Match.call prevents the use of variables

[reedacartwright]

Using match.call in functions doesn't evaluate variables so doing something like this fails:

target_taxon="primates"
homology_id("ENSGblah",target_taxon=target_taxon)

However, using ... to pass optional parameters to sub functions works:

ensembl_homology_id = function (id, return_format, ...) {
    end <- paste("homology/id", id, sep = "/")
    header = rensembl:::ensembl_header(return_format, c("json", "orthoxml", "xml"))
    q <- rensembl:::ensembl_body(list(NA,...), c("id","return_format"))
    req <- rensembl:::ensembl_GET(end, header, query = q)
    httr::content(req)
}

With this implemented, ensembl_body can be improved so you don't need an NA in the list.