The instance/type of a variable

jeanluca has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: The instance/type of a variable by dragonchild (Archbishop) on Oct 19, 2005 at 13:22 UTC
ref() is a good start. Scalar::Util provides a number of other options, such as looks_like_number() (which tells you if something is probably a number), blessed() (which returns the class it's blessed into, if any). As for int vs. float, that's easy - `int($a) == $a` means it's an int. The important point here is that when you program in Perl, you shouldn't have to worry about int vs. float. Personally, I tend to not worry about anything except reference, object, and non-reference. My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply] [d/l]
Re^2: The instance/type of a variable by jeanluca (Deacon) on Oct 19, 2005 at 13:51 UTC
All this helps a lot!!!! Thanks Luca	[reply]
Re: The instance/type of a variable by Zaxo (Archbishop) on Oct 19, 2005 at 13:03 UTC
ref returns the builtin type or class name of a variable containing a reference. After Compline, Zaxo	[reply]
Re: The instance/type of a variable by philcrow (Priest) on Oct 19, 2005 at 13:05 UTC
You can use ref for some of that: `if ( ref( $your_var ) =~ /HASH/ ) { ... }` [download] or in more draconian fashion `if ( ref( $your_var ) eq 'HASH' ) {...}` [download] It won't tell you whether a scalar is a string or a number. Phil	[reply] [d/l] [select]
Re: The instance/type of a variable by BerntB (Deacon) on Oct 19, 2005 at 13:03 UTC
Check `ref()`, it does what you want -- except differ between SCALAR types. To differ between scalars, I do kludgy stuff (like add 0 and see if the result is not-zero and =~ /^\s0\s$/.) (-: Someone else will certainly answer better. :-)	[reply] [d/l]
Re: The instance/type of a variable by jeanluca (Deacon) on Feb 11, 2006 at 16:14 UTC
The date is year-julian. One last question: If I would like to allow the following formats: `2005-111 2005111 2005` [download] Somehow this doesn't work: `$a = $some_date ; if ( $a =~ /\d{4}-?\d{3}?/ ) { .... }` [download] Any suggestions why this doesn't work ? Thanks a lot Luca	[reply] [d/l] [select]