[win32] various tweaks to makefiles

[p5sagit/p5-mst-13.2.git] / pod / perlsyn.pod

diff --git a/pod/perlsyn.pod b/pod/perlsyn.pod
index 9c3f661..205be7d 100644 (file)
--- a/pod/perlsyn.pod
+++ b/pod/perlsyn.pod
@@ -79,14 +79,16 @@ modifiers are:
     unless EXPR
     while EXPR
     until EXPR
+    foreach EXPR
 
 The C<if> and C<unless> modifiers have the expected semantics,
-presuming you're a speaker of English.  The C<while> and C<until>
-modifiers also have the usual "while loop" semantics (conditional
-evaluated first), except when applied to a do-BLOCK (or to the
-now-deprecated do-SUBROUTINE statement), in which case the block
-executes once before the conditional is evaluated.  This is so that you
-can write loops like:
+presuming you're a speaker of English.  The C<foreach> modifier is an
+iterator:  For each value in EXPR, it aliases $_ to the value and
+executes the statement.  The C<while> and C<until> modifiers have the
+usual "while loop" semantics (conditional evaluated first), except
+when applied to a do-BLOCK (or to the now-deprecated do-SUBROUTINE
+statement), in which case the block executes once before the
+conditional is evaluated.  This is so that you can write loops like:
 
     do {
        $line = <STDIN>;
@@ -270,15 +272,22 @@ implicitly local to the loop and regains its former value upon exiting
 the loop.  If the variable was previously declared with C<my>, it uses
 that variable instead of the global one, but it's still localized to
 the loop.  (Note that a lexically scoped variable can cause problems
-with you have subroutine or format declarations.)
+if you have subroutine or format declarations within the loop which
+refer to it.)
 
 The C<foreach> keyword is actually a synonym for the C<for> keyword, so
 you can use C<foreach> for readability or C<for> for brevity.  If VAR is
-omitted, $_ is set to each value.  If LIST is an actual array (as opposed
-to an expression returning a list value), you can modify each element of
-the array by modifying VAR inside the loop.  That's because the C<foreach>
-loop index variable is an implicit alias for each item in the list that
-you're looping over.
+omitted, $_ is set to each value.  If any element of LIST is an lvalue,
+you can modify it by modifying VAR inside the loop.  That's because
+the C<foreach> loop index variable is an implicit alias for each item
+in the list that you're looping over.
+
+If any part of LIST is an array, C<foreach> will get very confused if
+you add or remove elements within the loop body, for example with
+C<splice>.   So don't do that.
+
+C<foreach> probably won't do what you expect if VAR is a tied or other
+special variable.   Don't do that either.
 
 Examples: