R Vircurex API wrapper

client.R

library(rjson)
library(RCurl)

#Magic: this function chooses the endpoint type based on the name
# of the caller.
# Arguments are a list of values which are matched
# with their named defaults.
request <- function(added_args, named_args){
    
    #Matching nameless arguments to named arguments in declaration:
    if(length(added_args) > 0) for(i in 1:length(added_args)){
        named_args[[i]] <- added_args[[i]]
    }
    
    
    caller_details <- sys.calls()[[sys.nframe()-1]]
    request_type <- caller_details[[1]] #gets name of caller

    parameters <- ""

    # Any parameters to this call? If so, join them as k=v&k2=v2...
    if(length(named_args) > 0){
        
        argnames <- names(named_args)
        argnames <- argnames[nchar(argnames) > 0]
        
        kvpairs <- sapply(argnames, function(name) paste0(name, "=", named_args[name]))
        kvlist <- paste(kvpairs, collapse="&")
        
        parameters <- paste0("?", kvlist)
        
    }
    
    url <- paste0("https://api.vircurex.com/api/", request_type, ".json", parameters)
    fromJSON(json_str=getURL(url))
    
}

query_trade <- function(base = "BTC", alt="USD")
    request(as.list(match.call())[-1], formals())

#This works because request looks at the caller's name to pick an endpoint:
get_last_trade <- query_trade
get_lowest_ask <- query_trade
get_highest_bid <- query_trade
get_highest_bid <- query_trade
get_volume <- query_trade
get_info_for_1_currency <- query_trade
orderbook <- query_trade
trades <- query_trade