NAME

PerlX::Let - Syntactic sugar for lexical constants

VERSION

version v0.2.5

SYNOPSIS

  use PerlX::Let;

  let $x = 1,
      $y = "string" {

      if ( ($a->($y} - $x) > ($b->{$y} + $x) )
      {
        something( $y, $x );
      }

  }

DESCRIPTION

This module allows you to define lexical constants using a new let keyword, for example, code such as

  if (defined $arg{username}) {
    $row->update( { username => $arg{username} );
  }

is liable to typos. You could simplify it with

  let $key = "username" {

    if (defined $arg{$key}) {
      $row->update( { $key => $arg{$key} );
    }

  }

This is roughly equivalent to using

  use Const::Fast;

  {
    const $key => "username";

    if (defined $arg{$key}) {
      $row->update( { $key => $arg{$key} );
    }

  }

However, if the value does not contain a sigil, and the variable is a scalar, or you are using Perl v5.28 or later, this uses state variables so that the value is only set once.

If the code block is omitted, then this can be used to declare a state constant in the current scope, e.g.

  let $x = "foo";

  say $x;

KNOWN ISSUES

The parsing of assignments is rudimentary, and may fail when assigning to another variable or the result of a function.

Because this modifies the source code during compilation, the line numbers may be changed.

SEE ALSO

Const::Fast

Keyword::Simple

AUTHOR

Robert Rothenberg <rrwo@cpan.org>

COPYRIGHT AND LICENSE

This software is Copyright (c) 2019 by Robert Rothenberg.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)