This is 0.05

[perl/modules/Scope-Upper.git] / README

diff --git a/README b/README
index 499ba67abc7184f6ca249508eb9283ba139fa0bc..feecd5c772b15f2e41961756e0e81892159d3834 100644 (file)
--- a/README
+++ b/README
@@ -2,7 +2,7 @@ NAME
     Scope::Upper - Act on upper scopes.
 
 VERSION
-    Version 0.03
+    Version 0.05
 
 SYNOPSIS
         package X;
@@ -41,11 +41,32 @@ SYNOPSIS
          ...
         } # "pie: done" is printed
 
+        package Z;
+
+        use Scope::Upper qw/unwind want_at :words/;
+
+        sub try (&) {
+         my @result = shift->();
+         my $cx = SUB UP SUB;
+         unwind +(want_at($cx) ? @result : scalar @result) => $cx;
+        }
+
+        ...
+
+        sub zap {
+         try {
+          return @things; # returns to try() and then outside zap()
+         }
+        }
+
+        my @what = zap(); # @what contains @things
+
 DESCRIPTION
     This module lets you defer actions that will take place when the control
     flow returns into an upper scope. Currently, you can hook an upper scope
     end, or localize variables, array/hash values or deletions of elements
-    in higher contexts.
+    in higher contexts. You can also return to an upper level and know which
+    context was in use then.
 
 FUNCTIONS
   "reap $callback, $level"
@@ -102,13 +123,73 @@ FUNCTIONS
         in the upper scope. It's actually more powerful, as &func won't even
         "exists" anymore. $key is ignored.
 
-  "TOPLEVEL"
+  "unwind @values, $level"
+    Returns @values *from* the context indicated by $level, i.e. from the
+    subroutine, eval or format just above $level.
+
+    The upper level isn't coerced onto @values, which is hence always
+    evaluated in list context. This means that
+
+        my $num = sub {
+         my @a = ('a' .. 'z');
+         unwind @a => 0;
+        }->();
+
+    will set $num to 'z'. You can use "want_at" to handle these cases.
+
+  "want_at $level"
+    Like "wantarray", but for the subroutine/eval/format context just above
+    $level.
+
+    The previous example can then be "corrected" :
+
+        my $num = sub {
+         my @a = ('a' .. 'z');
+         unwind +(want_at(0) ? @a : scalar @a) => 0;
+        }->();
+
+    will righteously set $num to 26.
+
+WORDS
+  "TOP"
     Returns the level that currently represents the highest scope.
 
+  "HERE"
+    The current level - i.e. 0.
+
+  "UP $from"
+    The level of the scope just above $from.
+
+  "DOWN $from"
+    The level of the scope just below $from.
+
+  "SUB $from"
+    The level of the closest subroutine context above $from.
+
+  "EVAL $from"
+    The level of the closest eval context above $from.
+
+    If $from is omitted in any of those functions, the current level is used
+    as the reference level.
+
+  "CALLER $stack"
+    The level of the $stack-th upper subroutine/eval/format context. It kind
+    of corresponds to the context represented by "caller $stack", but while
+    e.g. "caller 0" refers to the caller context, "CALLER 0" will refer to
+    the top scope in the current context. For example,
+
+        reap ... => CALLER(0)
+
+    will fire the destructor when the current subroutine/eval/format ends.
+
 EXPORT
-    The functions "reap", "localize", "localize_elem", "localize_delete" and
-    "TOPLEVEL" are only exported on request, either individually or by the
-    tags ':funcs' and ':all'.
+    The functions "reap", "localize", "localize_elem", "localize_delete",
+    "unwind" and "want_at" are only exported on request, either individually
+    or by the tags ':funcs' and ':all'.
+
+    Same goes for the words "TOP", "HERE", "UP", "DOWN", "SUB", "EVAL" and
+    "CALLER" that are only exported on request, individually or by the tags
+    ':words' and ':all'.
 
 CAVEATS
     Be careful that local variables are restored in the reverse order in