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Re: xparse and space skipping

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Mon, 16 May 2011 23:54:41 +0200

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 Lars wrote  > 2. Sometimes, an existing command is redefined so that an optional  > argument is added at the end. In such cases, it may be preferable to make  > that argument such that it does not skip spaces, for compatibility with  > existing documents written under the assumption that spaces would not be  > skipped at that point. In other words, if  >  > \bar{apa} cepa  >  > used to have a space, and \bar for some reason in a package needs to be  > extended to support \bar{apa}[bepa], then \bar{apa} cepa should still have  > that space. in this particular case it would indeed be a bad change if a package "extends" a command in this way and the result is the loss of spaces in a document. On the other hand I don't think that a package author doing this would get very happy customers  > Therefore, the solution should be to provide both, but let the  > space-nonskipping variants come with a big warning in the xparse  > documentation, detailing why they are usually inappropriate. In  > particular, such documentation should suggest the argument order  >  > \bar[bepa]{apa}  >  > as preferable to  >  > \bar{apa}[bepa]  >  > since package authors are otherwise likely to pick one at random, never  > even considering the syntactical implications. This might be an option for a compromise (in fact you could even force this to be only available in the last argument at some technical cost, though I would advice to not go that far but put in big guidelines) something to think about a bit further I guess (but not tonight) frank