12.3. An Alternate Syntax for Globbing
Although we use the term globbing freely, and we talk about the glob operator, you might not see the word glob in very many of the programs that use globbing. Why not? Well, most legacy code was written before the glob operator was given a name. Instead, it was called up by the angle-bracket syntax, similar to reading from a filehandle:
my @all_files = <*>; ## exactly the same as my @all_files = glob "*";
The value between the angle brackets is interpolated similar to a double-quoted string, which means that Perl variables are expanded to their current Perl values before being globbed:
my $dir = "/etc"; my @dir_files = <$dir/* $dir/.*>;
Here, we've fetched all the non-dot and dot files from the designated directory, because $dir has been expanded to its current value.
So, if using angle brackets means both filehandle reading and globbing, how does Perl decide which of the two operators to use? Well, a filehandle has to be a Perl identifier. So if the item between the angle brackets is strictly a Perl identifier, it's a filehandle read; otherwise, it's a globbing operation. For example:
my @files = <FRED/*>; ## a glob my @lines = <FRED>; ## a filehandle read my $name = "FRED"; my @files = <$name/*>; ## a glob
The one exception is if the contents are a simple scalar variable (not an element of a hash or array), then it's an indirect filehandle read, where the variable contents give the name of the filehandle to be read:
my $name = "FRED"; my @lines = <$name>; ## an indirect filehandle read of FRED handle
Determining whether it's a glob or a filehandle read is made at compile time, and thus it is independent of the content of the variables.
If you want, you can get the operation of an indirect filehandle read using the readline operator, which also makes it clearer:
my $name = "FRED"; my @lines = readline FRED; ## read from FRED my @lines = readline $name; ## read from FRED
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