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Hi all,

I am new to Perl (I used to be a C/C++ user). And I want to write a
file convertor in Perl to learn it. And I use ActivePerl.

// Input.txt context
s 1 2
a 4 5
a 9 8

// Output.txt context I want
Sub (wire1, wire2);
Add (wire4, wire5);
Add (wire9, wire;

BTW, how to debug perl script in ActivePerl, can I set breakpoint in
it?

Any suggestions will be appreciated!
Best regards,
Davy

"Davy" <> wrote:

> Hi all,
>
> I am new to Perl (I used to be a C/C++ user). And I want to write a
> file convertor in Perl to learn it. And I use ActivePerl.
>
> // Input.txt context
> s 1 2
> a 4 5
> a 9 8
>
> // Output.txt context I want
> Sub (wire1, wire2);
> Add (wire4, wire5);
> Add (wire9, wire;

What have you been trying so far?

> BTW, how to debug perl script in ActivePerl, can I set breakpoint in
> it?

Yes, perldoc perldebug

Or look up perldebug in the HTML documentation (it's under core
documentation).


--
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Davy wrote:
> Hi all,
>
> I am new to Perl (I used to be a C/C++ user). And I want to write a
> file convertor in Perl to learn it. And I use ActivePerl.
>
> // Input.txt context
> s 1 2
> a 4 5
> a 9 8
>
> // Output.txt context I want
> Sub (wire1, wire2);
> Add (wire4, wire5);
> Add (wire9, wire;

I would split() the line,
_s_ubstitute the 's' with 'Sub' and the 'a' with 'Add'.
And then just print() the new first element, followed by ' (wire', followed
by the second element, followed by ', wire', followed by the third element,
followed by ');'.

> BTW, how to debug perl script in ActivePerl, can I set breakpoint in
> it?

Yes. See 'perldoc perldebug' for details.

jue

[Newsgroups trimmed]

Jürgen Exner <> wrote in comp.lang.perl.misc:
> Davy wrote:
> > Hi all,
> >
> > I am new to Perl (I used to be a C/C++ user). And I want to write a
> > file convertor in Perl to learn it. And I use ActivePerl.
> >
> > // Input.txt context
> > s 1 2
> > a 4 5
> > a 9 8
> >
> > // Output.txt context I want
> > Sub (wire1, wire2);
> > Add (wire4, wire5);
> > Add (wire9, wire;
>
> I would split() the line,
> _s_ubstitute the 's' with 'Sub' and the 'a' with 'Add'.

That would take one s/// for each expansion. I'd expect a real program
to have more than just "a" and "s", so that doesn't scale well. I'd
prefer a hash lookup in this case:

my %expand = (
a => 'Add',
s => 'Sub',
);

Then expansion is a single statement. It's also more maintainable and
presumably faster.

Anno
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Anno Siegel:
> Jürgen Exner:
>> Davy:

>>> // Input.txt context
>>> s 1 2
>>> a 4 5
>>> a 9 8
>>>
>>> // Output.txt context I want
>>> Sub (wire1, wire2);
>>> Add (wire4, wire5);
>>> Add (wire9, wire;
>>
>> I would split() the line,
>> _s_ubstitute the 's' with 'Sub' and the 'a' with 'Add'.
>
> That would take one s/// for each expansion.

Not necessarily:

#!/usr/local/bin/perl

use strict;
use warnings;

while (<DATA>) {

s/^(?:
a(?{'Add'})
|s(?{'Sub'})
|z(?{'Zzz'})
)
[[:blank:]](.)
[[:blank:]](.)$
/$^R (wire$1, wire$2);/x;

print;
}

__DATA__
s 1 2
a 4 5
a 9 8
t 0 0
a 1 2
z 2 2

--
Affijn, Ruud

"Gewoon is een tijger."

Dr.Ruud <rvtol+> wrote in comp.lang.perl.misc:
> Anno Siegel:
> > Jürgen Exner:
> >> Davy:
>
> >>> // Input.txt context
> >>> s 1 2
> >>> a 4 5
> >>> a 9 8
> >>>
> >>> // Output.txt context I want
> >>> Sub (wire1, wire2);
> >>> Add (wire4, wire5);
> >>> Add (wire9, wire;
> >>
> >> I would split() the line,
> >> _s_ubstitute the 's' with 'Sub' and the 'a' with 'Add'.
> >
> > That would take one s/// for each expansion.
>
> Not necessarily:

Well, the immediate implementation with s/// does.

> #!/usr/local/bin/perl
>
> use strict;
> use warnings;
>
> while (<DATA>) {
>
> s/^(?:
> a(?{'Add'})

No fair -- code insertions.

> |s(?{'Sub'})
> |z(?{'Zzz'})
> )
> [[:blank:]](.)
> [[:blank:]](.)$
> /$^R (wire$1, wire$2);/x;

Ah, I'd entirely forgotten about the $^R variable. That's a good use.

> print;
> }
>
> __DATA__
> s 1 2
> a 4 5

[...]

I think the purpose of code insertions is to prove that everything can be
done with a regex

I don't use them much. Last time I looked there were still scoping issues
with surrounding lexicals (but don't take my word for it), so the designation
as experimental was still appropriate.

Anno
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If you want to post a followup via groups.google.com, don't use
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Anno Siegel:
> Dr.Ruud:
>> Anno Siegel:
>>> Jürgen Exner:

>>>> I would split() the line,
>>>> _s_ubstitute the 's' with 'Sub' and the 'a' with 'Add'.
>>>
>>> That would take one s/// for each expansion.
>>
>> Not necessarily:
>
> Well, the immediate implementation with s/// does.
>
>> [...]
>
> No fair -- code insertions.

I just knew you would say that. And you're right.


> Ah, I'd entirely forgotten about the $^R variable. That's a good use.

I had never used it before.


> I think the purpose of code insertions is to prove that everything
> can be done with a regex
>
> I don't use them much. Last time I looked there were still scoping
> issues with surrounding lexicals (but don't take my word for it), so
> the designation as experimental was still appropriate.

Good remark. For those who want to know more, see perlre.

--
Affijn, Ruud

"Gewoon is een tijger."