Could you allow characters for `start.date` in `bdh()`?

[DavisVaughan]

bdh() has a nice ability to determine the start date from a character string that doesn't correspond to a date (ex. start_date <- "-11CY"). While easily reproducible with R, it could generally be useful to let us use this feature. The only change needed is to remove or alter the check in the top level bdh() function on the start.date argument.

library(Rblpapi)
#> Warning: package 'Rblpapi' was built under R version 3.4.4
#> Rblpapi version 0.3.8 using Blpapi headers 3.8.18.1 and run-time 3.8.18.1.
#> Please respect the Bloomberg licensing agreement and terms of service.
blpConnect()

security <- "CPI XYOY Index"
field    <- "PX_LAST"
start_date <- "-11CY"

cpi_xyoy_index <- bdh(security, field, start.date = start_date)
#> Error: start.date must be a Date object


con <- defaultConnection()

res <- Rblpapi:::bdh_Impl(
  con, security, field, 
  start_date_ = start_date, end_date_ = NULL, 
  options_ = NULL, overrides_ = NULL, verbose = FALSE, 
  identity_ = NULL, int_as_double =  FALSE
)

head(res[[1]])
#>         date PX_LAST
#> 1 2006-12-31     2.6
#> 2 2007-01-31     2.7
#> 3 2007-02-28     2.7
#> 4 2007-03-31     2.5
#> 5 2007-04-30     2.3
#> 6 2007-05-31     2.2

Created on 2018-06-26 by the reprex package (v0.2.0).

[johnlaing]

Interesting! I didn't know about this feature. Should be a very easy patch.

[DavisVaughan]

Thanks so much!

[johnlaing]

@DavisVaughan give this a try when you have a chance.

[DavisVaughan]

Sorry on the delay. Won't be able to test easily as I can't install from github at work. But the change looks correct to me and as shown above it definitely works if you bypass bdh and drop straight into bdh_Impl so I think we are good to go. Thanks!