Merge pull request Perl#8 from xenu/xenu/rfc-slurp-mode

New RFC: command-line flag for slurping

rfcs/rfc0011.md

@@ -0,0 +1,76 @@
+# Command-line flag for slurping
+
+## Preamble
+
+    Author: Tomasz Konojacki <me@xenu.pl>
+    Sponsor:
+    ID: 0011
+    Status: Draft
+
+## Abstract
+
+Introduce a new command-line flag for `perl`, `-g`, which sets `$/` to `undef`,
+and thus enables slurp mode. It is a simpler alias for `-0777`.
+
+## Motivation
+
+Slurping (i.e. reading a whole file at once, instead of line by line) is a very
+common operation in one-liners, and therefore it deserves its own dedicated
+flag.
+
+## Rationale
+
+Currently, `-0777` is the most common way to enable slurp mode in one-liners.
+It's a special case of `-0number`. When `number` is above `0o377` it sets `$/`
+to `undef`, which enables slurp mode.
+
+`-0number` suffers from the following problems:
+
+- The input record separator has to be specified with an octal number, which is
+  very unusual.
+
+- It's overly general, it can set `$/` to any character. Users rarely need
+  values other than `undef` or `"\n"`.
+
+- Its most common use, enabling slurp mode, is a special case hidden behind
+  a magic number.
+
+A dedicated flag for slurping would allow users to avoid the peculiarities of
+`-0number`.
+
+## Specification
+
+`-g` is an alias for `-0777`, they are completely equivalent.
+
+## Backwards Compatibility
+
+No breakage is expected. `perl -g` is currently a fatal error.
+
+## Security Implications
+
+Hopefully none.
+
+## Examples
+
+    # collapse consecutive newlines:
+    perl -i -gpE 's/\n+/\n/g' file.txt
+
+## Future Scope
+
+## Rejected Ideas
+
+- Long flag, e.g. `--slurp`. Perl currently doesn't support long flags and
+  adding them would be beyond the scope of this RFC.
+
+- Alternative spellings of the flag, e.g. `-R`, `-o`. The author believes none
+  of them are better or worse than `-g`. Unfortunately, the most natural choice,
+  `-s`, [is already taken](https://perldoc.perl.org/5.34.0/perlrun#-s).
+
+## Open Issues
+
+## Copyright
+
+Copyright (C) 2021 Tomasz Konojacki
+
+This document and code and documentation within it may be used, redistributed
+and/or modified under the same terms as Perl itself.