Extract lines from file, add to new files

[Left Right]

Ah, nevermind. I need to be more careful, there isn't an "'as'
star_target" after the first rule.

On Thu, Jan 11, 2024 at 10:33 PM Left Right <olegsivokon at gmail.com> wrote:
>
> By the way, in an attempt to golf this problem, I discovered this,
> which seems like a parser problem:
>
> This is what Python tells me about its grammar:
>
> with_stmt:
>     | 'with' '(' ','.with_item+ ','? ')' ':' block
>     | 'with' ','.with_item+ ':' [TYPE_COMMENT] block
>     | ASYNC 'with' '(' ','.with_item+ ','? ')' ':' block
>     | ASYNC 'with' ','.with_item+ ':' [TYPE_COMMENT] block
>
> with_item:
>     | expression 'as' star_target &(',' | ')' | ':')
>     | expression
>
> From which I figured why not something like this:
>
> with (open('example.txt', 'r'), open('emails.txt', 'w'),
> open('salutations.txt', 'w')) as e, m, s:
>     for line in e:
>         if line.strip():
>             (m if '@' in line else s).write(line)
>
> Which, surprise, parsers! But it seems like it's parse is wrong,
> because running this I get:
>
> ❯ python ./split_emails.py
> Traceback (most recent call last):
>   File "/home/?/doodles/python/./split_emails.py", line 1, in <module>
>     with (open('example.txt', 'r'), open('emails.txt', 'w'),
> open('salutations.txt', 'w')) as e, m, s:
> TypeError: 'tuple' object does not support the context manager protocol
>
> It seems to me it shouldn't have been parsed as a tuple. The
> parenthesis should've been interpreted just as a decoration.
>
> NB. I'm using 3.11.6.
>
> On Thu, Jan 11, 2024 at 10:20 PM Thomas Passin via Python-list
> <python-list at python.org> wrote:
> >
> > On 1/11/2024 1:27 PM, MRAB via Python-list wrote:
> > > On 2024-01-11 18:08, Rich Shepard via Python-list wrote:
> > >> It's been several years since I've needed to write a python script so I'm
> > >> asking for advice to get me started with a brief script to separate names
> > >> and email addresses in one file into two separate files:
> > >> salutation.txt and
> > >> emails.txt.
> > >>
> > >> An example of the input file:
> > >>
> > >> Calvin
> > >> calvin at example.com
> > >>
> > >> Hobbs
> > >> hobbs at some.com
> > >>
> > >> Nancy
> > >> nancy at herown.com
> > >>
> > >> Sluggo
> > >> sluggo at another.com
> > >>
> > >> Having extracted salutations and addresses I'll write a bash script using
> > >> sed and mailx to associate a message file with each name and email
> > >> address.
> > >>
> > >> I'm unsure where to start given my lack of recent experience.
> > >>
> > >  From the look of it:
> > >
> > > 1. If the line is empty, ignore it.
> > >
> > > 2. If the line contains "@", it's an email address.
> > >
> > > 3. Otherwise, it's a name.
> >
> > You could think about a single Python script that looks through your
> > input file and constructs all the message files without ever writing
> > separate salutation and address files at all.  Then you wouldn't need to
> > write the sed and mailx scripts.  It shouldn't be much harder than
> > peeling out the names and addresses into separate files.
> >
> > If you haven't written any Python for some years, the preferred way to
> > read and write files is using a "with" statement, like this:
> >
> > with open('email_file.txt', encoding = 'utf-8') as f:
> >      lines = f.readlines()
> >      for line in lines:
> >          if not line.strip():  # Skip blank lines
> >              continue
> >          # Do something with this line
> >
> > You don't need to close the file because when the "with" block ends the
> > file will be closed for you.
> >
> > If the encoding is not utf-8 and you know what it will be, use that
> > encoding instead.
> >
> > --
> > https://mail.python.org/mailman/listinfo/python-list