fetchTimestampMethods: Functions to use as custom fetchTimestamp methods.

In USGS-VIZLAB/vizlab: Utilities for building online data visualizations

Description

These functions serve common use cases for timestamp fetching. See also fetchTimestampHelpers, which allows you to write still more customized methods, and pre-defined fetchTimestamp() methods for several fetchers supported by vizlab.

'neverCurrent' - always writes a timestamp file for the current date and time. This means that whenever the timestamp is checked during the make process, the data file will be interpreted as out of date.

Usage

alwaysCurrent(viz)

neverCurrent(viz)

Arguments

viz	the identifier for a fetch item in viz.yaml

Details

alwaysCurrent - writes a timestamp file just once, the first time the data file is present when fetchTimestamp is called. Edits the modified time, mtime, of the timestamp file to equal the modified time of the data file, so that on subsequent builds the data file is always up to date relative to the timestamp file. REFETCHES MAY STILL OCCUR if there are changes to the fetch item's viz.yaml chunk, scripts, or other dependencies.

Examples

fetchTimestamp.myfetcher <- alwaysCurrent
fetchTimestamp.myotherfetcher <- neverCurrent

USGS-VIZLAB/vizlab documentation built on July 4, 2018, 5:16 p.m.