NAME

Finance::Currency::Convert::Esunbank - Query currency exchange rates from Esunbank

VERSION

v0.1.1

DESCRIPTION

This module crawl and parses currency exchange rates listed on this web page: https://www.esunbank.com.tw/bank/iframe/widget/rate/foreign-exchange-rate . All prices on this page are in TWD (Taiwan Dollar.) For this reason, it can only convert non-TWD currencies to TWD.

FUNCTIONS

The following functions are exportable, but not exported by default.

Some annotations with fictional Types are used in the following documentation just for the purpose of explaination. No Type-validation are implemented, nor are they defined. Not in this module.

"Num" referrer to a number, "Currency" is a short string such as 'TWD', 'USD'. The notation `Maybe[T]` means that the variable can contain a value either be of type T, or undef. See: Types::Standard or Moose::Util::TypeConstraints for more description of these notations.

convert_currency

Definition:

    ($error :Maybe[Str], $result :Maybe[Num]) =
        convert_currency(
            $amount :Num
            $from :Currency,
            $to :Currency
        )

When it is successful, $error is undef and $result contained the parsed output.

When error of some kind happens, $error contains the error message and $result is undef.

Example Usage:

    # Error-checking
    my ($err, $n) = convert_currency(100, 'USD', 'TWD');
    die "Error: $err": if $err;
    say "100 USD is about $n TWD";

    # Ignore error message. Checks the result directly.
    my $n = convert_currency(100, 'USD', 'TWD');
    if ( defined($n) ) {
        say "100 USD is about $n TWD";
    } else {
        say "Failed to convert 100 USD to TWD";
    }

get_currencies

With this function, the entire exchange rate table are parsed and returned in the special strucutre.

Definition:

    ($error :Maybe[Str], $result :Maybe[ArrayRef[Rate]]) =
        convert_currency(
            $amount :Num,
            $from :Currency,
            $to :Currency
        )

When it is successful, $error is undef and $result contained the parsed output.

When error of some kind happens, $error contains the error message and $result is undef.

Usage:

    # Error-checking
    my ($err, $o) = get_currencies();
    die "Error: $err": if $err;
    do_something($o);

    # Ignore error message. Checks the result directly.
    my $o = get_currencies();
    if ($o) {
        ...
    } else {
        ...
    }

The "Rate" type is a HashRef with 5 specific key-value pairs that looks like this:

    {
        currency         => "USD",
        zh_currency_name => "美金",
        en_currency_name => "USD",
        buy_at           => 33.06,
        sell_at          => 33.56
    }

This structure is just a directly translation of the rate exchange table shown on the source web page.

AUTHOR

Kang-min Liu <gugod@gugod.org>

LICENSE

This is free software, licensed under:

  The MIT (X11) License

cpanm Finance::Currency::Convert::Esunbank

perl -MCPAN -e shell
install Finance::Currency::Convert::Esunbank