Re: use constant moudle

In the second case, print is being interpreted as a function, i.e. print(WEEKDAYS)[1];, where the [1] doesn't work. Normally this gets a warning, but you've run into a case where it doesn't:

$ perl -we 'print (3+4),5;'
print (...) interpreted as function at -e line 1.
Useless use of a constant (5) in void context at -e line 1.
7
$ perl -we 'print (WEEKDAYS)[1];'
print (...) interpreted as function at -e line 1.
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.
$ perl -we 'print  (WEEKDAYS)[1];'
syntax error at -e line 1, near ")["
Execution of -e aborted due to compilation errors.
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Two workarounds in addition to your "case #1":

$ perl -we 'print +(3+4),5;'  # disambiguate
75
$ perl -we 'print((3+4),5);'  # explicit parens
75
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Tip: B::Deparse comes in handy for debugging here:

$ perl -MO=Deparse,-p -e 'print (3+4),5;'
(print(7), '???');
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Comment on Re: use constant moudle Select or Download Code

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Re^2: use constant module (was moudle) by kcott (Archbishop) on Feb 24, 2016 at 11:40 UTC
"Normally this gets a warning, but you've run into a case where it doesn't" Update: You only get the warning if you ask for it and put exactly one space between the `print` and the left parenthesis. Using zero or more than one space, and no warning is emitted. $ perl -we 'use constant WD => qw{Sun Mon}; print(WD)[1]' syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors. $ perl -we 'use constant WD => qw{Sun Mon}; print (WD)[1]' print (...) interpreted as function at -e line 1. syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors. $ perl -we 'use constant WD => qw{Sun Mon}; print (WD)[1]' syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors. $ perl -we 'use constant WD => qw{Sun Mon}; print (WD)[1]' syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors. [download] I tried up to five spaces: same result. Very weird! Original text: If you don't ask for warnings, you don't get warnings: `$ perl -e 'use constant WD => qw{Sun Mon}; print (WD)[1]' syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors.` [download] If you ask for warnings, you get warnings: `$ perl -we 'use constant WD => qw{Sun Mon}; print (WD)[1]' print (...) interpreted as function at -e line 1. syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors.` [download] There's ~~nothing special~~ something very strange about this case. — Ken	[reply] [d/l] [select]
Re^3: use constant module (was moudle) by Anonymous Monk on Feb 24, 2016 at 11:51 UTC
Sorry but you're wrong, look closely: `$ perl -we 'use constant WD => qw{Sun Mon}; print (WD)[1]' print (...) interpreted as function at -e line 1. syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors. $ perl -we 'use constant WD => qw{Sun Mon}; print (WD)[1]' syntax error at -e line 1, near ")[" Execution of -e aborted due to compilation errors.` [download]	[reply] [d/l]
Re^4: use constant module (was moudle) by kcott (Archbishop) on Feb 24, 2016 at 12:42 UTC
That's very strange and unexpected behaviour. I've investigated this further and updated my post with the results. — Ken	[reply]