Proposed fix for issue #180, download_hydat failing to update local database.

[gdelaplante]

180

Primary change

hydat now gets extracted to a temp directory instead of in the directory specified by dl_hydat_here. The newly extracted database is then copied over to the dl_hydat_here location and overwrites the existing database. This circumvents the issue where file.rename() was correctly noting that the directory had two files but only one name to be assigned, and is not dependent on hydat being named in a certain manner.

Secondary changes

Rejigged the messages and the order in which messages are displayed.

• If local hydat version is up to date, user is advised and asked to overwrite. If user selects no they are advised of quarterly updates to hydat.
• Information is given about hydat file size when requesting user input.
• The intended behavior of parameter ask is maintained so that the local copy of hydat is automatically overwritten even if current if ask = FALSE

In addition, the function hy_check() created at the bottom of download.R was moved up prior to the function call to hy_check(). This may not be a necessary change, but I couldn't figure out how it could work to call a function that had yet to be created!

[gdelaplante]

This is looking really good! Thank you for this. With respect to hy_check in an R package it doesn't usually matter where a function is defined as that all end up available once the package is loaded (either internally or as exported functions).

One thing I'd really like to do here is at least add some tests for the non-downloading behaviour. Like test for the messages. Is that something you'd be able to take on?

Again thanks so much for this. I like this logical flow much better.

I did notice that there is no test file for this function. I can pull something together for sure, however, I'm not too sure how to test all messages since some depend on there being an older version to overwrite, but should work for most. I'll also try to write a test to make sure the DB actually got updated and named properly, with no detritus in the directory. It'll take me some time to get to it though!