Minor code cleanups

[leofontenelle]

While the code seems to be running fine, I would like to provide a few suggestions of minor code improvements in read.dbc:

• Raise an error if input file does not exist, so that read.dbc does not even call dbc2dbf.
• Use on.exit() to avoid nesting code.
• Raise an error if dbc2dbf returns 0.
• Avoid unnecessary return()

Also, in both read.dbc and dbc2dbf I used a stopifnot(), which might or might not suit your preferences.

[danicat]

Thanks for your suggestions Leo. Here are my comments:

• I'm not raising error on read.dbc because I'm leaving the low level (file access) handling to the dbc2dbf function.
• Nice idea about on.exit(), I may implement it sometime in the future.
• dbc2dbf returns true on success and false when not, so your code actually introduces a bug, since you have written: if( dbc2dbf(file, out) ) stop("Could not uncompress file!") -> you need to negate the output of dbc2dbf to treat for errors. Also, you've introduced another bug when calling stopifnot(!file.exists(input.file)) -> please note you are negating twice.
• Finally, I prefer to use if/stop to give a more meaningful error message. The error message from stopifnot is something like Error: !file.exists(input.file) is not TRUE

I don't want to discourage you to contribute, but please be careful with the code you submit. Also, beware of over tuning / over pruning. This code is simple enough to be readable and usable. Sometimes we try to complicate simple things and take the chance to introduce bugs like those above.

[leofontenelle]

Thanks for the comments! I saw the opportunity for on.exit() and got carried away. Sorry for not testing the code before sending the suggestions, I haven't figured out how to do it yet. (Sorry for not sleeping on the suggestions either!)