From: Reece Dunn (msclrhd_at_[hidden])
Date: 2004-09-17 07:44:23
Throughout this e-mail, I assume the following aliases:
namespace io = boost::io;
namespace fmt = boost::io::format;
namespace css = boost::io::css;
NOTE: This is a design outline for features in a future version of the
library.
David Abrahams has suggested the ability to specify default formatting on a
stream. I have implemented a simple version of this so that you can do:
io::sequence_decorators< char > seq( "; " );
std::cout << '"' << seq.open( std::cout ) << "\"\n" // "[ "
<< '"' << seq.close( std::cout ) << "\"\n" // " ]"
<< '"' << seq.separator( std::cout ) << "\"\n"; // "; "
where separator( std::cout ) uses the separator value specified by seq and
the others use the values set on the std::cout stream. To change these
defaults, you can use:
std::cout << io::cdecorate( "[{ ", " }]" ); // [{ a, b, c }]
The problem with this is that it changes the defaults for all the formatting
used, thus you cannot have different defaults for sequences and n-ary types.
Cascading Style Sheets (CSS) are a web standard
[http://www.w3.org/Style/CSS/] used for controlling how HTML tags are
displayed to different devices (screen, printer and speech).
== Inlined Styles
In HTML you can specify "inlined" styles using a style attribute, e.g.:
<div style = "color: red;">Red Text</div>
My library equivalent is to use the decorate() function, e.g.:
fmt::range().decorate( "<-- ", " -->" );
== Dynamic Styles
You can also set CSS properties within script code, e.g.
tag.style.fontFamily = "Times New Roman";
This style behaviour is available in the new decorators, for example:
io::wrapper_decorators< char > wrap;
wrap.open = "<< ";
wrap.close = " >>";
A more complex example that uses nested format objects:
fmt::container_t< char, fmt::pair_t< char > > my_fo
= fmt::container( fmt::pair());
my_fo.elem.open = "<< ";
my_ob.elem.close = " >>";
my_ob.separator = " | ";
std::cout << io::object( ob, my_ob ); // output: [ << a, 5 >> | << b, -1
>> ]
== Cascading Style Sheets
HTML provides a <style> tag to specify styling across the document without
linking to an external file, e.g.:
<style>h1{ color: orange; font-size: 2pc; }</style>
The equivalent within my library would be to define the styling on a stream,
e.g.:
std::cout
<< css::element( "pair" )
[
( css::attribute( "open" ) = "<< " )
+ ( css::attribute( "close" ) = " >>" )
]
<< css::element( "container" )
[
css::attribute( "separator" ) = " | "
]
<< io::object( ob ) // output: [ << a, 5 >> | << b, -1 >> ]
<< css::element( "pair" )
[
css::attribute( "separator" ) = " = "
]
<< io::object( ob ); // output: [ << a = 5 >> | << b = -1 >> ]
HTML can import styling from an external CSS file. The equivalent would be
to use an object to hold the styling, e.g.:
css::stylesheet< char > style
= css::element( "pair" )
[
css::attribute( "separator" ) = " = "
]
+ css::element( "container" )
[
( css::attribute( "open" ) = "{ " )
+ ( css::attribute( "close" ) = " }" )
]
;
std::cout << style << io::object( ob ); // output: { [ a = 5 ], [ b = -1
] }
It should be possible to provide the ability to save/load styling to/from a
file and allow copying of style objects, e.g.:
css::stylesheet< char > style2( "mystyles.style" ); // load styling
style.load( "newstyles.style" );
style = style2;
style.save( "stylings.sty" );
NOTE: The css::stylesheet class will store the styles using something like:
std::map< std::string, std::map< std::string, std::string > >
therefore it will be possible to use my library to implement the load and
save facilities!
Regards,
Reece
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