[Rd] a better "source(echo=TRUE)" {was "....how to pause...."}

From: Martin Maechler <maechler_at_stat.math.ethz.ch>
Date: Tue 30 Nov 2004 - 22:51:12 EST

>>>>> "Duncan" == Duncan Murdoch <murdoch@stats.uwo.ca>
>>>>> on Sun, 28 Nov 2004 10:25:24 -0500 writes:

    Duncan> <........>
    Duncan> <........>

    Duncan> We already have code to source() from the clipboard, and it could     Duncan> address the problems above, but:

    Duncan> - Source with echo=T doesn't echo, it deparses, so some comments are     Duncan> lost, formatting is changed, etc.

yes, and we would have liked to have an alternative "source()" for a *very* long time...
Examples where I "hate" the non-echo (i.e. the loss of all comments and own-intended formatting) is when you use it for demos, etc, notably in R's own demo() and example() functions.

But to do this might be more tricky than at first thought: Of course you can readLines() the source file and writeLines() them to whatever your console is. The slightly difficult thing is to "see" which junks to ``send to R'' , i.e. to parse() and eval(). The basic problem seems to see when expressions are complete.

Maybe we should / could think about enhancing parse() {or a new function with extended behavior} such that it would not only return the parse()d expressions, but also indices (byte or even line counters) to the source text, indicating where each of the expression started and ended.

That way I could see a way to proceed.

Martin

    Duncan> <........>
    Duncan> <........>



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https://stat.ethz.ch/mailman/listinfo/r-devel Received on Tue Nov 30 22:56:57 2004

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