NAME Syntax::Operator::ExistsOr - an infix operator sensitive to hash element existence SYNOPSIS On a suitable perl version: use Syntax::Operator::ExistsOr; sub func ( %args ) { my $count = $args{count} \\ 10; say "Count is ", $count // ""; } func( count => 20 ); func(); func( count => undef ); DESCRIPTION This module provides an infix operator that similar to the defined-or // core perl operator, but which cares about hash element existence rather than definedness. Current stable versions of perl do not directly support custom infix operators, but the ability was added in the 5.37.x development cycle and is available from perl v5.37.7 onwards. The documentation of XS::Parse::Infix describes the situation in more detail. This module is therefore almost entirely useless on stable perl builds. While the regular parser does not support custom infix operators, they are supported via XS::Parse::Infix and hence XS::Parse::Keyword, and so custom keywords which attempt to parse operator syntax may be able to use it. This module does not provide wrapper functions for the operators, as their inherent short-circuiting behaviour would appear confusing when expressed in function-like syntax. OPERATORS \\ my $value = $hash{$key} \\ EXPR; The lefthand operand must be a hash element access (i.e. $hash{$key} or $href->{$key} for some expressions yielding a key and a hashref). If the hash contains the given key then the operator yields its value (even if that value is undef). If the key does not exist in the hash, then the righthand operand will be evaluated in scalar context and its value returned. This is a short-circuiting operator; if the hash does contain the key then the righthand side expression is not evaluated at all. This operator parses at the same precedence level as the logical-or operators (|| and //). existsor do { $hash{$key} existsor EXPR; }; Similar to the \\ operator but parses at the same level as the low-precedence or operator (or). This is unlikely to be very useful, as normally or would be used for value-less control flow. Such a potential use for this operator would be neater written exists $hash{$key} or EXPR; It is included largely for completeness. AUTHOR Paul Evans