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Re: Making sense of Directive[ ]


Forex Ample wrote:
> I stumbled upon the new Directive[ ] function, used to group Graphics 
> directives into one compound directive. However, I fail to see what it is 
> good for. In every example in the documentation, replacing Directive with 
> List seems to produce the exact same results. Anybody got a clue?

Not that I have a clue, but it is easy to make up examples, where there 
_is_ a difference:

Graphics[{{Red, Thick}, Line[{{0, 0}, {1, 1}}]}]

Graphics[{Directive[Red, Thick], Line[{{0, 0}, {1, 1}}]}]

the first line will not be red and thick, the second is. This makes 
something like the following easier:

mystyle = Directive[Red, Thick];

Graphics[{mystyle, Line[{{0, 0}, {1, 1}}]}]

where without Directive you would need:

mystylelist = {Red, Thick};

Graphics[{Sequence @@ mystylelist, Line[{{0, 0}, {1, 1}}]}]

anyway, I can hardly believe that this alone is enough to justify the 
introduction of Directive :-)


albert


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