Re: [RFC] linecut addition

[Steven Schubiger]

Jim Meyering <address@hidden> wrote:
> Your range_lines function reads only one buffer's worth of data.

Uhm, yes. I noticed it later on.

> While I did mention head, above, a subsequent message pointed
> to tail as a better source of relevant code:
> 
> >> However, another possibility is to extract the relevant parts of
> >> tail into a library and to use them from both programs.
> >> But it's too early to worry about this.
> 
> Before coding further, I strongly urge you to nail down the
> specification -- publicly.  Put it this way: write enough
> details that someone reading your description in a man page
> would not be disappointed.
> 
> I recommend giving a small, precise example to illustrate each use case.
> E.g., seq 100 | linecut --number --range ... would print this:
> ...

Follows shortly.

> Another reason to specify up front: I think you wanted to be able to
> specify a negative number, -N, as a range endpoint, representing the Nth
> line from the end of the file.  The implementation required to support
> that is very different from what's required for the other types of ranges.
> See tail's elide_* functions.

I see.

> I don't want to dissuade you from writing the tool, but rather to
> encourage you to use another language: please consider writing it
> first in Perl, Python, or Ruby.  Even if that first cut isn't
> terribly efficient, it will give you an easy way to experiment
> with features and algorithms without being distracted by the, um, ...
> features of C.  Who knows... once you've written it in a scripting
> language, you may not think it's worth rewriting in C.

The feature-set is quite frozen for now and I already have a working 
implementation in C (albeit a bit "slow" due to massive memory allocation).