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Re: usage / "More..."

• To: mathgroup at smc.vnet.net
• Subject: [mg47194] Re: usage / "More..."
• From: Felix Kossak <felix.kossak at scch.at>
• Date: Mon, 29 Mar 2004 04:22:40 -0500 (EST)
• Organization: Johannes Kepler Universitaet Linz
• References: <c3udnh$9og$1@smc.vnet.net> <c40s9s$mo7$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Thanks for your suggestion, but I do not yet know how to apply this. 
When coded in a package, the "usage" message is a string - or can it be 
something else? How do I add a button to a string? And why do usage 
messages of Mathematica standard packages not show such a button added 
to the string, yet it appears when called from the frontend?

Let's look at an example from a Mathematica standard package: eg 
"Graphics.m". In the frontend, I type "?Histogram", and I get a text 
plus the "More..." hyperlink. When I look at the full form of the cell, 
the whole thing is wrapped in "BoxData". Yet when I look at the package 
source, the usage message is just a string, without that "More..." button.

I actually tried to set a "usage" message to a "Cell[ BoxData[ ... ] ]", 
but then, when loading the package, I get an error message:

MessageName::messg: MyPlot::usage cannot be set to Cell[BoxData[RowBox[\
\[LeftSkeleton]1\[RightSkeleton]]], Print, CellTags -> Info3?812768]. It 
must \
be set to a string.

So there seems to be a mechanism (in the frontend?) which automatically 
adds this hyperlink. Do you know about this?

Thanks,
Felix



Ken Morgan wrote:
> "Felix Kossak" <felix.kossak at scch.at> wrote in message
> news:c3udnh$9og$1 at smc.vnet.net...
> 
>>Hi,
>>
>>I wonder how the "More..." hyperlinks appended to usage info are
>>generated as I want to have that feature for our own packages. I found a
>>posting by Bobby Treat dt 2002 suggesting to copy and modify the full
>>form of some existing usage text, but looking at the source of standard
>>Mathematica packages shows that the "More..." hyperlink is actually not
>>coded into the usage text itself. I also failed to find a hint in an
>>init.m file. I guess that the frontend generates this hyperlink
>>automatically, but based on what information? What do I have to do to
>>get those links to our own help notebooks?
>>
>>Thanks,
>>Felix
>>
> 
> 
> Here is how the "More..." button can be generated for the Plot usage:
> 
> Button[More?, RuleDelayed[ButtonData, "Plot"], Rule[Active, True],
> Rule[ButtonStyle, "RefGuideLink"]]
> 
> If you evaluate this, you will get a clickable "More..." button.
> 
> Ken
>