Author: larry
Date: Mon Apr 10 11:04:44 2006
New Revision: 8625
Modified:
doc/trunk/design/syn/S02.pod
Log:
Refactored long dot and embedded comments to be more orthogonal, so that
foo.#{ bar }.baz is now just a long dot whose <ws> happens to match #{}.
Modified: doc/trunk/design/syn/S02.pod
==============================================================================
--- doc/trunk/design/syn/S02.pod (original)
+++ doc/trunk/design/syn/S02.pod Mon Apr 10 11:04:44 2006
@@ -12,9 +12,9 @@
Maintainer: Larry Wall <[EMAIL PROTECTED]>
Date: 10 Aug 2004
- Last Modified: 7 Apr 2006
+ Last Modified: 10 Apr 2006
Number: 2
- Version: 21
+ Version: 22
This document summarizes Apocalypse 2, which covers small-scale
lexical items and typological issues. (These Synopses also contain
@@ -44,6 +44,7 @@
not to use thin spaces where they will make adjoining tokens look like
a single token. On the other hand, Perl doesn't use indentation as syntax,
so you are free to use any whitespace anywhere that whitespace makes sense.
+Comments always count as whitespace.
=back
@@ -79,34 +80,50 @@
=item *
Embedded comments are supported as a variant on quoting syntax, introduced
-by C<.#> and delimited by user-selected characters.
+by C<#> plus any user-selected bracketing characters (including Unicode):
- say .#( embedded comment ) "hello, world!";
+ say #( embedded comment ) "hello, world!";
- $object.#/ embedded comments /.say;
+ $object.#{ embedded comments }.say;
- $object.#[
+ $object.#「
embedded comments
- ].say;
+ 」.say;
-The delimiters of the C<.#//> embedded comment form may be chosen
-from the same set that are valid for ordinary C<q//> quote forms,
-and follow the same policy on the nesting of bracketing characters.
-Unlike the other two forms of comment, the embedded form does not
-count as whitespace.
-
-As a variant of the embedded form, a single dot followed by a space
-is equivalent to C<.#.> (plus an extra dot at the end) so you can
-write a small (generally whitespace only) comment as:
+There must be no space between the # and the opening bracket character.
+Brackets may be nested following the same policy as ordinary quote brackets.
+
+=item *
+
+In addition to the general comment forms above, there is a whitespace-only
+comment form that begins and ends with a single dot, separated by whitespace,
+which is equivalent to a single dot:
%hash. .{$key}
@array. .{$key}
-which is useful for lining up postfixes. This is known as the "long dot",
+This is useful for lining up postfixes. This is known as the "long dot",
partly because it substitutes for a dot without the need for a third dot:
$object. .say();
+The whitespace in the middle may include any of the comment forms above.
+Because comments always count as whitespace, the dots in
+
+ $object.#{ foo }.say
+
+reduce to a "long dot" rather than the range operator. Valid ways to
+insert a line break into a sequence of methods calls include:
+
+ $object. # comment
+ .say
+
+ $object.#[ comment
+ ].say
+
+ $object.
+ .say
+
=item *
In general, whitespace is optional in Perl 6 except where it is needed
@@ -139,21 +156,18 @@
$x. .++
- $x.#. .++
-
- $x. comment .++
-
$x.#( comment ).++
$x.
.++
- $x.#.
+ $x. # comment
+ # more comment
.++
- $x.#[ # comment
- # more comment
- ].++
+ $x.#『 comment
+ more comment
+ 』.++
$x.#[ comment 1
comment 2
@@ -164,14 +178,38 @@
].++
A consequence of the postfix rule is that (except when delimiting a
-a quote or comment) a dot with whitespace in front of it is always
-considered a method call on C<$_> where a term is expected. If a
-term is not expected at this point, it is a syntax error. (Unless,
-of course, there is an infix operator of that name beginning with
-dot. You could, for instance, define a Fortranly C<< infix:<.EQ.> >>
-if the fit took you. But you'll have to be sure to always put
-whitespace in front of it, or it would be interpreted as a postfix
-method call instead.)
+a quote or terminating a "long dot") a dot with whitespace in front
+of it is always considered a method call on C<$_> where a term is
+expected. If a term is not expected at this point, it is a syntax
+error. (Unless, of course, there is an infix operator of that name
+beginning with dot. You could, for instance, define a Fortranly C<<
+infix:<.EQ.> >> if the fit took you. But you'll have to be sure to
+always put whitespace in front of it, or it would be interpreted as
+a postfix method call instead.)
+
+For example,
+
+ foo .method
+
+and
+
+ foo
+ .method
+
+will always be interpreted as
+
+ foo $_.method
+
+but never as
+
+ foo.method
+
+Use some variant of
+
+ foo.
+ .method
+
+if you mean the postfix method call.
=back
@@ -509,7 +547,7 @@
Whitespace is not allowed before the parens, but there is a
corresponding C<.()> operator, plus the "long dot" forms that allow
-you to insert optional whitespace between dots:
+you to insert optional whitespace and commentsbetween dots:
&foo. .($arg1, $arg2);
&foo.#[
@@ -789,7 +827,7 @@
is the variable name, including any sigil. The package object can
be derived from a type name by use of the C<::> postfix operator:
- MyType .:: .{'$foo'}
+ MyType. .::. .{'$foo'}
MyType::<$foo> # same thing
(Directly subscripting the type with either square brackets or curlies
