{"id":20757,"date":"2022-11-10T20:29:35","date_gmt":"2022-11-10T14:59:35","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-when-is-it-advantageous-to-use-curly-braces-for-dereferencing-in-perl\/"},"modified":"2022-11-10T20:29:35","modified_gmt":"2022-11-10T14:59:35","slug":"solved-when-is-it-advantageous-to-use-curly-braces-for-dereferencing-in-perl","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-when-is-it-advantageous-to-use-curly-braces-for-dereferencing-in-perl\/","title":{"rendered":"[Solved] When is it advantageous to use curly braces for dereferencing in Perl?"},"content":{"rendered":"

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You are conflating two concepts.<\/p>\n

The first thing you need to learn is that there is there are two syntaxes<\/a> for deferencing.<\/p>\n

 Circumfix            Postfix\n \"Block syntax\"       \"Arrow syntax\"\n\n $BLOCK               EXPR->$*\n @BLOCK               EXPR->@*\n $BLOCK[$i]           EXPR->[$i]\n &BLOCK()             EXPR->()\n ...                  ...\n<\/code><\/pre>\n
Furthermore, both syntax have a simplification available to them.<\/p>\n
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Your array example is an example of a simplification available to the block syntax. If the block contains nothing but a simple scalar ($ref<\/code>), you can omit the curlies.<\/p>\n
${ $ref }                   # Can be simplified to $$ref\n@{ $ref }                   # Can be simplified to @$ref\n${ $ref }[$i]               # Can be simplified to $$ref[$i]\n&{ $ref }()                 # Can be simplified to &$ref()\n<\/code><\/pre>\n
If the block contains anything else, you can’t avail yourself of this simplification.<\/p>\n
@{ $refs{$key} }            # Can't be simplified\n@{ f() }                    # Can't be simplified\n@{ my $ref = f(); $ref }    # Can't be simplified\n\n&{ $refs{$key} }()          # Can't be simplified\n&{ f() }()                  # Can't be simplified\n&{ my $ref = f(); $ref }    # Can't be simplified\n<\/code><\/pre>\n
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Your code ref example, on the other hand, is an example of the switching from the block syntax to the arrow syntax. It’s not a simplification per se<\/em>.<\/p>\n
\"Block syntax\"               \"Arrow syntax\"\n&{ $hash{frogs} }()    \u21d2     $hash{frogs}->()\n<\/code><\/pre>\n
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Your code ref example is also an example of a simplification available to the arrow syntax. When the arrow is between [...]<\/code> or {...}<\/code>, and [...]<\/code>, {...}<\/code> or (...)<\/code>, the arrow can be omitted.<\/p>\n
$ref->{$k}->[$i]            # Can be simplified to $ref->{$k}[$i]\n$ref->{$k}->{$l}            # Can be simplified to $ref->{$k}{$l}\n$ref->{$k}->()              # Can be simplified to $ref->{$k}()\n\n$ref->[$i]->[$j]            # Can be simplified to $ref->[$i][$j]\n$ref->[$i]->{$k}            # Can be simplified to $ref->[$i]{$k}\n$ref->[$i]->()              # Can be simplified to $ref->[$i]()\n<\/code><\/pre>\n
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Finally, which should you use?<\/p>\n
The choice of whether to the block syntax or the arrow syntax is one of personal preference, but the following conventions are usually followed to maximize readability:<\/p>\n