[ In the future, post the code you actually ran rather than making stuff up. Your code does NOT produce the output you specified. In fact, it doesn't run at all. ]

I don't understand why, but it's a common misconception that operators return their left-hand argument. Why you expect the following to print 3? 

print( 3 + 4 );

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Then why would expect the following to print $text? 

print( $text =~ s/this/that/ );

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Operators are documented in perlop. s/// is no exception. Search for s/PATTERN/REPLACEMENT/ in the "Regexp Quote-Like Operators" section. It is documented to return the number of substitutions made.

What's the correct way to do it inline?

I'd say it's not correct to do it inline 

$text =~ s/this/that/;
print $text;

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You can manage with the following, but you're complicating your code again. 

print( do { $text =~ s/this/that/; $text } );

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In reply to Re: Inline substitution regex by ikegami
in thread Inline substitution regex by bradcan

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