Not as of yet, because someone else has been using my laptop while her PC is temporarily out of commission. I will be at this evening's meeting at
www.Out-Of-Sight.com though. Thanks. ---Be positive! When it comes to being defeated, if you think you're finished, you! really! are! finished! ----- Original Message ----- From: "Richard Dinger" <rrdinger@xxxxxxxxxx>
To: <pythonvis@xxxxxxxxxxxxx> Sent: Wednesday, April 30, 2014 11:24 PMSubject: [pythonvis] Re: thoughts on confusing threads - Re: How Python works ... was Re: print"Hello world."
I think all the jargon that we use is a primary source of bewilderment among newbies. At least the book 'How to Think like a Computer Scientist' has a glossary at the end of each chapter and attempts to explain new terms as they come up. Over time you will learn and become comfortable with the jargon.Now, as I recall, you said you got the hello program to run. Have you gone further in one of the books and is anything confusing you?Richard-----Original Message----- From: Charles RivardSent: Wednesday, April 30, 2014 4:20 PM To: pythonvis@xxxxxxxxxxxxxSubject: [pythonvis] thoughts on confusing threads - Re: How Python works ... was Re: print"Hello world."I agree that maybe this discussion should be taken up at a later date, whenpeople like me actually know what's being talked about. Right now, it's totally confusing. What I am doing, though, is saving these explanatory posts for future reference. ---Be positive! When it comes to being defeated, if you think you're finished,you! really! are! finished!----- Original Message ----- From: "Richard Dinger" <rrdinger@xxxxxxxxxx>To: <pythonvis@xxxxxxxxxxxxx> Sent: Tuesday, April 29, 2014 11:04 PM Subject: [pythonvis] How Python works ... was Re: print"Hello world."This sort of discussion serves mainly to confuse new programmers if they payany attention. So maybe this thread should be retired.That being said, there may still be some confusion over how the translationprocess works and when errors are discovered. Hopefully, the following will help clarify things.The .py file you write with your text editor is called a source code file. Something called the compiler reads and translates your python source code into what is called a bytecode representation. syntax errors are errors in the formal rules of the programming language (like misspelled words or missing quotes) and are discovered by thecompiler. Execution of the translation process stops when a syntax error isdiscovered. If there were no syntax or other compiler errors, the byte code isthen passed to the Python virtual machine, which executes the translated bytecode. If an error occurs during this execution phase it is called a runtime error since it happened while the program is running. And as usual, execution ishalted when such a run time error is discovered. Mark Lutz in 'Learning Python 3rd edition summarizes: When you instruct Python to run your script, there are a few steps that Python carries out before your code actually starts crunching away.Specifically, it's first compiled to something called "byte code" and thenrouted to something called a "virtual machine." Richard-----Original Message----- From: Octavian RasnitaSent: Tuesday, April 29, 2014 1:34 PM To: pythonvis@xxxxxxxxxxxxx Subject: [pythonvis] Re: print"Hello world." Yep, the results are: D:\>python z8.py File "z8.py", line 2 pritn "Goodbye world!" ^ SyntaxError: invalid syntax D:\> So the program is not ran.As I said, first the program is checked for syntax, is compiled in memory if the syntax is correct and if it has a syntax error no line is executed fromit. Then it is ran. But just like in any program made in any other language,there may appear runtime errors like no free space on hard disk, no memory,divide by zero etc.All these things can't be known at compile time. Probably a program asks touser to type 2 numbers and then divide one with the other. The user can type anything including 0 or strings.If the input is not checked then there may appear runtime errors, but that doesn't mean that the program has an error, It is just poorly made becauseit doesn't check the input data or it doesn't treat all the possible exceptions etc. (And this can happen in programs made in other languages also.) --Octavian----- Original Message ----- From: "James Scholes" <james@xxxxxxxxxxxxx>To: <pythonvis@xxxxxxxxxxxxx> Sent: Tuesday, April 29, 2014 9:14 PM Subject: [pythonvis] Re: print"Hello world."Richard Dinger wrote:I was unable to replicate your example. The first correct print statement did not print, I only got the error traceback.I should've realised that a syntax error would prevent the program from running at all. However, a traceback does not. For example, if you run the following code: print "Hello world!" print "Here comes a traceback when we try to divide by zero..." print 20 / 0 You will see: Hello world! Here comes a traceback when we try to divide by zero... Traceback (most recent call last): File "hello.py", line 3, in <module> print 20 / 0 ZeroDivisionError: integer division or modulo by zero You cannot divide a number by zero, so your program crashes and generates a traceback. However, as you can see, the file is syntactically correct, so the statements up to that point will run without a problem. Apologies for the error! -- James Scholes http://twitter.com/JamesScholes
