argra****@users*****
argra****@users*****
2014年 9月 28日 (日) 05:21:29 JST
Index: docs/perl/5.18.1/perldata.pod
diff -u docs/perl/5.18.1/perldata.pod:1.1 docs/perl/5.18.1/perldata.pod:1.2
--- docs/perl/5.18.1/perldata.pod:1.1 Sat Aug 24 17:14:45 2013
+++ docs/perl/5.18.1/perldata.pod Sun Sep 28 05:21:28 2014
@@ -273,6 +273,18 @@
=end original
+Up until Perl 5.18, the actual rules of what a valid identifier
+was were a bit fuzzy. However, in general, anything defined here should
+work on previous versions of Perl, while the opposite -- edge cases
+that work in previous versions, but aren't defined here -- probably
+won't work on newer versions.
+As an important side note, please note that the following only applies
+to bareword identifiers as found in Perl source code, not identifiers
+introduced through symbolic references, which have much fewer
+restrictions.
+If working under the effect of the C<use utf8;> pragma, the following
+rules apply:
+(TBT)
/ (?[ ( \p{Word} & \p{XID_Start} ) + [_] ]) \p{XID_Continue}* /x
@@ -283,6 +295,9 @@
=end original
+If not under C<use utf8>, the source is treated as ASCII + 128 extra
+controls, and identifiers should match
+(TBT)
/ (?aa) (?!\d) \w+ /x
@@ -293,6 +308,9 @@
=end original
+That is, any word character in the ASCII range, as long as the first
+character is not a digit.
+(TBT)
=begin original
@@ -305,6 +323,13 @@
=end original
+There are two package separators in Perl: A double colon (C<::>) and a single
+quote (C<'>). Normal identifiers can start or end with a double colon, and
+can contain several parts delimited by double colons.
+Single quotes have similar rules, but with the exception that they are not
+legal at the end of an identifier: That is, C<$'foo> and C<$foo'bar> are
+legal, but C<$foo'bar'> are not.
+(TBT)
=begin original
@@ -318,6 +343,14 @@
=end original
+Finally, if the identifier is preceded by a sigil --
+More so, normal identifiers can start or end with any number
+of double colons (::), and can contain several parts delimited
+by double colons.
+And additionally, if the identifier is preceded by a sigil --
+that is, if the identifier is part of a variable name -- it
+may optionally be enclosed in braces.
+(TBT)
=begin original
@@ -327,6 +360,10 @@
=end original
+While you can mix double colons with singles quotes, the quotes must come
+after the colons: C<$::::'foo> and C<$foo::'bar> are legal, but C<$::'::foo>
+and C<$foo'::bar> are not.
+(TBT)
=begin original
@@ -334,6 +371,8 @@
=end original
+Put together, a grammar to match a basic identifier becomes
+(TBT)
/
(?(DEFINE)
@@ -371,6 +410,11 @@
=end original
+Meanwhile, special identifiers don't follow the above rules; For the most
+part, all of the identifiers in this category have a special meaning given
+by Perl. Because they have special parsing rules, these generally can't be
+fully-qualified. They come in four forms:
+(TBT)
=over