package Function::Parameters;
-use strict;
-use warnings;
-
-our $VERSION = '0.03';
-
-use Devel::Declare;
-use B::Hooks::EndOfScope;
-use B::Compiling;
+use v5.14.0;
-sub guess_caller {
- my ($start) = @_;
- $start ||= 1;
+use warnings;
- my $defcaller = (caller $start)[0];
- my $caller = $defcaller;
+use Carp qw(confess);
- for (my $level = $start; ; ++$level) {
- my ($pkg, $function) = (caller $level)[0, 3] or last;
- #warn "? $pkg, $function";
- $function =~ /::import\z/ or return $caller;
- $caller = $pkg;
- }
- $defcaller
+use XSLoader;
+BEGIN {
+ our $VERSION = '1.0004';
+ XSLoader::load;
}
-sub _fun ($) { $_[0] }
-
-sub _croak {
- require Carp;
- {
- no warnings qw(redefine);
- *_croak = \&Carp::croak;
- }
- goto &Carp::croak;
+sub _assert_valid_identifier {
+ my ($name, $with_dollar) = @_;
+ my $bonus = $with_dollar ? '\$' : '';
+ $name =~ /^${bonus}[^\W\d]\w*\z/
+ or confess qq{"$name" doesn't look like a valid identifier};
}
-sub import {
- my $class = shift;
- my $keyword = @_ ? shift : 'fun';
- my $caller = guess_caller;
- #warn "caller = $caller";
-
- _croak qq{"$_" is not exported by the $class module} for @_;
-
- $keyword =~ /^[[:alpha:]_]\w*\z/ or _croak qq{"$keyword" does not look like a valid identifier};
-
- Devel::Declare->setup_for(
- $caller,
- { $keyword => { const => \&parser } }
- );
-
- no strict 'refs';
- *{$caller . '::' . $keyword} = \&_fun;
-}
-
-sub report_pos {
- my ($offset, $name) = @_;
- $name ||= '';
- my $line = Devel::Declare::get_linestr();
- substr $line, $offset + 1, 0, "\x{20de}\e[m";
- substr $line, $offset, 0, "\e[31;1m";
- print STDERR "$name($offset)>> $line\n";
+sub _assert_valid_attributes {
+ my ($attrs) = @_;
+ $attrs =~ /^\s*:\s*[^\W\d]\w*\s*(?:(?:\s|:\s*)[^\W\d]\w*\s*)*(?:\(|\z)/
+ or confess qq{"$attrs" doesn't look like valid attributes};
}
-sub parser {
- my ($declarator, $start) = @_;
- my $offset = $start;
- my $line = Devel::Declare::get_linestr();
-
- my $fail = do {
- my $_file = PL_compiling->file;
- my $_line = PL_compiling->line;
- sub {
- my $n = $_line + substr($line, $start, $offset - $start) =~ tr[\n][];
- die join('', @_) . " at $_file line $n\n";
- }
- };
-
- my $atomically = sub {
- my ($pars) = @_;
- sub {
- my $tmp = $offset;
- my @ret = eval { $pars->(@_) };
- if ($@) {
- $offset = $tmp;
- die $@;
- }
- wantarray ? @ret : $ret[0]
- }
- };
-
- my $try = sub {
- my ($pars) = @_;
- my @ret = eval { $pars->() };
- if ($@) {
- return;
- }
- wantarray ? @ret : $ret[0]
- };
-
- my $skipws = sub {
- #warn ">> $line";
- my $skip = Devel::Declare::toke_skipspace($offset);
- if ($skip < 0) {
- $skip == -$offset or die "Internal error: offset=$offset, skip=$skip";
- Devel::Declare::set_linestr($line);
- return;
- }
- $line = Devel::Declare::get_linestr();
- #warn "toke_skipspace($offset) = $skip\n== $line";
- $offset += $skip;
+my @bare_arms = qw(function method);
+my %type_map = (
+ function => {
+ name => 'optional',
+ default_arguments => 1,
+ check_argument_count => 0,
+ named_parameters => 1,
+ },
+ method => {
+ name => 'optional',
+ default_arguments => 1,
+ check_argument_count => 0,
+ named_parameters => 1,
+ attrs => ':method',
+ shift => '$self',
+ invocant => 1,
+ },
+ classmethod => {
+ name => 'optional',
+ default_arguments => 1,
+ check_argument_count => 0,
+ named_parameters => 1,
+ attributes => ':method',
+ shift => '$class',
+ invocant => 1,
+ },
+);
+for my $k (keys %type_map) {
+ $type_map{$k . '_strict'} = {
+ %{$type_map{$k}},
+ check_argument_count => 1,
};
+}
- $offset += Devel::Declare::toke_move_past_token($offset);
- $skipws->();
- my $manip_start = $offset;
+sub import {
+ my $class = shift;
- my $name;
- if (my $len = Devel::Declare::toke_scan_word($offset, 1)) {
- $name = substr $line, $offset, $len;
- $offset += $len;
- $skipws->();
+ if (!@_) {
+ @_ = {
+ fun => 'function',
+ method => 'method',
+ };
+ }
+ if (@_ == 1 && $_[0] eq ':strict') {
+ @_ = {
+ fun => 'function_strict',
+ method => 'method_strict',
+ };
+ }
+ if (@_ == 1 && ref($_[0]) eq 'HASH') {
+ @_ = map [$_, $_[0]{$_}], keys %{$_[0]};
}
- my $scan_token = sub {
- my ($str) = @_;
- my $len = length $str;
- substr($line, $offset, $len) eq $str or $fail->(qq{Missing "$str"});
- $offset += $len;
- $skipws->();
- };
+ my %spec;
+
+ my $bare = 0;
+ for my $proto (@_) {
+ my $item = ref $proto
+ ? $proto
+ : [$proto, $bare_arms[$bare++] || confess(qq{Don't know what to do with "$proto"})]
+ ;
+ my ($name, $proto_type) = @$item;
+ _assert_valid_identifier $name;
+
+ unless (ref $proto_type) {
+ # use '||' instead of 'or' to preserve $proto_type in the error message
+ $proto_type = $type_map{$proto_type}
+ || confess qq["$proto_type" doesn't look like a valid type (one of ${\join ', ', sort keys %type_map})];
+ }
- my $scan_id = sub {
- my $len = Devel::Declare::toke_scan_word($offset, 0) or $fail->('Missing identifier');
- my $name = substr $line, $offset, $len;
- $offset += $len;
- $skipws->();
- $name
- };
+ my %type = %$proto_type;
+ my %clean;
- my $scan_var = $atomically->(sub {
- (my $sigil = substr($line, $offset, 1)) =~ /^[\$\@%]\z/ or $fail->('Missing [$@%]');
- $offset += 1;
- $skipws->();
- my $name = $scan_id->();
- $sigil . $name
- });
-
- my $separated_by = $atomically->(sub {
- my ($sep, $pars) = @_;
- my $len = length $sep;
- defined(my $x = $try->($pars)) or return;
- my @res = $x;
- while () {
- substr($line, $offset, $len) eq $sep or return @res;
- $offset += $len;
- $skipws->();
- push @res, $pars->();
- }
- });
-
- my $many_till = $atomically->(sub {
- my ($end, $pars) = @_;
- my $len = length $end;
- my @res;
- until (substr($line, $offset, $len) eq $end) {
- push @res, $pars->();
- }
- @res
- });
-
- my $scan_params = $atomically->(sub {
- if ($try->(sub { $scan_token->('('); 1 })) {
- my @param = $separated_by->(',', $scan_var);
- $scan_token->(')');
- return @param;
- }
- $try->($scan_var)
- });
-
- my @param = $scan_params->();
-
- my $scan_pargroup_opt = sub {
- substr($line, $offset, 1) eq '(' or return '';
- my $len = Devel::Declare::toke_scan_str($offset);
- my $res = Devel::Declare::get_lex_stuff();
- Devel::Declare::clear_lex_stuff();
- $res eq '' and $fail->(qq{Can't find ")" anywhere before EOF});
- $offset += $len;
- $skipws->();
- "($res)"
- };
+ $clean{name} = delete $type{name} || 'optional';
+ $clean{name} =~ /^(?:optional|required|prohibited)\z/
+ or confess qq["$clean{name}" doesn't look like a valid name attribute (one of optional, required, prohibited)];
- my $scan_attr = sub {
- my $name = $scan_id->();
- my $param = $scan_pargroup_opt->() || '';
- $name . $param
- };
+ $clean{shift} = delete $type{shift} || '';
+ _assert_valid_identifier $clean{shift}, 1 if $clean{shift};
- my $scan_attributes = $atomically->(sub {
- $try->(sub { $scan_token->(':'); 1 }) or return '', [];
- my $proto = $scan_pargroup_opt->();
- my @attrs = $many_till->('{', $scan_attr);
- ' ' . $proto, \@attrs
- });
+ $clean{attrs} = join ' ', map delete $type{$_} || (), qw(attributes attrs);
+ _assert_valid_attributes $clean{attrs} if $clean{attrs};
+
+ $clean{default_arguments} =
+ exists $type{default_arguments}
+ ? !!delete $type{default_arguments}
+ : 1
+ ;
+ $clean{check_argument_count} = !!delete $type{check_argument_count};
+ $clean{invocant} = !!delete $type{invocant};
+ $clean{named_parameters} = !!delete $type{named_parameters};
- my ($proto, $attributes) = $scan_attributes->();
- my $attr = @$attributes ? ' : ' . join(' ', @$attributes) : '';
+ %type and confess "Invalid keyword property: @{[keys %type]}";
- $scan_token->('{');
+ $spec{$name} = \%clean;
+ }
+
+ for my $kw (keys %spec) {
+ my $type = $spec{$kw};
+
+ my $flags =
+ $type->{name} eq 'prohibited' ? FLAG_ANON_OK :
+ $type->{name} eq 'required' ? FLAG_NAME_OK :
+ FLAG_ANON_OK | FLAG_NAME_OK
+ ;
+ $flags |= FLAG_DEFAULT_ARGS if $type->{default_arguments};
+ $flags |= FLAG_CHECK_NARGS if $type->{check_argument_count};
+ $flags |= FLAG_INVOCANT if $type->{invocant};
+ $flags |= FLAG_NAMED_PARAMS if $type->{named_parameters};
+ $^H{HINTK_FLAGS_ . $kw} = $flags;
+ $^H{HINTK_SHIFT_ . $kw} = $type->{shift};
+ $^H{HINTK_ATTRS_ . $kw} = $type->{attrs};
+ $^H{+HINTK_KEYWORDS} .= "$kw ";
+ }
+}
- my $manip_end = $offset;
- my $manip_len = $manip_end - $manip_start;
- #print STDERR "($manip_start:$manip_len:$manip_end)\n";
+sub unimport {
+ my $class = shift;
- my $params = @param ? 'my (' . join(', ', @param) . ') = @_;' : '';
- #report_pos $offset;
- $proto =~ tr[\n][ ];
+ if (!@_) {
+ delete $^H{+HINTK_KEYWORDS};
+ return;
+ }
- if (defined $name) {
- my $pkg = __PACKAGE__;
- #print STDERR "($manip_start:$manip_len) [$line]\n";
- substr $line, $manip_start, $manip_len, " do { sub $name$proto; sub $name$proto$attr { BEGIN { ${pkg}::terminate_me(q[$name]); } $params ";
- } else {
- substr $line, $manip_start, $manip_len, " sub$proto$attr { $params ";
+ for my $kw (@_) {
+ $^H{+HINTK_KEYWORDS} =~ s/(?<![^ ])\Q$kw\E //g;
}
- #print STDERR ".> $line\n";
- Devel::Declare::set_linestr($line);
}
-sub terminate_me {
- my ($name) = @_;
- on_scope_end {
- my $line = Devel::Declare::get_linestr();
- #print STDERR "~~> $line\n";
- my $offset = Devel::Declare::get_linestr_offset();
- substr $line, $offset, 0, " \\&$name };";
- Devel::Declare::set_linestr($line);
- #print STDERR "??> $line\n";
- };
-}
-1
+'ok'
__END__
+=encoding UTF-8
+
=head1 NAME
Function::Parameters - subroutine definitions with parameter lists
=head1 SYNOPSIS
- use Function::Parameters;
+ use Function::Parameters qw(:strict);
+ # simple function
fun foo($bar, $baz) {
return $bar + $baz;
}
- fun mymap($fun, @args) :(&@) {
+ # function with prototype
+ fun mymap($fun, @args)
+ :(&@)
+ {
my @res;
for (@args) {
push @res, $fun->($_);
}
print "$_\n" for mymap { $_ * 2 } 1 .. 4;
-
- use Function::Parameters 'proc';
- my $f = proc ($x) { $x * 2 };
+ # method with implicit $self
+ method set_name($name) {
+ $self->{name} = $name;
+ }
+
+ # method with explicit invocant
+ method new($class: %init) {
+ return bless { %init }, $class;
+ }
+
+ # function with optional parameters
+ fun search($haystack, $needle = qr/^(?!)/, $offset = 0) {
+ ...
+ }
+
+ # method with named parameters
+ method resize(:$width, :$height) {
+ $self->{width} = $width;
+ $self->{height} = $height;
+ }
+
+ $obj->resize(height => 4, width => 5);
+
+ # function with named optional parameters
+ fun search($haystack, :$needle = qr/^(?!)/, :$offset = 0) {
+ ...
+ }
+
+ my $results = search $text, offset => 200;
+
=head1 DESCRIPTION
-This module lets you use parameter lists in your subroutines. Thanks to
-L<Devel::Declare> it works without source filters.
-
-WARNING: This is my first attempt at using L<Devel::Declare> and I have
-almost no experience with perl's internals. So while this module might
-appear to work, it could also conceivably make your programs segfault.
-Consider this module alpha quality.
-
-=head2 Basic stuff
-
-To use this new functionality, you have to use C<fun> instead of C<sub> -
-C<sub> continues to work as before. The syntax is almost the same as for
-C<sub>, but after the subroutine name (or directly after C<fun> if you're
-writing an anonymous sub) you can write a parameter list in parens. This
-list consists of comma-separated variables.
-
-The effect of C<fun foo($bar, $baz) {> is as if you'd written
-C<sub foo { my ($bar, $baz) = @_; >, i.e. the parameter list is simply
-copied into C<my> and initialized from L<@_|perlvar/"@_">.
-
-=head2 Advanced stuff
-
-You can change the name of the new keyword from C<fun> to anything you want by
-specifying it in the import list, i.e. C<use Function::Parameters 'spork'> lets
-you write C<spork> instead of C<fun>.
-
-If you need L<subroutine attributes|perlsub/"Subroutine Attributes">, you can
-put them after the parameter list with their usual syntax. There's one
-exception, though: you can only use one colon (to start the attribute list);
-multiple attributes have to be separated by spaces.
-
-Syntactically, these new parameter lists live in the spot normally occupied
-by L<prototypes|perlsub/"Prototypes">. However, you can include a prototype by
-specifying it as the first attribute (this is syntactically unambiguous
-because normal attributes have to start with a letter).
-
-Normally, Perl subroutines are not in scope in their own body, meaning the
-parser doesn't know the name C<foo> or its prototype when processing
-C<sub foo ($) { foo $bar[1], $bar[0]; }>, parsing it as
-C<$bar-E<gt>foo([1], $bar[0])>. Yes. You can add parens to change the
-interpretation of this code, but C<foo($bar[1], $bar[0])> will only trigger
-a I<foo() called too early to check prototype> warning. This module attempts
-to fix all of this by adding a subroutine declaration before the definition,
-so the parser knows the name (and possibly prototype) while it processes the
-body. Thus C<fun foo($x) :($) { $x }> really turns into
-C<sub foo ($); sub foo ($) { my ($x) = @_; $x }>.
+This module extends Perl with keywords that let you define functions with
+parameter lists. It uses Perl's L<keyword plugin|perlapi/PL_keyword_plugin>
+API, so it works reliably and doesn't require a source filter.
+
+=head2 Basics
+
+The anatomy of a function (as recognized by this module):
+
+=over
+
+=item 1.
+
+The keyword introducing the function.
+
+=item 2.
+
+The function name (optional).
+
+=item 3.
+
+The parameter list (optional).
+
+=item 4.
+
+The prototype (optional).
+
+=item 5.
+
+The attribute list (optional).
+
+=item 6.
+
+The function body.
+
+=back
+
+Example:
+
+ # (1) (2) (3) (4) (5) (6)
+ fun foo ($x, $y) :($$) :lvalue { ... }
+
+ # (1) (6)
+ my $f = fun { ... };
+
+In the following section I'm going to describe all parts in order from simplest to most complex.
+
+=head3 Body
+
+This is just a normal block of statements, as with L<C<sub>|perlsub>. No surprises here.
+
+=head3 Name
+
+If present, it specifies the name of the function being defined. As with
+L<C<sub>|perlsub>, if a name is present, the whole declaration is syntactically
+a statement and its effects are performed at compile time (i.e. at runtime you
+can call functions whose definitions only occur later in the file). If no name
+is present, the declaration is an expression that evaluates to a reference to
+the function in question. No surprises here either.
+
+=head3 Attributes
+
+Attributes are relatively unusual in Perl code, but if you want them, they work
+exactly the same as with L<C<sub>|perlsub/Subroutine-Attributes>.
+
+=head3 Prototype
+
+As with L<C<sub>|perlsub/Prototypes>, a prototype, if present, contains hints as to how
+the compiler should parse calls to this function. This means prototypes have no
+effect if the function call is compiled before the function declaration has
+been seen by the compiler or if the function to call is only determined at
+runtime (e.g. because it's called as a method or through a reference).
+
+With L<C<sub>|perlsub>, a prototype comes directly after the function name (if
+any). C<Function::Parameters> reserves this spot for the
+L<parameter list|/"Parameter list">. To specify a prototype, put it as the
+first attribute (e.g. C<fun foo :(&$$)>). This is syntactically unambiguous
+because normal L<attributes|/Attributes> need a name after the colon.
+
+=head3 Parameter list
+
+The parameter list is a list of variables enclosed in parentheses, except it's
+actually a bit more complicated than that. A parameter list can include the
+following 6 parts, all of which are optional:
+
+=over
+
+=item 1. Invocant
+
+This is a scalar variable followed by a colon (C<:>) and no comma. If an
+invocant is present in the parameter list, the first element of
+L<C<@_>|perlvar/@ARG> is automatically L<C<shift>ed|perlfunc/shift> off and
+placed in this variable. This is intended for methods:
+
+ method new($class: %init) {
+ return bless { %init }, $class;
+ }
+
+ method throw($self:) {
+ die $self;
+ }
+
+=item 2. Required positional parameters
+
+The most common kind of parameter. This is simply a comma-separated list of
+scalars, which are filled from left to right with the arguments that the caller
+passed in:
+
+ fun add($x, $y) {
+ return $x + $y;
+ }
+
+ say add(2, 3); # "5"
+
+=item 3. Optional positional parameters
+
+Parameters can be marked as optional by putting an equals sign (C<=>) and an
+expression (the "default argument") after them. If no corresponding argument is
+passed in by the caller, the default argument will be used to initialize the
+parameter:
+
+ fun scale($base, $factor = 2) {
+ return $base * $factor;
+ }
+
+ say scale(3, 5); # "15"
+ say scale(3); # "6"
+
+The default argument is I<not> cached. Every time a function is called with
+some optional arguments missing, the corresponding default arguments are
+evaluated from left to right. This makes no difference for a value like C<2>
+but it is important for expressions with side effects, such as reference
+constructors (C<[]>, C<{}>) or function calls.
+
+Default arguments see not only the surrounding lexical scope of their function
+but also any preceding parameters. This allows the creation of dynamic defaults
+based on previous arguments:
+
+ method set_name($self: $nick = $self->default_nick, $real_name = $nick) {
+ $self->{nick} = $nick;
+ $self->{real_name} = $real_name;
+ }
+
+ $obj->set_name("simplicio"); # same as: $obj->set_name("simplicio", "simplicio");
+
+Because default arguments are actually evaluated as part of the function body,
+you can also do silly things like this:
+
+ fun foo($n = return "nope") {
+ "you gave me $n"
+ }
+
+ say foo(2 + 2); # "you gave me 4"
+ say foo(); # "nope"
+
+=item 4. Required named parameters
+
+By putting a colon (C<:>) in front of a parameter you can make it named
+instead of positional:
+
+ fun rectangle(:$width, :$height) {
+ ...
+ }
+
+ rectangle(width => 2, height => 5);
+ rectangle(height => 5, width => 2); # same thing!
+
+That is, the caller must specify a key name in addition to the value, but in
+exchange the order of the arguments doesn't matter anymore. As with hash
+initialization, you can specify the same key multiple times and the last
+occurrence wins:
+
+ rectangle(height => 1, width => 2, height => 2, height => 5;
+ # same as: rectangle(width => 2, height => 5);
+
+You can combine positional and named parameters as long as the positional
+parameters come first:
+
+ fun named_rectangle($name, :$width, :$height) {
+ ...
+ }
+
+ named_rectangle("Avocado", width => 0.5, height => 1.2);
+
+=item 5. Optional named parameters
+
+As with positional parameters, you can make named parameters optional by
+specifying a default argument after an equals sign (C<=>):
+
+ fun rectangle(:$width, :$height, :$color = "chartreuse") {
+ ...
+ }
+
+ rectangle(height => 10, width => 5);
+ # same as: rectangle(height => 10, width => 5, color => "chartreuse");
+
+=cut
+
+=pod
+
+ fun get($url, :$cookie_jar = HTTP::Cookies->new(), :$referrer = $url) {
+ ...
+ }
+
+ my $data = get "http://www.example.com/", referrer => undef; # overrides $referrer = $url
+
+The above example shows that passing any value (even C<undef>) will override
+the default argument.
+
+=item 6. Slurpy parameter
+
+Finally you can put an array or hash in the parameter list, which will gobble
+up the remaining arguments (if any):
+
+ fun foo($x, $y, @rest) { ... }
+
+ foo "a", "b"; # $x = "a", $y = "b", @rest = ()
+ foo "a", "b", "c"; # $x = "a", $y = "b", @rest = ("c")
+ foo "a", "b", "c", "d"; # $x = "a", $y = "b", @rest = ("c", "d")
+
+If you combine this with named parameters, the slurpy parameter will end up
+containing all unrecognized keys:
+
+ fun bar(:$size, @whatev) { ... }
+
+ bar weight => 20, size => 2, location => [0, -3];
+ # $size = 2, @whatev = ('weight', 20, 'location', [0, -3])
+
+=back
+
+Apart from the L<C<shift>|perlfunc/shift> performed by the L<invocant|/"1.
+Invocant">, all of the above leave L<C<@_>|perlvar/@ARG> unchanged; and if you
+don't specify a parameter list at all, L<C<@_>|perlvar/@ARG> is all you get.
+
+=head3 Keyword
+
+The keywords provided by C<Function::Parameters> are customizable. Since
+C<Function::Parameters> is actually a L<pragma|perlpragma>, the provided
+keywords have lexical scope. The following import variants can be used:
+
+=over
+
+=item C<use Function::Parameters ':strict'>
+
+Provides the keywords C<fun> and C<method> (described below) and enables
+argument checks so that calling a function and omitting a required argument (or
+passing too many arguments) will throw an error.
+
+=item C<use Function::Parameters>
+
+Provides the keywords C<fun> and C<method> (described below) and enables
+"lax" mode: Omitting a required argument sets it to C<undef> while excess
+arguments are silently ignored.
+
+=item C<< use Function::Parameters { KEYWORD1 => TYPE1, KEYWORD2 => TYPE2, ... } >>
+
+Provides completely custom keywords as described by their types. A "type" is
+either a string (one of the predefined types C<function>, C<method>,
+C<classmethod>, C<function_strict>, C<method_strict>, C<classmethod_strict>) or
+a reference to a hash with the following keys:
+
+=over
+
+=item C<name>
+
+Valid values: C<optional> (default), C<required> (all functions defined with
+this keyword must have a name), and C<prohibited> (functions defined with this
+keyword must be anonymous).
+
+=item C<shift>
+
+Valid values: strings that look like scalar variables. This lets you specify a
+default L<invocant|/"1. Invocant">, i.e. a function defined with this keyword
+that doesn't have an explicit invocant in its parameter list will automatically
+L<C<shift>|perlfunc/shift> its first argument into the variable specified here.
+
+=item C<invocant>
+
+Valid values: booleans. If you set this to a true value, the keyword will
+accept L<invocants|/"1. Invocant"> in parameter lists; otherwise specifying
+an invocant in a function defined with this keyword is a syntax error.
+
+=item C<attributes>
+
+Valid values: strings containing (source code for) attributes. This causes any
+function defined with this keyword to have the specified
+L<attributes|attributes> (in addition to any attributes specified in the
+function definition itself).
+
+=item C<default_arguments>
+
+Valid values: booleans. This property is on by default; use
+C<< default_arguments => 0 >> to turn it off. This controls whether optional
+parameters are allowed. If it is turned off, using C<=> in parameter lists is
+a syntax error.
+
+=item C<check_argument_count>
+
+Valid values: booleans. If turned on, functions defined with this keyword will
+automatically check that they have been passed all required arguments and no
+excess arguments. If this check fails, an exception will by thrown via
+L<C<Carp::croak>|Carp>.
+
+=back
+
+The predefined type C<function> is equivalent to:
+
+ {
+ name => 'optional',
+ invocant => 0,
+ default_arguments => 1,
+ check_argument_count => 0,
+ }
+
+These are all default values, so C<function> is also equivalent to C<{}>.
+
+C<method> is equivalent to:
+
+ {
+ name => 'optional',
+ shift => '$self',
+ invocant => 1,
+ attributes => ':method',
+ default_arguments => 1,
+ check_argument_count => 0,
+ }
+
+
+C<classmethod> is equivalent to:
+
+ {
+ name => 'optional',
+ shift => '$class',
+ invocant => 1,
+ attributes => ':method',
+ default_arguments => 1,
+ check_argument_count => 0,
+ }
+
+C<function_strict>, C<method_strict>, and
+C<classmethod_strict> are like C<function>, C<method>, and
+C<classmethod>, respectively, but with C<< check_argument_count => 1 >>.
+
+=back
+
+Plain C<use Function::Parameters> is equivalent to
+C<< use Function::Parameters { fun => 'function', method => 'method' } >>.
+
+C<use Function::Parameters qw(:strict)> is equivalent to
+C<< use Function::Parameters { fun => 'function_strict', method => 'method_strict' } >>.
+
+=head2 Wrapping C<Function::Parameters>
+
+If you want to write a wrapper around C<Function::Parameters>, you only have to
+call its C<import> method. Due to its L<pragma|perlpragma> nature it always
+affects the file that is currently being compiled.
+
+ package Some::Wrapper;
+ use Function::Parameters ();
+ sub import {
+ Function::Parameters->import;
+ # or Function::Parameters->import(@custom_import_args);
+ }
+
+=head2 How it works
+
+The module is actually written in L<C|perlxs> and uses
+L<C<PL_keyword_plugin>|perlapi/PL_keyword_plugin> to generate opcodes directly.
+However, you can run L<C<perl -MO=Deparse ...>|B::Deparse> on your code to see
+what happens under the hood. In the simplest case (no argument checks, possibly
+an L<invocant|/"1. Invocant">, required positional/slurpy parameters only), the
+generated code corresponds to:
+
+ fun foo($x, $y, @z) { ... }
+ # ... turns into ...
+ sub foo { my ($x, $y, @z) = @_; sub foo; ... }
+
+ method bar($x, $y, @z) { ... }
+ # ... turns into ...
+ sub bar :method { my $self = shift; my ($x, $y, @z) = @_; sub bar; ... }
=head1 AUTHOR
=head1 COPYRIGHT & LICENSE
-Copyright 2009 Lukas Mai.
+Copyright 2010, 2011, 2012 Lukas Mai.
This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
projects / p5sagit/Function-Parameters.git / blobdiff