Write and Load functions from an external file

Hi All,

Would be grateful,if anyone can answer my queries.


I need to  share code. For example, if I am  working in C/C++, I would put
some function declarations in .h files that you would include. In PHP, I
would create files with the common functions in them and then "include()"
them. So far, I haven't been able to figure out what the standard practice
is in R.



The two options are:



1. Write everything in one file. No sharing of functions.

2. Write libraries - but you *have to package it* first to use it.

Neither is a good option. how you I share functions across two scripts?



there is "source()"

But are there any other way?

For example, in python, what I do is create common functions in a separate

file (say, called A), use those functions from file B by including it like I


would any other library. Then when I'm ready to 'release' it, I can package

the library and the script...



I did find something:-----

http://www.ma.hw.ac.uk/~stan/R/Rnotes.pdf<http://www.ma.hw.ac.uk/%7Estan/R/Rnotes.pdf>says
:--



To create and edit functions, use the (built-in) R function edit. (As usual,
type ?edit at

the command prompt for details|see Section 10.)

Alternatively the function source|also available via the File menu|can be
used to input

lengthy function denitions from an externally edited le. (The function dump
will write an

existing function denition to a file.)

But then source() also ,not only loads but parses the file too.


https://stat.ethz.ch/pipermail/r-help/2007-October/142938.html

You  can save one or more functions and datasets to a file (see ?save) then
on starting another session attach that file (see ?attach).

The process is like:---



foo <- function(x) mean(as.numeric(x), trim = 0.3)

save(foo, file = "myproject/rfunctions/saved.rda")



then, when starting a new session, use



attach("myproject/rfunctions/saved.rda")



The .rda extension on the filename is commonly used for saved R data

sets but you can also have function definitions in a saved file.

Are these the only ways,and the best ways,to do what I want?


*--
Thanks
Moumita*