How to tell perl to print to a file handle instead of printing the file handle?

Question

I'm trying to wrap my head around the way Perl handles the parsing of arguments to print.

Why does this

print $fh $stufftowrite

write to the file handle as expected, but

print($fh, $stufftowrite)

writes the file handle to STDOUT instead?

My guess is that it has something to do with the warning in the documentation of print:

Be careful not to follow the print keyword with a left parenthesis unless you want the corresponding right parenthesis to terminate the arguments to the print; put parentheses around all arguments (or interpose a + , but that doesn't look as good).

Should I just get used to the first form (which just doesn't seem right to me, coming from languages that all use parentheses around function arguments), or is there a way to tell Perl to do what I want?

So far I've tried a lot of combination of parentheses around the first, second and both parameters, without success.

Answer 1

On lists

The structure bareword (LIST1), LIST2 means "apply the function bareword to the arguments LIST1", while bareword +(LIST1), LIST2 can, but doesn't neccessarily mean "apply bareword to the arguments of the combined list LIST1, LIST2". This is important for grouping arguments:

my ($a, $b, $c) = (0..2);
print ($a or $b), $c;  # print $b
print +($a or $b), $c; # print $b, $c

The prefix + can also be used to distinguish hashrefs from blocks, and functions from barewords, e.g. when subscripting an hash: $hash{shift} returns the shift element, while $hash{+shift} calls the function shift and returns the hash element of the value of shift.

Indirect syntax

In object oriented Perl, you normally call methods on an object with the arrow syntax:

$object->method(LIST);   # call `method` on `$object` with args `LIST`.

However, it is possible, but not recommended, to use an indirect notation that puts the verb first:

method $object (LIST);   # the same, but stupid.

Because classes are just instances of themselves (in a syntactic sense), you can also call methods on them. This is why

new Class (ARGS);  # bad style, but pretty

is the same as

Class->new(ARGS);  # good style, but ugly

However, this can sometimes confuse the parser, so indirect style is not recommended.

But it does hint on what print does:

print $fh ARGS

is the same as

$fh->print(ARGS)

Indeed, the filehandle $fh is treated as an object of the class IO::Handle.

(While this is a valid syntactic explanation, it is not quite true. The source of IO::Handle itself uses the line print $this @_;. The print function is just defined this way.)