Question

$df{key} =10 ; return ; if $result == 10 ;

gives me an error. How can I achieve this?

Answer 1

The post-statement form of if only works with single statements. You will have to enclose multiple statements in a block after the if condition, which itself needs to be enclosed in parentheses:

if ( $result == 10 ) {

    $df{key} = 10;
    return;
}

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In this case, it is possible to combine the two statements with a post-statement conditional. The idea here is to combine the two statements in one by performing a Boolean evaluation.

However, this is not a good idea in general as it may short-circuit and fail to do what you expect, like when $df{key} = 0:

$df{key} = 10 and return if $result == 10;

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From perlsyn:

In Perl, a sequence of statements that defines a scope is called a block

… generally, a block is delimited by curly brackets, also known as braces. We will call this syntactic construct a BLOCK.

The following compound statements may be used to control flow:

if (EXPR) BLOCK

if (EXPR) BLOCK else BLOCK

if (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK