[Rcpp-devel] useDynLib

[Sean Robert McGuffee]

This link has a lot of information in it, but I don't understand much of it
because it seems to be written for people who already understand it.

http://cran.r-project.org/doc/manuals/R-exts.html

Under section 1.6: For example, I'm having trouble figuring out the meaning
of the following terms and or phrases:

name spaces, management system, package writer, top level package directory,
name space directives, imports, exports, register, shared objects, loaded,
S3-style methods, R code, R-style comments, processed as R code, search
path, calling library, exported variables, attached frame, implicit loads,
internal variable bindings, name space mechanism, code analysis,
compilation tools, definition corresponding to a global variable reference,
search strategy, the search, normal search path, are to be exported, all
variables that do not start with a period, base name space, export
variables, fully qualified variable reference, locate methods, generics,
S3method directives, base, R variables identifying these symbols, unexported
objects, dispatching, hooks, Load hooks, package code, running the load hook
function, R variables identifying these symbols, defined in the name space,
loading and attaching, operations, when a name space is used, hooks are
provided, 

and that's just to get me to the part where I become interested:

"There can be one or more useDynLib directives which allows shared objects
that need to be loaded to be specified in the NAMESPACE file.  The directive
     useDynLib(foo)"

This also is followed by other inconsistent examples:

"useDynLib(foo, myRoutine, myOtherRoutine)"

"myDLL = useDynLib(foo, myRoutine_sym = myRoutine, myOtherRoutine)"

Does anyone have any links to something more like an API of what appears to
be some type of function called useDynLib?
In particular, I'm looking to find out what arguments the method useDynLib
takes with descriptions of their types?

for example, an API type reference to C's strcpy:

man 3 strcpy

"
STRCPY(3)                BSD Library Functions Manual
STRCPY(3)

NAME
     stpcpy, strcpy, strncpy -- copy strings

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <string.h>

     char *
     stpcpy(char *s1, const char *s2);

     char *
     strcpy(char *restrict s1, const char *restrict s2);

     char *
     strncpy(char *restrict s1, const char *restrict s2, size_t n);

DESCRIPTION
     The stpcpy() and strcpy() functions copy the string s2 to s1 (including
the terminating `\0' character).

     The strncpy() function copies at most n characters from s2 into s1.  If
s2 is less than n characters long, the remainder of s1 is filled
     with `\0' characters.  Otherwise, s1 is not terminated.

     The source and destination strings should not overlap, as the behavior
is undefined.

RETURN VALUES
     The strcpy() and strncpy() functions return s1.  The stpcpy() function
returns a pointer to the terminating `\0' character of s1.

EXAMPLES
     The following sets chararray to ``abc\0\0\0'':

           char chararray[6];

           (void)strncpy(chararray, "abc", sizeof(chararray));

     The following sets chararray to ``abcdef'':

           char chararray[6];

           (void)strncpy(chararray, "abcdefgh", sizeof(chararray));

     Note that it does not NUL terminate chararray, because the length of
the source string is greater than or equal to the length argument.

     The following copies as many characters from input to buf as will fit
and NUL terminates the result.  Because strncpy() does not guaran-
     tee to NUL terminate the string itself, this must be done explicitly.

           char buf[1024];

           (void)strncpy(buf, input, sizeof(buf) - 1);
           buf[sizeof(buf) - 1] = '\0';

     This could be better achieved using strlcpy(3), as shown in the
following example:

           (void)strlcpy(buf, input, sizeof(buf));

     Note that, because strlcpy(3) is not defined in any standards, it
should only be used when portability is not a concern.

SECURITY CONSIDERATIONS
     The strcpy() function is easily misused in a manner which enables
malicious users to arbitrarily change a running program's functionality
     through a buffer overflow attack.  (See the FSA and EXAMPLES.)

SEE ALSO
     bcopy(3), memccpy(3), memcpy(3), memmove(3), strlcpy(3)

STANDARDS
     The strcpy() and strncpy() functions conform to ISO/IEC 9899:1990
(``ISO C90'').  The stpcpy() function is an MS-DOS and GNUism.  The
     stpcpy() function conforms to no standard.

HISTORY
     The stpcpy() function first appeared in FreeBSD 4.4, coming from
1998-vintage Linux.

BSD                             August 9, 2001
BSD
" 

 
 


On 3/31/11 5:52 PM, "Dirk Eddelbuettel" <edd at debian.org> wrote:

> 
> On 31 March 2011 at 17:29, Sean Robert McGuffee wrote:
> | Dear Rcpp List,
> | 
> | I?ve been looking at some R packages that use libraries and I have figured
> out
> | that there is a keyword in the NAMESPACE file that I would like to
> understand.
> | I?m at a complete loss for what the NAMESPACE file is or how to get help for
> | what goes in it. Has anyone found a resource for this type of info?
> 
> Sure, the 'Writing R Extensions' manual that comes with R, particularly
> Section 1.6 entitle 'Package name spaces'
> 
> Dirk
> 
> | 
> | I tried the obvious help in R, but as usual, that is of no help:
> | 
> | help(useDynLib)
> | No documentation for 'useDynLib' in specified packages and libraries:
> | you could try '??useDynLib'
> | > ??useDynLib
> | No help files found matching ?useDynLib? using fuzzy matching
> | 
> | Thanks,
> | Sean
> | 
> | ----------------------------------------------------------------------
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