++ed by:
PERLANCAR SHARYANTO

2 PAUSE users
1 non-PAUSE user.

E. Choroba

NAME

Syntax::Construct - Identify which non-feature constructs are used in the code.

VERSION

Version 0.18

SYNOPSIS

For some new syntactic constructs, there is the feature pragma. For the rest, there is Syntax::Construct.

  use Syntax::Construct qw( // ... /r );

  my $x = shift // 'default';
  my $y = $x =~ s/de(fault)/$1/r;
  if ($y =~ /^fault/) {
      ...
  }

There are two subroutines (not exported) which you can use to query the lists of constructs programmatically: introduced and deprecated (see below).

  my @constructs = Syntax::Construct::introduced();
  say "$_ was introduced in ",
      Syntax::Construct::introduced($_) for @constructs;

DESCRIPTION

This module provides a simple way of specifying syntactic constructs that are not implemented via the feature pragma, but are still not compatible with older versions of Perl.

It's the programmer's responsibility to track the constructs and list them (but see Perl::MinimumVersion on how to extract the information from existing code).

Using use Syntax::Construct qw( // ); doesn't really change anything if you're running Perl 5.10+, but it gives much better error messages in older versions:

  Unsupported construct //

instead of

  Search pattern not terminated

Three groups of people can benefit from the module:

  1. The authors of the module using Syntax::Construct win, as they have all the constructs in one place (i.e. Syntax::Construct's documentation) and they don't waste their time searching through perldeltas and other places.

  2. Users of their modules win as they get meaningful error messages telling them what Perl version they need to upgrade to.

  3. The programmer they hired to workaround the problem wins as they know what constructs to replace in the code to make it run in the ancient version.

EXPORT

Nothing. Using Syntax::Construct with no parameters is an error, giving it an empty list is a no-op (but you can then access the introduced and deprecated subroutines).

introduced

Without arguments, returns a list of all the supported constructs. With an argument, returns the version in which the given construct was introduced.

deprecated

Same as introduced, but for deprecated constructs.

RECOGNISED CONSTRUCTS

5.010

recursive-sort

"Recursive sort subs" in perl5100delta.

//

"Defined-or operator" in perl5100delta or "Logical Defined-Or" in perlop.

?PARNO

"Recursive Patterns" under "Regular expressions" in perl5100delta or "(?PARNO) (?-PARNO) (?+PARNO) (?R) (?0)" in perlre.

?<>

"Named Capture Buffers" under "Regular expressions" in perl5100delta or "(?<NAME>pattern)" in perlre.

?|

Not mentioned in any Delta. See (?|pattern) in "Extended patterns" in perlre.

quant+

"Possessive Quantifiers" under "Regular expressions" in perl5100delta or "Quantifiers" in perlre.

regex-verbs

"Backtracking control verbs" under "Regular expressions" in perl5100delta or "Special Backtracking Control Verbs" in perlre.

\K

"\K escape" under "Regular expressions" in perl5100delta or "Look-Around Assertions" in perlre.

\R

"Vertical and horizontal whitespace, and linebreak" under "Regular expressions" in perl5100delta or "Misc" in perlrebackslash.

\gN

"Relative backreferences" under "Regular expressions" in perl5100delta or "Capture groups" in perlre.

readline()

"Default argument for readline()" in perl5100delta.

stack-file-test

"Stacked filetest operators" in perl5100delta.

/p

/p (preserve) modifier and ${^PREMATCH}, ${^MATCH} and ${^POSTMATCH} variables. Not mentioned in any Delta. See "Variables related to regular expressions" in perlvar.

5.012

package-version

"New package NAME VERSION syntax" in perl5120delta

...

"The ... operator" in perl5120delta or "The Ellipsis Statement" in perlsyn

each-array

"each, keys, values are now more flexible" in perl5120delta

keys-array

"each, keys, values are now more flexible" in perl5120delta

values-array

"each, keys, values are now more flexible" in perl5120delta

delete-local

"delete local" in perl5120delta

length-undef

See the ninth bullet in "Other potentially incompatible changes" in perl5120delta.

\N

"\N experimental regex escape" in perl5120delta.

while-readdir

readdir in a while-loop condition populates $_. Not mentioned in any delta, but see readdir in perlfunc.

5.014

?^

"Regular Expressions" in perl5140delta.

/r

"Regular Expressions" in perl5140delta and "Modifiers" in perlre.

/d

"Regular Expressions" in perl5140delta and "Modifiers" in perlre.

/l

"Regular Expressions" in perl5140delta and "Modifiers" in perlre.

/u

"Regular Expressions" in perl5140delta and "Modifiers" in perlre.

/a

"Regular Expressions" in perl5140delta and "Modifiers" in perlre.

auto-deref

"Array and hash container functions accept references" in perl5140delta. See also push, pop, shift, unshift, splice, keys, values, and each in perlfunc.

^GLOBAL_PHASE

See New global variable ${^GLOBAL_PHASE} under "Other Enhancements" in perl5140delta.

\o

"Regular-expressions" in perl5140delta.

package-block

See package block syntax under "Syntactical Enhancements" in perl5140delta.

5.016

No non-feature constructs were introduced in this version of Perl.

5.018

computed-labels

"Computed Labels" in perl5180delta

5.020

attr-prototype

"subs now take a prototype attribute" in perl5200delta

drand48

"rand now uses a consistent random number generator" in perl5200delta

%slice

"New slice syntax" in perl5200delta

unicode6.3

"Unicode 6.3 now supported" in perl5200delta

\p{Unicode}

See New \p{Unicode} regular expression pattern property in "Core Enhancements" in perl5200delta.

utf8-locale

"use locale now works on UTF-8 locales" in perl5200delta

5.022

<<>>

"New double diamond operator" in perldelta

\b{}

"New b boundaries in regular expressions" in perldelta

/n

"Non Capturing Regular Expression Flag" in perldelta

unicode7.0

"Unicode 7.0 with correction is now supported" in perldelta

attr-const

"New :const subroutine attribute" in perldelta

fileno-dir

"fileno now works on directory handles" in perldelta

()x=

"Assignment to list repetition" in perldelta

hexfloat

"Floating point parsing has been improved" in perldelta

chr-inf

"Packing infinity or not a number into a character is now fatal" in perldelta

empty-slice

"List slices returning empty lists" in perldelta

/x-unicode

"qr foo x now ignores all Unicode pattern white space" in perldelta

AUTHOR

E. Choroba, <choroba at cpan.org>

BUGS

Please report any bugs or feature requests to the GitHub repository, see below.

Unstable Perl versions

In development versions of Perl, the deprecation is tested against the coming stable version -- e.g., 5.23 forbids all the deprecated constructs of 5.24. The behaviour of the module in such circumstances might still be, um, unstable.

SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc Syntax::Construct

You can also look for information at:

SEE ALSO

Perl::MinimumVersion

LICENSE AND COPYRIGHT

Copyright 2013 - 2015 E. Choroba.

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:

http://www.perlfoundation.org/artistic_license_2_0

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

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This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.

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