Hacker News Reader

Comment by lekevicius | Hacker News Reader

Does any other language require to use a special notation, similar to PHP’s “$”, any time a variable is referenced? I can only think of CSS, using “--“.

View on HN

These all use sigils on variables in one way or another: Unix Shells, AWK, Perl, Ruby, Tcl, Basic, PowerShell, DOS batch scripts

-AWK

Ah, yeah, I suppose it's more of a "field operator" for things like $1, $2, etc.

This is called a “sigil”

PHP got that from Perl AFAIK. Bash does it too, and TCL.

I'm pretty sure that historically shell is the common influence of PHP, Perl, and Tcl.

PHP also inherits shell's here doc syntax, e.g. <<EOF . Not sure if Perl has that.

Actually PHP started out as a bunch of cgi-bin scripts, if I recall. It was very much "a shell for the web".

It kind of annoys me that they all require $ on the left, whereas shell only requires it on the right, which somehow makes more sense to me, e.g.

    a=$b  # shell

    $a = $b  # PHP and I think Perl

> It kind of annoys me that they all require $ on the left, whereas shell only requires it on the right

Interesting - it makes it look like Bash uses $ to “read” from the variable, while in PHP/Perl $ only indicates that the rest of the symbol _is_ a variable.

>>PHP also inherits shell's here doc syntax, e.g. <<EOF . Not sure if Perl has that.

It does.

>>It kind of annoys me that they all require $ on the left

Larry Wall says he went that direction to make namespace clashing between $dog, @dog, %dog, and "sub dog {}" (scalar, array, hashtable, function) a non-issue.

http://www.wall.org/~larry/natural.html ("Disambiguation")

Ruby also has $ for global variables, which I assume it also got via Perl. And @ for instance variables, and @@ for class variables.

It's much worse in perl, because it changes based on how you're using it. E.g. an array vs an element of an array.

Back in the eighties, my father taught me that the “$” character in BASIC meant “string,” so when I later picked up PHP in ‘98 I mentally thought of $someVar as “string-someVar” (regardless of the actual type, which was of course no problem for PHP), kept that habit for well over a decade… I think it was partially my self-disgust over such silly and technically incorrect thinking that led me to bail for Node as soon that was a feasible alternative.

The dollar sign does kinda look like a loose piece of shoestring, though

I can't remember all details but in Lisp in small pieces, author describes variable handling with a table { creation, reference/access, modification, [deletion] }

with each category had it's own optional syntax, many language will avoid this through context in which the symbol is, thus (+ a 1) equates (+ (deref a) 1), but he meant that it was a choice and not an obligation and some systems used $ or other syntactic constructs.

It's more than what most of us know, Rosetta Code is a good way to find. https://rosettacode.org/wiki/Variables

krapp has already mentioned the Unix stuff. BASIC had a thing with a $ at the end of a string variable, iirc. Windows' CMD.EXE used %VAR% notation (and later !VAR! notation).

jquery, lodash, etc all added prefixes (or TIL: sigil) of somesort

jQuery's $ and lodash's _ are not prepended to a symbol to denote a variable. Both are objects actually. In the case of jQuery, $ === jQuery (the root jQuery object). The case that the parent is talking about is PHP's requirement that all variables are denoted as such `$variable_name`. (Perl and Bash also do this)

i forget that's what's actually being done under the hood.

That’s just (part of) the variable name and not really the same.

> jquery, lodash, etc all added prefixes (or TIL: sigil) of somesort

This is false they are not sigils at all. _ and $ are legal variable names in Javascript.

Basic uses them at the end for string variables... A$...

jsoniq uses the same notation https://www.jsoniq.org/

Reply on news.ycombinator.com