[p5sagit/p5-mst-13.2.git] / Changes

Incompatibilities
-----------------
    s'$lhs'$rhs' now does no interpolation on either side.  It used to
    interplolate $lhs but not $rhs.

    The second and third arguments of splice are now evaluated in scalar
    context (like the book says) rather than list context.

    Saying "shift @foo + 20" is now a semantic error because of precedence.

    "open FOO || die" is now incorrect.  You need parens around the filehandle.

    The elements of argument lists for formats are now evaluated in list
    context.  This means you can interpolate list values now.

    You can't do a goto into a block that is optimized away.  Darn.

    It is no longer syntactically legal to use whitespace as the name
    of a variable.

    Some error messages will be different.

    The caller function now a false value in a scalar context if there is
    no caller.  This lets library files determine if they're being required.

    m//g now attaches its state to the searched string rather than the
    regular expression.

New things
----------
    The -w switch is much more informative.

    References.  See t/op/ref.t for examples.

    Objects.  See t/op/ref.t for examples.

    => is now a synonym for comma.  This is useful as documentation for
    arguments that come in pairs, such as initializers for associative arrays,
    or named arguments to a subroutine.

    All functions have been turned into list operators or unary operators,
    meaning the parens are optional.  Even subroutines may be called as
    list operators if they've already been declared.

    More embeddible.  See main.c and embed_h.SH.

    The interpreter is now flattened out.  Compare Perl 4's eval.c with
    the perl 5's pp.c.  Compare Perl 4's 900 line interpreter loop in cmd.c
    with Perl 5's 1 line interpreter loop in run.c.  Eventually we'll make
    everything non-blocking so we can interface nicely with a scheduler.

    eval is now treated more like a subroutine call.  Among other things,
    this means you can return from it.

    Format value lists may be spread over multiple lines by enclosing in
    curlies.

    You may now define BEGIN and END subroutines for each package.  The BEGIN
    subroutine executes the moment it's parsed.  The END subroutine executes
    just before exiting.

    Flags on the #! line are interpreted even if the script wasn't
    executed directly.  (And even if the script was located by "perl -x"!)

    The ?: operator is now legal as an lvalue.

    List context now propagates to the right side of && and ||, as well
    as the 2nd and 3rd arguments to ?:.

    The "defined" function can now take a general expression.

    Lexical scoping available via "my".  eval can see the current lexical
    variables.

    Saying "package;" requires explicit package name on global symbols.
Commit	Line	Data
93a17b20	1	Incompatibilities
93a17b20	2	-----------------
79072805	3	s'$lhs'$rhs' now does no interpolation on either side. It used to
	4	interplolate $lhs but not $rhs.
	5
	6	The second and third arguments of splice are now evaluated in scalar
	7	context (like the book says) rather than list context.
	8
93a17b20	9	Saying "shift @foo + 20" is now a semantic error because of precedence.
	10
	11	"open FOO \|\| die" is now incorrect. You need parens around the filehandle.
79072805	12
79072805	13	The elements of argument lists for formats are now evaluated in list
93a17b20	14	context. This means you can interpolate list values now.
79072805	15
93a17b20	16	You can't do a goto into a block that is optimized away. Darn.
79072805	17
	18	It is no longer syntactically legal to use whitespace as the name
	19	of a variable.
	20
	21	Some error messages will be different.
93a17b20	22
	23	The caller function now a false value in a scalar context if there is
	24	no caller. This lets library files determine if they're being required.
	25
	26	m//g now attaches its state to the searched string rather than the
	27	regular expression.
	28
	29	New things
	30	----------
	31	The -w switch is much more informative.
	32
	33	References. See t/op/ref.t for examples.
	34
	35	Objects. See t/op/ref.t for examples.
	36
	37	=> is now a synonym for comma. This is useful as documentation for
	38	arguments that come in pairs, such as initializers for associative arrays,
	39	or named arguments to a subroutine.
	40
	41	All functions have been turned into list operators or unary operators,
	42	meaning the parens are optional. Even subroutines may be called as
	43	list operators if they've already been declared.
	44
	45	More embeddible. See main.c and embed_h.SH.
	46
	47	The interpreter is now flattened out. Compare Perl 4's eval.c with
	48	the perl 5's pp.c. Compare Perl 4's 900 line interpreter loop in cmd.c
	49	with Perl 5's 1 line interpreter loop in run.c. Eventually we'll make
	50	everything non-blocking so we can interface nicely with a scheduler.
	51
	52	eval is now treated more like a subroutine call. Among other things,
	53	this means you can return from it.
	54
	55	Format value lists may be spread over multiple lines by enclosing in
	56	curlies.
	57
	58	You may now define BEGIN and END subroutines for each package. The BEGIN
	59	subroutine executes the moment it's parsed. The END subroutine executes
	60	just before exiting.
	61
	62	Flags on the #! line are interpreted even if the script wasn't
	63	executed directly. (And even if the script was located by "perl -x"!)
	64
	65	The ?: operator is now legal as an lvalue.
	66
	67	List context now propagates to the right side of && and \|\|, as well
	68	as the 2nd and 3rd arguments to ?:.
	69
	70	The "defined" function can now take a general expression.
	71
	72	Lexical scoping available via "my". eval can see the current lexical
	73	variables.
	74
	75	Saying "package;" requires explicit package name on global symbols.