Perl: LWP::UserAgent Regarding rules for passing parameters - perl

Question

e.g.
I have a command
curl -H "Content-Type: application/json" -H "Authorization: Bearer ACCESS_TOKEN" -X GET https://api.xxx/v1/datapackages/yyy
(1) I am confused when to use [ ] while passing the parameters. which one below is correct and why?
without [ ]
my $r2 = $ua -> get("https://api.xxx/v1/datapackages/yyy",
'Content-Type' => 'application/json',
Authorization => 'Bearer '.$token,
);
or with [ ]
my $r2 = $ua -> get("https://api.xxx/v1/datapackages/yyy",
[
'Content-Type' => 'application/json',
Authorization => 'Bearer '.$token,
]
);
(2) I see sometimes the parameter is quoted and sometimes not. Should "Authorization" be quoted and write as
with ' '
'Authorization' => 'Bearer '.$token,
or without ' '
Authorization => 'Bearer '.$token,
Thanks a lot!

Answer 1

The documentation for get() says this:
get
my $res = $ua->get( $url );
my $res = $ua->get( $url , $field_name => $value, ... );
This method will dispatch a GET request on the given URL. Further arguments can be given to initialize the headers of the request. These are given as separate name/value pairs. The return value is a response object. See HTTP::Response for a description of the interface it provides.
So, that just talks about passing arguments as key/value pairs. It says nothing about using an array reference. So, if I were you, I'd stick with the first approach.
The "fat comma" (=>) is documented in perldoc perlop (because it's an operator) which says:
The => operator (sometimes pronounced "fat comma") is a synonym for the comma except that it causes a word on its left to be interpreted as a string if it begins with a letter or underscore and is composed only of letters, digits and underscores. This includes operands that might otherwise be interpreted as operators, constants, single number v-strings or function calls. If in doubt about this behavior, the left operand can be quoted explicitly.
Otherwise, the => operator behaves exactly as the comma operator or list argument separator, according to context.
Basically, if the thing on its left is a single word (by which I mean a sequence of alphanumeric characters and underscores), then you can omit the quote marks around it.