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Curiously, both Ruby and PHP, both with the same relative precedence as Perl for the ternary and assignment operators, bend the rules differently. For example, this Ruby program:

config = '' fred = 42 fred == 42 ? config = 'k1' : config = 'k2' print "config=#{config}\n"
and PHP program:
<?php $config = ''; $fred = 42; $fred == 42 ? $config = 'k1' : $config = 'k2'; echo "config=$config\n"; ?>
both run without error, but, unlike Perl (which produces config=k2), both Ruby and PHP produce config=k1.

Arguably, all three languages should produce a syntax error.

Update: gcc produces a syntax error "f.c:6: error: lvalue required as left operand of assignment" with this test program (further update: g++ compiles it happily though and with the same semantics as the Ruby and PHP test programs):

#include <stdio.h> int main() { int config = 0; int fred = 42; fred == 42 ? config = 1 : config = 2; printf("config=%d\n", config); return 0; }
Adding parentheses to line 6:
fred == 42 ? (config = 1) : (config = 2); // this works fred == 42 ? config = 1 : (config = 2); // also works fred == 42 ? (config = 1) : config = 2; // syntax error
makes it work the same as the Ruby and PHP test programs.


In reply to Re^2: Surprised by Perl parse of ternary operator by eyepopslikeamosquito
in thread Surprised by Perl parse of ternary operator by eyepopslikeamosquito

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