[svn:perl6-synopsis] r13575 - doc/trunk/design/syn

[la...@cvs.perl.org]

Author: larry
Date: Thu Feb 8 13:04:46 2007
New Revision: 13575

Modified:
doc/trunk/design/syn/S02.pod

Log:
Added mother-of-all-quoting-forms Q// for compositional sanity.
qn// is now gone, since Q// does that without having to "undo" a q//.

Modified: doc/trunk/design/syn/S02.pod
==============================================================================
--- doc/trunk/design/syn/S02.pod (original)
+++ doc/trunk/design/syn/S02.pod Thu Feb 8 13:04:46 2007
@@ -1917,6 +1917,26 @@

=item *

+In addition to C<q> and C<qq>, there is now the base form C<Q> which does
+I<no> interpolation unless explicitly modified to do so. So C<q> is really
+short for C<Q:q> and C<qq> is short for C<Q:qq>. In fact, all quote-like
+forms derive from C<Q> with adverbs:
+
+ q// Q :q //
+ qq// Q :qq //
+ rx// Q :regex //
+ s/// Q :subst ///
+ tr/// Q :trans ///
+
+Adverbs such as C<:regex> change the language to be parsed by switching
+to a different parser. This can completely change the interpreation
+of any subsequent adverbs as well as the quoted material itself.
+
+ q:s// Q :q :scalar //
+ rx:s// Q :regex :sigspace //
+
+=item *
+
Generalized quotes may now take adverbs:

Short Long Meaning
@@ -1924,8 +1944,6 @@
:x :exec Execute as command and return results
:w :words Split result on words (no quote protection)
:ww :quotewords Split result on words (with quote protection)
- :t :to Interpret result as heredoc terminator
- :n :none No escapes at all (unless otherwise adverbed)
:q :single Interpolate \\, \q and \' (or whatever)
:qq :double Interpolate with :s, :a, :h, :f, :c, :b
:s :scalar Interpolate $ vars
@@ -1934,6 +1952,10 @@
:f :function Interpolate & calls
:c :closure Interpolate {...} expressions
:b :backslash Interpolate \n, \t, etc. (implies :q at least)
+ :to Parse result as heredoc terminator
+ :regex Parse as regex
+ :subst Parse as substitution
+ :trans Parse as transliteration
:code Quasiquoting

Ordinarily the colon is required on adverbs, but the C<quote> declarator
@@ -1941,11 +1963,11 @@
without an intervening colon:

quote qw; # declare a P5-esque qw// meaning q:w
- quote qn; # completely raw quote qn//
- quote qnc; # q:n:c//, interpolate only closures
+ quote Qc; # Q:c//, interpolate only closures

-Actually, the first two are already assumed, because you get all of the
-forms that use as single character predeclared for free.
+Actually, those two are already assumed, because you get all of the
+forms that use a single character modifier predeclared for free. (Note
+this means that C<qx//> doesn't intepolate.)

If you want to abbreviate further, you may also give an explicit
definition as either a string or quasiquote:
@@ -1957,28 +1979,28 @@
In particular, all these forms disable the lookahead for an adverbial argument,
as if there were a space after the keyword. So although

- q:n($foo)
+ q:s($foo)

-will misinterpret C<$foo> as the C<:n> argument,
+will misinterpret C<$foo> as the C<:s> argument,

- qn(stuff)
+ qs(stuff)

-has the advantage of misinterpreting it as the argument to the C<qn()>
+has the advantage of misinterpreting it as the argument to the C<qs()>
function instead. C<:)>

But parens are special that way. (Even C<q()> is assumed to be a
function call rather than a quote.) Other bracketing characters are
special only if they can be mistaken for adverbial arguments, so

- qn[stuff]
+ qs[stuff]

is fine, and means

- q:n /stuff/
+ q:s /stuff/

while

- q:n[stuff]
+ q:s[stuff]

also happens to work because quote adverbs only allow the paren form of
bracketed adverbs.
@@ -1987,16 +2009,16 @@
adverbs and operators as standard macros. The main difference is that,
unlike

- quote qn = 'q:n';
+ quote qs = 'q:s';

declaring something like

- macro qn { 'q:n' }
+ macro qs { 'q:s' }

does I<not> disable the subsequent search for a parenthesized argument
to C<:n>. To get the equivalent, you need to add a space:

- macro qn { 'q:n ' }
+ macro qs { 'q:s ' }

All the uppercase adverbs are reserved for user-defined quotes.
All Unicode delimiters above Latin-1 are reserved for user-defined quotes.