> Dear All, > > is it somehow possible (ie via macros) to have a line in a scheme source code > file being a comment line by default and only when a certain symbol or group > of symbols is starting a line it is an uncommented / evaluated line? > Basically, the reverse of a normal source file where I need to introduce a > comment line. I would imagine a header line setting up this "comment"-mode, > and below this every line becomes a comment unless explicitly uncommented.
You could use "set-read-syntax!" or "set-sharp-read-syntax!" to define a sequence that either treats the line as a comment or reads and returns it as an expression. Dropping means to skip subsequent lines prefixed with the chosen sequence or returning the first expression that follows. Since an expression may straddle multiple prefixed lines, you may have to dynamically bind a flag that ignores the sequence in nested reads. This may need a bit of fiddling, but that is probably the approach I would try. felix
