Re: issue with font and lua code

[Hans Hagen <pragma@wxs.nl>]

On 7/20/2015 6:49 PM, Pablo Rodriguez wrote:
> Hans,
>
> I have the following sample (it includes Lua code for underscore
> hyphenation):
>
>      \startluacode
>          function document.addfunnyhyphen(tfmdata)
>              local underscore = utf.byte("_")
>              local char       = tfmdata.characters[underscore]
>              if not char then return end
>              tfmdata.characters[0xFE000]   = {
>                  width    = 0,
>                  height   = 0,
>                  depth    = 0,
>                  commands = {
>                      { "right", -char.width },
>                      { "down", char.depth },
>                      { "slot", 1, underscore },
>                  }
>              }
>          end
>      utilities.sequencers.appendaction("aftercopyingcharacters",
>      "after","document.addfunnyhyphen")
>      \stopluacode
>
>      \definehyphenationfeatures
>          [underscore]
>          [righthyphenchar="FE000]
>
>      \setuphyphenation
>          [method=traditional]
>
>      \sethyphenationfeatures
>          [strict]
>
>      \definefontfamily[svb][rm][SV Basic Manual]
>
>      \setupbodyfont[svb]
>
>      \starttext
>      \hyphenatedword{legibility}
>      \stoptext
>
> For some reason, the font gives the following error with the Lua code
> (font can be downloaded from http://dl.dafont.com/dl/?f=sv_basic_manual):
>
> lua error       > lua error on line 33 in file svb.tex:
> .../ctxbeta/tex/texmf-context/tex/context/base/font-ctx.lua:1194: bad
> argument #9 to 'define' (number expected, got nil)
> stack traceback:
> 	[C]: in function 'define'
> 	.../ctxbeta/tex/texmf-context/tex/context/base/font-ctx.lua:1194: in
> function <.../ctxbeta/tex/texmf-context/tex/context/base/font-ctx.lua:1049>
> 33 >>      \setupbodyfont[svb]
>
> The weird thing here is that the Lua code isn’t applied to the
> problematic font.
>
> Is there a way to fix this strange interaction?

in that font the underscore has no depth, so:

             commands = {
                 { "right", -char.width },
                 { "down", char.depth or 0 },
                 { "slot", 1, underscore },
             }

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