[Tutor] python parser

[bob gailer]

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.


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