[Tutor] python parser

[bob gailer]

johnf wrote:
> On Monday 22 December 2008 09:15:13 am bob gailer wrote:
>   
>> johnf wrote:
>>     
>>> I've been in the programming business for over 20 years and I have never
>>> had a need for a parser.  But recently I have need to convert code from
>>> one language to a my new language python.
>>>       
>> Pray tell: what is the other language, and why do you want to convert
>> programs?
>>
>> I assume you want to convert so you can then modify / extend the old
>> programs. If you just plan to run them in Python "as is" I see no value
>> in converting!
>>
>> It is hard to map programs in other languages to Python because Python
>> is so different. A direct translation would not take advantage of
>> python's uniqueness.
>>
>>     
>>> What a better way to learn the new
>>> language python than a new project.  I decided it might be time to learn
>>> a little something about parsers too.  However, I soon discovered that I
>>> was walking into the world of compiler writers and theories of computer
>>> scientist.  I paid for and downloaded a paper from O'Reilly books on what
>>> I thought was going to be on 'pyparser'.  But that turned out to be
>>> mostly theory.  And nothing about the use of pyparser.
>>>
>>> So I ask you guys is there a link to a practical tutorial that provides
>>> hands on information on the use of a python parser.  I'd like to see
>>> something that demo's converting a real language to python.  When I
>>> google parsers I have found a few simple code examples of parsing a
>>> float.  Not really much help (I could have done that using Regex) when
>>> you want to parse 'if,then' statements that can be recursive.
>>>       
>> FWIW I have written a parser for parts of the CMS Pipelines language. I
>> provide a form of BNF for the syntax, generate parsers from that, run a
>> "program" through that, which generates lists or dictionaries. I have no
>> need to create a program from that.
>>
>> The Pipelines language is very simple, so I am not dealing with control
>> structures, just sequences of words and symbols.
>>     
>
> Well I'm attempting to convert VFP and MsSQL (stored procedures and triggers) 
> to Python and Postgres (functions and triggers).  Actually, python is very 
> close to VFP and I would convert very well.  MsSQL is another question.
>   

I started writing a VFP - Python converter a few years ago. I will see 
if I have it around.

> It has been suggested that I just read one line at a time and convert.  I 
> could do that but I did want to expand my understanding by using a parser. 
> And the one line at a time does not lend it self to control structures.  
>
> Even if I do a get the convert to work there would still be a need for hand 
> coding.  But it would provide a good start.
>
> So far no links to tutorials?
>   


-- 
Bob Gailer
Chapel Hill NC 
919-636-4239