190 Million US Dollars. The project has been completed and commissioned by the Federal Government and the original contractors have been paid their Contractual sum and what is left now is the US$19Million US Dollars. Under this circumstance and upon your acceptance we will register You/your Company as a sub-contractor to the original contractors with my corporation, so that this fund can be transferred into your account without hitch whatsoever. Our reasons of soliciting your assistance to transfer this fund to your account is owing to the policy of the Federal Government of Nigeria, the code conduct debars us civil servants (Government Workers) from operating a foreign account, hence we seeking your assistance. After several deliberations with my colleagues, we decided to give you 25% as your entitlement for your assistance for providing your account, while 70% will be for us and the remaining 5% would be used to offset all local and foreign expenses that might be incurred during this transaction. However this is based on the ground that you would assure me of the following: 1 That after the successful transfer of the $19m us dollars into your account, you will give us our own fare share of 70% without running away with the money or setting on it to our detriment. 2 That you will treat this business with utmost secrecy, Confidentiality, understanding and sincerity, which this business demands. 3 You will assist us (by way of advice) to invest our own share in business venture in your country. 4 Upon your acceptance of this proposal I will send a TEXT for you to fill in your letter headed paper and return back to me, as we shall use this TEXT to raise an application for payment on your behalf as you will be made the recognized beneficiary of the fund. KINDLY FORWARD YOUR TELEPHONE AND FAX NUMBER to me also. PLEASE NOTE: that this business is 100% risk free and will not implicate you in any way, sir. Finally please if you feel you cannot do this business with us, kindly delete this message from your computer or destroy it as it will do you no good showing it to a third party or anybody whatsoever, please kindly do us this favor for God sake. The kind of business you do does not effect the business. Sincerely yours, MR. MICHEAL ADAM

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Re: [Python-Dev] SSL support in _socket
by Michael Hudson Feb. 13, 2002

Feb. 13, 2002

barry(a)zope.com (Barry A. Warsaw) writes: > It shouldn't have been this difficult to debug. Surely there must be > some way to tell setup.py not to delete .so's it can't import so we > have a prayer of finding the real problems. Maybe it just shouldn't install the shared libs if they fail to import? Cheers, M. -- It's actually a corruption of "starling". They used to be carried. Since they weighed a full pound (hence the name), they had to be carried by two starlings in tandem, with a line between them. -- Alan J Rosenthal explains "Pounds Sterling" on asr

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Re: [Python-Dev] syntactic sugar idea for {static,class}methods
by Michael Hudson Feb. 13, 2002

Feb. 13, 2002

barry(a)zope.com (Barry A. Warsaw) writes: > >>>>> "MH" == Michael Hudson <mwh(a)python.net> writes: > >> I'd leave them out of the picture, unless you mean to imply > >> that a list is acceptable in that position <wink>. > > MH> Well, it is, at the moment... > > Well, that's pretty neat! Maybe FAST, but neat. :) No, you're going to have to explain that. (Googling for "FAST" isn't terribly enlightening...). Cheers, M. -- well, take it from an old hand: the only reason it would be easier to program in C is that you can't easily express complex problems in C, so you don't. -- Erik Naggum, comp.lang.lisp

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Re: [Python-Dev] syntactic sugar idea for {static,class}methods
by Michael Hudson Feb. 13, 2002

Feb. 13, 2002

barry(a)zope.com (Barry A. Warsaw) writes: > >>>>> "MH" == Michael Hudson <mwh(a)python.net> writes: > > MH> Some time ago, Gareth McCaughan suggested a syntax for > MH> staticmethods. You'd write > > MH> class C(object): > | def static(arg) [staticmethod]: > | return 1 + arg > > | C.static(2) > | => 3 > > Very interesting! Why the square brackets though? Is that just for > visual offset or is there a grammar constraint that requires them? Um, no big reason; they were what Gareth suggested, so I implemented that. He may have got the idea from the slides from one of Guido's presentations -- it was reading them that reminded me I'd done this and wanted to mention it here. Note, though, that my patch allows an arbitrary number of *expressions* in the square brackets; in principle you can do things like: >>> def h() [apply, (lambda f:(lambda : f() + 1))]: ... return 1 ... and have `h' be 2 (except that this caused an abort at the moment -- I must have missed something in my symtable code). Not sure whether this is a good idea, of course, but allowing arbitrary expressions does actually make the compiling easier. Allowing arbitrary expressions without delimiters sounds like a bad idea, both for parsers and people. > I'd leave them out of the picture, unless you mean to imply that a > list is acceptable in that position <wink>. Well, it is, at the moment... Cheers, M. -- : exploding like a turd Never had that happen to me, I have to admit. They do that often in your world? -- Eric The Read & Dave Brown, asr

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Expat vs Windows
by Tim Peters Feb. 13, 2002

Feb. 13, 2002

Anyone understand what's going on with expat? I noticed pyexpat stopped compiling on Windows a day or two ago, but didn't have time to look at it. Today I see it compiles, but generates lots of linker warnings: Creating library ./pyexpat.lib and object ./pyexpat.exp LINK : warning LNK4049: locally defined symbol "_XML_GetSpecifiedAttributeCount" imported LINK : warning LNK4049: locally defined symbol "_XML_Parse" imported LINK : warning LNK4049: locally defined symbol "_XML_ErrorString" imported etc. Are we trying to break away from the SourceForge expat project? Seems a dubious idea, if so. In any case, I can make almost no time for repairing this on Windows, so need someone to explain what we're trying to accomplish here (btw, if someone already explained this on some mailing list, sorry, I'm hundreds of msgs behind the times).

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