parse/INSTALL feature request(s)

Hi,
I have a feature request for 'parse', and possibly the 'R CMD INSTALL' 
command to display more informative error information. Specifically, 
after making several modifications to a package on my system (the 
package name is irrelevant; I'm using R 2.3.1 on Debian):
$ R CMD INSTALL seas
* Installing *source* package 'seas' ...
** R
** data
** inst
** preparing package for lazy loading
Error in parse(file, n, text, prompt) : syntax error at
1222:       ylim <-
1223:     else
Execution halted
ERROR: lazy loading failed for package 'seas'
** Removing '/usr/local/lib/R/site-library/seas'

Of the 24 or so *.R source files in the edited package, I'm not sure 
where I had made the syntax error, but it would be very nice to see an 
error message that says something more helpful, such as "Error in 
parse(file, n, text, prompt) : syntax error in function 'foo' at ...". 

Is it possible for 'parse' to display the parent function name in which 
the error occurred? As for 'R CMD INSTALL' goes, I realize that all the 
*.R files are cat'ed together, then parsed as one file, so it is 
difficult report a file name and line number(s). Is this concatenating 
necessary? Or couldn't the individual files be parsed (and errors/line 
#'s reported for offending files), then combined in an environment for 
the INSTALL'ed package?

In the mean time, my solution to find the offending file is:
for(i in dir(pattern=".R$")){
    print(i)
    parse(i)
}

On 10/20/2006 8:32 PM, Michael Toews wrote:

Hi,
I have a feature request for 'parse', and possibly the 'R CMD INSTALL'
command to display more informative error information. Specifically,
after making several modifications to a package on my system (the
package name is irrelevant; I'm using R 2.3.1 on Debian):
$ R CMD INSTALL seas
* Installing *source* package 'seas' ...
** R
** data
** inst
** preparing package for lazy loading
Error in parse(file, n, text, prompt) : syntax error at
1222:       ylim <-
1223:     else
Execution halted
ERROR: lazy loading failed for package 'seas'
** Removing '/usr/local/lib/R/site-library/seas'

Of the 24 or so *.R source files in the edited package, I'm not sure
where I had made the syntax error, but it would be very nice to see an
error message that says something more helpful, such as "Error in
parse(file, n, text, prompt) : syntax error in function 'foo' at ...".

Yes, that would be nice, but I don't think it's possible:  if the parse
fails, R won't know enough to know that it was in the middle of parsing
function 'foo'.

What would be possible is to do like other preprocessors do, and put
comments into the source file to indicate the origin of each line:  then
the parser could tell you the location in the original file, which would
be a lot more useful.  This would slow things down a bit and make the
package bigger so we'd probably want it to be optional, but it would
help a lot in situations like yours.

Is it possible for 'parse' to display the parent function name in which
the error occurred? As for 'R CMD INSTALL' goes, I realize that all the
*.R files are cat'ed together, then parsed as one file, so it is
difficult report a file name and line number(s). Is this concatenating
necessary? Or couldn't the individual files be parsed (and errors/line
#'s reported for offending files), then combined in an environment for
the INSTALL'ed package?

I don't know the reason for putting them in one file.

In the mean time, my solution to find the offending file is:
for(i in dir(pattern=".R$")){
    print(i)
    parse(i)
}

That looks like a good idea; if it doesn't catch the error, then it's
probably something wrong with the last line in one of the files, e.g.
not having a newline at the end of it.

What would be possible is to do like other preprocessors do, and put
comments into the source file to indicate the origin of each line:  then
the parser could tell you the location in the original file, which would
be a lot more useful.

What would be possible is to do like other preprocessors do, and put
comments into the source file to indicate the origin of each line:  then
the parser could tell you the location in the original file, which would
be a lot more useful.

I think what you are referring to is already nicely implemented 

(in 
R/src/main/source.c lines 89 to 97), and the errors are correctly shown 
in my example as lines 1222 to 1223. However, these line numbers are 
irrelevant to the original files, as they been concatenated into one 
large file (I think on line 765 of R/src/scripts/INSTALL.in ).

single file is loaded into an R environment (on line 790 of INSTALL.in), 
which is also the region where my original error from 'R CMD INSTALL' 
was thrown. The loading is done by the 'tools:::makeLazyLoading' 
function, which loads in the single R-source file into a fresh 
environment for the package.

I'm unsure of why a single R source file is needed in INSTALL (which 
limits the ability to show any offending file names and their line 
numbers). The functions in R/src/library/tools/R/makeLazyLoad.R could 
perhaps be made a bit more versatile to individually read the R source 
files for a package using a 'pattern="\.R$"', and throw an error from 
'sys.source' displaying the file name, and other error messages from 
'parse'. This is simply a feature-request suggestion, but as Gabor 
advised, I should really develop my functions file-by-file.