[boost] [Boost-bugs] [ boost-Bugs-1676565 ] boost::format and operator priority rule

From: SourceForge.net (noreply_at_[hidden])
Date: 2007-03-08 09:37:47

Bugs item #1676565, was opened at 2007-03-08 06:37
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: boost::format and operator priority rule

Initial Comment:
boost::format uses operator % to "feed" a string to a formatter, as in

cout<<format("Choose %1% of %2%") % 5 % 37; //writes "Choose 5 of 37"

This leads to a compile-time error when arithmetic operations are used without parenthesizing, e.g.

cout<<format("Choose %1% of %2%") % total-remaining+1 % total; //WRONG, tries to apply operator - to a formatter

because operator % has a higher priority than operator - .

This is indeed quite a common case; I suggest that operator % be replaced with an operator with lower priority, such as << . I can't figure out why operator % was chosen, is there a reason to use it?

Thanks,

--federico poloni

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