Yes, what's really going on here is that, while the computer treats $a == $b as commutative, the human brain is linguistically wired, and tends to parse such constructs asymmetrically as a topic and a predicate. And as it happens, the topic likes to be first. For similar reasons most OO programmers will choose to write:

    foo.equals(0)
[download]

rather than:

    0.equals(foo)
[download]

Despite the fact that Ruby considers 0 to be a Real Object, I suspect that even Ruby programmers will prefer the first form to the second, because that's how our brains are wired.

The solution to all this in Perl 6 will be that assignment to an existing variable in boolean context will produce a warning under strictures, but assignment to a my declaration will not. The typical use for assignment in a boolean context is actually not the if statement but the while statement:

    while $item = shift(@foo) {...}
[download]

and in most cases this is probably better written as:

    while my $item = shift(@foo) {...}
[download]

or even better:

    for @foo -> $item {...}
[download]

Likewise,

    if $x = long_expression() {...}
[download]

can turn into

    given long_expression -> $x {...}
[download]

I suppose we might also allow the gcc-like workaround of putting extra parens when you want to hide the assignment from the boolean context.

---

---

• Are you posting in the right place? Check out Where do I post X? to know for sure.
• Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:

  <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>

• Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
• Want more info? How to link or How to display code and escape characters are good places to start.